Quenching circuit of optical detector and optical detection device

Abstract

The invention provides a quenching circuit of an optical detector and an optical detection device.The quenching circuit is used for controlling the working state of the optical detector, the optical detector is suitable for photovoltaic conversion, and the working voltage of the optical detector is higher than the avalanche breakdown voltage of the optical detector; the quenching circuit is used for quenching the optical detector after avalanche breakdown of the optical detector and outputting a corresponding electric signal, and the maximum voltage corresponding to the electric signal is lower than the difference value between the working voltage and the avalanche breakdown voltage. By adopting the technical scheme, the limitation on the working voltage of the optical detector can be reduced, and the performance of the optical detector is improved.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the field of photoelectric conversion technology, and in particular to a quenching circuit of a photodetector and a photodetection device. Background Art

[0002] The light detection device is an important component of laser detection. With the rapid development of semiconductor technology, it has become a trend to integrate light detectors and circuits into chips to make highly integrated, low-cost light detection devices. Among various light detectors, single photon avalanche diodes (SPADs) have extremely high gain, thus having good weak signal detection capabilities and time resolution capabilities, and are widely used in scenarios such as time-of-flight ranging and fluorescence lifetime imaging. SPAD devices are compatible with complementary metal oxide semiconductor (CMOS) processes, so SPAD devices can be integrated with CMOS readout circuit chips to achieve low-cost, high-performance SPAD sensors. The light detection device may include a SPAD sensor array and a readout chip, wherein the SPAD sensor can perform photoelectric conversion and output electrical signals, and the readout chip can read the electrical signals, perform signal processing and storage.

[0003] The CMOS process limits the operating voltage of the readout chip, and thus the electrical signal output by the SPAD cannot exceed the operating voltage of the readout chip, otherwise the readout chip cannot work effectively. The voltage of the electrical signal output by the SPAD is related to the reverse bias applied to both ends of the SPAD. Therefore, due to the operating voltage of the readout chip, the SPAD reverse bias is also greatly limited. The performance of the SPAD is related to the magnitude of the applied reverse bias. Generally speaking, the detection efficiency increases with the increase of the reverse bias. If the SPAD operates in a low-voltage environment, the coverage of the depletion region in the SPAD is low, which will have a negative impact on the detection efficiency, time jitter and other performance parameters of the SPAD. Therefore, how to provide a technical solution to reduce the limitations on the operating voltage of the photodetector and improve the performance of the photodetector has become an urgent problem to be solved. Summary of the invention

[0004] In view of this, the embodiments of the present disclosure provide a quenching circuit of a light detector and a light detection device, which can improve the performance of the light detector.

[0005] First, an embodiment of the present disclosure provides a quenching circuit of a photodetector, wherein the quenching circuit is used to control the working state of the photodetector, the photodetector is suitable for photoelectric conversion, and the working voltage of the photodetector is higher than the avalanche breakdown voltage of the photodetector;

[0006] The quenching circuit quenches the photodetector after the photodetector avalanche breakdown and outputs a corresponding electrical signal, wherein a maximum voltage corresponding to the electrical signal is lower than a difference between the operating voltage and the avalanche breakdown voltage.

[0007] Optionally, the maximum voltage corresponding to the electrical signal is proportional to an overvoltage, wherein the overvoltage is a difference between an operating voltage and an avalanche breakdown voltage.

[0008] Optionally, the quenching circuit includes a plurality of quenching resistors, and a ratio of a maximum voltage corresponding to the electrical signal to the overvoltage is determined by resistance values ​​of the plurality of quenching resistors.

[0009] Optionally, the quenching circuit is provided with a first voltage-applying end at one end away from the photodetector, suitable for loading a first power supply voltage;

[0010] The end of the photodetector away from the quenching circuit is provided with a second voltage-applying end suitable for loading a second power supply voltage;

[0011] The difference between the first power supply voltage and the second power supply voltage is the operating voltage.

[0012] Optionally, the quenching circuit further includes:

[0013] The signal output terminal is suitable for outputting the electrical signal, and the signal output terminal is arranged between the multiple quenching resistors.

