JP3554954B2 - Photodiode array - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement in a signal reading method of a photodiode array and an improvement in a method of modularization.
[0002]
[Prior art]
FIG. 6 is a circuit diagram showing an example of a conventional photodiode array.
In the figure, photodiodes 1a to 1d constitute a photodiode array 10, and switch circuits 8a to 8d and 9a to 9d constitute a multiplexer 11b.
[0003]
The anode of the photodiode 1a is connected to one end of the switch circuits 8a and 9a, and control signals from the control circuit 11a are connected to control terminals of the switch circuits 8a and 9a, respectively.
[0004]
The photodiodes 1b to 1d are also connected to the switch circuits 8b to 8d and 9b to 9d with the same circuit configuration as the photodiode 1a. In FIG. 4, the control line 15 connected from the control circuit 11a to the switch circuits 8a and 9a is represented by one line for simplicity, but the control lines 15 connected to each switch circuit are independent of each other. There are as many as the number of switch circuits.
[0005]
With the above configuration, the photocurrent output from the target photodiode is selected by the multiplexer 11b, and is output as a voltage signal from the current-voltage converter 11c connected to the output terminal of the multiplexer 11b. Such a photodiode array is described, for example, in Japanese Patent Application No. 7-206934 proposed by the present applicant.
[0006]
Next, FIG. 7 shows a production example of a photodiode array produced by the circuit configuration described in FIG.
In FIG. 1, a photodiode array 10 has light receiving portions 1a to 1d of a plurality of photodiodes arranged on an upper surface thereof and a plurality of wiring patterns 2 and 3 for a power supply line and a signal line. A pad at one end of each wiring pattern and a predetermined pad on the printed circuit board 4 are connected by a bonding wire 5. The lower surface of the photodiode array 10 is connected to the printed circuit board 4 by solder.
[0007]
The control circuit 11 on which the multiplexer and the current-voltage converter are mounted has an electrode surface formed on the lower surface thereof, and is connected to the pattern of the photodiode array 10 via the solder bump 6.
Such a photodiode array is described, for example, in Japanese Patent Application No. 8-18645 proposed by the present applicant.
[0008]
[Problems to be solved by the invention]
However, since the sensor unit and the control circuit unit of the photodiode array are usually manufactured as separate modules, a connection work between the sensor unit and the control circuit unit of the photodiode array is required in the conventional circuit configuration. For example, when producing a 256-channel photodiode array, it is necessary to perform as many as 256 connection operations using the bonding wires and solder bumps.
[0009]
In this case, in order to guarantee the performance as a photodiode array, all connection points need to be perfectly processed, and since all are precise operations, labor costs, material costs, and lead times increase. There was a problem that invited.
[0010]
SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and eliminates a connection step between a sensor component and a control circuit component of a photodiode array using a bonding wire, a solder bump, or the like, so that production can be easily performed in a short time and electric power can be obtained. It is an object of the present invention to provide a highly reliable photodiode array which eliminates the problem of poor coupling.
[0011]
[Means for Solving the Problems]
In order to achieve such an object, the invention according to claims 1 and 2 utilizes a difference in the natural oscillation frequency of an oscillation circuit with a photodiode provided for each photodiode , so that frequency components for the number of photodiodes are reduced. Detecting the frequency spectrum of the target photodiode from the integrated output signal to generate an output signal capable of detecting the optical power signal of the target photodiode. is there.
[0012]
According to the third and fourth aspects of the present invention, the whole circuit can be miniaturized by using a strip line resonator having a simple structure with a frequency band handled by an oscillation circuit with a photodiode and a microwave band or a millimeter wave band. The sensor section of the diode array and the control circuit section such as the signal selection circuit can be formed as a monolithic IC on the same substrate. Therefore, it is possible to eliminate a complicated manufacturing process using bonding wires, solder bumps, and the like, and to manufacture a highly reliable photodiode array.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a circuit diagram showing one embodiment of a photodiode array according to the present invention. This figure shows the first and 256th channel circuits of a photodiode array having 256 channels.
