JPH0414729B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a distance measuring device used in, for example, a camera, which measures the distance to a distance-measuring object by receiving a signal light reflected from the distance-measuring object. The present invention relates to a light receiving device, and particularly to a light receiving device having a light receiving element and an amplifier circuit.

[Prior Art] Generally, in this type of distance measuring device, a pair of light-receiving elements arranged in close proximity receive signal light reflected from a distance-measuring object, and the light-receiving element generated by the signal light By determining the ratio of photovoltaic currents, the distance to the object to be measured is determined.

FIGS. 2 and 3 show this type of distance measuring device. First, as shown in FIG. 2, a pulsed signal light from a light emitting element 1 made of an LED or the like is transmitted to an object to be measured 3a or 3b via a converging lens 2 on the projecting side.
The signal light 4a or 4b that is incident on and reflected by
is incident on a photodetecting element (SPD) 6 having a pair of light receiving elements 7a and 7b. This photodetecting element 6 is composed of an N-type semiconductor substrate 6c serving as a cathode, and P-type semiconductor layers 6a and 6b forming anodes formed on one main surface of this semiconductor substrate. Now, if the signal light 4a reflected from the object 3a to be measured at a short distance is incident, as shown in FIG.
is incident, a large photovoltaic current flows through the light receiving element 7a, and a small photovoltaic current flows through the light receiving element 7b. Furthermore, if the signal light 4b reflected from the object to be measured 3b located at a long distance is incident, the third
As shown in the figure, there are many signal lights 4 on the light receiving element 7b.
b is incident, a large photovoltaic current flows through the light receiving element 7b, and a small photovoltaic current flows through the light receiving element 7a. Then, as shown in FIG.
The photovoltaic current flowing in
0 and the other input terminal of the operational amplifier 12 via the resistor 11. It is also input to one input terminal of the operational amplifier 12. On the other hand, the photovoltaic current flowing through the light receiving element 7b is converted into a voltage value corresponding to the photovoltaic current by the light receiving device 8b, and one input terminal and output terminal of the operational amplifier 12 are connected via a buffer amplifier 13 and a resistor 14 to a resistor 15. A reference voltage source 16 is connected to the other input terminal via a resistor 17. Since the operational amplifier 12 and the resistors 11, 14, 15, and 17 constitute a differential amplifier, an output corresponding to the difference between the voltages input to the two input terminals of the operational amplifier 12 appears at the operational output terminal 18. It turns out. This calculation output terminal 18
The output appearing in is a value corresponding to the ratio of the photovoltaic currents of the light receiving elements 7a and 7b, and as a result, distance information to the distance measuring object 3a or 3b is obtained.

Next, the conventional light receiving devices 8a and 8b in the distance measuring device configured as described above will be explained based on FIG. Since the light receiving devices 8a and 8b both have the same circuit configuration, FIG.
It shows. In FIG. 5, 4 is the signal light reflected from the object to be measured, 7 is a light receiving element whose cathode is connected to the reference potential point Vref, and 19 is an npn transistor whose base is connected to the anode of this light receiving element 7. 20 is an AC signal bypass capacitor connected between the emitter of this signal amplification transistor 19 and the ground, 21 and 22 are pnp transistors forming a current mirror circuit, and one pnp The emitter of the transistor 21 is connected to the power supply potential point Vcc, and its base and collector are connected to the collector of the signal amplifying transistor 19, and the emitter of the other pnp transistor 22 is connected to the power supply potential point Vcc, and its base is connected to the power supply potential point Vcc. It is connected to the base of the pnp transistor 21. 23 and 24 are logarithmic compression diodes connected between the collector of the pnp transistor 22 of this current mirror circuit and the ground, which are composed of diode-connected npn transistors, and the anode of the logarithmic compression diode 23 is connected to the ground of this light receiving device. It is connected to the output terminal 9. Reference numeral 25 denotes a bias current source connected between the power supply potential point Vcc and the base of the signal amplifying transistor 19, and is composed of, for example, a transistor. 26 is an NPN transistor for absorbing direct current, which is connected between the base of the signal amplification transistor 19 and the ground, and whose base is connected to the emitter of the signal amplification transistor 19; 27 is the signal amplification transistor 1;
A constant current source for setting a circuit bias is connected between the emitter of No. 9 and ground, and is composed of, for example, a transistor. 28 is an inverting input terminal 28
a, has a non-inverting input terminal 28b, an output terminal 28c and a control terminal 28d, the inverting input terminal 28a is connected to the anode of the logarithmic compression diode 23, and the output terminal 28c is connected to the inverting input terminal 28a,
A buffer amplifier 29 for setting the initial currents of the logarithmic compression diodes 23 and 24 is connected between the control end 28d of this buffer amplifier and ground,
A capacitor 30, 31, and 32 are constant current sources, resistors, and diodes that constitute a reference voltage generation circuit for setting the initial voltage of the logarithmic compression diodes 23 and 24. The connection point between the source 30 and the resistor 31 is the non-inverting input terminal 28 of the buffer amplifier 28.
The constant current source 30 is made up of, for example, a transistor, and the diode 32 is made up of a diode-connected npn transistor.

