Circuit for reducing noise point of avalanche diode and photoelectric detector

Abstract

The embodiment of the utility model discloses a circuit for reducing noise points of an avalanche diode and a photoelectric detector. The circuit comprises an actual photoelectric receiving module, a reference photoelectric receiving module and a differential amplification module, the actual photoelectric receiving module comprises a first avalanche diode, the reference photoelectric receiving module comprises a second avalanche diode, the first avalanche diode and the second avalanche diode have the same electrical characteristics, the first avalanche diode has a photoelectric receiving function, and the second avalanche diode has a photoelectric shielding function; one end of the actual photoelectric receiving module and one end of the reference photoelectric receiving module are electrically connected with two input ends of the differential amplification module respectively; and the other end of the actual photoelectric receiving module and the other end of the reference photoelectric receiving module respectively receive power supply signals. According to the circuit for reducing the noise point of the avalanche diode, the thermal noise, the peak noise and other bottom noise caused by the electrical characteristics of the avalanche diode are effectively suppressed, and the acquisition precision of effective avalanche pulse signals is improved.

Description

Technical Field

[0001] The embodiments of the utility model relate to the field of laser radar technology, and in particular to a circuit and a photoelectric detector for reducing the noise of an avalanche diode. Background Art

[0002] In the optoelectronic receiving module of the laser radar, avalanche diodes are generally used to collect optical signals. However, during the collection process, there is noise caused by dark current and heat generated by the avalanche diode itself, that is, background noise such as thermal noise and spike noise. The generation of background noise such as thermal noise and spike noise will annihilate the effective photogenerated avalanche pulse signal, shorten the effective avalanche time, and further increase the difficulty of extracting the effective avalanche pulse signal.

[0003] At present, the existing technology is to use high-pass / low-pass filters to filter the signals generated by avalanche diodes to suppress the background noise such as thermal noise and spike noise generated by the avalanche diodes themselves. However, for different avalanche diodes or different effective avalanche pulse signal extraction circuits, it is necessary to continuously test and modify the filtering parameters of the high-pass / low-pass filter, and the relationship between the debugging of the filtering parameters and the noise reduction effect is not easy to determine, resulting in poor noise suppression effect of the high-pass / low-pass filter. Utility Model Content

[0004] The embodiments of the utility model provide a circuit and a photodetector for reducing the noise of an avalanche diode, which effectively suppresses background noise such as thermal noise and spike noise caused by the electrical characteristics of the avalanche diode itself, and reduces the influence of background noise in the collection process of effective avalanche pulse signals.

[0005] In a first aspect, an embodiment of the utility model provides a circuit for reducing avalanche diode noise, comprising an actual photoelectric receiving module, a reference photoelectric receiving module and a differential amplification module;

[0006] The actual photoelectric receiving module includes a first avalanche diode, and the reference photoelectric receiving module includes a second avalanche diode. The first avalanche diode and the second avalanche diode have the same electrical characteristics. The first avalanche diode has a photoelectric receiving function, and the second avalanche diode has a photoelectric shielding function.

[0007] One end of the actual photoelectric receiving module and one end of the reference photoelectric receiving module are electrically connected to two input ends of the differential amplification module respectively;

[0008] The other end of the actual photoelectric receiving module and the other end of the reference photoelectric receiving module receive power signals respectively.

[0009] Optionally, the actual photoelectric receiving module further includes a filtering unit and a voltage dividing unit;

[0010] The two input terminals of the differential amplifier module include a first input terminal;

[0011] The power supply signal includes a negative polarity bias signal;

[0012] One end of the filter unit is electrically connected to the cathode of the first avalanche diode, and the other end of the filter unit receives the negative polarity bias signal;

[0013] One end of the voltage dividing unit is electrically connected to the anode of the first avalanche diode, and the other end of the voltage dividing unit is electrically connected to the first input end.

[0014] Optionally, the reference photoelectric receiving module further includes a filtering unit and a voltage dividing unit;

[0015] The two input terminals of the differential amplifier module include a second input terminal;

[0016] The power supply signal includes a negative polarity bias signal;

[0017] One end of the filter unit is electrically connected to the cathode of the second avalanche diode, and the other end of the filter unit receives the negative polarity bias signal;

[0018] One end of the voltage dividing unit is electrically connected to the anode of the second avalanche diode, and the other end of the voltage dividing unit is electrically connected to the second input end.