[0014] Optionally, the plurality of quenching resistors include:

[0015] a first quenching resistor and a second quenching resistor;

[0016] The first quenching resistor, the second quenching resistor and the photodetector are connected in sequence.

[0017] Optionally, a ratio of a maximum voltage corresponding to the electrical signal to the overvoltage is determined by resistance values ​​of the first quenching resistor and the second quenching resistor.

[0018] Optionally, the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage is: the ratio of the resistance value of the first quenching resistor to the sum of the resistance values ​​of the first quenching resistor and the second quenching resistor.

[0019] Optionally, the first supply voltage is less than an overvoltage.

[0020] Optionally, the photodetector is a single photon avalanche diode.

[0021] Accordingly, an embodiment of the present disclosure further provides a light detection device, comprising:

[0022] The light detection chip includes a light detector, which is suitable for performing photoelectric conversion and outputting corresponding electrical signals;

[0023] a readout chip, comprising a readout circuit, adapted to read out the electrical signal;

[0024] The operating voltage of the photodetector is higher than the avalanche breakdown voltage of the photodetector,

[0025] The maximum voltage corresponding to the electrical signal is lower than the difference between the operating voltage and the avalanche breakdown voltage.

[0026] Optionally, the maximum voltage corresponding to the electrical signal is proportional to an overvoltage, wherein the overvoltage is a difference between an operating voltage and an avalanche breakdown voltage.

[0027] Optionally, the light detection device further includes:

[0028] A quenching circuit, used to control the working state of the photodetector and output the electrical signal;

[0029] The quenching circuit includes a plurality of quenching resistors, and the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage is determined by the resistance values ​​of the plurality of quenching resistors.

[0030] Optionally, the quenching circuit further includes:

[0031] A signal output terminal is suitable for outputting the electrical signal. The signal output terminal is arranged between the multiple quenching resistors and is connected to the readout circuit.

[0032] Optionally, at least one quenching resistor is provided on the light detection chip.

[0033] Optionally, the multiple quenching resistors include a first quenching resistor and a second quenching resistor, and the first quenching resistor, the second quenching resistor and the photodetector are connected in sequence; the quenching circuit also includes a signal output end, suitable for outputting an electrical signal, and the signal output end is arranged between the first quenching resistor and the second quenching resistor.

[0034] Optionally, the second quenching resistor is provided on the light detection chip.

[0035] Optionally, the readout chip further includes a first voltage-applying terminal connected to an end of the first quenching resistor away from the second quenching resistor, and suitable for loading a first supply voltage.

[0036] Optionally, the light detection chip further includes a first voltage-applying terminal connected to an end of the first quenching resistor away from the second quenching resistor, and suitable for loading a first supply voltage.

[0037] Optionally, the light detection chip further comprises a second voltage-applying terminal connected to an end of the light detector away from the quenching circuit and suitable for loading a second supply voltage, wherein a difference between the first supply voltage and the second supply voltage is the operating voltage.

[0038] The quenching circuit of the embodiment of the present disclosure is used to control the working state of the photodetector; the photodetector is loaded with an operating voltage higher than the avalanche breakdown voltage of the photodetector, which can cause the photodetector to undergo avalanche breakdown, thereby obtaining a high gain; the avalanche current of the photodetector is output through the quenching circuit to obtain a corresponding electrical signal, and the quenching circuit of the present disclosure makes the maximum voltage corresponding to the electrical signal lower than the difference between the operating voltage and the avalanche breakdown voltage, thereby reducing the limitation on the working voltage of the photodetector and improving the performance of the photodetector.

[0039] By adopting the optical detection device of the embodiment of the present disclosure, by loading the optical detector in the optical detection chip with an operating voltage higher than the avalanche breakdown voltage of the optical detector, the optical detector can be caused to undergo avalanche breakdown, thereby obtaining high gain; after the avalanche breakdown of the optical detector, the optical detection chip can output a corresponding electrical signal to the readout circuit of the readout chip, and the maximum voltage corresponding to the electrical signal is lower than the difference between the operating voltage and the avalanche breakdown voltage of the optical detector, thereby increasing the operating voltage of the optical detector, reducing the limitation of the readout circuit on the operating voltage of the optical detector, and improving the performance of the optical detector and the optical detection device. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments of the present disclosure or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 A schematic structural diagram of a light detection device is shown.