The buffer amplifier 28 is constructed as shown in FIG. 6. In FIG. 6, 28e is an npn transistor whose base is connected to the inverting input terminal 28a, and 28f is an npn transistor whose base is connected to the non-inverting input terminal 28b. is connected to the power supply potential point Vcc,
This is an npn transistor whose emitter is connected to the emitter of the npn transistor 28e, and forms a differential amplifier with the npn transistor 28e. 28g are these npn transistors 28
A constant current source is connected between the emitter connection point of e and 28f and the ground, and 28h and 28i are pnp transistors that form a current mirror circuit.The emitters of both pnp transistors are connected to the power supply potential point Vcc, and their bases are common. The collector of one pnp transistor 28h is connected to the base and the above npn
connected to the collector of the transistor 28e, and
It is for transmitting differential outputs from npn transistors 28e and 28f. 28j and 28k are npn transistors that constitute a current mirror circuit, and both
The emitters of the npn transistors are grounded and their bases are commonly connected, the collector of one npn transistor 28j is connected to the base and the collector of the pnp transistor 28i, and the collector of the other npn transistor 28j is connected to the base and the collector of the pnp transistor 28i.
The collector of transistor 28k is connected to output terminal 28c and then to inverting input terminal 28a.

Next, the operation of the light receiving device configured in this manner will be explained. First, when there is no signal, that is, when the pulsed signal light 4 reflected from the object to be measured is not incident on the light receiving element 7, the amplification transistor 19
Since the current flowing through is determined by the constant current source 27, the remaining current after subtracting the base current of the amplification transistor 19 from the bias current of the bias current source 25 flows through the npn transistor 26. Further, when external light (light of approximately constant intensity due to sunlight and its reflected light, etc.) is incident on the light receiving element 7, a direct current photovoltaic current is generated in the light receiving element 7. However, most of this direct current photovoltaic current flows into the npn transistor 26 for the following reason, and the current flowing into the base of the amplification transistor 19 due to this direct current photovoltaic current can be ignored. In other words, the DC photovoltaic current initially flows into the base of the amplification transistor 19, is multiplied by the amplification factor h _FE 19, and then flows into the base of the amplification transistor 19.
9 flows out from the emitter, but because it is a direct current, it does not flow into the capacitor 20 and flows into the npn transistor 26.
It will flow into the base of. As a result, the DC photovoltaic current is drawn away through the collector of the npn transistor 26 and feedback is applied, so that the current flowing into the base of the amplification transistor 19 is reduced to 1/
(h _FE (19) x h _FE (26)), which is very small and can be ignored.

Therefore, the current flowing into the collector of the amplification transistor 19 has a constant current value determined by the constant current source 27 when there is no signal. A current having the same value as the current flowing into the collector flows out from the collector of the PNP transistor 22 constituting the current mirror circuit. On the other hand, constant current source 30 and resistor 31
A reference voltage of a reference voltage generating circuit composed of a diode 32 and a diode 32 is connected to a non-inverting input terminal 28b of a buffer amplifier 28, and a pnp transistor 2
Since the collector of No. 2 is connected to the inverting input terminal 28a and the output terminal 28c of the buffer amplifier 28,
The current flowing from the collector of the pnp transistor 22 is divided into the logarithmic compression diodes 23, 24 and the buffer amplifier 28 so that the anode potential of the logarithmic compression diode 23 (the output terminal 28c potential of the buffer amplifier 28) becomes equal. Therefore, the reference voltage of the reference voltage generation circuit appears at the output terminal 9 of the light receiving device 8.