[0019] Optionally, the filtering unit includes a first resistor and a first capacitor;

[0020] In the actual optoelectronic receiving module, one end of the first resistor is electrically connected to the cathode of the first avalanche diode, and the other end of the first resistor receives the negative polarity bias signal;

[0021] In the reference photoelectric receiving module, one end of the first resistor is electrically connected to the cathode of the second avalanche diode, and the other end of the first resistor receives the negative polarity bias signal;

[0022] One end of the first capacitor is electrically connected to one end of the first resistor, and the other end of the first capacitor is grounded.

[0023] Optionally, the voltage dividing unit includes a second resistor;

[0024] In the actual optoelectronic receiving module, one end of the second resistor is electrically connected to the anode of the first avalanche diode, and the other end of the second resistor is electrically connected to the first input end;

[0025] In the reference photoelectric receiving module, one end of the second resistor is electrically connected to the anode of the second avalanche diode, and the other end of the second resistor is electrically connected to the second input end.

[0026] Optionally, the differential amplification module includes a differential operational amplifier and an amplification gain unit;

[0027] The differential operational amplifier comprises a non-phase input terminal, an inverting input terminal and an output terminal;

[0028] The amplification gain unit comprises a first end, a second end, a third end, a fourth end, a fifth end and a sixth end;

[0029] One end of the actual optoelectronic receiving module is electrically connected to the first end;

[0030] One end of the reference photoelectric receiving module is electrically connected to the second end;

[0031] The third terminal is electrically connected to the non-phase input terminal;

[0032] The fourth terminal is electrically connected to the inverting input terminal;

[0033] The fifth terminal is grounded;

[0034] The sixth end is electrically connected to the output end.

[0035] Optionally, the amplification gain unit further includes a third resistor, a fourth resistor, a fifth resistor and a sixth resistor;

[0036] One end of the third resistor is electrically connected to the first end, and the other end of the third resistor is electrically connected to the third end;

[0037] One end of the fourth resistor is electrically connected to the third end, and the other end of the fourth resistor is electrically connected to the fifth end;

[0038] One end of the fifth resistor is electrically connected to the second end, and the other end of the fifth resistor is electrically connected to the fourth end;

[0039] One end of the sixth resistor is electrically connected to the fourth end, and the other end of the sixth resistor is electrically connected to the sixth end.

[0040] Optionally, the differential operational amplifier further includes a first power supply terminal and a second power supply terminal;

[0041] The first power supply terminal receives a positive phase power supply signal;

[0042] The second power supply terminal receives a negative phase power supply signal.

[0043] Optionally, the differential amplification module further includes a first capacitor energy storage unit and a second capacitor energy storage unit;

[0044] One end of the first capacitor energy storage unit is electrically connected to the first power supply end, and the other end of the first capacitor energy storage unit is grounded;

[0045] One end of the second capacitor energy storage unit is electrically connected to the second power supply end, and the other end of the second capacitor energy storage unit is grounded.

[0046] In a second aspect, an embodiment of the utility model further provides a photodetector, comprising a circuit for reducing avalanche diode noise as described in any one of the first aspects.

[0047] The embodiment of the utility model provides a circuit and a photodetector for reducing the noise of an avalanche diode. The circuit includes an actual photoelectric receiving module, a reference photoelectric receiving module and a differential amplifier module; the actual photoelectric receiving module includes a first avalanche diode, the reference photoelectric receiving module includes a second avalanche diode, the first avalanche diode and the second avalanche diode have the same electrical characteristics, the first avalanche diode has a photoelectric receiving function, and the second avalanche diode has a photoelectric shielding function; one end of the actual photoelectric receiving module and one end of the reference photoelectric receiving module are electrically connected to two input ends of the differential amplifier module respectively; the other end of the actual photoelectric receiving module and the other end of the reference photoelectric receiving module respectively receive power supply signals. The circuit for reducing the noise of the avalanche diode utilizes a first avalanche diode with a photoelectric receiving function and a second avalanche diode with a photoelectric shielding function, and the two are electrically connected to the two input ends of the differential amplifier module respectively. The differential amplifier module effectively suppresses the background noise such as thermal noise and spike noise caused by the electrical characteristics of the avalanche diode itself through differential processing, reduces the influence of the background noise in the collection process of the effective avalanche pulse signal, improves the collection accuracy of the effective avalanche pulse signal, and, only the avalanche diode needs to be designed and a set of the first avalanche diode and the second avalanche diode needs to be obtained, thereby avoiding the problem of subsequently re-measuring the electrical characteristics of different avalanche diodes or re-modifying the filtering parameters of the filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0049] Figure 1 It is a schematic diagram of the structure of a circuit for reducing avalanche diode noise provided by an embodiment of the utility model. DETAILED DESCRIPTION

[0050] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0051] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. It should be noted that the directional words such as "upper", "lower", "left", "right" and the like described in the embodiments of the present invention are described at the angles shown in the accompanying drawings and should not be understood as limitations on the embodiments of the present invention. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is formed "on" or "under" another element, it can not only be directly formed "on" or "under" another element, but also indirectly formed "on" or "under" another element through an intermediate element. The terms "first", "second" and the like are only used for descriptive purposes and do not represent any order, quantity or importance, but are only used to distinguish different components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific circumstances.

