JPH06120743A - Light receiving pre-amplifier and light receiver - Google Patents

Abstract

PURPOSE:To obtain a pre-amplifier in which a dynamic range can be enlarged by a large output amplitude, and a light receiver in which a circuit constitution is simple, eye opening is sufficient, and a parallel transmission can be appropriately attained, in a light receiving pre-amplifier and a light receiver. CONSTITUTION:This device is equipped with an input FET 10 whose gate terminal 10a to which a current signal from a light receiving element is inputted, and an output FET 12 whose gate terminal 12a is connected with the signal terminal 10b of the input FET 10, which amplifies the current signal into a prescribed voltage signal, and outputs it. And also, a feedback resistance 14 is interposed between the gate terminal 10a of the input FET 10 and the output terminal 19 of the output FET 12, and a constant current source 15 which increases the change of the amplitude value of the output potential of the output FET 12 corresponding to the change of an optical signal is interposed between the gate terminal 10a of the input FET 10 and a power source 17.

Description

Detailed Description of the Invention

(Table of Contents) Industrial Application Field of the Prior Art (FIGS. 29 to 33) Problems to be Solved by the Invention Means for Solving the Problems (FIGS. 1 to 4) Operation (FIGS. 1 to 6) Example • Description of first example (FIGS. 7 to 13) • Description of second example (FIG. 14) • Description of third example (FIG. 15) • Description of fourth example (FIG. 16, FIG. 16) 17) -Explanation of the fifth embodiment (Fig. 18) -Explanation of the sixth embodiment (Fig. 19) -Explanation of the seventh embodiment (Fig. 20) -Explanation of the eighth embodiment (Figs. 21, 22)- Description of ninth embodiment (FIG. 23) • Description of tenth embodiment (FIG. 24) • Description of eleventh embodiment (FIG. 25) • Description of twelfth embodiment (FIG. 26) • Description of thirteenth embodiment (FIG. 27) Description of 14th Example (FIG. 28) Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preamplifier for optical reception and an optical receiving device. In recent years, with the increase in speed of communication devices and computers, inter-device communication by optical signals is required. For this reason, there is a demand for an optical receiving device that is small in size, low in cost, and requires no adjustment. In particular, cost reduction and low power consumption are desired in optical communication devices having a bit rate of 1 Gbps or less.

[0003]

2. Description of the Related Art FIG. 29 is a block diagram showing a configuration of a conventional optical receiving apparatus. In FIG. 29, 1A is a transimpedance type preamplifier for optical reception, which will be described later with reference to FIG. The preamplifier 1A amplifies a current signal obtained by photoelectrically converting an optical signal by a light receiving element (photoelectric conversion element such as a photodiode) 2 into a predetermined voltage signal and outputs the voltage signal.

Reference numeral 3C is a reference detection circuit which will be described later with reference to FIGS. 31 and 32. The reference detection circuit 3C detects the center potential of the upper and lower levels (amplitude) of the output signal of the preamplifier 1A. And generates the potential as a reference reference potential (reference potential) for the amplification operation in the limiter amplifier 4,
Is output to. And the limiter amplifier 4 is
The output signal of the preamplifier (1) is amplified based on the reference reference potential from the reference detection circuit 3C.

Here, the conventional transimpedance type preamplifier 1A is, for example, as shown in FIG.
One field effect transistor (hereinafter referred to as FET) 1
0, 11A, 12, 13A and feedback resistance (resistance value Rf)
14 and two diodes 20 and 21. The FET 11A functions as a load resistance, and F
The ET 13A functions as a constant current source (load resistance).

In the conventional preamplifier 1A, the current signal obtained by photoelectrically converting the optical signal by the light receiving element 2 is input to the gate terminal 10a of the input FET 10 via the input terminal 18. It has become. Also,
Drain terminal (one signal terminal) of the input FET 10
0b is connected to the first power supply (positive power supply Vdd or GND (Ground, 0V)) 16 via the load resistance FET 11A, and its source terminal (the other signal terminal) 1
0c is connected to the second power supply (GND or negative power supply Vss) 17 via the diode 20.

The gate terminal 12a of the output FET 12 is
The drain terminal 10b of the input FET 10 is connected, the drain terminal 12b thereof is connected to the first power supply 16, and the source terminal 12c thereof is connected to the second power supply 17 via the diode 21 and the load resistance FET 13A.
Connected to the source terminal 12 of the output FET 12
The amplification result amplified to a predetermined voltage signal is output from the output terminal 19 connected to c.

Further, the gate terminal 1 of the input FET 10
0a and the output terminal 19 of the output FET 12 (diode 2
1) and the gate terminal 10a of the input FET 10
A feedback resistor 14 that feeds back and supplies the output signal of the output FET 12 is provided in the. FET1 for load resistance
The gate terminal 11a and the source terminal 11c of 1A are the drain terminal 10a of the input FET 10 and the output FE.
The drain terminal 11b is connected to the gate terminal 12a of the T12 and the first power supply 16. The gate 13a and the source terminal 13c of the load resistance FET 13A are connected to the second power supply 17, and the drain terminal 13b thereof is connected to the feedback resistance 14 and the diode 21.

In such a transimpedance preamplifier 1A, an optical fiber (not shown) is provided from the transmission side.
The current signal Iin obtained by photoelectrically converting the optical signal representing the digital signal received via the light receiving element 2 through the input terminal 18 is the gate terminal 10a of the input FET 10.
Is supplied to. The potential of the drain terminal 10b of the input FET 10 is the gate terminal 13a of the output FET 12.
Source terminal 12c of the output FET 12
Is output from the output terminal 19 as an amplification result.

On the other hand, the reference detection circuit 3C, for example, as shown in FIG. 31, the high level peak potential detection circuit 3a for detecting the high level peak potential of the output signal of the preamplifier 1A and the output of the preamplifier 1A. A low level peak potential detection circuit 3b for detecting a low level peak potential of a signal and peak potentials respectively detected by these detection circuits 3a and 3b are averaged and the averaged result is used as a predetermined reference reference potential (reference potential). It is composed of an average value detection circuit 3c for outputting to the limiter amplifier 4.

The high-level peak potential detection circuit 3a
32A is composed of a diode D1 and a capacitor C1 as shown in FIG. 32A, and the low level peak potential detection circuit 3b is composed of a diode D2 and a capacitor C2 as shown in FIG. The value detection circuit 3c is composed of two resistors R1 and R2 having the same resistance value, as shown in FIG.

[0012]

By the way, the output voltage with respect to the input current of the conventional preamplifier 1A configured as shown in FIG. 30 has the characteristics shown in FIG.
For example, when 5V is used as the power supply voltage, the output amplitude of the preamplifier 1A is saturated when it exceeds about 0.6V. Therefore, if excessive light is input to the light receiving element 2, the duty of the output waveform of the preamplifier 1A changes, and the eye pattern (or eye diagram) may be crushed and identification may not be performed.

The eye pattern is a waveform pattern in which a received and demodulated baseband signal sequence is superimposed on a cathode ray tube by time sweep synchronized with bits, and the degree of intersymbol interference due to transmission line distortion is determined by an aperture ratio (eye opening). : Evaluation is made by the portion which does not overlap when all pulse waveforms that can occur over two sections of the signal interval are displayed in an overlapping manner. Therefore, the dynamic range of the receiving circuit is limited.

Therefore, in the circuit shown in FIG. 30, it is conceivable to provide a diode in parallel with the feedback resistor 14. In such a configuration, the diode is turned on when the input current Iin exceeds a certain current. As a result, by forming a bypass path for the photocurrent, the input current Iin can be limited to a certain amplitude or less. However, in such a configuration, the duty of the output waveform of the preamplifier 1A changes in principle, the eye pattern is crushed, and a sufficient eye opening cannot be obtained. When it is necessary to identify each channel by a common clock when transmitting optical signals of multiple channels in parallel, if the eye pattern in the received signal of each optical signal does not have a sufficient eye opening, The channel cannot be identified, and the circuit having the above configuration cannot be applied to the system.

As described above, in the conventional optical pre-amplifier for optical reception shown in FIG. 30, since a sufficiently large output amplitude cannot be obtained, waveform distortion occurs when excessive light is input to the light receiving element 2, and a wide area is generated. There is a problem that a dynamic range and a sufficient eye opening cannot be obtained. On the other hand, FIG.
In the conventional optical receiver shown in FIG. 9, since the preamplifier 1A has a wide dynamic range, the input voltage to the reference detection circuit 3C has a wide range of amplitude. The peak potential detection circuits 3a and 3b in the reference detection circuit 3C are shown in FIG.
As described above in (a) and (b), it is often composed of a diode and a capacitor.

However, both peak potential detecting circuits 3a,
In the configuration in which the output of 3b is input to the average value detection circuit 3c,
It is very difficult to accurately obtain the center potential (reference reference potential, that is, reference potential) for all levels. In particular, when the input level is low, a large error is likely to occur. Due to such an error in the reference potential, when a plurality of received signals (channels) are identified by a common clock in a receiver for optical parallel transmission that communicates signals of a plurality of channels in parallel between the devices, the conventional As for the optical receiving preamplifier, as described above, it is difficult to always obtain a sufficient eye opening, and it is impossible to reliably identify a plurality of received signals. In addition, the reference detection circuit 3C
Since the capacitors C1 and C2 having a larger capacity have a smaller error, it is necessary to provide a considerably large capacitor in the IC when configuring the optical parallel receiver circuit with the same IC, which causes a cost increase. .

As described above, in the conventional optical receiver shown in FIG. 29, the reference detection circuit 3C cannot detect an accurate reference with respect to the dynamic range of the output of the preamplifier 1A, and is always sufficient. Since it is not possible to obtain a large eye opening, it is difficult to apply it when identifying each channel with a common clock when receiving in parallel.

Further, when feedback is applied in the circuit using a variable gain circuit or the like, there is a problem that oscillation may always occur. Furthermore, in a device including a plurality of conventional optical receivers arranged in parallel, a reference detection circuit 3C having a large-capacity capacitor is required for each channel, and therefore the circuit scale including the IC becomes large and the cost becomes high. was there.

The present invention was devised in view of the above-mentioned problems, and an optical system capable of obtaining a large output amplitude with a simple circuit configuration and ensuring a wide dynamic range and a sufficient eye opening is provided. In addition to providing the reception preamplifier, there is no possibility of oscillation even if feedback control is applied, the reference voltage can be kept constant, and a sufficient eye opening can always be obtained. An object of the present invention is to provide an optical receiving device that realizes reduction in size and low power consumption.

[0020]

FIG. 1 is a block diagram showing the principle of an optical receiving preamplifier according to the first invention. In FIG.
Is an optical receiving preamplifier of the present invention, and 10 is an input field effect transistor (hereinafter referred to as FET).
The ET 10 receives a current signal Iin obtained by photoelectrically converting an optical signal by a light receiving element through an input terminal 18 and a gate terminal 10
a signal terminal (drain terminal) 10b
Is connected to the first power supply (positive power supply Vdd or GND) 16 via the resistance element 11, and the other signal terminal (source terminal) 10c is connected to the second power supply (GND or negative power supply Vss) 17. ing.

Reference numeral 12 is an output FET.
12, the gate terminal 12a is connected to one signal terminal 10b of the input FET 10, one signal terminal (drain terminal) 12b is connected to the first power supply 16, and
The other signal terminal (source terminal) 12c is connected to the second power source 17 via a resistance element (which functions as a constant current source) 13.
Output terminal 1 connected to the signal terminal 12c for amplifying the current signal Iin from the light receiving element to a predetermined voltage signal.
It is output from 9.

Reference numeral 14 is a feedback resistor (resistance value Rf), which is provided between the gate terminal 10a of the input FET 10 and the output terminal 19 of the output FET 12 and is connected to the gate terminal 10a of the input FET 10. Output FET12
It is for feeding back and supplying the output signal of. 15 is a constant current source provided by the present invention.
Is provided between the gate terminal 10a of the input FET 10 and the second power supply 17, and is an output F for a change in the optical signal.
The change in the amplitude value of the output potential of the ET 12 can be magnified (claim 1).

The constant current source 15 is composed of a constant current supply FET 150 and a monitor FET 151. In the constant current supply FET 150, one signal terminal (drain terminal) 150b is connected to the gate terminal 10a of the input FET 10, and the other signal terminal (source terminal) 150c is connected to the second terminal via the resistance element 152.
Is connected to the power supply 17.

The monitor FET 151 has the same characteristics as the constant current supply FET 150, and one signal terminal (drain terminal) 151b is connected to the first power supply 16 via the resistance element 153. Connected to the gate terminal 150a of the constant current supply FET 150, the other signal terminal (source terminal) 151c and gate terminal 1
51a is connected to the second power supply 17 (claim 2).

The gate terminal 151a of the monitor FET 151 is connected to the first power supply 16 and the second power supply 17 via two resistance elements, and the other signal terminal 151c of the monitor FET 151 is connected to the resistance. It may be connected to the second power supply 17 via an element (claim 3). In addition, the gate terminal 151a of the monitor field effect transistor 151 is connected to the first power source 1 via a variable resistor.
6 and the second power supply 17, and the other signal terminal 151c of the monitoring FET 151 may be connected to the second power supply 17 via a resistance element (claim 4).

FIG. 2 is a block diagram showing the principle of the optical receiving apparatus of the second invention. In FIG. 2, 1 is a preamplifier which amplifies a current signal Iin from a light receiving element 2 described later into a predetermined voltage signal and outputs it. In this preamplifier 1, the constant current source 15 is connected to the gate terminal 1 of the input FET 10 as in the case shown in FIG.
0a and the second power supply 17 are provided.

Reference numeral 2 is a light receiving element for converting the received optical signal into a current signal and supplying it to the input terminal 18 of the preamplifier 3. Reference numeral 3 is a reference reference potential generating circuit. Reference numeral 4 is a limiter amplifier. Is for generating the center potential of the amplitude of the output signal of the preamplifier 1 as a predetermined reference reference potential and outputting it to the limiter amplifier 4.
The output signal of the preamplifier 1 is amplified based on a predetermined reference reference potential from the reference reference potential generation circuit 3.

As described above, the preamplifier 1 in the second invention also includes the input FET 10, the resistance element 11, the output FET 12, the resistance element 13, and the feedback resistance 14 as in the case shown in FIG. , A constant current source 15 that is interposed between the gate terminal 10a of the input FET 10 and the second power supply 17 and that can expand the change of the amplitude value of the output potential of the output FET 12 with respect to the change of the optical signal. (Claim 5).

The reference reference potential generation circuit 3 detects the high level peak potential detection circuit for detecting the high level peak potential of the output signal of the preamplifier 1 and the low level peak potential of the output signal of the preamplifier 1. And a mean value detection circuit for averaging the peak potentials respectively detected by these peak potential detection circuits and outputting the averaged result as a predetermined reference reference potential to the limiter amplifier 4. (Claim 6).