[0042] Figures 2 to 4 Schematic diagrams of three quenching circuits in the embodiments of the present disclosure are respectively shown.

[0043] Figure 5 A schematic diagram of the working state of the light detector in an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0044] The single photon avalanche diode (SPAD) works in Geiger mode, and an operating voltage is applied to the SPAD. The operating voltage is a reverse bias voltage higher than the avalanche breakdown voltage. When the SPAD receives a photon, an avalanche can be triggered. After the SPAD is triggered, an external circuit is required to reduce the voltage across the SPAD to quench it, and then restore the voltage across the SPAD to the operating voltage, waiting for the next photon trigger. In practical applications, the photodetector is used in conjunction with a quenching circuit, wherein the quenching circuit is used to quench the avalanche of the photodetector. At the same time, the avalanche current is output through the quenching circuit.

[0045] As an optional implementation, refer to Figure 1 , Figure 1 A schematic structural diagram of a light detection device is shown.

[0046] The optical detection device M includes: an optical detection chip M1 and a readout chip M2, wherein the optical detection chip M1 can convert an optical signal into an electrical signal and output it, and the readout chip M2 can read the electrical signal output by the optical detection chip M1, and perform signal processing and storage; the optical detection chip M1 includes an optical detector 11, and the readout chip M2 includes a quenching circuit 12 and a readout circuit (not shown in the figure), wherein the optical detector 11 is connected in series with the quenching circuit 12, and a signal output terminal S0 is provided between the optical detector 11 and the quenching circuit 12, and the signal output terminal S0 is used to output an electrical signal to the readout circuit; a first voltage application terminal S1 is provided at one end of the quenching circuit 12 away from the optical detector 11, and is used to load a first power supply voltage V S1 The end of the photodetector 11 away from the quenching circuit 12 is provided with a second voltage-applying end S2 for applying a second supply voltage V S2 .

[0047] Specifically, the readout circuit may be a complementary metal-oxide-semiconductor (CMOS) circuit, and the photodetector may be a SPAD. SPAD includes the following periodic working states: to be measured, triggered, quenched, and recovered.

[0048] Both ends of SPAD are connected through V S1 and V S2 Load the working voltage, which is the first supply voltage V S1 With the second supply voltage V S2 The voltage difference (V S1 -V S2 ) and is higher than the breakdown voltage. When the SPAD does not receive a photon, the SPAD is turned off and is in a state of waiting for a photon to be tested. The circuit between the first voltage-applying terminal S1 and the second voltage-applying terminal S2 is open, and the voltage V corresponding to the signal output terminal S0 isS0 Equal to the first supply voltage V of the first voltage-adding terminal S1 S1 At this time, the voltage difference across the SPAD is the operating voltage.

[0049] When receiving a photon, the SPAD may be triggered to avalanche, undergo avalanche breakdown, and output an avalanche current.

[0050] After the SPAD avalanches, the avalanche current flows through the quenching circuit. The voltage divider of the quenching circuit quickly reduces the voltage difference between the two ends of the SPAD to below the avalanche breakdown voltage, quenching the avalanche. The voltage V at the signal output terminal S0 is S0 Reduce to the second supply voltage V S2 and avalanche breakdown voltage V BD The sum (V S2 +V BD ).

[0051] After the avalanche of the SPAD is quenched, it enters a recovery state, and under the action of the voltage difference between the first voltage-applying terminal S1 and the second voltage-applying terminal S2, the bias voltage at both ends of the SPAD gradually increases to the operating voltage. Thereafter, the SPAD enters a test state again.

[0052] It can be seen that during the SPAD triggering, quenching and recovery process, the output voltage of the signal output terminal S0 is (V S2 +V BD )~V S1 The maximum value is V S1 To ensure the normal operation of the COMS circuit, V S1 cannot exceed the operating voltage of the CMOS circuit, so the operating voltage of the SPAD (V S1 -V S2 ) are also restricted.

