JP6706105B2 - Transimpedance amplifier and optical signal receiver - Google Patents

Description

The present invention relates to a transimpedance amplifier and an optical signal receiving device that receive a current signal output from a photoelectric conversion element, convert it into a single-phase voltage signal, and convert it into a differential signal whose phase is mutually inverted and output the differential signal. Related to technology for improving performance.

An optical signal receiving device that constitutes a receiving unit of an optical communication device receives an intensity-modulated optical signal by a photoelectric conversion element such as a photodiode, and a signal whose current value changes from the photoelectric conversion element according to the intensity of input light. (Current signal) is converted into a single-phase voltage signal, and the single-phase voltage signal is inverted into two phases to facilitate connection with the subsequent differential type processing circuit or transmission line. The voltage signal is converted and output.

A circuit having the current-voltage conversion function and the conversion output function of converting into two-phase voltage signals is generally called a transimpedance amplifier (hereinafter referred to as TIA).

FIG. 8 shows a conventional configuration example of the TIA.
This TIA receives a current signal Iin output from a photoelectric conversion element such as a photodiode by a current-voltage conversion circuit (hereinafter referred to as an IV circuit) 11, and a voltage proportional to the magnitude of the current signal Iin. Is converted into a single-phase voltage signal Vin.

Here, the IV circuit 11 is configured to feed back the output signal of the inverting amplifier 11a to the input terminal via the feedback resistor R, and the resistance value of the feedback resistor R is greater than the input impedance of the amplifier 11a. If high enough, the voltage signal Vin is approximately represented as:
Vin=-Iin・R

By inputting this single-phase voltage signal Vin to one input terminal of the differential amplifier circuit 12 and inputting a DC reference voltage Vref to the other input terminal, the two output terminals of the differential amplifier circuit 12 are It is possible to output voltage signals Vout(+) and Vout(-) having a magnitude substantially proportional to the differential input (Vin-Vref) and having mutually inverted phases.

Here, if there is a difference between the average potential of the voltage signal Vin and the reference voltage Vref, the difference in the direct current component is amplified, so that the operating points of the pair of differential transistors forming the differential amplifier circuit 12 are from normal regions. As a result, the output signal is deviated and the output signal is reduced in amplitude or distorted.

Therefore, in this circuit example, the low-pass filter (LPF) 13 extracts the average potential Vave, which is the DC component of the voltage signal Vin, and inputs this to the differential amplifier circuit 12 as the reference voltage Vref.

The TIA having the above configuration is disclosed in Patent Document 1, for example. In Patent Document 1, the current-voltage conversion circuit is called a "transimpedance amplifier" and the entire circuit including the differential amplifier circuit is an optical signal receiving circuit. However, in the present invention, the current-voltage conversion circuit and the differential circuit are used. The entire circuit including the amplifier circuit will be called TIA.

JP, 2007-243510, A

In the above-described conventional TIA, a single-phase voltage signal Vin is input to one input terminal of the differential amplifier circuit 12, and a DC voltage Vref equal to the average potential of the voltage signal Vin is input to the other input terminal to amplify the signal. Therefore, the operation of the pair of differential transistors forming the differential amplifier circuit 12 is not completely symmetrical, and depending on the circuit configuration, the amplitude of the output voltage signals Vout(+) and Vout(-) may vary. Are not equal.

That is, the differential amplifier circuit 12 generally includes load resistors R1 and R2 having the same resistance value between the collectors of the pair of differential transistors Tr1 and Tr2 and the power supply Vcc on the high potential side, as shown in FIG. It has a configuration in which the emitters are connected to each other via resistors R3 and R4 having the same resistance value, and the connection point is connected to a power source on the low potential side via a common resistor R5 (or a constant current source). By applying the signals IN(+) and IN(-) to the bases of the transistors Tr1 and Tr2, two signals, an in-phase signal and an in-phase signal, which are proportional to the difference signal [IN(+)-IN(-)] Vout(+) and Vout(-) are output.