At this time, the high-level peak potential detection circuit is configured by the same circuit as the preamplifier 1, and the input signal to the gate terminal 10a of the input FET 10 in this high-level peak potential detection circuit is set to the non-input state. In this case, the output signal of the output FET 12 may be output to the average value detection circuit as a high level peak potential (claim 7).

Further, when receiving the optical signal whose power is adjusted by the automatic power adjustment circuit on the optical transmission side, the fixed reference potential is generated as the predetermined reference reference potential by the limiter amplifier as the above-mentioned reference reference potential generation circuit. Alternatively, the fixed reference potential generating circuit 3A for outputting to 4 may be used (claim 8). Further, as the constant current source 15 in the preamplifier 1, as described above with reference to FIG. 1, one signal terminal is connected to the gate terminal 10a of the input FET 10 and the other signal terminal is connected to the gate terminal 10a via the resistance element. FET for constant current supply connected to the second power supply 17 and the constant current supply F
It is composed of a monitor FET having the same characteristics as ET, and one signal terminal of the monitor FET is connected to the first power supply 16 via a resistance element and a constant current supply F is provided.
It is also possible to use one in which the other signal terminal and gate terminal of the monitor FET are connected to the gate terminal of ET and the second power supply 17 is connected (claim 9).

On the other hand, in FIG. 2, 5 is a reference potential generation circuit, 6 is a comparison amplifier, 7 is an electro-absorption optical modulator, and the electro-absorption optical modulator 7 receives the received optical signal according to the bias voltage. It is input to the light receiving element 2 after being attenuated,
The comparison amplifier 6 compares the output signal of the average value detection circuit forming the reference reference potential generation circuit 3 with a predetermined reference potential, amplifies the deviation, and outputs it as a bias voltage of the electroabsorption optical modulator 7. The amount of attenuation of the optical signal by the electroabsorption optical modulator 7 is controlled. In addition, the reference potential generation circuit 5
Generates the predetermined reference potential to the comparison amplifier 6 and outputs it to the comparison amplifier 6 (claim 10).

In the case where the electro-absorption optical modulator 7 for attenuating the received optical signal according to the bias voltage and inputting it to the light receiving element 2 is provided, as shown by a chain double-dashed line in FIG.
The reference reference potential generation circuit is configured as a fixed reference potential generation circuit 3A that generates a fixed reference potential as a predetermined reference reference potential and outputs the fixed reference potential to the limiter amplifier 4, and outputs the output signal based on the output signal of the preamplifier 1. A center potential generating circuit (circuit having the same configuration as the above-mentioned standard reference potential generating circuit 3) 3B for generating a center potential of the amplitude of the center potential generating circuit 3B and a reference potential generating circuit 5 by a comparison amplifier 6. It is configured to amplify the deviation by comparing it with a predetermined reference potential from and output it as a bias voltage of the electro-absorption optical modulator 7 to control the attenuation amount of the optical signal by the electro-absorption optical modulator 7. (Claim 11).
At this time, the fixed reference potential generating circuit 3A may also serve as the reference potential generating circuit 5 (claim 12).

FIG. 3 is a block diagram of the principle of the optical receiving apparatus of the third invention. In FIG. 3, 100 is an optical receiving process including a light receiving element 2, a preamplifier 1 and a limiter amplifier 4 similar to those described above. In the present invention, a plurality of such optical reception processing units 100 are provided in parallel. Then, in the preamplifier 1 in each optical reception processing unit 100, the constant current source 15 is provided between the gate terminal 10a of the input FET 10 and the second power supply 17 as in the case shown in FIGS. It is configured to be interposed (claim 13).

At this time, as described above with reference to FIG. 1, the constant current source 15 has one signal terminal connected to the gate terminal 10a of the input FET 10 and the other signal terminal connected to the second terminal via the resistance element. It is composed of a constant current supply FET connected to the power supply 17 and a monitor FET having the same characteristics as the constant current supply FET, and one signal terminal of the monitor FET is connected to the first power supply via a resistance element. 16 connected to the gate terminal of the FET for constant current supply,
The other signal terminal and gate terminal of the monitor FET,
It may be connected to the second power source 17 (claim 14). When such a constant current source 15 is provided, a fixed reference potential generation circuit that generates a fixed reference potential as a predetermined reference reference potential and outputs the fixed reference potential to the limiter amplifier 4 in each optical reception processing unit 100 is provided with a plurality of sets of optical reception processing. It may be commonly provided to the section 100 (claim 15).

Further, the constant current source 15 is connected to each optical reception processing section 1
One signal terminal provided for each 00
A constant current supply FET connected to the gate terminal 10a of the other and the other signal terminal connected to the second power supply 17 via a resistance element, and a plurality of sets having the same characteristics as the constant current supply FET. It is composed of a monitor FET common to the light reception processing unit 100, one signal terminal of the monitor FET is connected to the first power supply 16 via a resistance element, and the gate of each constant current supply FET is connected. Alternatively, the other signal terminal and gate terminal of the monitor FET may be connected to the second power supply 17 (claim 16).

Further, each optical reception processing section 100 is provided with a low level peak potential detection circuit for detecting the low level peak potential of the output signal of the preamplifier 1 and has the same circuit configuration as the preamplifier 1 for input. Optical reception of a plurality of sets of high level peak potential detection circuits for detecting the output signal of the output FET when the input signal to the gate terminal of the FET is in a non-input state as the high level peak potential of the output signal of the preamplifier 1. The low-level peak potentials detected by the respective low-level peak potential detection circuits and the high-level peak potentials detected by the common high-level peak potential detection circuits are averaged and provided to the processing units 100 in common. Each optical reception processing unit 100 includes an average value detection circuit that outputs the result to the limiter amplifier 4 as a predetermined reference reference potential.
It may be provided (Claim 17).

Further, at least one optical reception processing unit (for example, the uppermost optical reception processing unit in FIG. 3) 100 to which a data signal having a mark ratio of 1/2 is input among a plurality of sets of optical reception processing units 100. An average value detection circuit 33 for detecting the average value of the output signal of the preamplifier 1 in the optical reception processing unit 100 is provided, and the output signal of the average value detection circuit 33 is
Limiter amplifier 4 in plural sets of optical reception processing units 100
It may be commonly used as the predetermined reference reference potential (claim 18). At this time, a clock signal can be used as a data signal having a mark rate of 1/2 (claim 19).

On the other hand, as shown in FIG. 3, each optical reception processing section 100 attenuates the received optical signal according to the bias voltage and then inputs the attenuated optical signal to the light receiving element 2.
And a reference reference potential generating circuit 3 that generates a center potential of the amplitude of the output signal as a predetermined reference reference potential based on the output signal of the preamplifier 1 and outputs it to the miter amplifier 4, and the reference reference potential generating circuit 3 A comparison amplifier 6 for comparing the output signal of the above-mentioned output signal with a predetermined reference potential, amplifying the deviation, outputting it as a bias voltage of the electro-absorption optical modulator 7, and controlling the amount of attenuation of the optical signal by the electro-absorption optical modulator 7. In addition, the reference potential generation circuit 5 for generating the predetermined reference potential to the comparison amplifier 6 in each optical reception processing section 100 may be provided in common for a plurality of sets of optical reception processing sections 100 (claims). 20).

Further, as shown in FIG. 3, each optical reception processing section 100 is provided with an electroabsorption type optical modulator 7 for attenuating the received optical signal according to the bias voltage and inputting it to the light receiving element 2. , At least one optical reception processing unit 100 (for example, the uppermost optical reception processing unit in FIG. 3) to which a data signal having a mark ratio of 1/2 is input among the plurality of sets of optical reception processing units 100. An average value detection circuit 33 for detecting the average value of the output signal of the preamplifier 1 in the processing section 100 and an output signal of the average value detection circuit 33 are compared with a predetermined reference potential and the deviation thereof is amplified to obtain an electric field absorption type. A comparison amplifier 6 that outputs the bias voltage of the optical modulator 7 and controls the amount of attenuation of the optical signal by the electroabsorption optical modulator 7, and a reference potential generation circuit 5 that generates a predetermined reference potential for the comparison amplifier 6 are provided. The ratio The output signal of the amplifier 6, which may be used in common as the bias voltage of the electroabsorption modulator 7 in a plurality of sets of the light reception processing unit 100 (Claim 21).

At this time, the output signal of the average value detection circuit 33 may be commonly used as a predetermined reference reference potential of the limiter amplifiers 4 in the plurality of sets of optical reception processing units 100 (claim 22), or the mark ratio. A clock signal may be used as the 1/2 data signal (claim 23). Further, among the plurality of sets of optical reception processing units 100, at least one optical reception processing unit (for example, the uppermost optical reception processing unit in FIG. 3) 100 to which a data signal having a mark ratio of ½ is input, the optical signal An average value detection circuit 33 for detecting the average value of the output signal of the preamplifier 1 in the reception processing unit 100 is provided, and each optical reception processing unit 100 attenuates the received optical signal according to the bias voltage and then receives the light. The electric field absorption type optical modulator 7 input to the element 2 is compared with the output signal of the average value detection circuit 33 and a predetermined reference potential, and the deviation is amplified and output as the bias voltage of the electric field absorption type optical modulator 7 to output the electric field. A comparison amplifier 6 for controlling the amount of attenuation of an optical signal by the absorption type optical modulator 7.
And a reference potential generation circuit 5 for generating the predetermined reference potential to the comparison amplifier 6 in each optical reception processing unit 100 may be provided (claim 24).

At this time, the output signal of the average value detection circuit 33 may be commonly used as a predetermined reference reference potential of the limiter amplifiers 4 in the plurality of sets of optical reception processing units 100 (claim 25), or the mark ratio. A clock signal may be used as the 1/2 data signal (claim 26). Figure 4 is the fourth
FIG. 4 is a principle configuration diagram of the optical receiving device of the invention of the present invention. As shown in FIG. 4, the fourth invention includes the same light receiving element 2, preamplifier 1 and limiter amplifier 4 as described above.
After the limiter amplifier 4, a differential amplifier 8 and an E are provided.
A CL (Emitter Coupled Logic) output buffer 9 is provided.

Here, the differential amplifier 8 includes a pair of FETs 80 and 81 for inputting the output signal and the inverted output signal of the limiter amplifier 4 to gate terminals 80a and 81a, respectively, and one signal of the pair of FETs 80 and 81. The terminals (drain terminals) 80b and 81b are connected to the first power supply (positive power supply Vdd or GND) 16 via the resistance elements 82 to 84, and the other signal terminal (source terminal) 80c of the pair of FETs 80 and 81 is connected. , 81c to the second power source (GN
D or negative power supply Vss) 17 and a pair of FETs 8
The potential of one of the signal terminals 80b and 81b of 0 and 81 is output as a differential amplification result. Further, the ECL output buffer 9 operates by receiving the output signal of the differential amplifier 8.

Then, the pair of FEs in the differential amplifier 8
The constant current source 15 is provided between the other signal terminals 80c and 81c of T80 and 81 and the second power supply 17. The constant current source 15 is composed of a constant current supply FET 150 and a monitor FET 151, similar to the one shown in FIG. The constant current supply FET 150 has one signal terminal (drain terminal) 150b connected to a pair of FETs 80,
81 is connected to the other signal terminals 80c and 81c of 81, and the other signal terminal (source terminal) 150c is connected to the second power supply 17 via the resistance element 152.

The monitor FET 151 has the same characteristics as the constant current supply FET 150, and one signal terminal (drain terminal) 151b is connected to the first power source 16 via the resistance element 153. Connected to the gate terminal 150a of the constant current supply FET 150, the other signal terminal (source terminal) 151c and gate terminal 1
51a is connected to the second power source 17 (claim 2
7).

The optical receiving device of the fifth invention is a device having substantially the same structure as that shown in FIG. 2, and includes a light receiving element 2 for converting a received optical signal into a current signal, and this light receiving element 2. Preamplifier 1 that amplifies the current signal of the current signal into a predetermined voltage signal and outputs the amplified voltage signal, and the preamplifier 1 based on a predetermined reference reference potential.
The light receiving element 2 is provided with a limiter amplifier 4 for amplifying the output signal of
And the element forming the electro-absorption optical modulator 7 are integrally formed by two P-N junctions formed on the same substrate (claim 28).

The optical receiving device of the sixth invention is a device having substantially the same configuration as that shown in FIG. 3, and includes a light receiving element 2 for converting a received optical signal into a current signal, and this light receiving element 2. Preamplifier 1 that amplifies the current signal of the current signal into a predetermined voltage signal and outputs the amplified voltage signal, and the preamplifier 1 based on a predetermined reference reference potential.
A plurality of sets of optical reception processing units 100 each including a limiter amplifier 4 that amplifies the output signal of the optical receiver, and an electro-absorption optical modulator 7 that amplifies the received optical signal according to a bias voltage and then inputs the optical signal to the light receiving element 2. Therefore, the electroabsorption optical modulator 7 in each optical reception processing unit 100 is interposed between ribbon fibers to which optical signals of a plurality of channels are input in parallel, and the plurality of electroabsorption optical modulators are connected to the ribbon. It is configured as a multi-channel optical attenuator integrally formed in parallel with each optical fiber in the fiber at the same pitch (claim 29).

[0048]

In the optical receiving preamplifier of the first aspect of the invention described above, it is generated by the constant current source 15 provided between the gate terminal 10a of the input FET 10 and the second power source (negative power source Vss or GND) 17. When the current to be applied is Ics, this current does not flow to the input terminal 18 side but only to the feedback resistor 14 side. Therefore, the voltage component represented by Ics × Rf is output terminal 19
Will increase the DC voltage of
It becomes maximum when there is no current signal Iin from the light receiving element to the input terminal 18.

The characteristic of the potential of the output terminal 19 corresponding to the input current Iin when the constant current source 15 is added is shown in FIG. 5 together with the characteristic of the conventional circuit without the constant current source 15.
As shown in FIG. 5, when the constant current source 15 is added,
It can be seen that saturation does not occur even when the input current Iin increases. Therefore, even if the optical signal power is excessive,
The output waveform of the preamplifier 1 does not cause waveform distortion due to saturation, the dynamic range can be expanded, and a sufficient eye opening can be obtained (claim 1).