[0052] The term "including" and its variations used in the present invention are open inclusions, that is, "including but not limited to". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment".

[0053] It should be noted that the concepts such as "first" and "second" mentioned in the present invention are only used to distinguish the corresponding contents, and are not used to limit the order or interdependence.

[0054] It should be noted that the modifications of "one" and "plurality" mentioned in the present invention are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0055] Figure 1 is a schematic diagram of a circuit for reducing noise of an avalanche diode provided by an embodiment of the utility model, such as Figure 1As shown, the circuit for reducing avalanche diode noise includes an actual photoelectric receiving module 10, a reference photoelectric receiving module 20 and a differential amplifier module 30; the actual photoelectric receiving module 10 includes a first avalanche diode APD1, the reference photoelectric receiving module 20 includes a second avalanche diode APD2, the first avalanche diode APD1 and the second avalanche diode APD2 have the same electrical characteristics, the first avalanche diode APD1 has a photoelectric receiving function, and the second avalanche diode APD2 has a photoelectric shielding function; one end of the actual photoelectric receiving module 10 and one end of the reference photoelectric receiving module 20 are electrically connected to two input ends of the differential amplifier module 30, respectively; the other end of the actual photoelectric receiving module 10 and the other end of the reference photoelectric receiving module 20 receive power signals, respectively.

[0056] Specifically, the actual photoelectric receiving module 10 includes a first avalanche diode APD1, and the reference photoelectric receiving module 20 includes a second avalanche diode APD2, wherein the avalanche diode refers to a PN junction after a reverse bias is applied, and the light incident to the avalanche diode is absorbed by the PN junction to form a photocurrent, and when the reverse voltage on the PN junction increases to a certain value, the carriers multiply, and the photocurrent also multiplies, reaching an avalanche breakdown state. The first avalanche diode APD1 has a photoelectric receiving function, and the second avalanche diode APD2 has a photoelectric shielding function. In other words, the light incident to the first avalanche diode APD1 can be absorbed by the PN junction and form a corresponding photoelectric signal, and the light incident to the second avalanche diode APD2 cannot be absorbed by the PN junction and will not form a corresponding photoelectric signal. The first avalanche diode APD1 and the second avalanche diode APD2 have the same electrical characteristics, then under the same reverse voltage value, at a similar position, the size and polarity of the background noise such as thermal noise and spike noise generated by the first avalanche diode APD1 and the second avalanche diode APD2 are the same. Exemplarily, the first avalanche diode APD1 normally receives incident light, and the second avalanche diode APD2 with the same electrical characteristics as the first avalanche diode APD1 but without the photoelectric receiving function can be customized from the manufacturer. The second avalanche diode APD2 can be a version that does not receive light or a version with a shielded light receiving area.

[0057] The circuit for reducing the noise of the avalanche diode includes an actual photoelectric receiving module 10, a reference photoelectric receiving module 20 and a differential amplifier module 30. Among them, one end of the actual photoelectric receiving module 10 is electrically connected to an input end of the differential amplifier module 30, and the other end of the actual photoelectric receiving module 10 receives a power signal. Then, under the action of a certain reverse bias voltage, the first avalanche diode APD1 in the actual photoelectric receiving module 10 generates a photoelectric signal including an effective avalanche pulse signal, thermal noise, spike noise, etc. One end of the reference photoelectric receiving module 20 is electrically connected to the other input end of the differential amplifier module 30, and the other end of the reference photoelectric receiving module 20 receives a power signal. Then, under the action of the same reverse bias voltage, the photoelectric signal generated by the second avalanche diode APD2 in the reference photoelectric receiving module 20 includes thermal noise, spike noise, etc. The differential amplifier module 30 performs differential processing to subtract the photoelectric signal generated by the first avalanche diode APD1 from the photoelectric signal generated by the second avalanche diode APD2. Since the size and polarity of the background noise such as thermal noise and spike noise in the corresponding photoelectric signals of the two are exactly the same, after the differential amplifier module 30 is subjected to differential processing, the effective avalanche pulse signal generated by the first avalanche diode APD1 can be obtained at the output end of the differential amplifier module 30, and the effective avalanche pulse signal is not doped with background noise such as thermal noise and spike noise, thereby achieving effective suppression of background noise such as thermal noise and spike noise, so that the effective avalanche pulse signal can be accurately extracted. In addition, the output end of the differential amplifier module 30 can also be electrically connected to an analog-to-digital conversion module, a voltage-current conversion module, etc., and the effective avalanche pulse signal obtained at the output end of the differential amplifier module 30 can be further analyzed to obtain depth information corresponding to the effective avalanche pulse signal. It should be noted that in the process of subtracting the background noise such as thermal noise and spike noise, only two avalanche diodes need to be customized in advance, namely the first avalanche diode APD1 with photoelectric receiving function and the second avalanche diode APD2 with photoelectric shielding function, and there is no need to adjust the parameters of the two avalanche diodes afterwards.