Here, the reverse saturation current of the diodes 23, 24, and 32 is I _S , the current flowing from the collector of the pnp transistor 22 is I _C 22, the current flowing into the logarithmic compression diodes 23 and 24 is I23, and the constant current source 3
0 is the current flowing through I30, and the resistance value of resistor 31 is R.
31. If the Boltzmann constant is k, the absolute temperature is T, and the electron charge is q, the anode potential of the logarithmic compression diode 23 is 2kT/qlnI(23)/I _S , and the reference voltage of the reference voltage generation circuit is kT/qlnI (30)/I _S +R (31)
, I(30). Then, since both voltages are equal, KT/qlnI(30)/I _S +R(31), I(30) = 2kT
/qln I(23)/I _S relationship.

On the other hand, when the pulsed signal light 4 reflected from the object to be measured is incident on the light receiving element 7, a pulsed photovoltaic current is generated in the light receiving element 7 due to the pulsed signal light 4. Become. This pulsed photovoltaic current flows into the base of the amplification transistor 19, is multiplied by h _FE 19 and flows from the emitter of the amplification transistor 19 into the capacitor 20. At this time,
Since the pulsed photovoltaic current multiplied by h _FE 19 is an alternating current, it does not flow into the base of the npn transistor 26, so no feedback is applied.

Therefore, the current flowing into the collector of the amplifying transistor 19 becomes the sum of the current value determined by the constant current source 27 and the pulsed photovoltaic current value multiplied by h _FE 19 flowing through the capacitor. The same current flowing into the collector flows out from the collector of the pnp transistor 22 constituting the current mirror circuit. On the other hand, buffer amplifier 28
Since the capacitor 29 is connected to the control terminal 28d of the buffer amplifier 28, the response to the output terminal 28c to the potential change of the inverting input terminal 28a is delayed, and when there is no signal, there is a delay in the response from the collector of the PNP transistor 22 to the output terminal 28c. The increment flowing out,
In other words, the pulsed photovoltaic current multiplied by h _FE 19 flows into the logarithmic compression diodes 23 and 24, and due to this increase, the anode potential of the logarithmic compression diode 23 increases, which appears at the output terminal 9 of the light receiving device. become.

At this time, the potential of the output terminal 9 becomes 2 kT/qln I _C (22)+h _FE (19) I _L 7/ _IS , where the pulsed photovoltaic current of the light receiving element 7 is I _L 7.

A distance measuring device shown in FIG. 4 is constructed using two light receiving devices 8 constructed in this manner. Now, the photovoltaic currents of the light receiving elements 7a and 7b generated by the pulsed signal light 4 reflected from the object to be measured are I _L
7a, I _L 7b, 2kT/qln I _C (22) + h _FE (19) I _L (7a)/I _S , 2kT/qln I _C ( 22) +h _FE (19) I _L (7b)/I _S potential will appear.

Here, since the reference potential in the reference voltage generation circuit of the light receiving devices 8a and 8b is set to a sufficiently small value, I _C 22 is h _FE 19I _L 7a and h _FB 19I _L 7b.
, and the voltage of the reference voltage source 16 is
When V _S is assumed, the output of the operational amplifier 12 is as shown in the following equation. V _S +2kT/qlnh _FE (19) I _L (7b)/I _S −2kT/
qln h _FE (19) I _L (7a) / I _S = V _S +2kT / qln I _L (7b) / I _L (
7a) Therefore, a voltage corresponding to the ratio of the photovoltaic currents I _L 7a and I _L 7b in the light receiving elements 7a and 7b appears at the output terminal 18, and this voltage is exactly the value that allows the distance to the object to be measured to be obtained. It is something that has become popular.

[Problem that the invention seeks to solve]

In the above-mentioned light receiving device, since the anode of the light receiving element 7 is directly connected to the base of the amplification transistor 19, it is easily affected by low frequency external light such as fluorescent lamps, and under such conditions, Errors are likely to occur in the distance measurement results to the distance measurement object, and
The initial current flowing through the logarithmic compression diodes 23 and 24, that is, the current when there is no signal, is set by the reference voltage of the reference voltage generation circuit, so the initial current changes due to the influence of temperature changes, resulting in a linear output voltage. This had the problem of changing gender.

This invention was made in view of the above points, and is less affected by low frequency external light such as fluorescent lamps.
Moreover, it is an object of the present invention to obtain a light receiving device that is less affected by temperature changes.