[0053] CMOS technology with a process of 130nm or above can make the circuit work at a higher voltage, but the CMOS process has high power consumption and high cost, and cannot meet the needs of high-density SPAD sensors. For processes below 65nm, the operating voltage of CMOS circuits is usually 3.3V or 5V. In some application scenarios, V S2 =-V BD , then V S1 =V EX , V EX The SPAD operating voltage is higher than the avalanche breakdown voltage V BD Therefore, CMOS circuits require SPADs to work with V EX Cannot exceed 3.3V or 5V, while SPAD works with V EX Usually between 10 and 20V, if V EXIf it is too low, the depletion region in the SPAD will be smaller, and the detection efficiency, time jitter and other performance will be negatively affected.

[0054] In order to solve the above technical problems, the embodiment of the present disclosure provides a quenching circuit of a photodetector for controlling the working state of the photodetector. The photodetector is loaded with a working voltage higher than the avalanche breakdown voltage of the photodetector so that the photodetector can undergo avalanche breakdown and obtain an extremely high gain (10 6 After the photodetector avalanche breakdown, the quenching circuit quenches the photodetector and outputs a corresponding electrical signal, wherein the maximum voltage corresponding to the electrical signal is lower than the difference between the operating voltage and the avalanche breakdown voltage.

[0055] Specifically, the operating voltage of the photodetector may be: the voltage difference across the photodetector when the photodetector is in the test state; or the maximum voltage difference across the photodetector during the entire operating cycle of the photodetector.

[0056] By adopting the above technical solution, the photodetector is loaded with an operating voltage higher than the avalanche breakdown voltage of the photodetector, which can cause the photodetector to undergo avalanche breakdown, thereby obtaining extremely high gain and sensitivity; after the photodetector avalanches, the photodetector is quenched by a quenching circuit and an electrical signal is output, and the maximum voltage of the output electrical signal is lower than the difference between the operating voltage and the avalanche breakdown voltage, thereby reducing the limitation of the readout circuit on the operating voltage of the photodetector and improving the performance of the photodetector.

[0057] As an optional implementation, the maximum voltage corresponding to the electrical signal may be positively correlated with an overvoltage, wherein the overvoltage is a difference between an operating voltage and an avalanche breakdown voltage of the photodetector.

[0058] For example, when the maximum voltage corresponding to the electrical signal is positively correlated with the overvoltage, the maximum value of the overvoltage of the photodetector can be determined based on the limitation of the maximum voltage of the electrical signal in the application scenario of the photodetector. For example, when the photodetector is connected to a CMOS readout circuit, the maximum voltage of the electrical signal is not greater than the operating voltage of the readout circuit. Based on the positive correlation between the maximum voltage corresponding to the electrical signal and the overvoltage, the range of the overvoltage of the photodetector, such as the maximum value, is determined. Thus, the overvoltage of the photodetector can be adjusted within a range not exceeding the above-mentioned maximum value of the overvoltage, thereby adjusting the performance of the photodetector and reducing the limitation on the operating voltage of the photodetector.

[0059] As a specific example, the maximum voltage corresponding to the electrical signal may be proportional to the overvoltage.

[0060] In some embodiments, the maximum voltage of the electrical signal is determined based on the limitation of the maximum voltage of the electrical signal in the application scenario of the light detector; the maximum range of the overvoltage can be determined based on the maximum voltage of the electrical signal and the proportional relationship between the maximum voltage of the electrical signal and the overvoltage.

[0061] In some embodiments, the quenching circuit includes a plurality of quenching resistors, and the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage is determined by the resistance values ​​of the plurality of quenching resistors.