Further, in the constant current source 15, a constant current supply FE for supplying a desired constant current Ics as a drain current.
T150 and a monitor FET 151 having the same characteristics as the constant current supply FET 150, and a monitor FET
The change in the threshold voltage is monitored from the change in the drain current Id flowing through 151, and the increase in the threshold voltage is made equal to the decrease in the gate-source voltage of the constant current supply FET 150 to obtain the constant current. Gate of supply FET 150
The source-to-source voltage can be changed so as to cancel the variation of the threshold voltage. Thereby, the variation of the threshold voltage can be automatically compensated by the gate-source voltage of the constant current supply FET 150, and the constant current supply FET 1
A constant drain current can be supplied as the desired constant current Ics regardless of the threshold voltage of 50 (claim 2).

Further, the potential of the gate terminal 151a of the FET 151 for monitoring is set appropriately by dividing the potential of the gate terminal 151a of the FET 151 for monitoring by resistance division with two resistance elements or a variable resistor. The gate-source voltage of the supply FET 150 can be adjusted, and fluctuations in the drain current of the constant current supply FET 150 due to fluctuations in the power supply voltage are suppressed (claims 3 and 4).

In the above-described optical receiver of the second invention, the current signal from the light receiving element 2 is amplified by the preamplifier 1 to a predetermined voltage signal, and then the predetermined reference reference potential from the reference reference potential generating circuit 3 is applied. Based on this, the output signal of the preamplifier 1 is amplified by the limiter amplifier 4. Here, the preamplifier 1 is configured similarly to that of the first invention shown in FIG. 1, and even if the optical signal power is excessive, the output waveform of the preamplifier 1 is waveform distortion due to saturation. And the dynamic range of the preamplifier 1 is greatly expanded as compared with the conventional one as shown in FIG. 5 (Claim 5).

At this time, in the reference reference potential generating circuit 3, the average value of the outputs of the high level peak potential detecting circuit and the output of the low level peak potential detecting circuit, that is, the center potential of the amplitude of the output signal of the preamplifier 1. Is detected by the average value detection circuit and the potential thereof is output to the limiter amplifier 4 as a predetermined reference reference potential, the dynamic range of the preamplifier 1 is significantly widened.
The input level of the signal from the reference reference potential generating circuit 3 to the reference reference potential generating circuit 3 is sufficiently large. Even if some error occurs in the reference reference potential generating circuit 3, the ratio of the error to the input level is sufficiently small. The generation circuit 3 can accurately obtain a predetermined reference reference potential (claim 6).

Further, the high level peak potential detection circuit is
Input FET composed of the same circuit as the preamplifier 1.
By making the input signal to the gate terminal 10a of 10 non-input state, the output signal of the output FET 12 becomes the maximum value as shown in FIG. 5, and this signal becomes the high-level peak potential as the standard reference potential generating circuit 3 Is given to the average value detection circuit (Claim 7).

When the optical receiver of the present invention receives an optical signal whose power is adjusted by the automatic power adjustment circuit on the optical transmission side, the optical power from the optical transmission side is constant, so The power fluctuation of the optical signal generated is relatively small. Therefore, even if a predetermined reference reference potential for the limiter amplifier 4 is not generated on the basis of the output signal of the preamplifier 1 and a fixed potential is used as the predetermined reference reference potential, no accuracy problem occurs. . Therefore, in such a case, the fixed reference potential generation circuit 3 that generates the fixed reference potential and outputs it to the limiter amplifier 4 is used as the reference reference potential generation circuit.
By using A, the fixed reference potential can be used as a predetermined standard reference potential (claim 8).

Further, the constant current source 15 in the preamplifier 1
By using a constant current supply FET and a monitor FET as shown in FIG. 1, a constant drain current is supplied as a desired constant current regardless of the threshold voltage of the constant current supply FET. It is possible (claim 9). By the way, in the optical receiver shown in FIG.
The electro-absorption optical modulator 7 has the characteristics shown in FIG. 6 and has a function of changing the amount of attenuation of the received optical signal depending on the applied bias voltage. The optical signal output from the electro-absorption optical modulator 7 is converted into an electric signal by the light receiving element 2, amplified by the preamplifier 1, and input to the limiter amplifier 4. At the same time, the reference reference potential generation circuit 3 detects the center potential of the amplitude of the output signal of the preamplifier 1 and supplies it to the limiter amplifier 4 as a predetermined reference reference potential.

The reference reference potential obtained by the reference reference potential generation circuit 3 is compared with the reference potential from the reference potential generation circuit 5 in the comparison amplifier 6, and its output attenuates the optical signal in the electroabsorption optical modulator 7. The amount is controlled. Therefore, by controlling the electro-absorption optical modulator 7 so that the attenuation amount of the electro-absorption optical modulator 7 is large when the optical power is large and the attenuation amount is small when the optical power is small, the reference reference potential is reduced. Is kept substantially constant (reference potential from the reference potential generating circuit 5) (claim 10).

Further, the reference potential generating circuit 5, which is similar to the above,
When the comparison amplifier 6 and the electro-absorption optical modulator 7 are provided, the central potential generating circuit (circuit having the same configuration as the standard reference potential generating circuit 3) 3B outputs the output signal of the preamplifier 1 based on the output signal of the preamplifier 1. Amplification amount of the optical signal in the electroabsorption optical modulator 7 is generated by the output of the comparison amplifier 6 so that the center potential of the amplitude is generated and the center potential is held at the predetermined reference potential from the reference potential generation circuit 5. Can also be controlled.

With such control, the power fluctuation of the optical signal received by the light receiving element 2 becomes relatively small. Therefore, when the automatic power adjusting circuit is used on the optical transmitting side (claim 8).
Similarly, the predetermined reference reference potential for the limiter amplifier 4 is not generated based on the output signal of the preamplifier 1 one by one,
A fixed potential can be used as the predetermined reference reference potential, and the fixed reference potential generation circuit 3 that generates the fixed reference potential and outputs it to the limiter amplifier 4 is used as the standard reference potential generation circuit.
By using A, the fixed reference potential can be used as a predetermined standard reference potential (claim 11). At this time, the fixed reference potential generation circuit 3A and the reference potential generation circuit 5 can be used in common,
The dual use also makes it possible to simplify the circuit configuration (claim 12).

In the above-described optical receiving apparatus of the third invention, a plurality of sets of optical reception processing units 100 each including the light receiving element 2, the preamplifier 1 and the limiter amplifier 4 are provided in parallel, and optical signals of a plurality of channels are provided in parallel. Can be received. In such a configuration, the preamplifier 1 in each optical reception processing unit 100 has the same configuration as that of the first invention shown in FIG. 1, and even if the optical signal power is excessive, The output waveform of the amplifier 1 does not cause waveform distortion due to saturation, and the dynamic range of the preamplifier 1 of each optical reception processing section 100 is greatly expanded as compared with the conventional one as shown in FIG.

At this time, the constant current source 15 in the preamplifier 1 is composed of a constant current supply FET and a monitor FET as shown in FIG. A constant drain current can be supplied as a desired constant current regardless of the threshold voltage of the supply FET (claim 14). When such a constant current source 15 is provided, variations in the output potential of the preamplifier 1 in each optical reception processing unit 100 are reduced, so that fixed reference potential generation circuits are provided in a plurality of sets of optical reception processing units 100. The fixed reference potential generated from the fixed reference potential generation circuit can be generated as a predetermined reference reference potential and output to the limiter amplifier 4 in each optical reception processing unit 100 (claim 15).

Further, the constant current source 15 is connected to each optical reception processing section 1
The constant current supply FET provided for each 00 and the monitor FET common to the plurality of sets of the light reception processing units 100 also make it possible to configure the constant current supply FETs in each light reception processing unit 100. A constant drain current can be supplied as a desired constant current regardless of the threshold voltage, and since the monitoring FET is shared, the circuit configuration can be simplified (claim 16).

By the way, in order to generate a predetermined reference reference potential to the limiter amplifier 4, each optical reception processing section 100 is provided with a low level peak potential detection circuit and an average value detection circuit, and a plurality of sets of optical reception processing. High level peak potential detection circuit common to the section 100 (with the same circuit configuration as the preamplifier 1, the gate terminal 1 of the input FET 10)
0a input signal is not input), and in each optical reception processing section 100, the average value of the output of the low level peak potential detection circuit and the output of the common high level peak potential detection circuit (that is, The average value detection circuit detects the center potential of the amplitude of the output signal of the preamplifier 1 and outputs the potential to the limiter amplifier 4 as a predetermined reference reference potential.

Therefore, the high-level peak potential detection circuit is shared and the circuit configuration is simplified, and the dynamic range of the preamplifier 1 in each optical signal processing section 100 is significantly larger than that of the conventional one as described above. Since it is wide, the input level of the signal from the preamplifier 1 to the low level peak potential detection circuit is sufficiently high, and even if some error occurs in this low level peak potential detection circuit, the input level of the error Is sufficiently small, and a predetermined standard reference potential can be accurately obtained (claim 17).

If there is an optical reception processing unit 100 to which a data signal having a mark ratio of 1/2 is input, such an optical reception processing unit 100 detects the average value of the output signals of the preamplifier 1. By providing the average value detection circuit 33, the output signal of the average value detection circuit 33 can be commonly used as a predetermined reference reference potential of the limiter amplifiers 4 in the plurality of sets of optical reception processing units 100, and The circuit configuration of each optical reception processing unit 100 can be made simpler (claim 18).

At this time, when the optical signals of a plurality of channels are processed in parallel, a clock signal is usually input to at least one channel, and the optical reception processing section 100 for receiving the clock signals is present. I mean,
Since the clock signal is a data signal having a mark rate of exactly 1/2, if this clock signal is used for the generation of a predetermined reference reference potential by the average value detection circuit 33, the mark rate is generated for the generation of a predetermined reference reference potential. It is not necessary to separately provide the optical reception processing unit 100 for inputting 1/2 data signal (claim 19).

On the other hand, in the optical receiver shown in FIG.
Each optical reception processing unit 100 is provided with the same electroabsorption type optical modulator 7 as described above, the optical signal output from the electroabsorption type optical modulator 7 is converted into an electric signal by the light receiving element 2, and the preamplifier 1
Is input to the limiter amplifier 4, and at the same time, the reference reference potential generation circuit 3 detects the center potential of the amplitude based on the output signal of the preamplifier 1 and supplies it to the limiter amplifier 4 as a predetermined reference potential. There is.

Then, in each optical reception processing section 100,
The reference reference potential obtained by the reference reference potential generation circuit 3 is compared with the reference potential from the reference potential generation circuit 5 common to all the light reception processing units 100 by the comparison amplifier 6,
The output controls the amount of attenuation of the optical signal in the electro-absorption optical modulator 7, and the reference reference potential is always held substantially constant (claim 20).

If there is an optical reception processing unit 100 to which a data signal having a mark ratio of 1/2 is input, the average value detection circuit 33 outputs the output of the preamplifier 1 in the optical reception processing unit 100. The average value of the signal is detected, the comparison amplifier 6 compares the output signal of the average value detection circuit 33 with a predetermined reference potential from the reference potential generation circuit 5, amplifies the deviation, and the electric field absorption type optical modulator 7 It is output as a bias voltage, and the amount of attenuation of the optical signal by the electroabsorption optical modulator 7 is controlled. The output of the comparison amplifier 6 is commonly used as the bias voltage of the electro-absorption optical modulator 7 in each of the other optical reception processing units 100, and the output of the electro-absorption optical modulator 7 is used in each optical reception processing unit 100. The amount of attenuation of the optical signal is controlled. Thereby, the circuit configuration of each of the other optical reception processing units 100 can be simplified (claim 2).
1).

At this time, the output signal of the average value detection circuit 33 is commonly used as a predetermined reference reference potential of the limiter amplifier 4 in each optical reception processing section 100, so that the circuit configuration of each optical reception processing section 100 can be improved. In addition to further simplification (claim 22), the clock signal is used as the data signal of the mark rate 1/2, so that the optical reception processing unit 10 for inputting the data signal of the mark rate 1/2 is input as described above.
It is not necessary to separately provide 0 (claim 23).

Further, if there is an optical reception processing unit 100 to which a data signal having a mark ratio of 1/2 is input, the average value detection circuit 33 in such an optical reception processing unit 100 causes the output signal of the preamplifier 1 to be output. Of the average value detection circuit 33 in each optical reception processing unit 100, the output signal of the average value detection circuit 33 is compared with a predetermined reference potential from the reference potential generation circuit 5, and the deviation is amplified to generate an electric field. It is output as the bias voltage of the absorption type optical modulator 7, and the attenuation amount of the optical signal by the electroabsorption type optical modulator 7 is controlled. Here, a predetermined reference potential to be compared with the output signal of the average value detection circuit 33 in the comparison amplifier 6 can be appropriately adjusted for each optical reception processing unit 100 (claim 24).

At this time, similarly to the above, the output signal of the average value detection circuit 33 is commonly used as a predetermined reference reference potential of the limiter amplifier 4 in each optical reception processing section 100, thereby simplifying the circuit configuration. (Claim 2)
5) Using the clock signal as the data signal with the mark rate of 1/2, it is not necessary to separately provide the optical reception processing unit 100 for inputting the data signal with the mark rate of 1/2 (claim 2).
6).

The optical receiving device of the fourth invention described above is provided with the same light receiving element 2, preamplifier 1 and limiter amplifier 4 as described above, and the differential amplifier 8 and the ECL output are provided at the subsequent stage of the limiter amplifier 4. In the differential amplifier 8 having the buffer 9, a constant current source 15 having the same configuration as that shown in FIG. 1 is provided between the other signal terminals 80c and 81c of the pair of FETs 80 and 81 and the second power supply 17. It is installed.

By using such a constant current source 15, as described above, the fluctuation amount of the threshold voltage can be automatically compensated by the gate-source voltage of the constant current supply FET 150, and the change of the current value is small. Since the desired constant current Ics can be supplied, it is possible to suppress gain variation, output amplitude variation, and output potential variation in the differential amplifier 8 (claim 2).
7).

In the optical receiving device of the fifth invention described above, in the device having substantially the same structure as the device shown in FIG. 2, the light receiving element 2 and the element forming the electro-absorption type optical modulator 7 are formed on the same substrate. By integrally forming the two P-N junctions, the circuit configuration can be downsized and the cost can be reduced (Claim 28). In the optical receiving device of the sixth invention described above, as in the device shown in FIG. 3, a plurality of optical reception processing units 100 each including the light receiving element 2, the preamplifier 1, the limiter amplifier 4, and the electroabsorption optical modulator 7 are provided. When the sets are arranged in parallel, a multi-channel optical attenuator (a plurality of electroabsorption optical modulators 7) integrally formed in parallel with each optical fiber in the ribbon fiber at the same pitch is provided between the ribbon fibers. , With a simple configuration,
It is possible to control the attenuation amounts of the optical signals of a plurality of channels in parallel (claim 29).

[0076]

Embodiments of the present invention will be described below with reference to the drawings. (A) Description of First Embodiment FIG. 7 is a circuit diagram showing an optical receiving preamplifier in the first embodiment of the present invention, and FIG. 8 is a block diagram showing an optical receiving apparatus as the second embodiment of the present invention. Is.