When a single-phase voltage signal Vin is input to one input terminal of the differential amplifier circuit and a DC voltage Vref equal to the average potential of Vin is input to the other input terminal, the current source of the differential amplifier circuit is With an ideal constant current source, the two transistors Tr1 and Tr2 perform amplifying operations in a substantially symmetrical manner, and the output signals Vout(+) and Vout(-) have substantially the same amplitude.

On the other hand, as shown in Patent Document 1, in order to obtain a high dynamic range with a low power supply voltage, it is effective to use a resistor as a current source of the differential amplifier circuit as shown in FIG. When a single-phase voltage signal Vin is input to one input terminal and a DC voltage Vref equal to the average potential of Vin is input to the other input terminal of the differential amplifier circuit having various circuit configurations, the output signal Vout(+) , Vout(-) have different amplitudes.

That is, in the differential amplifier circuit in which the current source is configured by the resistor, the constant current operation is not sufficiently performed, the common mode gain of the differential amplifier circuit is not suppressed, and the current flowing in the current source resistor depends on the state of the voltage signal Vin. Because of the change, the current of the current source resistance increases when Vin is high level, and the current of the current source resistance decreases when Vin is low level. This acts so as to emphasize the amplitude change of the output signal Vout(+), and causes asymmetry in which the amplitude of Vout(+) becomes larger than the amplitude of Vout(-), which causes signal distortion.

In Patent Document 1, a constant power source of the differential amplifier circuit is replaced with a resistor in order to maximize the amplitude of the voltage signal output from the current-voltage conversion circuit using a single power supply of about 3 volts. As a means for improving the asymmetry of the output waveform, the output of this differential amplifier circuit is limited by another differential amplifier circuit to shape the waveform, but multi-level modulation such as pulse amplitude modulation is used. In optical communication, the TIA is required to have a function of linearly amplifying a signal, so that the above means cannot be applied to the TIA for the above applications.

Even when the current source of the differential amplifier circuit is an ideal constant current source, the single-phase voltage signal Vin is input to one input terminal of the differential amplifier circuit and Vin of the other input terminal is input. In the configuration in which the DC voltage Vref equal to the average potential is input and the signal is amplified, the operation of the pair of differential transistors forming the differential amplifier circuit is not completely symmetrical, so that the two output signals are phased in the high frequency region. A shift occurs, which is a cause of signal quality deterioration.

Further, in the conventional TIA described above, a single-phase voltage signal Vin is input to one input terminal of the differential amplifier circuit 12, and a DC voltage Vref equal to the average potential of the voltage signal Vin is input to the other input terminal. Since the configuration is such that the input signal is amplified, the TIA having a configuration in which the differential signals whose phases are inverted to each other are input to the two input terminals of the differential amplifier circuit 12 cannot obtain a high gain, and the S of the receiving section is not obtained. The /N ratio could not be increased.

The present invention solves the above problems and provides a TIA capable of outputting differential signals with equal amplitude and good symmetry without phase shift, capable of linear operation, and having high gain, and an optical signal receiving apparatus using the same. The purpose is to do.

In order to achieve the above object, the transimpedance amplifier according to claim 1 of the present invention comprises:
A current-voltage conversion circuit (21) for converting an input current signal into a single-phase voltage signal,
A phase for receiving a single-phase voltage signal output from the current-voltage conversion circuit at the first terminal of the transistor and outputting two-phase voltage signals whose phases are inverted from each other from the second terminal side and the third terminal side of the transistor. A dividing circuit (22),
A level matching circuit (23) for receiving the two-phase voltage signals output from the phase division circuit and outputting the combined average potentials of the two-phase voltage signals;
The inverting input terminal receives one of the two-phase voltage signals whose average potentials have been adjusted by the level adjusting circuit and the other non-inverting input terminal, and amplifies the difference component of the two-phase voltage signals input to the two input terminals. And a differential amplifier circuit (24) for outputting the amplified signal from the inverting output terminal and the non-inverting output terminal as signals whose phases are mutually inverted ,
The current-voltage conversion circuit includes an inverting amplifier (21a) and a feedback resistor (R), and the input current signal is input to an input terminal of the inverting amplifier and output from the inverting amplifier. Is fed back to the input terminal of the inverting amplifier via the feedback resistor .