[0062] The application scenarios of photodetectors limit the maximum voltage corresponding to the electrical signal they output. In order to obtain the expected performance, the photodetector needs to have a certain operating voltage and corresponding overvoltage. According to the limit value of the maximum voltage corresponding to the electrical signal and the overvoltage required by the photodetector, the ratio of the two can be obtained, and then the resistance values ​​of multiple quenching resistors can be set accordingly to meet the above ratio relationship. The photodetector is made to work under the required operating voltage and overvoltage conditions, and the output electrical signal does not exceed the voltage limit of the readout circuit, etc., which can not only ensure the performance of the photodetector, but also ensure the working safety of the subsequent circuit.

[0063] In some embodiments, a first voltage-applying terminal is provided at one end of the quenching circuit away from the photodetector, which is suitable for loading a first power supply voltage; a second voltage-applying terminal is provided at one end of the photodetector away from the quenching circuit, which is suitable for loading a second power supply voltage; wherein the difference between the first power supply voltage and the second power supply voltage is the working voltage of the photodetector. Through the first voltage-applying terminal and the second voltage-applying terminal, a reverse bias voltage can be applied to both ends of the photodetector as its working voltage, and the working voltage exceeds the avalanche breakdown voltage of the photodetector. The photodetector works in Geiger mode and can obtain extremely high gain.

[0064] In some embodiments, the quenching circuit further includes a signal output terminal adapted to output an electrical signal, and the signal output terminal is disposed between the plurality of quenching resistors.

[0065] When the photodetector is triggered to avalanche and avalanche breakdown occurs, the photodetector is turned on. By setting the signal output end between multiple quenching resistors, the maximum voltage value of the output electrical signal is less than the voltage value loaded on the first voltage-applying end through the voltage dividing effect of the quenching resistors.

[0066] In some embodiments, the first supply voltage loaded on the first voltage-applying terminal is smaller than the overvoltage of the photodetector, so that the maximum voltage corresponding to the electrical signal output by the photodetector is smaller than the overvoltage of the photodetector.

[0067] In order to enable those skilled in the art to better understand and implement the embodiments of the present disclosure, the concepts, schemes, principles and advantages of the embodiments of the present disclosure are described in detail below with reference to the accompanying drawings and through specific application examples.

[0068] As an optional implementation, the quenching circuit includes a first quenching resistor and a second quenching resistor, and the first quenching resistor, the second quenching resistor and the first end of the photodetector are connected in sequence.

[0069] Combined with reference Figures 2 to 4 , Figures 2 to 4 Schematic diagrams of three quenching circuits in the embodiments of the present disclosure are respectively shown.

[0070] Combined with reference Figures 2 to 4 The quenching circuit 12 may include: a first quenching resistor R1 and a second quenching resistor R2. The quenching circuit 12 is used to control the working state of the photodetector 11. The photodetector 11 is provided with: a first end 11a and a second end 11b.

[0071] In some embodiments, the first quenching resistor R1 , the second quenching resistor R2 , and the first end 11 a of the photodetector 11 are connected in sequence.

[0072] In a specific implementation, the type of the first quenching resistor may be determined according to specific circumstances.

[0073] For example, the first quenching resistor may be a single resistor element.

[0074] For another example, the first quenching resistor may be a resistor unit formed by connecting a plurality of resistor elements in series and / or in parallel.

[0075] In a specific implementation, the type of the second quenching resistor may be determined according to specific circumstances.

[0076] For example, the second quenching resistor may be a single resistor element.

[0077] For another example, the second quenching resistor may be a resistor unit formed by connecting a plurality of resistor elements in series and / or in parallel.

[0078] It should be noted that in the embodiment of the present disclosure, there is no limitation on the types of the first quenching resistor and the second quenching resistor, as long as the first quenching resistor and the second quenching resistor can provide corresponding resistance values.

[0079] In a specific implementation, the type of the light detector can be determined according to specific circumstances.

[0080] For example, the photodetector may be a SPAD. For another example, the photodetector may be an avalanche photodiode (APD). For another example, the photodetector may be a silicon photomultiplier (SiPM).

[0081] It should be noted that the type of photodetector is not limited in the embodiments of the present disclosure. As long as the photodetector has an avalanche breakdown voltage, when the reverse bias voltage at both ends of the photodetector exceeds the avalanche breakdown voltage, avalanche can be triggered by photons.