In FIG. 8, reference numeral 1 is a transimpedance type preamplifier for optical reception, which will be described later with reference to FIG. 7, and this preamplifier 1 includes a light receiving element (photoelectric conversion element such as a photodiode) 2 The current signal Iin obtained by photoelectrically converting the optical signal is amplified to a predetermined voltage signal and output. Reference numeral 3 is a reference reference potential generating circuit that detects and generates the center potential of the amplitude as a predetermined reference reference potential based on the output signal of the preamplifier 1. The reference reference potential generating circuit 3 is a preamplifier 1A. , A low-level peak potential detection circuit 30 for detecting the low-level peak potential of the output signal, a high-level peak potential detection circuit 31 for detecting the high-level peak potential of the output signal of the preamplifier 1, and these detection circuits 30, An average value detection circuit 3c that averages the peak potentials detected by 31 and outputs the averaged result as a predetermined reference reference potential.

Reference numeral 4 is a limiter amplifier for amplifying the output signal of the preamplifier 1 based on the reference reference potential from the reference reference potential generating circuit 3. The low-level peak potential detection circuit 30, the high-level peak potential detection circuit 31, and the average value detection circuit 3c in the reference reference potential generation circuit 3 are respectively shown in FIGS. 31 (b), (a), ( It is configured as described in c).

The transimpedance type preamplifier 1 in this embodiment has four field effect transistors (hereinafter referred to as FETs) 10, 11A, 12, 13A and feedback resistors as shown in FIG. (Resistance value Rf) 14, constant current source 15, and two diodes 2
It is composed of 0 and 21. The FET 11A functions as a load resistance, and the FET 13A functions as a constant current source (load resistance).

This preamplifier 1 is basically constructed similarly to that shown in FIG. 30, and the current signal Iin obtained by photoelectrically converting the optical signal by the light receiving element 2 receives the input terminal 18. Is input to the gate terminal 10a of the input FET 10 via. Regarding this input FET 10, the drain terminal (one signal terminal) 10b is F
1st power supply (GND (Ground, 0V) via ET11A
Alternatively, the source terminal (the other signal terminal) 10c is connected to the second power source (negative power source Vss or GND) 17 via the diode 20 while being connected to the positive power source Vdd) 16.

Regarding the output FET 12, the gate terminal 12a is connected to the drain terminal 10b of the input FET 10, the drain terminal 12b is connected to the first power source 16, and the source terminal 12c is connected via the diode 21 and the FET 13A. From the output terminal 19 connected to the second power source 17 and connected to the source terminal 12c,
The amplification result amplified to the predetermined voltage signal is output.

Further, the gate terminal 1 of the input FET 10
0a and the output terminal 19 of the output FET 12 (diode 2
1) and the gate terminal 10a of the input FET 10
A feedback resistor 14 for feeding back and supplying the output signal of the output FET 12 is provided between the output FET 12 and the output FET 12 at the gate terminal 10a of the input FET 10.
The output signal of is fed back and supplied.

Regarding the FET 11A for load resistance, the gate terminal 11a and the source terminal 11c are the drain terminal 10a of the input FET 10 and the output FET1.
The second drain terminal 11b is connected to the first power source 16 while being connected to the second gate terminal 12a. Also,
Regarding the FET 13A for load resistance, the gate 13a and the source terminal 13c are connected to the second power supply 17, and the drain terminal 13b is connected to the feedback resistor 14 and the diode 21.

In the preamplifier 1 of this embodiment, the constant current source 15 capable of magnifying the change of the amplitude value of the output potential of the output FET 12 with respect to the change of the optical signal is the input F.
It is provided between the gate terminal 10 a of the ET 10 and the second power supply 17. The constant current source 15 is an F for constant current supply.
It is configured to include an ET 150, a monitor FET 151, and a level adjustment FET 154. All the FETs used here are depletion (depletio).
n; or normally on) type.

In the constant current supply FET 150, the drain terminal (one signal terminal) 150b is connected to the gate terminal 10a of the input FET 10, and the source terminal (the other signal terminal) 150c is connected via the resistance element 152. Two
Is connected to the power supply 17. The resistance element 152
May be replaced with a diode 152A as shown in FIG.

Further, in the level adjusting FET 154, the drain terminal 154b is connected to the first power source 16, the source terminal 154c is connected to the gate terminal 150a of the constant current supplying FET 150 and the resistance adjusting element 155 is used. 2 is connected to the power supply 17. The level adjusting FET 154 and the resistance element 155 are used to reduce the voltage applied to the gate terminal 150a of the constant current supply FET 150. However, when the power supply voltage is high, A in FIG. FETs for constant current supply directly
It is connected to the gate terminal 150a of 150, and is for level adjustment F
The ET 154 and the resistance element 155 may be omitted. In this case, the constant current source 15 has exactly the same configuration as that shown in FIG.

Further, the monitor FET 151 has the same characteristics as the constant current supply FET 150, and the drain terminal (one signal terminal) 151b is connected to the resistance element 153.
Is connected to the first power supply 16 via the gate terminal 154a of the level adjusting FET 154, and the source terminal (the other signal terminal) 151c and the gate terminal 151a are connected to the second power supply 17.

In the optical receiving apparatus of the first embodiment constructed as described above, the current signal Iin from the light receiving element 2 is amplified by the preamplifier 1 to a predetermined voltage signal, and then the reference reference potential generating circuit 3 outputs it. Predetermined reference reference potential (preamplifier 1A
The output signal of the preamplifier 1 is amplified by the limiter amplifier 4 based on the central potential of the upper and lower levels of the output signal of 1.

Here, in the preamplifier 1 of the present embodiment, an optical signal representing a digital signal received from the transmitting side via an optical fiber (not shown) is photoelectrically converted by the light receiving element 2 and obtained. The current signal Iin is supplied to the gate terminal 10a of the input FET 10 through the input terminal 18.
The potential of the drain terminal 10b of the input FET 10 is supplied to the gate terminal 13a of the output FET 12, and the potential of the source terminal 12c of the output FET 12 is output from the output terminal 19 as the amplification result.

Then, the gate terminal 1 of the input FET 10
Since the constant current source 15 is provided between 0a and the second power source 17, the current Ics generated from the constant current source 15 does not flow to the input terminal 18 side but only to the feedback resistor 14 side.
As described above, the voltage component represented by Ics × Rf increases the DC voltage at the output terminal 19. This DC voltage becomes maximum when there is no current signal Iin from the light receiving element to the input terminal 18.

Therefore, when the constant current source 15 is added, saturation does not occur even if the optical signal power becomes excessive and the input current Iin becomes large, and the output waveform of the preamplifier 1 causes waveform distortion due to saturation. Therefore, the dynamic range can be expanded and a sufficient eye opening can be obtained. Also,
By using the preamplifier 1 shown in FIG. 7 as a preamplifier in the optical receiving apparatus shown in FIG. By setting the preamplifier 1 to have a high gain, the output amplitude of the preamplifier 1 becomes large, so that the error generated in the reference reference potential generation circuit 3 which gives the reference reference potential of the limiter amplifier 4 can be ignored, and the reference reference potential generation circuit. 3 makes it possible to accurately obtain a predetermined reference reference potential. Further, as a result, the adjustment terminal in the reference reference potential generation circuit 3 can be eliminated, and the gain required for the reference reference potential generation circuit 3 can be reduced, so that the circuit scale can be reduced and the power consumption can be reduced. It will be possible.

By the way, the current I flowing from the constant current source 15
When cs becomes excessive, saturation occurs in the vicinity of Iin = 0 in the characteristic of FIG. 5 (see FIG. 11). However, for example, when a constant current source having the same configuration as FET 13A is formed, Ics∝Wg Since it is (gate width), saturation can be prevented by selecting an appropriate gate width so that saturation does not occur.

Normally, the drain current Id in the FET is
Is represented by the following formula (1). Id∝β · (Vgs−Vth) ² (1) where Vth is the threshold voltage of the FET (negative value in the case of depletion type), Vgs is the gate-source voltage of the FET, and β is the standard. Gm (drain conductance) parameter.

As can be seen from the above equation (1), the FET
If the same configuration as 13A is used as the constant current source 15, the fluctuation of the threshold voltage Vth and the parameter β is
The drain current Id given as the constant current Ics changes greatly, and the characteristics of the preamplifier 1 also largely vary. Therefore, in the constant current source 15 of the present embodiment, the monitor FET 151 having the same characteristics as the constant current supply FET 150 is connected to the constant current supply FET 150 via the level adjustment FET 154, and the monitor FET 151 is connected to the constant current supply FET 150. The change of the threshold voltage Vth is monitored from the change of the drain current Id flowing, and the threshold voltage Vth is monitored.
The increase amount ΔVth of th is made equal to the decrease amount ΔVgs of the gate-source voltage Vgs of the constant current supply FET 150, and the gate-source voltage Vgs of the constant current supply FET 150 is set.
Is changed so as to cancel the variation ΔVth of the threshold voltage Vth.

Accordingly, the variation Δ of the threshold voltage Vth
Vth can be automatically compensated by the gate-source voltage Vgs of the FET 150 for constant current supply.
A constant drain current can be supplied as the desired constant current Ics regardless of the threshold voltage Vth of the ET150. For example, when the threshold voltage Vth changes by + ΔVth, the drain current Id decreases from the equation (1). By arranging the elements used in the circuit in very close places, it is considered that all the elements move in the same direction. According to the configuration of the present embodiment, the change in + ΔVth reduces the current I ₁ flowing through the resistance element 153.

As a result, the potential at point A in FIG. 7 rises,
Gate-source voltage Vgs of level adjustment FET 154
Therefore, the drain current I ₂ of the level adjusting FET 154 increases, and the gate-source voltage Vgs of the constant current supply FET 150 increases by ΔVgs.
At this time, if ΔVgs = ΔVth from the equation (1), the current Ics does not change. In order to set ΔVgs = ΔVth, the values of the resistance elements 152, 153 and 155 may be set appropriately.

The fluctuation of β is compensated in the same manner as the fluctuation of the threshold voltage Vth described above. 10A to 10E, threshold voltage fluctuations ΔVth, parameter fluctuations Δβ, temperature, resistance fluctuations ΔR, power supply voltage fluctuations Δ.
The simulation result of the change of the current I with respect to Vss is
Comparison is made between the case of the constant current source 15 of this embodiment (◯) and the case of the constant current source of the same configuration as the FET 13A (×).

As shown in FIGS. 10A and 10B, the current change due to the threshold voltage fluctuation ΔVth and the parameter fluctuation Δβ in the constant current source 15 is greatly suppressed. Regarding the resistance variation ΔR, when the resistance fluctuates small, the potential at the point A in FIG. 7 rises, so the current increases, but when the resistance decreases, the current increases as shown in FIG. It is better to do so, and since the output amplitude fluctuation is suppressed, rather good results are obtained.

Regarding the temperature fluctuation, as shown in FIG. 10 (c), the current decreases as the temperature rises. This is because the fluctuation due to the resistance is more dominant than the fluctuations in the threshold voltage Vth and the parameter β. Since the resistance increases as the temperature rises, the output amplitude fluctuation is suppressed. With respect to the power supply voltage fluctuation, the current fluctuation increases as shown in FIG. This is because the drain current Id in the equation (1) depends on the drain-source voltage Vds when the gate width becomes narrow.

Therefore, when the demand for the fluctuation of the power supply voltage is strict, for example, the constant current source 15 described above is used as shown in FIG.
15A shown in FIG. 13 or the constant current source 1 shown in FIG.
5B is conceivable. In the constant current source 15A shown in FIG. 12, the gate terminal 151a of the monitoring FET 151 is connected via two resistance elements 156 and 157,
Each is connected to the first power supply 16 and the second power supply 17, and the other signal terminal 1 of the monitoring FET 151 is connected.
51c is connected to the second power supply 17 via the resistance element 158.

Further, in the constant current source 15B shown in FIG.
Gate terminal 15 of monitor field effect transistor 151
1a is connected to the first power source 16 and the second power source 17 via the variable resistor 159, and the monitoring FET is used.
The other signal terminal 151c of 151 is connected to the second power supply 17 via a diode (resistive element) 158A. In the constant current source 15B shown in FIG. 13, the resistor element 152 in the constant current source 15 is replaced with the diode 152A as described above.

By using the constant current sources 15A and 15B as shown in FIG. 12 or FIG.
The potential of the gate terminal 151a of 151 is appropriately set by resistance division with the two resistance elements 156 and 157 or the variable resistor 159, and the FE for constant current supply is set.
The potential of the gate terminal 150a of T150, that is, the gate-source voltage Vgs of the constant current supply FET 150 can be adjusted, and the constant current supply FET with respect to the power supply voltage fluctuation
The fluctuation of the drain current of 150 is suppressed.

As an example, considering the case where the power supply Vss increases, the drain-source voltage Vds acting on the constant current supply FET 150 increases, so the increase of the power supply Vss acts in the direction of increasing the drain current. But Figure 1
2. Since the potential at point C in FIG. 13 is higher than at point D, the gate-source voltage Vgs of the monitoring FET 151 increases and the current I ₂ increases. Therefore, E in FIGS.
The potential at the point drops, and as a result, the constant current supply FET 150
The gate-source voltage Vgs of is reduced, and the current increase is suppressed.

As described above, in the constant current sources 15, 15A and 15B as shown in FIG. 7, FIG. 12 and FIG. 13, a constant drain current can be set to a desired constant value without depending on variations in FET characteristics due to processes. The current Ics can be obtained, and by using such constant current sources 15, 15A and 15B in the preamplifier 1, the yield of the preamplifier 1 can be improved and the circuit of the preamplifier 1 can be obtained. The variation in characteristics can be made extremely small.

In particular, when the current value of the constant current source becomes excessive due to the fluctuation of the FET element parameter, the photocurrent is saturated near zero and the gain decreases as shown by A in FIG. , 15A, 15B, the
As indicated by B, there is no concern about saturation, and the advantage of the expansion of the output amplitude (expansion of the dynamic range) of the preamplifier 1 described above can be maximized.

In the first embodiment, the standard reference potential generating circuit 3 shown in FIG. 8 may be constructed as shown in FIG. In the standard reference potential generating circuit 3 shown in FIG.
The low level peak potential detection circuit 30 and the average value detection circuit 32 are the same as those shown in FIG. 8, but the high level peak potential detection circuit 31A is configured by the same circuit as the preamplifier 1 shown in FIG. There is.