[0058] In addition, the two input ends of the differential amplifier module 30 are electrically connected to one end of the actual photoelectric receiving module 10 and one end of the reference photoelectric receiving module 20, respectively, wherein the actual photoelectric receiving module 10 includes a first avalanche diode APD1, and the reference photoelectric receiving module 20 includes a second avalanche diode APD2, and the first avalanche diode APD1 and the second avalanche diode APD2 have the same electrical characteristics. Exemplarily, the second avalanche diode APD2 with the photoelectric shielding function can be replaced with an equivalent adjustable capacitor (or a high-speed diode). The electrical characteristics of the second avalanche diode APD2 and the equivalent adjustable capacitor (or high-speed diode) need to be similar, that is, the thermal noise, spike noise, etc. included in the photoelectric signal corresponding to the second avalanche diode APD2 are similar to the differential signal, etc. included in the electrical signal corresponding to the equivalent adjustable capacitor (or similar to the noise included in the electrical signal corresponding to the high-speed diode, and the high voltage of the high-speed diode can be adjusted by a variable resistor to simulate the electrical characteristics of the avalanche diode as much as possible). After that, after the differential processing of the differential amplifier module 30, the effective avalanche pulse signal generated by the first avalanche diode APD1 can also be obtained at the output end of the differential amplifier module 30, and the effective avalanche pulse signal is not doped with background noise such as thermal noise and spike noise.

[0059] The technical solution in the embodiment of the utility model is that the circuit includes an actual photoelectric receiving module, a reference photoelectric receiving module and a differential amplifier module; the actual photoelectric receiving module includes a first avalanche diode, the reference photoelectric receiving module includes a second avalanche diode, the first avalanche diode and the second avalanche diode have the same electrical characteristics, the first avalanche diode has a photoelectric receiving function, and the second avalanche diode has a photoelectric shielding function; one end of the actual photoelectric receiving module and one end of the reference photoelectric receiving module are electrically connected to the two input ends of the differential amplifier module respectively; the other end of the actual photoelectric receiving module and the other end of the reference photoelectric receiving module respectively receive power signals. The circuit for reducing the noise of the avalanche diode utilizes a first avalanche diode with a photoelectric receiving function and a second avalanche diode with a photoelectric shielding function, and the two are electrically connected to the two input ends of the differential amplifier module respectively. The differential amplifier module effectively suppresses the background noise such as thermal noise and spike noise caused by the electrical characteristics of the avalanche diode itself through differential processing, reduces the influence of the background noise in the collection process of the effective avalanche pulse signal, improves the collection accuracy of the effective avalanche pulse signal, and, only the avalanche diode needs to be designed and a set of the first avalanche diode and the second avalanche diode needs to be obtained, thereby avoiding the problem of subsequently re-measuring the electrical characteristics of different avalanche diodes or re-modifying the filtering parameters of the filter.

[0060] Optionally, continue to refer to Figure 1The actual optoelectronic receiving module 10 also includes a filtering unit 40 and a voltage dividing unit 50; the two input ends of the differential amplifier module 30 include a first input end 31; the power supply signal includes a negative polarity bias signal -HVL; one end of the filtering unit 40 is electrically connected to the negative pole of the first avalanche diode APD1, and the other end of the filtering unit 40 receives the negative polarity bias signal -HVL; one end of the voltage dividing unit 50 is electrically connected to the positive pole of the first avalanche diode APD1, and the other end of the voltage dividing unit 50 is electrically connected to the first input end 31.