[0082] As an optional implementation, continue to combine reference Figures 2 to 4 The quenching circuit 12 may further include: a first voltage-applying terminal S1, the first voltage-applying terminal S1 being disposed at an end of the first quenching resistor R1 away from the second quenching resistor R2, the first voltage-applying terminal S1 being used to load a first power supply voltage V S1 .

[0083] The second end 11b of the photodetector 11 may be provided with a second voltage-applying end S2, and the second voltage-applying end S2 is used to apply a second supply voltage V S2 , wherein the first supply voltage V S1 and the second supply voltage V S2 The difference is the operating voltage.

[0084] Specifically, the difference between the first power supply voltage and the second power supply voltage is the operating voltage, and the operating voltage may be: the difference between the first power supply voltage loaded on the first voltage-applying terminal and the second power supply voltage loaded on the second voltage-applying terminal.

[0085] As an optional implementation, the first supply voltage and / or the second supply voltage are adjustable. By adjusting the first supply voltage and / or the second supply voltage, the operating voltage of the photodetector can be adjusted, thereby adjusting the performance of the photodetector.

[0086] In some embodiments, the first supply voltage is adjustable.

[0087] It should be noted that the adjustment method of the working voltage of the photodetector in the embodiment of the present disclosure is not limited, as long as the difference between the first power supply voltage and the second power supply voltage can be adjusted. For example, the second power supply voltage can also be adjusted. For another example, the first power supply voltage and the second power supply voltage can also be adjusted at the same time.

[0088] As an optional implementation, continue to combine reference Figures 2 to 4 The quenching circuit 12 may further include: a signal output terminal S0, wherein the signal output terminal S0 is arranged between the first quenching resistor R1 and the second quenching resistor R2.

[0089] Specifically, the signal output terminal is arranged between the first quenching resistor and the second quenching resistor. After the photodetector undergoes avalanche breakdown, the avalanche current can flow through the second quenching resistor and then be output.

[0090] As an optional implementation manner, the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage of the photodetector is determined by the resistance values ​​of the first quenching resistor and the second quenching resistor.

[0091] By adopting the above technical solution, the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage can be adjusted by adjusting the resistance value of the first quenching resistor and / or the resistance value of the second quenching resistor. Thus, when the maximum voltage corresponding to the output electrical signal is determined, the maximum range or maximum value of the overvoltage can be adjusted so that the working voltage of the photodetector meets the application requirements, thereby reducing the influence of the output electrical signal on the working voltage of the photodetector and improving the performance of the photodetector.

[0092] As an optional implementation manner, the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage is: the ratio of the resistance value of the first quenching resistor to the sum of the resistance values ​​of the first quenching resistor and the second quenching resistor.

[0093] The maximum range or maximum value of the overvoltage can be determined based on the limitation of the maximum voltage of the output electrical signal in the application scenario, and the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage. By setting the resistance of the first quenching resistor and / or the second quenching resistor, the size of the above ratio can be adjusted to obtain the maximum value of the overvoltage that meets the application needs. For example, when the maximum voltage corresponding to the electrical signal limited by the application scenario is low, and the photodetector needs to work under a higher overvoltage, the resistance of the first quenching resistor can be reduced, and / or the resistance of the second quenching resistor can be increased to reduce the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage. Therefore, when the maximum voltage corresponding to the electrical signal is determined, the overvoltage can take a larger range, and the photodetector can work under a higher operating voltage. The influence of the output electrical signal on the operating voltage of the photodetector can be further reduced, thereby adjusting the performance of the photodetector, for example, to obtain a higher detection efficiency.

[0094] Continue to combine references Figures 2 to 4 ,as well as Figure 5 , Figure 5 The working state diagram of the light detector in the embodiment of the present disclosure is shown. Figure 4 The horizontal axis represents the reverse bias voltage across the photodetector, and the vertical axis represents the current of the photodetector.

[0095] The first supply voltage V is applied through the first voltage-adding terminal S1 S1 , the second supply voltage V is loaded through the second voltage-adding terminal S2 S2 , so that the working voltage of the photodetector 11 is (V S1 -V S2 ).