[Means for solving problems]

The light receiving device according to the present invention is such that a pulsed electromotive current from the light receiving device is amplified by a current amplifying transistor, and a voltage corresponding to the pulsed electromotive current appears in a logarithmic compression diode element. a first current exchange means that connects a low frequency attenuation capacitor between the base of the amplification transistor and receives the collector current of the current amplification transistor and outputs a current corresponding to the collector current to the logarithmic compression diode element; A second current exchange means is provided for receiving the current flowing through the logarithmic compression diode element and making the emitter current of the current amplifying transistor a value corresponding to this current.

[Effect]

In this invention, the low-frequency attenuation capacitor suppresses the transmission of low-frequency electromotive current generated from low-frequency external light from a fluorescent lamp or the like from the light receiving element to the base of the current amplification transistor. At the same time, the first current exchange means and the second current exchange means set the initial current flowing through the logarithmic compression diode element based on the collector current and emitter current of the current amplification transistor, thereby controlling the temperature change. This suppresses the influence of

〔Example〕

An embodiment of the present invention will be described below based on FIG. 1. In FIG. 1, reference numeral 7 denotes a light receiving element 34 whose cathode is connected to the power supply potential point Vcc and whose anode is grounded via a load resistor 33. 35 is a low frequency attenuation capacitor connected between the anode of the light receiving element 7 and the base of the current amplifying transistor 19; 35 is a base to which a bias voltage is supplied;
For base bias connected between the base of
The npn transistor 36 is a first current mirror circuit composed of a pair of pnp transistors 21 and 22. The emitters of both pnp transistors are connected to the power supply potential point Vcc, and the bases are commonly connected. The base and collector of the other pnp transistor 22 are connected to the collector of the amplification transistor 19, and the collector of the other pnp transistor 22 is connected to the anode of the logarithmic compression diode 23, and the emitter area ratio of the pnp transistors 21 and 22 is 1:n. pnp transistor 2
The current value flowing through the pnp transistor 21 is n times the current value flowing through the pnp transistor 21. Reference numeral 37 denotes a first constant current source which is connected in parallel to the PNP transistor 21 and through which a constant current I37, which is larger than the constant current I27 of the second constant current source 27, flows, and is constituted by, for example, a transistor. 38 is an npn transistor whose base is connected to the base of the logarithmic compression diode 24 to form a current mirror circuit, and is set so that the same current value as that of the logarithmic compression diode 24 flows. 39 is a pair of pnp
In the second current mirror circuit composed of transistors 40 and 41, the emitters of both pnp transistors are connected to the power supply potential point Vcc, and their bases are commonly connected.
The base and collector of the above npn transistor 3
8 collector. 42 is a third current mirror circuit composed of a pair of npn transistors 43 and 44, the emitters of both transistors are grounded and their bases are commonly connected, and the base and collector of one are connected to the pnp transistor 4.
1, and the current value flowing through the npn transistor 44 is m times the current value flowing through the pnp transistor 40.
The emitter area ratios of the pnp transistors 40, 41 and the npn transistors 43, 44 are set. 46 is a pair of npn transistors 4
7 and 48, the emitters of both transistors are grounded and their bases are commonly connected, and the base and collector of one npn transistor 47 are connected to the collector of the pnp transistor 44. The collector of the other transistor 48 is connected to the power supply potential point Vcc via a third constant current source 45 (through which a constant current I45 flows), and the collector of the other transistor 48 is connected to the current amplifying transistor 19.
is connected to the emitter of both transistors 4 and 4.
7 and 48 are set so that equal current flows through them. 49 is a fourth constant current source connected between the anode of the logarithmic compression diode 23 and the ground, through which a constant current I49 flows.