[0061] Specifically, the actual optoelectronic receiving module 10 includes a filter unit 40, a first avalanche diode APD1 and a voltage divider unit 50. Among them, one end of the filter unit 40 is electrically connected to the cathode of the first avalanche diode APD1, and the other end of the filter unit 40 receives the negative polarity bias signal -HVL. One end of the voltage divider unit 50 is electrically connected to the anode of the first avalanche diode APD1, and the other end of the voltage divider unit 50 is electrically connected to the first input terminal 31. That is, between the negative polarity bias signal -HVL and the first input terminal 31, the filter unit 40, the first avalanche diode APD1 and the voltage divider unit 50 are electrically connected in sequence.

[0062] Optionally, continue to refer to Figure 1 , the reference photoelectric receiving module 20 also includes a filtering unit 40 and a voltage dividing unit 50; the two input ends of the differential amplifier module 30 include a second input end 32; the power supply signal includes a negative polarity bias signal -HVL; one end of the filtering unit 40 is electrically connected to the negative pole of the second avalanche diode APD2, and the other end of the filtering unit 40 receives the negative polarity bias signal -HVL; one end of the voltage dividing unit 50 is electrically connected to the positive pole of the second avalanche diode APD2, and the other end of the voltage dividing unit 50 is electrically connected to the second input end 32.

[0063] Specifically, the reference photoelectric receiving module 20 also includes a filter unit 40, a second avalanche diode APD2 and a voltage divider unit 50. Among them, one end of the filter unit 40 is electrically connected to the cathode of the second avalanche diode APD2, and the other end of the filter unit 40 receives the negative polarity bias signal -HVL. One end of the voltage divider unit 50 is electrically connected to the anode of the second avalanche diode APD2, and the other end of the voltage divider unit 50 is electrically connected to the second input terminal 32. That is, between the negative polarity bias signal -HVL and the second input terminal 32, the filter unit 40, the second avalanche diode APD2 and the voltage divider unit 50 are electrically connected in sequence.

[0064] It should be noted that in order to ensure that the thermal noise, spike noise and other background noises in the photoelectric signal generated by the first avalanche diode APD1 are the same in size and polarity as the thermal noise, spike noise and other background noises in the photoelectric signal generated by the second avalanche diode APD2, it is necessary to ensure that the reverse bias voltage applied to the first avalanche diode APD1 is the same as the reverse bias voltage applied to the second avalanche diode APD2, that is, both are electrically connected to the negative polarity bias signal -HVL, and the negative polarity bias signal -HVL is connected to the first avalanche diode APD1 / the second avalanche diode APD2 after being filtered by the same filter unit 40. Afterwards, the photoelectric signals generated by the first avalanche diode APD1 / the second avalanche diode APD2 are connected to the two input ends of the differential amplifier module 30 after passing through the same voltage divider unit 50. In the differential amplifier module 30, the background noises such as thermal noise and spike noise of the same size and polarity can be subtracted and eliminated, and only a valid avalanche pulse signal is obtained at the output end of the differential amplifier module 30.

[0065] In a specific embodiment, optionally, continue to refer to Figure 1 The filtering unit 40 includes a first resistor R1 and a first capacitor C1; in the actual photoelectric receiving module 10, one end of the first resistor R1 is electrically connected to the cathode of the first avalanche diode APD1, and the other end of the first resistor R1 receives a negative polarity bias signal -HVL; in the reference photoelectric receiving module 20, one end of the first resistor R1 is electrically connected to the cathode of the second avalanche diode APD2, and the other end of the first resistor R1 receives a negative polarity bias signal -HVL; one end of the first capacitor C1 is electrically connected to one end of the first resistor R1, and the other end of the first capacitor C1 is grounded.

[0066] Specifically, the filtering unit 40 includes a first resistor R1 and a first capacitor C1, and the filtering unit 40 can be applied to both the actual photoelectric receiving module 10 and the reference photoelectric receiving module 20. In the actual photoelectric receiving module 10, one end of the first resistor R1 is electrically connected to the cathode of the first avalanche diode APD1, the other end of the first resistor R1 receives the negative polarity bias signal -HVL, one end of the first capacitor C1 is electrically connected to one end of the first resistor R1, and the other end of the first capacitor C1 is grounded. Exemplarily, one end of the first capacitor C1 can be electrically connected to one end of the first resistor R1 close to the cathode of the first avalanche diode APD1, and one end of the first capacitor C1 can also be electrically connected to one end of the first resistor R1 close to the negative polarity bias signal -HVL. In the reference photoelectric receiving module 20, one end of the first resistor R1 is electrically connected to the negative electrode of the second avalanche diode APD2, the other end of the first resistor R1 receives the negative polarity bias signal -HVL, one end of the first capacitor C1 is electrically connected to one end of the first resistor R1, and the other end of the first capacitor C1 is grounded. Exemplarily, one end of the first capacitor C1 can be electrically connected to one end of the first resistor R1 close to the negative electrode of the second avalanche diode APD2, and one end of the first capacitor C1 can also be electrically connected to one end of the first resistor R1 close to the negative polarity bias signal -HVL.