In such a configuration, the input FE of the preamplifier 1 forming the high level peak potential detection circuit 31A.
By setting the input signal to the gate terminal 10a of T10 to the non-input state, the output signal of the output FET 12 becomes the maximum value as shown in FIG. 5, and this signal becomes the high-level peak potential and the standard reference potential generation circuit 3 Average value detection circuit 32
Given to.

Such a high level peak potential detecting circuit 31A can be used because the amplitude of the output signal of the preamplifier 1 can be increased because the preamplifier 1 has the configuration shown in FIG. Standard reference potential generation circuit 3
This is because the error that occurs in (1) can be ignored and the high level peak potential is no longer required to be detected with high accuracy.

(B) Description of Second Embodiment FIG. 14 is a block diagram showing an optical receiving apparatus as a second embodiment of the present invention. In the figure, the same reference numerals as those used above indicate the same parts. Therefore, the description thereof will be omitted. This FIG.
In the apparatus of the second embodiment shown in FIG. 1, an automatic power adjustment circuit (Automati) is provided on the transmission side (not shown) of the optical signal transmission side.
(C power controller: APC) is used for constant optical output transmission, and instead of the standard reference potential generating circuit 3 used in the first embodiment, a fixed reference potential is a predetermined standard reference potential. The fixed reference potential generating circuit 3A is generated and is output to the limiter amplifier 4.

When the optical power from the optical transmitting side is kept constant by APC, the power fluctuation of the optical signal input to the light receiving element 2 of the optical receiving device becomes relatively small, and therefore, it is shown in FIGS. Even if a predetermined reference reference potential for the limiter amplifier 4 is not generated by the reference reference potential generation circuit 3 based on the output signal of the preamplifier 1 but a fixed potential is used as the predetermined reference reference potential, There is no accuracy problem.

Therefore, in the second embodiment, as described above,
A fixed reference potential generation circuit 3A that generates a fixed reference potential is used as the reference reference potential generation circuit, and the fixed reference potential is supplied to the limiter amplifier 4 as a predetermined reference reference potential. As a result, the circuit configuration can be simplified as compared with the first embodiment. (C) Description of Third Embodiment FIG. 15 is a block diagram showing an optical receiving apparatus as a third embodiment of the present invention. In the figure, the same reference numerals as those used above denote the same parts, The description is omitted.

In the apparatus of the third embodiment shown in FIG. 15,
The apparatus of the first embodiment shown in FIG. 8 is provided with a reference potential generation circuit 5, a comparison amplifier 6 and an electroabsorption type optical modulator 7. The electro-absorption optical modulator 7 attenuates the received optical signal according to the bias voltage and then inputs it to the light receiving element 2. For example, the electro-absorption optical modulator 7 has characteristics as shown in FIG. It has the function of changing the attenuation of the received optical signal.

The comparison amplifier 6 includes the standard reference potential generating circuit 3
The output signal of the average value detection circuit (see reference numeral 32 in FIG. 8) is compared with a predetermined reference potential, and the deviation is amplified and output as the bias voltage of the electroabsorption optical modulator 7. It controls the amount of attenuation of the optical signal by the modulator 7. The reference voltage generation circuit 5 generates a predetermined reference potential for the comparison amplifier 6 and outputs it to the comparison amplifier 6.

With the above configuration, in the device of the third embodiment, the optical signal output from the electro-absorption optical modulator 7 is
It is converted into an electric signal by the light receiving element 2, amplified by the preamplifier 1, and input to the limiter amplifier 4. At the same time,
The reference potential generation circuit 3 detects the center potential of the amplitude of the output signal of the preamplifier 1 and supplies it to the limiter amplifier 4 as a predetermined reference reference potential.

The reference reference potential obtained by the reference reference potential generation circuit 3 is compared with the reference potential from the reference potential generation circuit 5 in the comparison amplifier 6, and its output attenuates the optical signal in the electroabsorption optical modulator 7. The amount is controlled. Therefore, by controlling the electro-absorption optical modulator 7 so that the attenuation amount of the electro-absorption optical modulator 7 is large when the optical power is large and the attenuation amount is small when the optical power is small, the reference reference potential is reduced. The reference reference potential from the generation circuit 3 is always kept substantially constant (reference potential from the reference potential generation circuit 5).

(D) Description of Fourth Embodiment FIG. 16 is a block diagram showing an optical receiving apparatus as a fourth embodiment of the present invention. In the figure, the same reference numerals as those used above denote the same parts. Therefore, the description thereof will be omitted. This FIG.
The apparatus of the fourth embodiment shown in FIG. 9 also includes a reference potential generating circuit 5, a comparison amplifier 6, and an electroabsorption type optical modulator 7, as in the third embodiment.

In the fourth embodiment, instead of the reference reference potential generation circuit 3 used in the third embodiment, a fixed reference potential is generated as a predetermined reference reference potential and is output to the limiter amplifier 4. The generation circuit 3A is used. Further, a center potential generating circuit (circuit having the same configuration as the standard reference potential generating circuit 3 shown in FIG. 8 or 9) that generates a center potential of the amplitude of the output signal based on the output signal of the preamplifier 1 is provided. The comparison amplifier 6 compares the output signal of the central potential generation circuit 3B with a predetermined reference potential from the reference potential generation circuit 5, amplifies the deviation, and outputs it as a bias voltage of the electroabsorption optical modulator 7. However, the amount of attenuation of the optical signal by the electro-absorption optical modulator 7 is controlled.

With the above-described structure, in the device of the fourth embodiment, the center potential generation circuit 3B generates the center potential of the amplitude of the output signal of the preamplifier 1, and the center potential is used as a reference. The output of the comparison amplifier 6 controls the attenuation amount of the optical signal in the electroabsorption optical modulator 7 so that the potential generation circuit 5 holds the reference potential.

By such control, the power fluctuation of the optical signal received by the light receiving element 2 becomes relatively small,
As in the case of the second embodiment described above, a predetermined reference reference potential for the limiter amplifier 4 is not generated based on the output signal of the preamplifier 1, but a fixed potential is used as the predetermined reference reference potential. be able to. Therefore, also in the fourth embodiment, the fixed reference potential generating circuit 3A for generating the fixed reference potential.
Is used to supply the fixed reference potential to the limiter amplifier 4 as a predetermined reference reference potential.

As shown in FIG. 17, the fixed reference potential generating circuit 3A and the reference potential generating circuit 5 can be used in common, and with such a configuration, the circuit configuration becomes simpler. Can be one. (E) Description of Fifth Embodiment FIG. 18 is a block diagram showing an optical receiving apparatus as a fifth embodiment of the present invention. In the figure, the same reference numerals as those already described denote the same parts, The description is omitted.

The following fifth to eighth embodiments (FIG. 18 to FIG.
In the apparatus shown in FIG. 21), a plurality of sets of optical reception processing units 100 each including a light-receiving element 2, a preamplifier 1 and a limiter amplifier 4 similar to those described above are provided for each of a plurality of channels of optical signals received in parallel. The items provided corresponding to the channels will be described. Now, in the device of the fifth embodiment shown in FIG. 18, the preamplifier 1 in each optical reception processing unit 100 is
Similar to the one shown in FIG. 7, the constant current source 15 is connected to the input FE.
It is configured to be interposed between the gate terminal 10a of T10 and the second power supply 17. Further, as the constant current source 15,
Besides the one shown in FIG. 7, the constant current sources 15A and 15B shown in FIGS. 12 and 13 are used.

Then, the constant current source 15 (or 15 A,
15B) is provided in the preamplifier 1 of each optical reception processing unit 100, a fixed reference potential generation circuit that generates a fixed reference potential as a predetermined reference reference potential and outputs the fixed reference potential to the limiter amplifier 4 in each optical reception processing unit 100 is provided. , A plurality of sets of optical reception processing units 100 can be provided in common. With the configuration described above, in the device of the fifth embodiment, a plurality of sets of optical reception processing units 100 each including the light receiving element 2, the preamplifier 1 and the limiter amplifier 4 are provided in parallel, and optical signals of a plurality of channels are received in parallel. be able to.

In such a configuration, the preamplifier 1 in each optical reception processing section 100 is configured similarly to that of the first embodiment shown in FIG. 7, so that the optical signal power is excessive. However, the output waveform of the preamplifier 1 does not cause waveform distortion due to saturation, and the dynamic range of the preamplifier 1 of each optical reception processing unit 100 is significantly expanded as compared with the conventional case as shown in FIG. .

At this time, as the constant current source 15 in the preamplifier 1, the constant current source 15 shown in FIG.
2. Since the constant current sources 15A and 15B shown in FIG. 13 are used, the threshold voltage of the constant current supply FET (see reference numeral 150 in FIGS. 7, 12, and 13) in each optical reception processing unit 100. A constant drain current can be supplied as a desired constant current regardless of Vth.
The variation in the circuit characteristics of the preamplifier 1 in 00, that is, the variation in the output potential of the preamplifier 1 in each optical reception processing unit 100 can be made extremely small.

Therefore, as described above, the fixed reference potential generation circuit 3A is provided in common to a plurality of sets of optical reception processing units 100, and the fixed reference potential from this fixed reference potential generation circuit is supplied to each optical reception processing unit 100. Can be collectively used as the predetermined reference reference potential of the limiter amplifier 4 in FIG. 1, which contributes to simplification of the circuit configuration. An externally adjustable one may be used as the fixed reference potential generating circuit 3A.

(F) Description of Sixth Embodiment FIG. 19 is a block diagram showing an optical receiving apparatus as a sixth embodiment of the present invention. In the figure, the same reference numerals as those used above denote the same parts. Therefore, the description thereof will be omitted. This FIG.
In the device of the sixth embodiment shown in FIG. 3, a constant current supply FET 150 is provided for each preamplifier 1 of each optical reception processing unit 100, and a monitoring FET 151 having the same characteristics as the constant current supply FET 150 and a level are provided. FE for adjustment
T154 is commonly provided to the constant current supply FET 150 in the preamplifier 1 of the plurality of sets of optical reception processing units 100.

In each constant current supply FET 150, the drain terminal (one input terminal) 150b is connected to the gate terminal 1 of the input FET 10 as in the first embodiment shown in FIG.
0a, source terminal (other signal terminal) 150
c is connected to the second power supply 17 via the resistance element 152, and the gate terminal 150a is connected to the source terminal 154c of the common level adjusting FET 154.

The level adjusting FET 154 is shown in FIG.
Similarly to the first embodiment shown in FIG.
4b is connected to the first power supply 16 and the source terminal 154c
Is connected to the gate terminal 150a of the constant current supply FET 150 and is also connected to the second power supply 17 via the resistance element 155. Furthermore, the monitor FET 151
In the same manner as in the first embodiment shown in FIG. 7, the drain terminal 151b is connected to the first power source 1 via the resistance element 153.
6 and the gate terminal 154a of the level adjusting FET 154, and the source terminal 151c and the gate terminal 151a are connected to the second power supply 17.

The level adjusting FET 154 and the resistance element 155 may be omitted, and the drain terminal 151b of the monitor FET 151 may be directly connected to the gate terminal 150a of the constant current supply FET 150. Also, FE for monitor
As shown in FIGS. 12 and 13, the gate terminal 151a of T151 is connected to the resistance elements 156 and 157 and the variable resistor 159.
You may comprise so that it may be connected to the power supplies 16 and 17 via.

With the above-described structure, in the device of the sixth embodiment, as in the fifth embodiment, in each optical reception processing section 100, a constant drain is provided regardless of the threshold voltage Vth of the constant current supply FET 150. The current can be supplied as a desired constant current, and the variation in the output potential of the preamplifier 1 in each optical reception processing unit 100 can be made extremely small. Therefore, also in the sixth embodiment, as in the fifth embodiment, in order to generate a predetermined reference reference potential for the limiter amplifier 4, a fixed reference potential generation circuit 3A (common to each optical reception processing unit 100 is provided. 18) can be used. Moreover, since the monitoring FET 151 and the level adjusting FET 154 are shared by the plurality of sets of optical reception processing units 100, the circuit configuration can be further simplified.

In the light reception processing unit 100 to which a normal signal (data signal whose mark ratio does not become 1/2) is input, the standard reference potential generating circuit 3 as shown in FIGS. 8 and 9 is used. While a predetermined reference reference potential of the limiter amplifier 4 can be generated, a clock signal as an input signal, or a mark ratio by coding such as a scrambler is approximately 1 /
Optical reception processing unit 10 to which any of the two data signals is input
At 0, an average value detection circuit 33, which will be described later with reference to FIG. 22, can be used to generate a predetermined reference reference potential of the limiter amplifier 4.

(G) Description of Seventh Embodiment FIG. 20 is a block diagram showing an optical receiving apparatus as a seventh embodiment of the present invention. In the figure, the same reference numerals as those used above denote the same parts. Therefore, the description thereof will be omitted. This FIG.
In the device of the seventh embodiment shown in FIG.
In addition, a low level peak potential detecting circuit 30 and an average value detecting circuit 32 similar to those described above are provided. And
The high-level peak potential detection circuit 31A is commonly provided for a plurality of sets of light reception processing units 100.

This high level peak potential detection circuit 31A
Is similar to that of the first embodiment shown in FIG. 9 and has the same circuit configuration as the preamplifier 1 shown in FIG.
The output signal of the output FET 12 when the input signal to the gate terminal 10a of 10 is in the non-input state is detected as the high level peak potential of the output signal of the preamplifier 1 to detect the average value in each optical signal processing unit 100. It is output to the circuit 32.

With the above-mentioned configuration, in the device of the seventh embodiment, in each optical reception processing section 100, the average of the output of the low level peak potential detection circuit 30 and the output of the common high level peak potential detection circuit 31A. The value (that is, the central potential of the amplitude of the output signal of the preamplifier 1) is used as the average value detection circuit 3
2 and outputs the potential to the limiter amplifier 4 as a predetermined reference reference potential.

That is, also in the seventh embodiment, as in the case of the fifth embodiment, since the output amplitude of the preamplifier 1 for each channel is large, circuits for a plurality of channels are provided in parallel in the same IC. Also, the relative variation in the IC chip can be ignored, and the potential of the high-level peak potential detection circuit 31A that gives the reference reference potential can be made common to each channel. As a result, the circuit configuration can be simplified and the power consumption can be further reduced.

(H) Description of Eighth Embodiment FIG. 21 is a block diagram showing an optical receiving apparatus as an eighth embodiment of the present invention. In the figure, the same reference numerals as those used above denote the same parts. Therefore, the description thereof will be omitted. This FIG.
In the device of the eighth embodiment shown in FIG.
00, the output signal of the preamplifier 1 in this optical reception processing unit 100 is input to the optical reception processing unit 100 (for example, the uppermost optical reception processing unit in FIG. 21) to which the data signal of the mark ratio 1/2 is input. Average value detection circuit 3 for detecting the average value of
3, the output signal of the average value detection circuit 33 is commonly used as a predetermined reference reference potential of the limiter amplifiers 4 in the plurality of sets of optical reception processing units 100.