[0096] When the photodetector 11 does not receive a photon, the photodetector 11 is in a state of waiting for a photon to be detected, the photodetector 11 is cut off, the current I is 0, and the reverse bias voltage V at both ends of the photodetector is the first supply voltage V S1 With the second supply voltage V S2 The voltage difference, that is, the working voltage (V S1 -V S2 ), the voltage at the signal output terminal S0 is V S1 .

[0097] When the photodetector 11 receives a photon, an avalanche is triggered, and the photodetector 11 undergoes an avalanche breakdown. The photodetector instantly changes from cutoff to conduction, and the current I of the photodetector 11 instantly increases from 0 to I MAX .

[0098] After the photodetector avalanches, current flows through the quenching circuit. Due to the voltage divider effect of the quenching resistor, the voltage difference V across the photodetector 11 is rapidly reduced to the avalanche breakdown voltage V BD Next, the avalanche in the photodetector 11 is quenched. The photodetector is turned from on to off, and the current I of the photodetector 11 changes from I MAX Reduced to 0.

[0099] During the avalanche triggering to quenching process, the voltage V at the signal output terminal S0 is S0 From V S1 Reduce to (V S1 -(V S1 -V S2 -V BD )*k), wherein k=R1 / (R1+R2), that is, the ratio of the first quenching resistor R1 to the sum of the resistance values ​​of the first quenching resistor R1 and the second quenching resistor R2.

[0100] In summary, the overvoltage V EX is (V S1 -V S2 -V BD ), the voltage V corresponding to the electrical signal at the signal output terminal S0 S0 The value range is (V S1 -(V S1 -V S2 -V BD )*k~V S1 ).

[0101] In some embodiments, the first voltage supply voltage V S1 The voltage corresponding to the electrical signal at the signal output terminal S0 is less than the overvoltage, and the minimum voltage corresponding to the electrical signal output by the photodetector to the subsequent circuit is 0. S1) range changes, the output voltage is not less than 0 and less than the overvoltage, which can not only ensure the normal operation of the subsequent circuit, but also make the overvoltage higher than the maximum voltage limited by the readout circuit, thereby ensuring the performance of the light detector.

[0102] The second pressurizing end S2 is loaded with negative pressure, for example, V S2 =-V BD -(1-k)V EX The first pressure terminal S1 is loaded with V S1 =k*V EX The operating voltage of the photodetector is V S1 -V S2 =V BD +V EX .

[0103] At this time, the voltage variation range of the signal output terminal S0 is (0~k*V Ex ) range. Where k = R1 / (R1+R2), the resistance values ​​of the first quenching resistor R1 and the second quenching resistor R2 are both greater than 0, then k is less than 1, and the voltage V corresponding to the electrical signal at the signal output terminal S0 is S0 The maximum value is less than the overvoltage V EX .

[0104] By adopting the technical solution of the embodiment of the present disclosure, a plurality of quenching resistors are provided, a first supply voltage is applied to one end of the quenching circuit away from the light detector, the first supply voltage is less than the overvoltage, an electrical signal is drawn from between the plurality of quenching resistors, and a voltage V corresponding to the electrical signal at the signal output end is S0 The maximum value is less than the overvoltage V EX , which can reduce the limitation of the output electrical signal on the working voltage of the photodetector and improve the performance of the photodetector.

[0105] Accordingly, the voltage V corresponding to the electrical signal can be S0 The maximum value of the overvoltage V required for the photodetector to achieve the performance required by the application EX , so that the value of k can be determined, and then the resistance value of the quenching resistor can be set.

[0106] In some embodiments, the overvoltage determined by the maximum voltage limit of the signal output terminal and the k value can be higher than the maximum overvoltage required for the actual application of the photodetector, so that the operating voltage of the photodetector can be adjusted within a larger range, so as to further reduce the limitation of the output electrical signal on the operating voltage of the photodetector and improve the adjustment range of the photodetector performance.