Further, in the transimpedance amplifier according to claim 1 of the present invention,
A transistor forming the phase dividing circuit is a bipolar transistor in which the first terminal is a base, the second terminal is a collector, and the third terminal is an emitter, or the first terminal is a gate and the second terminal is a drain. The third terminal is any one of a field effect transistor of a source.

Further, in the transimpedance amplifier according to claim 1 of the present invention,
The level matching circuit,
A level shift circuit (23a) for reducing the average potential of the voltage signal output from the second terminal side of the transistor of the phase division circuit by a predetermined voltage by utilizing the forward voltage drop of the transistor or diode. It is characterized by being

Further, in the transimpedance amplifier according to claim 1 of the present invention,
The level matching circuit,
A level shift circuit (23b) for increasing the average potential of the voltage signal output from the third terminal side of the transistor of the phase division circuit by a predetermined voltage by utilizing the forward voltage drop of the transistor or diode. It is characterized by being

The transimpedance amplifier according to claim 2 of the present invention is the transimpedance amplifier according to claim 1 ,
The level matching circuit,
An error compensating voltage generator (23c) for generating an error compensating voltage capable of voltage variation by manual operation is provided, and the error compensating voltage is at least one of two phase voltage signals output from the phase dividing circuit, or It is characterized in that it is superimposed on at least one of the two-phase voltage signals input to the differential amplifier circuit to reduce the error of the average potential of the two-phase voltage signals.

The transimpedance amplifier according to claim 3 of the present invention is the transimpedance amplifier according to claim 1 or 2 .
The level matching circuit,
The difference between the average potentials of the two-phase voltage signals input to the differential amplifier circuit or the difference between the average potentials of the two-phase voltage signals output from the differential amplifier circuit is detected and the difference is reduced. Has an error voltage detection circuit (23e) for obtaining an error compensation voltage necessary for that, and inputs the error compensation voltage to at least one of the two-phase voltage signals output from the phase division circuit or to the differential amplifier circuit. The difference between the average potentials is reduced by superimposing it on at least one of the two-phase voltage signals.

The optical signal receiving device according to claim 4 of the present invention is
A photoelectric conversion element (1) that receives an optical signal and outputs a current signal;
An optical signal receiving device having a transimpedance amplifier (20) for receiving a current signal output from the photoelectric conversion element,
The transimpedance amplifier, characterized in that it is a transimpedance amplifier according to any one of claims 1-3.

As described above, in the TIA of the present invention, the single-phase voltage signal output from the current-voltage conversion circuit is applied to the first terminal of the transistor of the phase division circuit, and the phases are inverted from each other from the second terminal side and the third terminal side. The two-phase voltage signals are output, the average potentials of the two-phase voltage signals are adjusted by the level adjustment circuit, and then applied to the differential amplifier circuit.

Therefore, the differential amplifier circuit receives the voltage signals whose average potentials are equalized and whose phases are inverted to each other. Therefore, a symmetrical two-phase voltage signal having the same amplitude is output from the differential amplifier circuit. Since the gain can be obtained and there is no need to limit the signal for waveform shaping as in the conventional case, a TIA capable of linear operation can be realized.

Further, by applying the present invention to the TIA of the optical signal receiving device, it becomes possible to receive with a high S/N ratio even if the attenuation of the optical signal input to the photoelectric conversion element in the transmission path is large, and the long distance can be achieved. Optical communication becomes possible.

Configuration diagram of an embodiment of the present invention The figure which shows the example of a circuit of the principal part of embodiment of this invention. The figure which shows the example of a circuit of the principal part of embodiment of this invention. The figure which shows another circuit example of the principal part of embodiment of this invention. The figure which shows another circuit example of the principal part of embodiment of this invention. The figure which shows the characteristic of embodiment of this invention and a conventional circuit. The figure which shows the characteristic of embodiment of this invention and a conventional circuit. Diagram showing conventional circuit Diagram showing a circuit example of a differential amplifier circuit

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows the configuration of an optical signal receiving device including a TIA 20 and a photoelectric conversion element 1 to which the present invention is applied.