[0067] In another specific embodiment, optionally, continue to refer to Figure 1 , the voltage dividing unit 50 includes a second resistor R2; in the actual photoelectric receiving module 10, one end of the second resistor R2 is electrically connected to the positive electrode of the first avalanche diode APD1, and the other end of the second resistor R2 is electrically connected to the first input terminal 31; in the reference photoelectric receiving module 20, one end of the second resistor R2 is electrically connected to the positive electrode of the second avalanche diode APD2, and the other end of the second resistor R2 is electrically connected to the second input terminal 32.

[0068] Specifically, the voltage divider unit 50 includes a second resistor R2, and the voltage divider unit 50 can be applied to both the actual photoelectric receiving module 10 and the reference photoelectric receiving module 20. In the actual photoelectric receiving module 10, one end of the second resistor R2 is electrically connected to the positive electrode of the first avalanche diode APD1, and the other end of the second resistor R2 is electrically connected to the first input terminal 31. The second resistor R2 can balance the voltage value between the first avalanche diode APD1 and the differential amplifier module 30, ensuring that the first avalanche diode APD1 and the differential amplifier module 30 are both in normal working state. In the reference photoelectric receiving module 20, one end of the second resistor R2 is electrically connected to the positive electrode of the second avalanche diode APD2, and the other end of the second resistor R2 is electrically connected to the second input terminal 32. The second resistor R2 can balance the voltage value between the second avalanche diode APD2 and the differential amplifier module 30, ensuring that the second avalanche diode APD2 and the differential amplifier module 30 are both in normal working state.

[0069] Optionally, continue to refer to Figure 1 The differential amplifier module 30 includes a differential operational amplifier U and an amplification gain unit 33; the differential operational amplifier U includes a non-inverting input terminal, an inverting input terminal and an output terminal; the amplification gain unit 33 includes a first terminal 331, a second terminal 332, a third terminal 333, a fourth terminal 334, a fifth terminal 335 and a sixth terminal 336; one end of the actual photoelectric receiving module 10 is electrically connected to the first terminal 331; one end of the reference photoelectric receiving module 20 is electrically connected to the second terminal 332; the third terminal 333 is electrically connected to the non-inverting input terminal; the fourth terminal 334 is electrically connected to the inverting input terminal; the fifth terminal 335 is grounded; and the sixth terminal 336 is electrically connected to the output terminal.

[0070] Further, continue to refer to Figure 1 The amplification gain unit 33 also includes a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6; one end of the third resistor R3 is electrically connected to the first end 331, and the other end of the third resistor R3 is electrically connected to the third end 333; one end of the fourth resistor R4 is electrically connected to the third end 333, and the other end of the fourth resistor R4 is electrically connected to the fifth end 335; one end of the fifth resistor R5 is electrically connected to the second end 332, and the other end of the fifth resistor R5 is electrically connected to the fourth end 334; one end of the sixth resistor R6 is electrically connected to the fourth end 334, and the other end of the sixth resistor R6 is electrically connected to the sixth end 336.

[0071] Specifically, the differential amplifier module 30 includes a differential operational amplifier U and an amplification gain unit 33. The differential operational amplifier U includes a non-inverting input terminal, a reverse input terminal and an output terminal; the amplification gain unit 33 includes a first terminal 331, a second terminal 332, a third terminal 333, a fourth terminal 334, a fifth terminal 335 and a sixth terminal 336. The amplification gain unit 33 also includes a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6. One end of the actual photoelectric receiving module 10 is electrically connected to the first end 331, the non-inverting input terminal is electrically connected to the third end 333, and one end of the third resistor R3 is electrically connected to the first end 331, and the other end of the third resistor R3 is electrically connected to the third end 333, that is, the third resistor R3 is used to connect one end of the actual photoelectric receiving module 10 with the non-inverting input terminal of the differential operational amplifier U. One end of the reference photoelectric receiving module 20 is electrically connected to the second end 332, and the inverting input end is electrically connected to the fourth end 334, and one end of the fifth resistor R5 is electrically connected to the second end 332, and the other end of the fifth resistor R5 is electrically connected to the fourth end 334, that is, the fifth resistor R5 is used to connect one end of the reference photoelectric receiving module 20 with the inverting input end of the differential operational amplifier U. One end of the fourth resistor R4 is electrically connected to the third end 333, and the other end of the fourth resistor R4 is electrically connected to the fifth end 335, and the fifth end 335 is grounded, that is, the non-inverting input end of the differential operational amplifier U is grounded through the fourth resistor R4. The inverting input end is electrically connected to the fourth end 334, and the output end is electrically connected to the sixth end 336, and one end of the sixth resistor R6 is electrically connected to the fourth end 334, and the other end of the sixth resistor R6 is electrically connected to the sixth end 336, that is, the sixth resistor R6 is used to connect the inverting input end and the output end of the differential operational amplifier U.