Next, the operation of the light receiving device configured in this manner will be explained. First, a description will be given of a time when the pulsed signal light 4 reflected from the object to be measured is not incident on the light receiving element 7, that is, when there is no signal. Now, if the initial current flowing through the logarithmic compression diodes 23 and 24 is I23, then the first current mirror circuit 36
The current flowing through the pnp transistor 22 is I23
+I49, and the current flowing through the pnp transistor 21 becomes 1/n{I23+I49}. Therefore, the collector of the current amplification transistor 19 has I37+
A current of 1/n {I23+I49} will flow. Further, a current I23 equal to the initial current flows through the transistor 38, and is multiplied by m by the second and third current mirror circuits 39 and 42.
A current mI23 flows through the npn transistor 44 of the third current mirror circuit 42.
Since a current I45-mI23 flows through the npn transistor 47 of the fourth current mirror circuit, a current I45-mI23 also flows through the npn transistor 48. Therefore, the current flowing out from the emitter of the current amplifying transistor 19 is I
It becomes 27+I45-mI23. In the current amplifying transistor 19, the base current is almost negligible and the collector current and emitter current match, so the area ratio m, n, Constant current values I37, I2 of the first to fourth constant current sources 37, 27, 45, 49
It is sufficient to set 7, I45, and I49. Therefore, since the initial current I23 of the logarithmic compression diodes 23 and 24 can be set by the above-mentioned constant, it can be set arbitrarily and has a large design latitude.

Next, the mechanism by which the initial current I23 flows through the logarithmic compression diodes 23 and 24 when there is no signal will be explained. Now, assuming that no current is flowing through the logarithmic compression diodes 23 and 24, the transistor 38 is in a non-conducting state, so the npn transistor 44 of the third current mirror circuit 42 is also in a non-conducting state, and the fourth current mirror circuit A current equal to the constant current source I45 flowing to the second constant current source 45 flows through the 46 npn transistors 47 and 48. Then, the first current mirror circuit 36
I45+I27-I3 for pnp transistor 21
7 current flows through the pnp transistor 22, and the n
A current of {I45+I27-I37} will flow. Since this n{I45+I27-I37} is larger than the constant current I49 flowing to the fourth constant current source 49, the logarithmic compression diodes 23 and 24 have n
A current of {I45+I27-I37}-I49 will flow in, and the current will be stabilized at the initial current I23. On the other hand, if a current I'23 larger than the initial current I23 flows through the compression diodes 23 and 24, the current flowing through the npn transistor 44 of the third current mirror circuit 42 becomes mI'23. If this mI'23 is larger than the constant current of the third constant current source 45, the npn transistors 47 and 48 of the fourth current mirror circuit 46 become non-conductive. Since the constant current I37 of the first constant current source 37 is larger than the second constant current source I27, the pnp transistors 21 and 22 of the first current mirror circuit 36 also become non-conductive, and the logarithmic compression diode 23, 2
The current value flowing into I23 is reduced, and the initial current I23
It will become stable.

As is clear from the above, the logarithmic compression diode 2
The initial current I23 flowing through the circuits 3 and 24 is determined by the first to fourth current mirror circuits and the first to fourth constant current sources, and the initial current I23 is a stable constant current that is less affected by temperature changes. It is something that becomes.

Also, when external light, for example, light with a substantially constant intensity such as sunlight or low frequency light such as a fluorescent lamp is incident on the light receiving element 7, a direct current or low frequency electromotive current is generated in the light receiving element 7. Since transmission to the base of the current amplifying transistor 19 is blocked by the low frequency attenuation capacitor 34, it does not have any influence.

On the other hand, when the pulsed signal light 4 reflected from the object to be measured is incident on the light receiving element 7, a pulsed photovoltaic current I _L 7 is generated in the light receiving element 7 due to the pulsed signal light 4. will be done. This pulsed photovoltaic current I _L 7 flows into the base of the current amplifying transistor 19 via the load resistor 33 and the low frequency attenuation capacitor 34, is multiplied by h _FE 19 and flows into the bypass capacitor 20. At this time, since the constant currents of the first and second constant current sources 37 and 27 are set to be sufficiently large compared to the value h _FE 19 times the electromotive current flowing into the base of the current amplification transistor 19, the current amplification The potential variation in the base-emitter voltage of the transistor 19 is very small, and the variation in the voltage across the load resistor 33 is also very small, and almost all of the pulsed photovoltaic current I _L 7 in the light receiving element 7 is current amplified. It will flow to the base of transistor 19. and h _FE
As the photovoltaic current I _L 7 multiplied by 19 flows into the bypass capacitor 20, this h _FE 19, I _L 7
A current corresponding to the first current mirror circuit 36
The current flows through the pnp transistor 21, and n·h _FE 19, I _L 7 flows through the pnp transistor 22.
As a result, the logarithmic compression diodes 23 and 24 have I
A current of 23+nh _FE 19, I _L 7 will flow, and an incremental compression compression voltage corresponding to the pulsed photovoltaic current I _L 7 of the light receiving element 7 will appear at the power terminal.