In FIG. 1, a current-voltage conversion circuit 21 converts an input current signal Iin into a single-phase voltage signal Vin, and basically, it feeds back between the input terminal and the output terminal of the inverting amplifier 21a. The resistor R is connected so that a current equal to the input current signal Iin flows from the output terminal to the input terminal, and a single-phase voltage signal Vin equal to -Iin·R is output from the output terminal. ..

The single-phase voltage signal Vin is input to the phase division circuit 22. The phase dividing circuit 22 converts the input single-phase voltage signal Vin into two-phase voltage signals Va(-) and Vb(+) whose phases are mutually inverted.

The phase division circuit 22 can be configured by using a bipolar transistor or a field effect transistor (FET), and FIG. 2 shows a circuit example using a bipolar transistor.

The circuit of FIG. 2A has a configuration in which the voltage signal Vin is applied to the base (first terminal) of the transistor Tr11, and resistors R11 and R12 are connected to the collector (second terminal) and the emitter (third terminal), A voltage signal Va(-) whose phase is inverted with respect to the voltage signal Vin is output from the collector side, and a voltage signal Vb(+) in phase with the voltage signal Vin is output from the emitter side.

Further, instead of the transistor Tr1 shown in FIG. 2A, a cascode circuit including two transistors Tr12 and Tr13 may be used as shown in FIG. 2B. In the case of this configuration, the transistor Tr13 forming a base-grounded amplifier circuit is connected between the collector (second terminal) of the transistor Tr12 that receives the voltage signal Vin at the base (first terminal) and the load resistor R11. The bias voltage Vbb is applied to the base of the transistor Tr13. In the case of this circuit, the voltage signal Vin is received at the base (first terminal) of the transistor Tr12, and the voltage signal Vin is received from the collector side of the transistor Tr13 connected to the transistor Tr12 and the emitter side (third terminal) of the transistor Tr12. The signals of the opposite phase and the same phase are output with respect to.

In this way, when the voltage signals whose phases are inverted to each other are generated by the phase dividing circuit 22 using transistors, a difference occurs in the average potentials of the output two-phase voltage signals Va(-) and Vb(+). For example, in the configuration shown in FIG. 2A, since there is usually a potential difference ΔV of about 1 to 2 V between the collector voltage and the emitter voltage of the transistor Tr11 in the normal operating range, this potential difference ΔV is two phases. Appears as the difference between the average potentials of the voltage signals Va(-) and Vb(+). If the voltage signals Va(-) and Vb(+) having the potential difference ΔV are applied as they are to the differential amplifier circuit 24, which will be described later, the potential difference ΔV is also amplified and expanded and output. Therefore, in a power supply of about 3V generally used in optical communication devices, the operating points of the pair of differential transistors forming the differential amplifier circuit 24 become unbalanced and deviate from the normal range, resulting in an output signal. Amplitude will be reduced and distortion will occur.

Therefore, in this embodiment, the two-phase voltage signals Va(-) and Vb(+) output from the phase division circuit 22 are received, and the average potentials of the voltage signals Va(-) and Vb(+) are adjusted. A level matching circuit 23 for outputting the output is provided.

Various methods can be considered as the level matching circuit 23. As one of the methods, of the two-phase voltage signals Va(-) and Vb(+), the one having the higher average potential (Va(-) in the above circuit example) is supplied by the first level shift circuit 23a. For example, it shifts to the lower side by ΔV/2, and conversely, the voltage signal of the lower average potential (Vb(+) in the above circuit example) is shifted to the higher side by ΔV/2 by the second level shift circuit 23b. The difference ΔV between the average potentials of the two voltage signals Va(−) and Vb(+) is set to almost zero and the result is output.

More specifically, as shown in FIG. 3, the first shift circuit 23a is formed by an emitter follower circuit using a transistor Tr21 and an emitter resistor R21, and a voltage signal Va(-) is applied to the base of the transistor Tr21. The voltage signal Va(-)' shifted to the lower side by the voltage drop between the base and the emitter of the transistor Tr21 (≈ΔV/2) is output from the emitter. It is also possible to connect a diode instead of the transistor Tr21 of this emitter follower circuit, apply the voltage signal Va(-) to the anode side, and shift to the lower side by the forward voltage drop of the diode to output.