[0014]
In the oscillation circuit 101 with the photodiode constituting one channel of the photodiode array, the anode of the photodiode 21 is connected to the base of the transistor 23 and one end of the strip line resonator 20, and the cathode is connected to one end of the resistor 26. The other end of the strip line resonator 20 is connected to one end of the output resistor 25 and the collector of the transistor 23, and the emitter of the transistor 23 is grounded. Further, a transistor driving voltage Vc is applied to the collector of the transistor 23, and a reverse bias voltage -Vb of the photodiode is reverse-biased to the other end of the resistor 26.
[0015]
Circuits similar to the above-described oscillation circuit with a photodiode are arranged on the same substrate by the number of channels, and the other ends of the output resistors 25 of all channels are all integrated into the output signal line 30. Connected to.
[0016]
Here, the operation of the embodiment shown in FIG. 1 will be described. In the oscillation circuit 101 with a photodiode constituting one channel shown in FIG. 1, a transistor driving voltage Vc and a reverse bias voltage -Vb of the photodiode are applied in advance. At this time, the reverse bias voltage -Vb of the photodiode is set to about -0.5V.
[0017]
Here, when light is incident on the photodiode 21, a reverse current is generated therein, and as this increases, the gain of the transistor 23 becomes 1 or more. At this time, oscillation is started by the closed loop of the strip line resonator 20 and the transistor 23.
[0018]
The oscillation frequency at this time is determined by the resonance length of the λ / 2 resonator (not shown) of the strip line resonator 20, and the amplitude of the oscillation depends on the gain of the transistor 23.
[0019]
That is, the oscillation frequency of the output signal of the oscillation circuit 101 with the photodiode is determined by the resonance length of the λ / 2 resonator of the strip line resonator 20, and the amplitude depends on the power of light incident on the photodiode 21.
[0020]
From the output signal obtained here, the signal 30 can be detected by using the signal readout device 40 to detect the frequency spectrum of the oscillation circuit 101 with the photodiode, thereby detecting the optical power signal 50 of one channel.
[0021]
FIG. 2 shows an output example of the optical power signal thus obtained. This is an example in which an output signal of a photodiode array having 256 channels is detected by using an FFT analyzer, a spectrum analyzer, or the like to detect an optical power signal incident on each photodiode.
[0022]
A specific embodiment of the circuit configured as described above will be described with reference to FIG.
FIG. 3 shows an embodiment of a photodiode array having 256 channels, similarly to FIG.
[0023]
In the oscillation circuit 101 with the photodiode constituting one channel of the photodiode array, the anode of the photodiode 21 is connected to the base of the transistor 23 via one λ / 2 resonator 20 a of the strip line resonator 20. The other λ / 2 resonator 20 b coupled via the strip line coupler 24 is connected to the collector of the transistor 23, one end of a DC cut capacitor 27 forming a bias T circuit, and one end of an RF cut inductance 28. You.
[0024]
A reverse bias voltage -Vb of the photodiode is applied to a cathode of the photodiode 21 via a resistor 26 via a resistor 26, and a resistor 29, a DC cut capacitor 27 constituting the bias T circuit, and an RF cut are applied to a collector of the transistor 23. The transistor driving voltage Vc is applied through the application inductance 28.
[0025]
Circuits similar to the above-described oscillation circuit with photodiode are arranged on the same substrate by the number of channels, and the other ends of the output resistors 25 of all channels are all integrated with the output signal line 30.
[0026]
3, the oscillation frequency of the oscillation circuit 101 with a photodiode is determined by the resonance length L1 of the λ / 2 resonators 20a and 20b of the strip line resonator 20. By slightly changing the length of the resonance length L1 for each oscillation circuit with a photodiode, it is possible to configure an oscillation circuit with a photodiode having a different oscillation frequency in all channels.
[0027]
The output signals of the oscillation circuits with photodiodes obtained in this way are connected via a bias T circuit composed of a DC cut capacitor and an RF cut inductance, and the output signals of all channels are integrated. The resulting output signal 30 is obtained.
[0028]
It is possible to detect the optical power signal 50 of the target channel by detecting the frequency spectrum of the target oscillator circuit with the photodiode using the output signal 30 obtained here using the signal reading device 40. .