Here, the reference reference potential of the limiter amplifier 4 of each channel is input with a data signal (mark signal generated by scrambling the data with a scrambler or the like) having a mark ratio of 1/2. It can be obtained by the average value detection circuit 33 which receives the output of the preamplifier 1 of the channel. This average value detection circuit 33
22 is, for example, a low-pass filter type circuit including a resistance element 33a and a capacitor 33b, as shown in FIG. The average value detection circuit 33 detects the average value and generates a reference reference potential when a data signal having a mark ratio of 1/2 is input. Therefore, the average reference value is substantially the same as the reference reference potential described above. It functions similarly to the generation circuit 3.

With the configuration described above, in the apparatus of the eighth embodiment, when there is the optical reception processing unit 100 to which the data signal having the mark ratio of 1/2 is input, the optical reception processing unit 1 of that channel is used.
At 00, an average value detection circuit 33 for detecting the average value of the output signal of the preamplifier 1 is provided, so that the output signal of the average value detection circuit 33 is supplied to the limiter amplifiers 4 of the plurality of sets of optical reception processing units 100. It can be commonly used as a predetermined reference potential, and each optical reception processing unit 100 can be used.
The circuit configuration of can be further simplified.

When receiving optical signals of a plurality of channels in parallel, a clock signal is normally input to at least one channel, and there is an optical reception processing unit 100 for receiving and processing the clock signals. If this clock signal is used for the generation of the predetermined reference reference potential by the average value detection circuit 33, the optical reception processing unit 10 for inputting the data signal of the mark ratio 1/2 for the generation of the predetermined reference reference potential.
It is not necessary to separately provide 0, and the device having the configuration of this embodiment can be easily realized.

Furthermore, since the low-pass filter type average value detection circuit 33 can be used, the high level peak potential detection circuit and the low level peak potential detection circuit (FIG. 31,
It is not necessary to use a diode like (see 32),
The error of the standard reference potential can be suppressed to be small. (I) Description of Ninth Embodiment FIG. 23 is a block diagram showing an optical receiving apparatus as a ninth embodiment of the present invention. In the figure, the same reference numerals as those already described denote the same parts, The description is omitted.

The following ninth to eleventh embodiments (see FIG. 23)
25), a plurality of sets of optical reception processing units 100 each including a light receiving element 2, a preamplifier 1, a limiter amplifier 4, and an electroabsorption type optical modulator 7 similar to those described above,
A description will be given of the optical signals of a plurality of channels received in parallel corresponding to each channel. Now, FIG. 23
In the device of the ninth embodiment shown in FIG.
In addition to the light receiving element 2, the preamplifier 1, the limiter amplifier 4, the comparison amplifier 6 and the electro-absorption type optical modulator 7 described above, the center potential of the amplitude of this output signal is determined based on the output signal of the preamplifier 1. A reference reference potential generation circuit 3 (or an average value detection circuit 33 described above with reference to FIG. 22) for generating a predetermined reference reference potential and outputting it to the mitter amplifier 4 is provided.

Further, the reference potential generating circuit 5 for generating a predetermined reference potential to the comparison amplifier 6 in each optical reception processing section 100 is provided in common for a plurality of sets of optical reception processing sections 100. The comparison amplifier 6 in the optical reception processing unit 100 compares the output signal of the reference reference potential generation circuit 3 (or the average value detection circuit 33) with a predetermined reference potential from the common reference potential generation circuit 5, and determines the deviation. The signal is amplified and output as a bias voltage of the electro-absorption optical modulator 7, and the attenuation amount of the optical signal by the electro-absorption optical modulator 7 is controlled.

In the light reception processing unit 100 to which a normal signal (data signal whose mark ratio does not become 1/2) is input, the standard reference potential generating circuit 3 as shown in FIGS. 8 and 9 is used. A predetermined reference reference potential of the limiter amplifier 4 is generated, while a clock signal or, as an input signal,
In the optical reception processing unit 100 to which any one of the data signals having a mark ratio of approximately ½ is input by the encoding of the scrambler or the like, instead of the standard reference potential generation circuit 3, the average value detection circuit described above with reference to FIG. Limiter amplifier 4 using 33
To generate a predetermined standard reference potential of.

With the above-described structure, also in the apparatus of the ninth embodiment, in each optical reception processing section 100, the electroabsorption type optical modulator 7 is used.
The optical signal output from the light receiving element 2 is converted into an electrical signal by the light receiving element 2, amplified by the preamplifier 1 and input to the limiter amplifier 4, and at the same time, by the reference reference potential generation circuit 3 (or the average value detection circuit 33), The center potential of the amplitude is detected based on the output signal of the preamplifier 1 and is supplied to the limiter amplifier 4 as a predetermined reference potential.

By distributing the reference potential generated from the reference potential generation circuit 5 provided in common to each channel, the reference reference potential generation circuit 3 (or the average value detection circuit) in all the optical reception processing units 100. The output of the comparison amplifier 6 (bias voltage) controls the attenuation amount of the optical signal in the electroabsorption optical modulator 7 so that the reference reference potentials obtained in 33) become the same.

(J) Description of Tenth Embodiment FIG. 24 is a block diagram showing an optical receiving apparatus as a tenth embodiment of the present invention. In the figure, the same reference numerals as those used above denote the same parts. Therefore, the description thereof will be omitted. This Figure 2
In the apparatus of the tenth embodiment shown in FIG. 4, each optical reception processing unit 10
0 includes the light receiving element 2, the preamplifier 1, the limiter amplifier 4, and the electroabsorption type optical modulator 7 described above.

Further, of the plurality of sets of optical reception processing units 100, the optical reception processing unit (for example, the uppermost optical reception processing unit in FIG. 24) 100 to which the data signal having the mark ratio of 1/2 is input.
The average value detection circuit 33 (FIG. 22) for detecting the average value of the output signal of the preamplifier 1 in the optical reception processing unit 100.
(Reference) and the output signal of the average value detection circuit 33 and a predetermined reference potential are compared, the deviation is amplified and output as a bias voltage of the electroabsorption optical modulator 7 to output the electroabsorption optical modulator 7.
There is provided a comparison amplifier 6 for controlling the amount of attenuation of the optical signal due to and a reference potential generation circuit 5 for generating a predetermined reference potential for the comparison amplifier 6.

The output signal of the comparison amplifier 6 is converted into the electroabsorption type optical modulator 7 in the plurality of sets of optical reception processing units 100.
Is commonly used as the bias voltage of the optical reception processing units 1 and
It is commonly used as a predetermined reference reference potential of the limiter amplifier 4 in 00. With the above configuration, the tenth
In the apparatus of the embodiment, when there is the optical reception processing unit 100 to which the data signal having the mark ratio of 1/2 is input, the output signal of the preamplifier 1 is output by the average value detection circuit 33 in the optical reception processing unit 100 of the channel. Of the average value detection circuit 33, the comparison amplifier 6 compares the output signal of the average value detection circuit 33 with a predetermined reference potential from the reference potential generation circuit 5, amplifies the deviation, and biases the electroabsorption optical modulator 7. The voltage is output as a voltage, and the attenuation amount of the optical signal by the electro-absorption optical modulator 7 is controlled.

Further, in this embodiment, the attenuation amount of the optical signal by the electroabsorption optical modulator 7 in the optical reception processing units 100 other than the optical reception processing unit 100 to which the data signal having the mark ratio of 1/2 is input is also: It is controlled by the same output (bias voltage) from the comparison amplifier 6. With this configuration, in the case of parallel transmission in which the variation between channels is small, an optical input with almost the same power can be obtained for each channel, so that feedback of the reference reference potential to only one channel is sufficient for all channels. An eye opening can be obtained.
This makes it possible to mount the capacitor in the reference detection circuit 3 outside the IC, reduce the circuit scale, and reduce power consumption.

At this time, the output signal of the average value detection circuit 33 is commonly used as a predetermined reference reference potential of the limiter amplifier 4 in each optical reception processing section 100, so that the circuit configuration of each optical reception processing section 100 is improved. In addition to the simplification, the clock signal is used as the data signal with the mark rate of 1/2, so that it is not necessary to separately provide the optical reception processing unit 100 for inputting the data signal with the mark rate of 1/2, as described above. .

In the structure of the tenth embodiment,
It is possible to use a method in which the optical reception processing unit 100 of the channel provided with the average value detection circuit 33 transmits the clock signal and the optical reception processing units 100 of the other respective channels transmit the respective parallel data signals. In this case, the average value detection circuit 33 can accurately detect the center potential by inputting the clock signal having the mark ratio of 1/2 from the optical reception processing unit 100 of the channel that transmits the clock signal. At this time, the reference potential generating circuit 3 shown in FIGS. 8 and 9 can be used in place of the average value detecting circuit 33 to detect the center potential similarly.

Further, in the optical reception processing section 100 of the channel provided with the average value detection circuit 33, it is possible to transmit the data signal without transmitting the clock signal. , A data signal is coded by a transmission line coding device such as a scrambler into a signal having a mark ratio close to 1/2, and the data signal is received via the preamplifier 1. The circuit 33 (or the standard reference voltage generating circuit 3) can obtain an accurate average value potential.

(K) Description of Eleventh Embodiment FIG. 25 is a block diagram showing an optical receiving apparatus as an eleventh embodiment of the present invention. In the figure, the same reference numerals as those used above denote the same parts. Therefore, the description thereof will be omitted. This Figure 2
In the apparatus of the eleventh embodiment shown in FIG. 5, each optical reception processing unit 10
0 is provided with a light receiving element 2, a preamplifier 1, a limiter amplifier 4, an electroabsorption type optical modulator 7, a comparison amplifier 6 and a reference potential generation circuit 5 similar to those described above, and a plurality of sets of optical reception processing units 100. In the optical reception processing unit (for example, the uppermost optical reception processing unit in FIG. 25) 100 to which a data signal having a mark ratio of ½ is input, the optical reception processing unit 100
The average value detection circuit 33 (see FIG. 22) for detecting the average value of the output signal of the preamplifier 1 in FIG.

Then, the output signal of the average value detection circuit 33 is commonly used as a comparison target with the predetermined reference potential from the reference potential generation circuit 5 in the comparison amplifier 6 in each optical reception processing section 100, and a plurality of signals are used. Optical reception processing unit 1
It is also commonly used as a predetermined reference reference potential of the limiter amplifier 4 in 00. With the above configuration, the first
In the device of the first embodiment, when there is an optical reception processing unit 100 to which a data signal having a mark ratio of 1/2 is input, the output signal of the preamplifier 1 is output by the average value detection circuit 33 in the optical reception processing unit 100. Of the common average value detection circuit 33 and the predetermined reference potential from the reference potential generation circuit 5 for each channel in each optical reception processing unit 100. Thus, a bias voltage different for each channel can be supplied to the electro-absorption optical modulator 7, and the attenuation amount of the optical signal by the electro-absorption optical modulator 7 can be controlled for each channel.

Therefore, when there are variations in the power of the optical signals of the channels transmitted in parallel, it is possible to adjust the attenuation amount of the optical signals by changing the reference voltage according to each signal. Further, similarly to the tenth embodiment, the output signal of the average value detection circuit 33 is commonly used as the predetermined reference reference potential of the limiter amplifier 4 in each optical reception processing section 100, thereby simplifying the circuit configuration. In addition to the above, the optical reception processing unit 100 inputs a data signal with a mark rate of 1/2 by using a clock signal as a data signal with a mark rate of 1/2.
It is not necessary to separately provide.

Also in the eleventh embodiment, the standard reference potential generating circuit 3 shown in FIGS. 8 and 9 may be used in place of the average value detection circuit 33 as in the tenth embodiment. Of course, also in this case, the standard reference potential generating circuit 3 can detect an accurate average value potential. (L) Description of Twelfth Embodiment FIG. 26 is a block diagram showing an optical receiving apparatus as a twelfth embodiment of the present invention. In the figure, the same reference numerals as those already described denote the same parts, The description is omitted.

In the device of the twelfth embodiment shown in FIG. 26, the light receiving element 2, the preamplifier 1, the reference reference potential generating circuit 3 and the limiter amplifier 4 similar to those described above are provided, and the limiter amplifier 4 is provided in the subsequent stage. A differential amplifier 8 and an ECL (Emitter Coupled Logic) output buffer 9 are provided. Here, the differential amplifier 8 includes a pair of FETs 80, which inputs the output signal and the inverted output signal of the limiter amplifier 4 to the gate terminals 80a and 81a, respectively.
81, and the drain terminals (one signal terminal) 80b and 81b of the pair of FETs 80 and 81 are connected to the resistance elements 82 to 8 respectively.
4 is connected to the first power source 16 and the source terminals (the other signal terminal) 8 of the pair of FETs 80 and 81 are connected.
0c and 81c are connected to the second power source 17, and a pair of FEs are connected.
The potential of the drain terminals 80b and 81b of T80 and 81 is output as a differential amplification result.

The ECL output buffer 9 operates by receiving the output signal of the differential amplifier 8 and is composed of a pair of FETs.
It is configured to have a pair of FETs 91 and 92 for receiving the potentials of the drain terminals 80b and 81b of 80 and 81, respectively. The pair of FETs 8 in the differential amplifier 8
0, 81 source terminals 80c, 81c and the second power supply 17
A constant current source 15 is provided between and. The constant current source 15 is composed of a constant current supply FET 150, a monitor FET 151, and a level adjustment FET 154, like the one shown in FIG.

In the constant current supply FET 150, the drain terminal (one signal terminal) 150b is connected to the pair of FETs 80 and 8.
1 is connected to the source terminals (the other signal terminal) 80c and 81c, the source terminal (the other signal terminal) 150c is connected to the second power supply 17 via the resistance element 152, and the gate terminal 150a is set to the level. FET for adjustment 154
Of the source terminal 154c.

The level adjusting FET 154 is shown in FIG.
Similarly to the first embodiment shown in FIG.
4b is connected to the first power supply 16 and the source terminal 154c
Is connected to the gate terminal 150a of the constant current supply FET 150 and is also connected to the second power supply 17 via the resistance element 155. Furthermore, the monitor FET 151
Similarly to the first embodiment shown in FIG. 7, it has the same characteristics as the constant current supply FET 150, and the drain terminal 151b is connected to the first power supply 1 via the resistance element 153.
6 and the gate terminal 154a of the level adjusting FET 154, and the source terminal 151c and the gate terminal 151a are connected to the second power supply 17.