The second shift circuit 23b is composed of a diode D21 and a resistor R22 connected between the anode side of the diode D21 and the power source Vcc on the high potential side, and the voltage signal Vb is applied to the cathode side of the diode D21. (+) is applied, and the voltage signal Vb(+)' shifted to the higher side by the amount of the forward voltage drop of the diode D21 (≈ΔV/2) is output from the anode side.

As described above, of the two-phase voltage signals, the one with the higher average potential is shifted lower, the one with the lower average potential is shifted higher, and the average potentials of the two voltage signals are combined to obtain the inverting input of differential amplifier circuit 24. By inputting to the terminals and the non-inverting input terminals, the operating points of the pair of differential transistors forming the differential amplifier circuit 24 can be balanced.

It should be noted that only the voltage signal with the higher average potential (Va(-) in the above circuit example) is shifted to the lower side by approximately ΔV to match the voltage signal with the lower average potential, or vice versa. It is also possible to adopt a method in which only the lower voltage signal (Vb(+) in the above circuit example) is shifted to the higher side by approximately ΔV and matched with the higher average voltage signal Va(-). When these methods are adopted, the voltage shift by the transistors and diodes of the first shift circuit 23a and the second shift circuit 23b may be a two-stage configuration.

In the above-described embodiment, the case where the voltage to be shifted is fixed has been described as the level matching circuit. However, when it is desired to more accurately match the average potentials of the two-phase voltage signals, for example, as shown in FIG. An error compensation voltage generator 23c capable of varying the voltage is provided, and the error compensation voltage E is supplied to at least the voltage signals Va(-) and Vb(+) via the error voltage application circuit 23d including a resistance coupling circuit. On the other hand, it is superposed (either addition or subtraction is possible) on at least one of the voltage signals Va(-)' and Vb(+)'. Thereby, the average potentials of the two-phase voltage signals input to the differential amplifier circuit 24 or the two-phase voltage signals output from the differential amplifier circuit 24 can be accurately matched.

Further, as shown in FIG. 5, an error voltage detection circuit 23e for automatically detecting the error voltage of the average potential is provided, and the error compensation voltage E is applied so as to reduce the detected error voltage. It is input to the differential amplifier circuit 24 by being superposed on at least one of the voltage signals Va(-) and Vb(+) or at least one of the voltage signals Va(-)' and Vb(+)' via It is also possible to automatically and accurately match the average potential of the voltage signal or the average potential of the voltage signal output from the differential amplifier circuit 24.

FIG. 5A is an example of a circuit that automatically adjusts the average potential of the voltage signal input to the differential amplifier circuit 24. The error voltage detection circuit 23e of this circuit example has a voltage signal Va(-)'. , Vb(+)′ average potential difference is detected, an error compensation voltage E required for reducing the difference is determined, and an error compensation voltage application circuit provided on the input side of the first shift circuit 23a is detected. It is superimposed on the voltage signal Va(-) via 23d.

Further, FIG. 5B is a circuit example in which the average potential of the voltage signal output from the differential amplifier circuit 24 is automatically adjusted, and the error voltage detection circuit 23e in this circuit example is the differential amplifier circuit 24. The difference E′ between the average potentials of the voltage signals output from the detector is detected, and the error compensation voltage E necessary for reducing the difference is calculated by using the differential gain A of the differential amplifier circuit 24 as E′/A. Calculated, it is superimposed on the voltage signal Va(-) via the error compensation voltage applying circuit 23d provided on the input side of the first shift circuit 23a.

In the above circuit example, the difference between the average potentials of the two-phase voltage signals is detected, the error compensation voltage E required to reduce the difference is obtained, and the error compensation voltage E is input to the circuit on the preceding stage from the detection position of the difference between the average potentials. Although it is superposed on one of the two-phase signals, it may be superposed via the error compensation voltage applying circuit 23d inserted in the signal line at the detection position. Further, not only one of the two-phase signals but also the error-compensating voltage may be superimposed on both of them to reduce the difference in average potential. Further, as a modified example of detecting the error voltage of the two-phase voltage signals output from the differential amplifier circuit 24 as shown in FIG. 5B, when the differential amplifier circuit 24 has a multi-stage configuration, whichever The error voltage can also be detected from the output of the stage.