[0029]
Here, an operation example of the oscillator using the stripline resonator will be described with reference to FIGS. FIG. 4 shows an embodiment in which an oscillation circuit with a photodiode using the stripline resonator described in FIG. 1 is simply manufactured, and FIG. 5 shows an output signal thereof.
[0030]
In FIG. 4, a strip line oscillation circuit 20 composed of a strip line resonator 20 in which .lambda. / 2 resonators 20a and 20b having a resonance length of 30 mm are coupled by a strip line coupler 24 and a hetero bipolar transistor 23 is a transistor driving circuit. The application voltage Vc and a simulation signal voltage Vs, which is a simulation input signal of the photodiode, are applied via a resistor Rs.
[0031]
When the output signal 30 of such an oscillator is measured using an oscilloscope, a waveform shown in FIG. 5 is obtained. In this example, since the resonance length of the λ / 2 resonator is 30 mm, it oscillates at 1.2 GHz. Further, since the magnitude of the amplitude depends on the magnitude of the simulation signal voltage Vs, when the simulation signal voltage Vs and the resistor Rs are replaced with photodiodes, an output of 1.2 GHz having an amplitude corresponding to the incident light intensity of the photodiode is obtained. A signal is obtained.
[0032]
By spectrum analysis of this output signal to obtain a frequency component of 1.2 GHz, an optical power signal of the photodiode can be obtained.
[0033]
It should be noted that the foregoing description has been directed to specific preferred embodiments for the purpose of explanation and illustration of the present invention. Therefore, the present invention is not limited to the above-described embodiment, but includes many more changes and modifications without departing from the spirit thereof.
[0034]
【The invention's effect】
As described above, the present invention has the following effects.
According to the first and second aspects of the present invention, since the output signal selecting means of the photodiode array detects the frequency spectrum of the oscillation circuit with the photodiode, the photodiode and the control circuit can be built on the same substrate. Therefore, a connection step using a bonding wire, a solder bump, or the like becomes unnecessary. Therefore, it is possible to easily manufacture a photodiode array in a short time, and it is possible to provide a highly reliable photodiode array because the problem of poor electrical coupling is eliminated.
[0035]
According to the third and fourth aspects of the present invention, since the sensor unit of the photodiode array and the control circuit unit such as the signal selection circuit can be formed as a monolithic IC on the same substrate, the component configuration of the photodiode array is extremely low. It becomes simple. Therefore, it is possible to easily control the quality and to manufacture a highly reliable photodiode array.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing one embodiment of a photodiode array according to the present invention.
FIG. 2 is a diagram showing an example of an output signal of a photodiode array according to the present invention.
FIG. 3 is a circuit diagram showing a specific example of a photodiode array according to the present invention.
FIG. 4 is a circuit diagram showing an embodiment of an oscillator using a stripline resonator.
FIG. 5 is a diagram illustrating an example of an output signal of an oscillator using a stripline resonator.
FIG. 6 is a configuration diagram illustrating an example of a conventional photodiode array.
FIG. 7 is a configuration diagram showing a specific example of a conventional photodiode array.
[Explanation of symbols]
Reference Signs List 20 stripline resonator 20a λ / 2 resonator 20b λ / 2 resonator 21 photodiode 23 transistor 24 stripline coupler 25 output resistor 26 resistor 27 DC cut capacitor 28 RF cut inductance 29 resistor 30 Integrated output signal 40 Signal readout device 50 Optical power signal 101 Oscillation circuit with photodiode

Claims (4)

In a photodiode array configured by arranging a plurality of photodiodes,
With the photodiode
Oscillation circuits with photodiodes each including a resonator and a compound transistor are configured on the same substrate for each of the photodiodes , and are arranged by the number of the photodiodes. A photodiode array having different oscillation frequencies . 2. The photodiode according to claim 1, wherein the photodiode array is configured to generate an integrated output signal in which all signals output from oscillation circuits with photodiodes having different oscillation frequencies. array. 2. The photodiode array according to claim 1, wherein the oscillation circuit with the photodiode has an oscillation frequency band in a microwave band or a millimeter wave band, and the photodiode array is configured as a microwave monolithic IC. The photodiode array according to claim 1, wherein the resonator uses a stripline resonator.

Images