The level adjusting FET 154 and the resistance element 155 may be omitted, and the drain terminal 151b of the monitoring FET 151 may be directly connected to the gate terminal 150a of the constant current supply FET 150. Also, FE for monitor
As shown in FIGS. 12 and 13, the gate terminal 151a of T151 is connected to the resistance elements 156 and 157 and the variable resistor 159.
You may comprise so that it may be connected to the power supplies 16 and 17 via.

With the configuration described above, in the device of the twelfth embodiment, in the differential amplifier 8, between the other signal terminals 80c and 81c of the pair of FETs 80 and 81 and the second power supply 17, shown in FIG. As described above, by interposing the constant current source 15 having the same configuration as that described above, the fluctuation amount of the threshold voltage Vth can be automatically compensated by the gate-source voltage Vgs of the constant current supply FET 150 as described above. Since the desired constant current Ics having a small value change can be supplied, it is possible to suppress the gain change, the output amplitude change, and the output potential change in the differential amplifier 8.
The device of this embodiment has an optimum configuration when an ECL interface is required.

(M) Description of thirteenth embodiment FIG. 27 is a circuit diagram showing the essential parts of an optical receiving apparatus according to the thirteenth embodiment of the present invention. The apparatus of the thirteenth embodiment is shown in FIGS. 17, and is applied to the apparatus shown in FIGS. That is, the electro-absorption optical modulator 7 and the light receiving element 2 used in such a device are integrated circuits (I
C) can be configured as shown in FIG. 27, for example. In FIG. 27, 7A is an electro-absorption optical modulator that constitutes the electro-absorption optical modulator 7, 2 is a light receiving element, and the two elements 7A and 2 are formed on the same substrate.
One P-N junction is integrally configured.

The electro-absorption optical modulator 7A has the structure shown in FIG.
A terminal to which the output voltage (bias voltage V _B ) of the comparison amplifier 6 shown in FIGS. 17 and 23 to 25 is supplied is provided, and the optical input signal from the optical fiber (not shown) is subjected to this electroabsorption optical modulation. When input to the element 70, the optical signal is attenuated according to the bias voltage V _B , and the output optical signal is the light receiving element 2
Is input to the preamplifier 1 shown in FIGS. 15 to 17 and 23 to 25. As a result, the circuit configuration can be downsized and the cost can be reduced.

(N) Description of Fourteenth Embodiment FIG. 28 is a block diagram showing the essential parts of an optical receiving apparatus as a fourteenth embodiment of the present invention. The apparatus of the fourteenth embodiment is shown in FIG.
25 is applied to the device shown in FIG. 25, and as shown in FIG. 28, each optical reception processing unit 10 shown in FIGS.
The electro-absorption optical modulator 7 of No. 0 is interposed between the ribbon fibers 71, 71 to which optical signals of a plurality of channels are input in parallel, and the electro-absorption optical modulator 7 of each of the ribbon fibers 71 is provided. The electro-absorption optical modulator array 72 is integrally formed in parallel with the optical fiber 71a at the same pitch, and the electro-absorption optical modulator array 72 and the ribbon fiber 71 constitute a multi-channel optical attenuator 70. There is.

With the above arrangement, in the device of the fourteenth embodiment, the ribbon fiber 71 is supplied with a multi-channel optical input from one end side (not shown), and the optical signal of each channel is output from the optical fiber 71a. Then, the signals are input to the electroabsorption optical modulator array 72 composed of a plurality of electroabsorption optical modulators 7 for each channel. In this electroabsorption modulator array 72, the bias voltage can be individually adjusted for each modulator of each channel, and after the attenuation amount is adjusted for each channel, the optical signal of each channel is adjusted to the ribbon. It is transmitted through the optical fiber 71a corresponding to each channel provided in the fiber 71, and the attenuation amount of the optical signals of a plurality of channels can be controlled in parallel with such a simple configuration.

[0167]

As described in detail above, according to the optical receiver preamplifier of the present invention, by providing the constant current source, the waveform is not distorted even when the input signal is excessive, and the occurrence of saturation is prevented. It can be prevented and the dynamic range can be expanded, and a sufficient eye opening can be obtained, so it is effective when punching out signals of each channel with a common clock such as parallel transmission, and the circuit scale per channel is small. Therefore, it is possible to group a plurality of channels in parallel in the same IC.

Particularly, by configuring the constant current source so that the variation of the threshold voltage can be automatically compensated by the gate-source voltage of the constant current supply FET, the threshold of the constant current supply FET can be improved. A constant drain current can be supplied as a desired constant current regardless of the value voltage, and variations in the circuit characteristics of the preamplifier can be reliably suppressed. Further, according to the optical receiver of the present invention, by using the preamplifier having the constant current source, the preamplifier can have a high gain, and the reference reference potential generation that gives the reference reference potential of the limiter amplifier is generated. Since the error generated in the circuit can be ignored, the adjustment terminal can be deleted to realize no adjustment, and the circuit scale can be reduced and the power consumption can be reduced.

Further, according to the optical receiver of the present invention, the reference reference potential can be kept constant even in the case of a parallel transmission receiver with a wide dynamic range, and a sufficient eye opening can always be obtained. Further, when the variation in the circuit characteristics is small, it is not necessary to provide the standard reference potential generating circuit for each channel, and it is possible to realize circuit miniaturization, low power consumption, and low cost.

In the optical receiver having the differential amplifier and the ECL output buffer, the differential amplifier is
The fluctuation of the threshold voltage is controlled by the gate of the FET for constant current supply
By providing a constant current source configured to automatically compensate by the source-to-source voltage, it is possible to supply a desired constant current with a small change in current value, so gain change, output amplitude change, and output potential change in the differential amplifier can be suppressed. It can be suppressed and becomes an optimum device for use in the ECL interface.

Furthermore, the two light-receiving elements and the elements forming the electro-absorption optical modulator are formed on the same substrate by two Ps.
By integrally configuring by -N junction, the circuit configuration can be significantly downsized and the cost can be reduced. Furthermore, when a plurality of sets of optical reception processing units each including a light receiving element, a preamplifier, a limiter amplifier, and an electro-absorption optical modulator are provided in parallel, they are integrally formed in parallel with each optical fiber in the ribbon fiber at the same pitch. By interposing the multi-channel optical attenuator between the ribbon fibers, there is also an advantage that the attenuation amounts of optical signals of a plurality of channels can be controlled in parallel with an extremely simple configuration.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of an optical receiving preamplifier of a first invention.

FIG. 2 is a principle configuration diagram of an optical receiving device of a second invention.

FIG. 3 is a principle configuration diagram of an optical receiving device of a third invention.

FIG. 4 is a principle configuration diagram of an optical receiving device of a fourth invention.

FIG. 5 is a graph showing the input / output characteristics of the optical receiving preamplifier of the first invention.

FIG. 6 is a graph showing the characteristics of the electro-absorption optical modulator according to the present invention.

FIG. 7 is a circuit diagram showing an optical receiving preamplifier in the first embodiment of the present invention.

FIG. 8 is a block diagram showing an optical receiving device as a first embodiment of the present invention.

FIG. 9 is a block diagram showing a modification of the reference reference potential generating circuit in the first embodiment.

10A to 10E are graphs showing changes in the output current value with respect to various variations of the constant current source in the optical receiving preamplifier of the present embodiment.

FIG. 11 is a graph for explaining the action of the constant current source in the optical receiving preamplifier of the present embodiment.

FIG. 12 is a circuit diagram showing a first modification of the constant current source in the optical receiving preamplifier of the present embodiment.

FIG. 13 is a circuit diagram showing a second modification of the constant current source in the optical receiving preamplifier of the present embodiment.

FIG. 14 is a block diagram showing an optical receiving device as a second embodiment of the present invention.

FIG. 15 is a block diagram showing an optical receiving device as a third embodiment of the present invention.

FIG. 16 is a block diagram showing an optical receiving device as a fourth embodiment of the present invention.

FIG. 17 is a block diagram showing a modification of the fourth embodiment of the present invention.

FIG. 18 is a block diagram showing an optical receiving device as a fifth embodiment of the present invention.

FIG. 19 is a block diagram showing an optical receiving device as a sixth embodiment of the present invention.

FIG. 20 is a block diagram showing an optical receiving device as a seventh embodiment of the present invention.

FIG. 21 is a block diagram showing an optical receiving device as an eighth embodiment of the present invention.

FIG. 22 is a circuit diagram showing a configuration example of an average value detection circuit in an eighth example.

FIG. 23 is a block diagram showing an optical receiving device as a ninth embodiment of the present invention.

FIG. 24 is a block diagram showing an optical receiving device as a tenth embodiment of the present invention.

FIG. 25 is a block diagram showing an optical receiving device as an eleventh embodiment of the present invention.

FIG. 26 is a block diagram showing an optical receiving device as a twelfth embodiment of the present invention.

FIG. 27 is a circuit configuration diagram showing a main part of an optical receiving device as a thirteenth embodiment of the present invention.

FIG. 28 is a configuration diagram showing a main part of an optical receiving device as a fourteenth embodiment of the present invention.

FIG. 29 is a block diagram showing a conventional optical receiver.

FIG. 30 is a circuit diagram showing a conventional transimpedance type optical receiving preamplifier.

FIG. 31 is a block diagram showing a reference detection circuit in a conventional optical receiver.

32 (a) to 32 (c) are circuit diagrams each showing a configuration of each circuit in the reference detection circuit of FIG.

FIG. 33 is a graph showing an input / output characteristic of a conventional transimpedance type optical preamplifier for optical reception.

[Explanation of symbols]

1 Pre-amplifier for optical reception 2 Light receiving element 3 Reference reference potential generation circuit 3A Fixed reference potential generation circuit 3B Center potential generation circuit 4 Limiter amplifier 5 Reference potential generation circuit 6 Comparison amplifier 7 Electroabsorption optical modulator 7A Electroabsorption light Modulation element 8 Differential amplifier 9 ECL output buffer 10 Input field effect transistor 10a to 13a Gate terminal 10b to 13b Drain terminal (one signal terminal) 10c to 13c Source terminal (other signal terminal) 11 Resistance element 11A For load resistance Field effect transistor (resistive element) 12 Output field effect transistor 13 Resistive element 13A Load resistance field effect transistor (resistive element) 14 Feedback resistor 15, 15A, 15B Constant current source 16 First power supply 17 Second power supply 18 Input Terminal 19 Output terminal 20,21 Diode 30 Low Bell peak potential detection circuit 31, 31A High level peak potential detection circuit 32, 33 Average value detection circuit 33a Resistance element 33b Capacitor 70 Multi-channel optical attenuator 71 Ribbon fiber 71a Optical fiber 72 Electroabsorption optical modulator array 91, 92 Field effect transistor 150 constant current supply field effect transistor 151 monitor field effect transistor 152, 153 resistance element 152A diode 154 level adjusting field effect transistor 150a, 151a, 154a gate terminal 150b, 151b, 154b drain terminal (one signal terminal) 150c, 151c, 154c Source terminal (other signal terminal) 155-158 Resistance element 158A Diode 159 Variable resistor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H04B 10/04 10/06

Claims (29)