With the above configuration, the voltage signals Va(-)' and Vb(+)' whose phases are mutually inverted and whose average potentials are always matched by automatic control can be input to the differential amplifier circuit 24.

Further, if R11 and R12 of the phase division circuit of FIG. 2 are set to the same resistance value, the amplitudes of Va(-) and Vb(+) can be made almost equal, and the phases of the differential amplifier circuit 24 are inverted from each other. Since a voltage signal whose amplitude and average potential are uniform can be input, the operation of the differential amplifier circuit has the best symmetry, and even when the current source is composed of a resistor, the output signal Vout whose amplitude is uniform is obtained. (+) and Vout(-) can be obtained.

Since the differential amplifier circuit 24 amplifies the difference between the input signals Va(-)' and Vb(+)' whose phases are mutually inverted by the differential gain A, the single-phase voltage signal Vin is output by the differential amplifier circuit. It is possible to obtain an output signal having a larger amplitude than that of the conventional configuration for amplification. As a result, the gain of the entire TIA can be increased.

FIG. 6 shows simulation results of frequency characteristics of transimpedance gain (dBohm) at two output terminals (Vout(+) and Vout(-)) of the conventional circuit and the circuit of the embodiment of the present invention. Both circuits have a power supply voltage of 3.3 V, and the current source of the differential amplifier circuit is a resistor. Further, the circuit of the embodiment of the present invention uses the automatic control circuit of FIG. 5A, and the resistance values of R11 and R12 of the phase division circuit are both 50Ω. Further, as a transistor forming a circuit, InP HBT having ft: 230 GHz and fmax: 400 GHz is used. The frequency to be analyzed was 100 kHz to 50 GHz in the frequency range generally used in optical communication.

As shown in FIG. 6B, in the conventional circuit, a difference of about 3 dB occurs in the gains of the two output signals from the low frequency region. As described above, this is because the single-phase voltage signal is input to one of the input terminals of the differential amplifier circuit in which the current source is composed of a resistor to amplify the signal, so that the differential signal is generated depending on the state of the voltage signal Vin. This is because the current of the amplifier circuit changes and the operation of the circuit becomes asymmetric.

On the other hand, in the circuit according to the embodiment of the present invention shown in FIG. 6A, voltage signals having the same amplitude and inverted phases are input to the two input terminals of the differential amplifier circuit. Even in the differential amplifier circuit, the circuit operates with good symmetry, and the gains of the two output signals have almost the same characteristics.

FIG. 7 shows the transimpedance gain (dBohm) and its phase characteristics when the current source of the differential amplifier circuit is replaced with an ideal constant current source in the conventional circuit of FIG. 6 and the circuit of the embodiment of the present invention. The simulation result is shown. The phase of Vout(-) shows a phase shifted by 180 degrees.

Looking at the gain of the conventional circuit of FIG. 7B, the gains of the two output signals in the low frequency region are equal because the current source of the differential amplifier circuit is an ideal constant current source. However, the gain difference appears from 30 GHz or more, and the difference at 50 GHz is 1.5 dB. In addition, the phase characteristics of the two output signals have a phase shift of 17 degrees at 50 GHz. This phase shift causes deterioration of jitter in the subsequent circuit. On the other hand, in the circuit according to the embodiment of the present invention, as shown in FIG. 7A, the gain and phase of the two output signals have the same characteristics in the entire frequency range. Further, comparing the gains of the circuit of the present invention and the conventional circuit, although the cutoff frequency Fc is almost the same, the circuit of the embodiment of the present invention has a gain of about 4 dB higher than that of the conventional circuit. There is.

From the above, it can be seen that the circuit of the embodiment of the present invention can output a differential signal having equal amplitude and good phase symmetry and good symmetry, and high gain.