[0072] It can be understood that the resistance values ​​of the third resistor R3, the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6 can determine the amplification gain of the differential operational amplifier U. For example, the voltage at the non-inverting input terminal of the differential operational amplifier U can be V1, the voltage at the inverting input terminal of the differential operational amplifier U can be V2, and the voltage at the output terminal of the differential operational amplifier U can be Vout, then Vout = V1 [(R4 / R3+R4)(R6 / R5+1)] - V2 (R6 / R5). In order to simplify the calculation and reduce the complexity of the amplification gain, the special case of R3 = R5 and R4 = R6 can be used, then Vout = R4 / R3 (V1-V2) or Vout = R6 / R5 (V2-V1). In this way, the effective avalanche pulse signal is extracted from the background noise such as thermal noise and spike noise.

[0073] Optionally, continue to refer to Figure 1, the differential operational amplifier U also includes a first power supply terminal 61 and a second power supply terminal 62; the first power supply terminal 61 receives a positive power supply signal; the second power supply terminal 62 receives a negative power supply signal. Further, continue to refer to Figure 1 The differential amplifier module 30 also includes a first capacitor energy storage unit 63 and a second capacitor energy storage unit 64; one end of the first capacitor energy storage unit 63 is electrically connected to the first power supply terminal 61, and the other end of the first capacitor energy storage unit 63 is grounded; one end of the second capacitor energy storage unit 64 is electrically connected to the second power supply terminal 62, and the other end of the second capacitor energy storage unit 64 is grounded.

[0074] Specifically, the differential operational amplifier U also includes a first power supply terminal 61 and a second power supply terminal 62. The first power supply terminal 61 can receive a positive power supply signal, and the second power supply terminal 62 can receive a negative power supply signal, so the differential operational amplifier U is in a normal working state under the action of the positive power supply signal and the negative power supply signal. And, the differential amplifier module 30 also includes a first capacitor energy storage unit 63 and a second capacitor energy storage unit 64. One end of the first capacitor energy storage unit 63 is electrically connected to the first power supply terminal 61, and the other end of the first capacitor energy storage unit 63 is grounded, that is, one end of the first capacitor energy storage unit 63 receives a positive power supply signal, and the first capacitor energy storage unit 63 can reasonably store and release electrical energy. Exemplarily, the first capacitor energy storage unit 63 may include a second capacitor C2 and a third capacitor C3, wherein the first power supply terminal 61 is electrically connected to one end of the second capacitor C2 and one end of the third capacitor C3, respectively, and the other end of the second capacitor C2 and the other end of the second capacitor C2 are grounded respectively. One end of the second capacitor energy storage unit 64 is electrically connected to the second power supply terminal 62, and the other end of the second capacitor energy storage unit 64 is grounded, that is, one end of the second capacitor energy storage unit 64 receives the negative phase power supply signal, and the second capacitor energy storage unit 64 can reasonably store and release electrical energy. Exemplarily, the second capacitor energy storage unit 64 may include a second capacitor C2 and a third capacitor C3, wherein the second power supply terminal 62 is electrically connected to one end of the second capacitor C2 and one end of the third capacitor C3, respectively, and the other end of the second capacitor C2 and the other end of the second capacitor C3 are grounded, respectively.

[0075] Based on the same concept, the embodiment of the present invention further provides a photodetector. The photodetector includes a circuit for reducing avalanche diode noise as provided in any one of the embodiments of the present invention. Therefore, the photodetector provided in the embodiment of the present invention has the corresponding beneficial effects of the circuit for reducing avalanche diode noise provided in the embodiment of the present invention, which will not be described in detail here.