[Claims] 1. A current signal obtained by photoelectrically converting an optical signal by a light receiving element is input to a gate terminal (10a), and one signal terminal (10b) is connected to a first power source via a resistance element (11). An input field effect transistor (10) connected to (16) and having the other signal terminal (10c) connected to a second power supply (17); and a gate terminal (12a) connected to the input field effect transistor. (10) is connected to the one signal terminal (10b),
One signal terminal (12b) is connected to the first power source (16), and the other signal terminal (12c) is connected to the second power source (17) via a resistance element (13),
The current signal is amplified to a predetermined voltage signal and output terminal (1
Output field effect transistor (12) output from 9)
And between the gate terminal (10a) of the input field effect transistor (10) and the output terminal (19) of the output field effect transistor (12), and the input field effect transistor (10). A feedback resistor (14) for feeding back and supplying the output signal of the output field effect transistor (12) to the gate terminal (10a) of the output terminal, the gate terminal (10a) of the input field effect transistor (10) and the second Is installed between the power source (17) of
An optical receiving preamplifier, comprising: a constant current source (15) capable of enlarging a change in the amplitude value of the output potential of the output field effect transistor (12) with respect to a change in an optical signal. 2. The constant current source (15) has one signal terminal (150b) connected to the gate terminal (10a) of the input field effect transistor (10) and the other signal terminal (150c). The resistance element (15
A constant current supply field effect transistor (150) connected to the second power supply (17) via 2), and a monitor field effect transistor having the same characteristics as the constant current supply field effect transistor (150). (151)
One of the signal terminals (151b) of the monitoring field effect transistor (151) is connected to the first power source (16) through a resistance element (153) and the constant current is supplied. Terminal (1) of the field effect transistor (150) for
50a), and the other signal terminal (151c) and gate terminal (151a) of the monitoring field effect transistor (151) are connected to the second power supply (17). Item 3. The optical receiver preamplifier according to Item 1. 3. The monitor field effect transistor (15)
The gate terminal (151a) of 1) is connected to the first power supply (16) and the second power supply (17) via two resistance elements, respectively, and the monitoring field effect transistor (151) 3. The other signal terminal (151c) of the above is connected to the second power supply (17) through a resistance element.
A preamplifier for optical reception according to claim 1. 4. The field effect transistor for monitoring (15)
The gate terminal (151a) of 1) is through a variable resistor,
It is connected to the first power supply (16) and the second power supply (17), and the other signal terminal (151c) of the monitor field effect transistor (151) is connected to the second signal terminal (151c) via a resistance element. 3. The power supply (17) according to claim 2, characterized in that
A preamplifier for optical reception according to claim 1. 5. A light receiving element (2) for converting a received optical signal into a current signal, and a preamplifier (1) for amplifying and outputting a current signal from the light receiving element (2) into a predetermined voltage signal. A limiter amplifier (4) that amplifies the output signal of the preamplifier (1) based on a predetermined reference reference potential, and a center potential of the amplitude of the output signal of the preamplifier (1) as the predetermined reference reference potential. And a standard reference potential generation circuit (3, 3A) for generating the output as the output to the limiter amplifier (4), and the preamplifier (1) photoelectrically converts the optical signal by the light receiving element (2). The current signal thus obtained is input to the gate terminal (10a), one signal terminal (10b) is connected to the first power supply (16) via the resistance element (11), and the other signal terminal ( 1
0c) is connected to a second power source (17), and an input field effect transistor (10) is connected to the gate terminal (12a) is connected to the one signal terminal (10b) of the input field effect transistor (10). Is
One signal terminal (12b) is connected to the first power source (16), and the other signal terminal (12c) is connected to the second power source (17) via a resistance element (13),
An output field effect transistor (12) for amplifying and outputting the current signal into a predetermined voltage signal, a gate terminal (10a) of the input field effect transistor (10), and an output of the output field effect transistor (12). A feedback resistor (14) provided between the terminal (19) and for feeding back and supplying the output signal of the output field effect transistor (12) to the gate terminal (10a) of the input field effect transistor (10). And between the gate terminal (10a) of the input field effect transistor (10) and the second power supply (17),
An optical receiving device comprising a constant current source (15) capable of expanding a change in the amplitude value of an output potential of the output field effect transistor (12) with respect to a change in an optical signal. 6. A high level peak potential detection circuit for detecting the high level peak potential of the output signal of the preamplifier (1) by the reference reference potential generation circuit (3), and the preamplifier (1). A low level peak potential detection circuit for detecting the low level peak potential of the output signal, and the peak potentials respectively detected by these high level peak potential detection circuit and low level peak potential detection circuit are averaged, and the averaged result is 6. An average value detection circuit which outputs the predetermined reference reference potential to the limiter amplifier (4).
The optical receiver described. 7. The high level peak potential detection circuit is constituted by the same circuit as the preamplifier (1), and the gate terminal (10a) of the input field effect transistor (10) in the high level peak potential detection circuit. ), The output field-effect transistor (1
7. The optical receiving device according to claim 6, wherein the output signal of 2) is output to the average value detection circuit as a high level peak potential. 8. The limiter amplifier, wherein the reference reference potential generating circuit generates a fixed reference potential as the predetermined reference reference potential when receiving an optical signal whose power is adjusted by the automatic power adjustment circuit on the optical transmission side. The optical receiving device according to claim 5, wherein the optical receiving device is configured as a fixed reference potential generating circuit (3A) for outputting to (4). 9. The constant current source (15) has one signal terminal connected to the input field effect transistor (1).
0) gate terminal (10a) and the other signal terminal through a resistance element to the second power supply (17).
A field effect transistor for constant current supply connected to the field effect transistor, and a monitor field effect transistor having the same characteristics as the field effect transistor for constant current supply, wherein one signal terminal of the monitor field effect transistor is
It is connected to the first power supply (16) through a resistance element and is also connected to the gate terminal of the constant current supply field effect transistor, and the other signal terminal and gate terminal of the monitoring field effect transistor are The optical receiving device according to claim 5, wherein the optical receiving device is connected to the second power supply (17). 10. An electro-absorption optical modulator (7) for attenuating a received optical signal according to a bias voltage and then inputting it to the light receiving element (2), and a standard reference potential generating circuit (3). The output signal of the average value detection circuit is compared with a predetermined reference potential, the deviation is amplified and output as a bias voltage of the electroabsorption optical modulator (7), and the electroabsorption optical modulator (7) is output. A comparison amplifier (6) for controlling the attenuation amount of the optical signal by the reference amplifier, and a reference potential generation circuit (5) for generating the predetermined reference potential for the comparison amplifier (6) and outputting it to the comparison amplifier (6). The optical receiver according to claim 6, further comprising: 11. An electro-absorption optical modulator (7) for attenuating a received optical signal according to a bias voltage and inputting the attenuated optical signal to the light receiving element (2) is provided, and the reference reference potential generating circuit is provided with: A fixed reference potential generating circuit (3A) that generates a fixed reference potential as the predetermined reference reference potential and outputs it to the limiter amplifier (4), and outputs the output signal based on the output signal of the preamplifier (1). Potential generation circuit (3B) for generating the central potential of the amplitude of
And an output signal of the central potential generation circuit (3B) and a predetermined reference potential are compared, the deviation is amplified and output as a bias voltage of the electroabsorption optical modulator (7), A comparison amplifier (6) for controlling the amount of attenuation of an optical signal by a modulator (7), and a reference potential generation for generating the predetermined reference potential for the comparison amplifier (6) and outputting it to the comparison amplifier (6). An optical receiver according to claim 5, characterized in that it is provided with a circuit (5). 12. The optical receiving device according to claim 11, wherein the fixed reference potential generating circuit (3A) also serves as the reference potential generating circuit (5). 13. A light receiving element (2) for converting a received optical signal into a current signal, and a preamplifier (1) for amplifying and outputting a current signal from the light receiving element (2) into a predetermined voltage signal.
A plurality of sets of optical reception processing units (100) each including a limiter amplifier (4) for amplifying an output signal of the preamplifier (1) based on a predetermined reference reference potential are provided in parallel, and each of the optical reception processing units described above is provided. The current signal obtained by the preamplifier (1) in (100) photoelectrically converting the optical signal by the light receiving element (2) is input to the gate terminal (10a), and one signal terminal (10b) is input. It is connected to the first power supply (16) through the resistance element (11) and the other signal terminal (1
0c) is connected to a second power source (17), and an input field effect transistor (10) is connected to the gate terminal (12a) is connected to the one signal terminal (10b) of the input field effect transistor (10). Is
One signal terminal (12b) is connected to the first power source (16), and the other signal terminal (12c) is connected to the second power source (17) via a resistance element (13),
An output field effect transistor (12) for amplifying and outputting the current signal into a predetermined voltage signal, a gate terminal (10a) of the input field effect transistor (10), and an output of the output field effect transistor (12). A feedback resistor (14) provided between the terminal (19) and for feeding back and supplying the output signal of the output field effect transistor (12) to the gate terminal (10a) of the input field effect transistor (10). And between the gate terminal (10a) of the input field effect transistor (10) and the second power supply (17),
An optical receiving device comprising a constant current source (15) capable of expanding a change in the amplitude value of an output potential of the output field effect transistor (12) with respect to a change in an optical signal. 14. The constant current source (15) has one signal terminal connected to the input field effect transistor (1).
0) gate terminal (10a) and the other signal terminal through a resistance element to the second power supply (17).
A field effect transistor for constant current supply connected to the field effect transistor, and a monitor field effect transistor having the same characteristics as the field effect transistor for constant current supply, wherein one signal terminal of the monitor field effect transistor is
It is connected to the first power supply (16) through a resistance element and is also connected to the gate terminal of the constant current supply field effect transistor, and the other signal terminal and gate terminal of the monitoring field effect transistor are Optical receiver according to claim 13, characterized in that it is connected to the second power supply (17). 15. A fixed reference potential generating circuit, which generates a fixed reference potential as the predetermined reference reference potential and outputs the fixed reference potential to the limiter amplifier (4) in each of the optical reception processing sections (100), comprises: The optical receiving device according to claim 14, wherein the optical receiving device is provided in common to the reception processing unit (100). 16. The constant current source (15) is provided for each of the optical reception processing sections (100), and one signal terminal thereof is used as a gate terminal (10a) of the input field effect transistor (10). A constant current supply field-effect transistor connected to the second power supply (17) through a resistance element and connected to the other signal terminal, and has the same characteristics as the constant current supply field-effect transistor. , A monitoring field-effect transistor common to the plurality of sets of optical reception processing units (100), and one signal terminal of the monitoring field-effect transistor is
It is connected to the first power source (16) through a resistance element and is also connected to the gate terminal of each of the constant current supplying field effect transistors, and the other signal terminal and gate terminal of the monitoring field effect transistor. Is connected to the second power supply (17). 17. The optical reception processing unit (100),
The preamplifier (1) is provided with a low level peak potential detecting circuit for detecting a low level peak potential, and has the same circuit configuration as the preamplifier (1). A high level peak potential detection circuit for detecting the output signal of the output field effect transistor when the input signal to the gate terminal is in a non-input state as the high level peak potential of the output signal of the preamplifier (1),
The optical reception processing units (100) are commonly provided to the plural sets of optical reception processing units (100), and the optical reception processing units (100) are provided with the low level peak potentials detected by the low level peak potential detection circuits. An average value detection circuit for averaging the common high level peak potentials detected by the high level peak potential detection circuit and outputting the averaged result as the predetermined reference reference potential to the limiter amplifier (4) is provided. The optical receiving device according to claim 13, wherein the optical receiving device comprises: 18. The plurality of sets of optical reception processing units (100)
An average value detection circuit for detecting the average value of the output signals of the preamplifier (1) in at least one optical reception processing unit to which a data signal having a mark ratio of 1/2 is input. (33) is provided, and the output signal of the average value detection circuit (33) is commonly used as the predetermined reference reference potential of the limiter amplifiers (4) in the plurality of sets of optical reception processing units (100). 14. The optical receiving device according to claim 13, wherein: 19. The optical receiving apparatus according to claim 18, wherein the data signal having the mark rate of 1/2 is a clock signal. 20. An electro-absorption optical modulator (7), which receives the optical signal received by each of the optical reception processing units (100) after being attenuated in accordance with a bias voltage and then input to the light receiving element (2).
And a reference reference potential generation circuit (3) that generates a center potential of the amplitude of the output signal as the predetermined reference reference potential based on the output signal of the preamplifier (1) and outputs the reference potential to the limiter amplifier (4). ) And an output signal of the reference reference potential generating circuit (3) and a predetermined reference potential are compared, the deviation is amplified and output as a bias voltage of the electroabsorption optical modulator (7), A comparison amplifier (6) for controlling the amount of attenuation of the optical signal by the optical modulator (7), and the predetermined reference potential to the comparison amplifier (6) in each of the optical reception processing units (100). 14. The optical receiving device according to claim 13, wherein a reference potential generating circuit (5) for generating is provided in common to the plurality of sets of optical reception processing units (100). 21. Each of the optical reception processing units (100),
An electro-absorption optical modulator (7) for attenuating the received optical signal according to a bias voltage and inputting it to the light receiving element (2) is provided, and among the plurality of sets of optical reception processing units (100) , An average value detection circuit (33) for detecting the average value of the output signal of the preamplifier (1) in at least one optical reception processing unit to which a data signal having a mark rate of 1/2 is input. ) And the output signal of the average value detection circuit (33) and a predetermined reference potential are compared, the deviation is amplified and output as a bias voltage of the electro-absorption type optical modulator (7), A comparison amplifier (6) for controlling the amount of attenuation of the optical signal by the optical modulator (7) and a reference potential generation circuit (5) for generating the predetermined reference potential to the comparison amplifier (6) are provided. The output signal of the comparison amplifier (6) is The set of the light reception processing unit electric field absorption type optical modulator in (100) (7)
14. The optical receiving device according to claim 13, wherein the optical receiving device is commonly used as a bias voltage of the optical receiver. 22. The output signal of the average value detection circuit (33) is commonly used as the predetermined reference reference potential of the limiter amplifier (4) in the plurality of sets of optical reception processing sections (100). The optical receiving device according to claim 21, which is characterized in that: 23. The optical receiving apparatus according to claim 21, wherein the data signal having the mark ratio of 1/2 is a clock signal. 24. The plurality of sets of optical reception processing units (100)
An average value detection circuit for detecting the average value of the output signals of the preamplifier (1) in at least one optical reception processing unit to which a data signal having a mark ratio of 1/2 is input. (33) is provided, and each of the optical reception processing units (100) attenuates a received optical signal according to a bias voltage and then inputs the attenuated optical signal to the light receiving element (2) ( 7)
And an output signal of the average value detection circuit (33) is compared with a predetermined reference potential, the deviation thereof is amplified and output as a bias voltage of the electro-absorption optical modulator (7). A comparison amplifier (6) for controlling the amount of attenuation of the optical signal by the modulator (7), and a reference potential for generating the predetermined reference potential to the comparison amplifier (6) in each of the optical reception processing units (100). Optical receiver according to claim 13, characterized in that it is provided with a generating circuit (5). 25. The output signal of the average value detection circuit (33) is commonly used as the predetermined reference reference potential of the limiter amplifier (4) in the plurality of sets of optical reception processing sections (100). The optical receiving device according to claim 24, which is characterized in that: 26. The optical receiver according to claim 25, wherein the data signal having the mark ratio of 1/2 is a clock signal. 27. A light receiving element (2) for converting a received optical signal into a current signal, and a preamplifier (1) for amplifying and outputting a current signal from the light receiving element (2) into a predetermined voltage signal, A limiter amplifier (4) for amplifying the output signal of the preamplifier (1) based on a predetermined reference reference potential, and a gate terminal (80a, 81a) for the output signal and the inverted output signal of the limiter amplifier (4), respectively. A pair of field effect transistors (80, 81) input to
One signal terminal (80b, 81b) of the pair of field effect transistors (80, 81) is connected to a resistance element (82-84).
Is connected to the first power source (16) via the other, and the other signal terminals (80c, 81c) of the pair of field effect transistors (80, 81) are connected to the second power source (17). A differential amplifier (8) for outputting the potential of one of the signal terminals (80b, 81b) of the pair of field effect transistors (80, 81) as a differential amplification result, and an output signal of the differential amplifier (8). Working ECL
An output buffer (9), and the other signal terminals (80c, 81) of the pair of field effect transistors (80, 81) in the differential amplifier (8).
c) and the second power source (17), a constant current source (1
5) is interposed, and the constant current source (15) connects one signal terminal (150b) to the other signal terminal (80c, 80) of the pair of field effect transistors (80, 81).
81c) and the other signal terminal (15
0c) via the resistance element (152) to the second power source (1
Constant current supply field effect transistor (150) connected to 7), and a monitor field effect transistor (151) having the same characteristics as the constant current supply field effect transistor (150).
One of the signal terminals (151b) of the monitoring field effect transistor (151) is connected to the first power source (16) through a resistance element (153) and the constant current is supplied. Terminal (1) of the field effect transistor (150) for
50a), and the other signal terminal (151c) and gate terminal (151a) of the monitoring field effect transistor (151) are connected to the second power supply (17). Receiver. 28. A light receiving element (2) for converting a received optical signal into a current signal, and a preamplifier (1) for amplifying and outputting a current signal from the light receiving element (2) to a predetermined voltage signal. A limiter amplifier (4) that amplifies the output signal of the preamplifier (1) based on a predetermined reference reference potential, and attenuates the received optical signal according to a bias voltage before inputting it to the light receiving element (2). And an element constituting the electro-absorption optical modulator (7) are formed on the same substrate. An optical receiving device, characterized in that the optical receiving device is integrally configured by N-junction. 29. A light receiving element (2) for converting a received optical signal into a current signal, and a preamplifier (1) for amplifying and outputting a current signal from the light receiving element (2) to a predetermined voltage signal.
A limiter amplifier (4) that amplifies an output signal of the preamplifier (1) based on a predetermined reference reference potential, and a received optical signal is attenuated according to a bias voltage and then input to the light receiving element (2). A plurality of optical reception processing units (100) each including an electro-absorption optical modulator (7) for parallel operation, wherein the electro-absorption optical modulators (7) in the respective optical reception processing units (100) are A multi-channel, which is interposed between ribbon fibers to which optical signals of a plurality of channels are input in parallel, and in which a plurality of the electro-absorption optical modulators are integrally formed in parallel with each optical fiber in the ribbon fiber at the same pitch. An optical receiver, which is configured as an optical attenuator.