In the light-receiving device configured as described above, the anode potential of the logarithmic compression diode 23 is obtained which has almost no influence on low-frequency external light such as from a fluorescent lamp due to the low-frequency attenuation capacitor 34, and the logarithm Initial current I23 flowing through the compression diode
are the first to fourth current mirror circuits 36, 3
9, 42, 46 and the first to fourth constant current sources 3
7, 27, 45, and 49, the anode potential of the logarithmic compression diode 23 is not easily affected by temperature fluctuations, disturbances, etc., and a highly accurate one can be obtained.

In the above embodiment, the load resistor 33 is used, but instead of the load resistor 33, a diode, a series body of a diode and a resistor, a combination of a resistor, a capacitor, and a diode, a coil, etc. can be used. The impedance is low, and for AC, a high impedance may be used.

In addition, in the above embodiment, the case where the light receiving device 8 is applied to one that measures the distance to a distance-measuring object has been described, but it is also possible to apply the light receiving device 8 to a position determination circuit based on the ratio of incident light or to measure the absolute value of the incident light itself. It may also be applied to devices.

[Effects of the Invention] As described above, the present invention connects a low frequency attenuation capacitor between the light receiving element and the base of the current amplification transistor, and receives the collector current of the current amplification transistor and converts it into the collector current. a first current exchange means that outputs a corresponding current to the logarithmic compression diode element; and a second current exchange means that receives the current flowing through the logarithmic compression diode element and sets a value corresponding to this current as the emitter current of the current amplification transistor.
Since the present invention is equipped with a current exchange means, it has the effect of obtaining a logarithmic compression voltage that is less affected by low-frequency external light such as fluorescent lamps and less affected by temperature fluctuations. It is something.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIGS. 2 and 3 show pulsed signal light and a light receiving element 7.
a, 7b and a plan view of the light receiving element, FIG. 4 is a schematic circuit diagram showing a distance measuring device, FIG. 5 is a circuit diagram showing a conventional light receiving device, and FIG. 6 is the same as that shown in FIG. FIG. 2 is a circuit diagram showing a buffer amplifier 28; In the figure, 7 is a light receiving element, 19 is a current amplification transistor, 20 is a bypass capacitor, 23, 2
4 is a logarithmic compression diode, 27 is a second constant current source, 34 is a low frequency attenuation capacitor, 36, 3
9, 42, 46 are first to fourth current mirror circuits, and 37, 45 are first and third constant current sources. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A light receiving element that generates a pulsed electromotive current in response to a pulsed signal light, a low frequency attenuation capacitor having one electrode connected to one end of this light receiving element, and a low frequency attenuation capacitor for this low frequency attenuation. a current amplification transistor whose base is connected to the other electrode of the capacitor; a bypass capacitor connected to the emitter of the current amplification transistor; and a first transistor that receives the collector current of the current amplification transistor and outputs a current corresponding to the collector current. a current exchange means, a logarithmic compression diode element receiving the output current of the first current exchange means, a first current exchanger that receives the current flowing through the logarithmic compression diode element and sets a value corresponding to the current as the emitter current of the current amplification transistor. 2. A light receiving device equipped with a current exchange means. 2 The first current exchange means consists of a pair of transistors, one transistor is connected to the collector of the current amplification transistor, the other transistor is connected to the logarithmic compression diode element, and the current value flowing through the other transistor is A first current mirror circuit having a relationship such that the current value flowing through the transistor is n times, and a first constant current source connected in parallel to one transistor of the first current mirror circuit. A light receiving device according to claim 1, characterized in that: 3. The second current exchange means includes a logarithmic compression diode element and a transistor forming a current mirror circuit, a second current mirror circuit consisting of a pair of transistors, one of which is connected to the transistor, and a pair of transistors. a third current mirror circuit consisting of a transistor, one of which is connected to the other transistor of the second current mirror circuit; and a third current mirror circuit consisting of a pair of transistors, one of which is connected to the other transistor of the third current mirror circuit. a fourth current mirror circuit which is connected in parallel to the transistor of the second transistor and is connected to a third constant current source, and the other transistor is connected to the emitter of the current amplifying transistor; and a second constant current source connected in parallel to the transistor, such that the current value flowing through the other transistor of the third current mirror circuit is m times the current value flowing through the logarithmic compression diode element. 3. The light receiving device according to claim 1, wherein the first to fourth transistors are set at .