[0076] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A circuit for reducing noise of an avalanche diode, characterized in that: It includes an actual photoelectric receiving module, a reference photoelectric receiving module and a differential amplification module; The actual photoelectric receiving module includes a first avalanche diode, and the reference photoelectric receiving module includes a second avalanche diode. The first avalanche diode and the second avalanche diode have the same electrical characteristics. The first avalanche diode has a photoelectric receiving function, and the second avalanche diode has a photoelectric shielding function. One end of the actual photoelectric receiving module and one end of the reference photoelectric receiving module are electrically connected to two input ends of the differential amplification module respectively; The other end of the actual photoelectric receiving module and the other end of the reference photoelectric receiving module receive power signals respectively.

2. The circuit according to claim 1, characterized in that The actual photoelectric receiving module also includes a filtering unit and a voltage dividing unit; The two input terminals of the differential amplifier module include a first input terminal; The power supply signal includes a negative polarity bias signal; One end of the filter unit is electrically connected to the cathode of the first avalanche diode, and the other end of the filter unit receives the negative polarity bias signal; One end of the voltage dividing unit is electrically connected to the anode of the first avalanche diode, and the other end of the voltage dividing unit is electrically connected to the first input end.

3. The circuit according to claim 1, characterized in that The reference photoelectric receiving module also includes a filtering unit and a voltage dividing unit; The two input terminals of the differential amplifier module include a second input terminal; The power supply signal includes a negative polarity bias signal; One end of the filter unit is electrically connected to the cathode of the second avalanche diode, and the other end of the filter unit receives the negative polarity bias signal; One end of the voltage dividing unit is electrically connected to the anode of the second avalanche diode, and the other end of the voltage dividing unit is electrically connected to the second input end.

4. The circuit according to any one of claims 2 or 3, characterized in that: The filtering unit includes a first resistor and a first capacitor; In the actual optoelectronic receiving module, one end of the first resistor is electrically connected to the cathode of the first avalanche diode, and the other end of the first resistor receives the negative polarity bias signal; In the reference photoelectric receiving module, one end of the first resistor is electrically connected to the cathode of the second avalanche diode, and the other end of the first resistor receives the negative polarity bias signal; One end of the first capacitor is electrically connected to one end of the first resistor, and the other end of the first capacitor is grounded.

5. The circuit according to any one of claims 2 or 3, characterized in that: The voltage dividing unit includes a second resistor; In the actual optoelectronic receiving module, one end of the second resistor is electrically connected to the anode of the first avalanche diode, and the other end of the second resistor is electrically connected to the first input end; In the reference photoelectric receiving module, one end of the second resistor is electrically connected to the anode of the second avalanche diode, and the other end of the second resistor is electrically connected to the second input end.

6. The circuit according to claim 1, characterized in that The differential amplification module includes a differential operational amplifier and an amplification gain unit; The differential operational amplifier comprises a non-phase input terminal, an inverting input terminal and an output terminal; The amplification gain unit comprises a first end, a second end, a third end, a fourth end, a fifth end and a sixth end; One end of the actual optoelectronic receiving module is electrically connected to the first end; One end of the reference photoelectric receiving module is electrically connected to the second end; The third terminal is electrically connected to the non-phase input terminal; The fourth terminal is electrically connected to the inverting input terminal; The fifth terminal is grounded; The sixth end is electrically connected to the output end.

7. The circuit according to claim 6, characterized in that The amplification gain unit further includes a third resistor, a fourth resistor, a fifth resistor and a sixth resistor; One end of the third resistor is electrically connected to the first end, and the other end of the third resistor is electrically connected to the third end; One end of the fourth resistor is electrically connected to the third end, and the other end of the fourth resistor is electrically connected to the fifth end; One end of the fifth resistor is electrically connected to the second end, and the other end of the fifth resistor is electrically connected to the fourth end; One end of the sixth resistor is electrically connected to the fourth end, and the other end of the sixth resistor is electrically connected to the sixth end.

8. The circuit according to claim 6, characterized in that The differential operational amplifier also includes a first power supply terminal and a second power supply terminal; The first power supply terminal receives a positive phase power supply signal; The second power supply terminal receives a negative phase power supply signal.

9. The circuit according to claim 8, characterized in that The differential amplification module further includes a first capacitor energy storage unit and a second capacitor energy storage unit; One end of the first capacitor energy storage unit is electrically connected to the first power supply end, and the other end of the first capacitor energy storage unit is grounded; One end of the second capacitor energy storage unit is electrically connected to the second power supply end, and the other end of the second capacitor energy storage unit is grounded.

10. A photoelectric detector, characterized in that: A circuit for reducing avalanche diode noise as claimed in any one of claims 1 to 9.

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