In the above embodiment, an example in which a bipolar transistor is used as the transistor forming the phase division circuit 22 is shown, but the transistors Tr11 to Tr13 in the circuit shown in FIG. 2 are replaced with field effect transistors (FETs). It is also possible. In this case, the bases, collectors, and emitters of the transistors Tr11 to Tr13 may be replaced by the gates, drains, and sources of the FETs, and the gates, drains, and sources corresponding to the bases, collectors, and emitters of the transistors Tr11, Tr12 may be replaced by the circuits. It may be a first terminal, a second terminal, and a third terminal, respectively. Further, the current-voltage conversion circuit 21 and the differential amplifier circuit 24 are not limited to the bipolar transistors, but may be field-effect transistors (FETs).

1... Photoelectric conversion element, 20... TIA (transimpedance amplifier), 21... Current-voltage conversion circuit, 22... Phase division circuit, 23... Level matching circuit, 23a... First shift circuit, 23b... Second shift circuit 23c Error compensation voltage generator 23d Error compensation voltage application circuit 23e Error voltage detection circuit 24 Differential amplifier circuit

Claims (4)

A current-voltage conversion circuit (21) for converting an input current signal into a single-phase voltage signal,
A phase for receiving a single-phase voltage signal output from the current-voltage conversion circuit at the first terminal of the transistor and outputting two-phase voltage signals whose phases are inverted from each other from the second terminal side and the third terminal side of the transistor. A dividing circuit (22),
A level matching circuit (23) for receiving the two-phase voltage signals output from the phase division circuit and outputting the combined average potentials of the two-phase voltage signals;
The inverting input terminal receives one of the two-phase voltage signals whose average potentials have been adjusted by the level adjusting circuit and the other non-inverting input terminal, and amplifies the difference component of the two-phase voltage signals input to the two input terminals. And a differential amplifier circuit (24) for outputting the amplified signal from the inverting output terminal and the non-inverting output terminal as signals whose phases are mutually inverted ,
The current-voltage conversion circuit includes an inverting amplifier (21a) and a feedback resistor (R), and the input current signal is input to an input terminal of the inverting amplifier and output from the inverting amplifier. The voltage signal of is fed back to the input terminal of the inverting amplifier via the feedback resistor,
A transistor forming the phase dividing circuit is a bipolar transistor in which the first terminal is a base, the second terminal is a collector, and the third terminal is an emitter, or the first terminal is a gate and the second terminal is a drain. , The third terminal is any one of a source field effect transistor,
The level matching circuit lowers the average potential of the voltage signal output from the second terminal side of the transistor of the phase division circuit by a predetermined voltage by utilizing the forward voltage drop of the transistor or the diode. (23a) is included,
The level matching circuit raises the average potential of the voltage signal output from the third terminal side of the transistor of the phase division circuit by a predetermined voltage by utilizing the forward voltage drop of the transistor or the diode. A transimpedance amplifier including (23b) . The level matching circuit,
An error compensating voltage generator (23c) for generating an error compensating voltage capable of voltage variation by manual operation is provided, and the error compensating voltage is at least one of two phase voltage signals output from the phase dividing circuit, or The transimpedance amplifier according to claim 1, wherein the differential impedance circuit is superposed on at least one of the two-phase voltage signals to reduce an error in average potential of the two-phase voltage signals. .. The level matching circuit,
The difference between the average potentials of the two-phase voltage signals input to the differential amplifier circuit or the difference between the average potentials of the two-phase voltage signals output from the differential amplifier circuit is detected and the difference is reduced. Has an error voltage detection circuit (23e) for obtaining an error compensation voltage necessary for that, and inputs the error compensation voltage to at least one of the two-phase voltage signals output from the phase division circuit or to the differential amplifier circuit. The transimpedance amplifier according to claim 1, wherein the transimpedance amplifier is superimposed on at least one of the two-phase voltage signals to reduce the difference between the average potentials. A photoelectric conversion element (1) that receives an optical signal and outputs a current signal;
An optical signal receiving device having a transimpedance amplifier (20) for receiving a current signal output from the photoelectric conversion element,
The transimpedance amplifier, an optical signal receiving apparatus, characterized in that the transimpedance amplifier according to any one of claims 1-3.

Images