[0107] The present disclosure also provides a light detection device, which is further combined with reference to Figures 2 to 4The light detection device M may include: a light detection chip M1 and a readout chip M2, wherein the light detection chip may include a light detector 11, and the light detector 11 may perform photoelectric conversion and output a corresponding electrical signal; the readout chip M2 may include a readout circuit (not shown in the figure), which is suitable for reading out the electrical signal, performing signal processing and storage; the operating voltage of the light detector 11 is higher than the avalanche breakdown voltage of the light detector, wherein the maximum voltage corresponding to the electrical signal is lower than the difference between the operating voltage and the avalanche breakdown voltage.

[0108] Specifically, the maximum voltage corresponding to the electrical signal read out by the readout circuit is lower than the difference between the working voltage loaded at both ends of the photodetector and the avalanche breakdown voltage of the photodetector.

[0109] By adopting the above technical scheme, by loading the light detector in the light detection chip with an operating voltage higher than the avalanche breakdown voltage of the light detector, the light detector can undergo avalanche breakdown when receiving photons, thereby improving the gain of the light detector; after the light detector undergoes avalanche breakdown, the light detection chip can output a corresponding electrical signal to the readout circuit of the readout chip, and the maximum voltage corresponding to the electrical signal is lower than the difference between the operating voltage of the light detector and the avalanche breakdown voltage, thereby improving the operating voltage of the light detector, reducing the limitation on the operating voltage of the light detector formed by the readout circuit, and improving the performance of the light detector and the light detection device.

[0110] As an optional implementation, the readout chip may include a CMOS circuit. The readout chip including the CMOS circuit may be 3D stacked with the light detection chip, and the light detector may be stacked above the circuit, and the circuit does not occupy the photosensitive area of ​​the light detector. This can achieve sufficient photosensitive area for the light detector under high pixel density, and can also be compatible with the use of low-power, high-performance CMOS circuits.

[0111] As an optional implementation, the manufacturing process of the readout circuit may be no greater than 65 nm. CMOS process platforms with a manufacturing process below 65 nm are more advanced, with lower power consumption and cost.

[0112] As an optional implementation, the maximum voltage corresponding to the electrical signal may be positively correlated with an overvoltage, wherein the overvoltage is a difference between an operating voltage and an avalanche breakdown voltage of the photodetector.

[0113] When the maximum voltage corresponding to the electrical signal is positively correlated with the overvoltage, the maximum value of the overvoltage of the photodetector can be determined based on the limitation of the maximum voltage of the electrical signal in the application scenario of the photodetector. For example, when the photodetector is connected to a CMOS readout circuit, the maximum voltage of the electrical signal is not greater than the operating voltage of the readout circuit. Based on the positive correlation between the maximum voltage corresponding to the electrical signal and the overvoltage, the range of the overvoltage of the photodetector, such as the maximum value, is determined. Thus, the overvoltage of the photodetector can be adjusted within a range not exceeding the above-mentioned maximum value of the overvoltage, thereby adjusting the performance of the photodetector and reducing the limitation on the operating voltage of the photodetector.

[0114] As a specific example, the maximum voltage corresponding to the electrical signal may be proportional to the overvoltage.

[0115] In some embodiments, the maximum voltage of the electrical signal is determined based on the limitation of the maximum voltage of the electrical signal in the application scenario of the light detector; the maximum range of the overvoltage can be determined based on the maximum voltage of the electrical signal and the proportional relationship between the maximum voltage of the electrical signal and the overvoltage.

[0116] In some embodiments, the light detection device M further includes a quenching circuit for controlling the working state of the light detector. For example, after the light detector is triggered to avalanche, the quenching circuit can quench the avalanche and output an avalanche signal.

[0117] In some embodiments, the quenching circuit includes a plurality of quenching resistors, and the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage is determined by the resistance values ​​of the plurality of quenching resistors.

[0118] The application scenarios of photodetectors limit the maximum voltage corresponding to the electrical signal they output. In order to obtain the expected performance, the photodetector needs to have a certain operating voltage and corresponding overvoltage. According to the limit value of the maximum voltage corresponding to the electrical signal and the overvoltage required by the photodetector, the ratio of the two can be obtained, and then the resistance values ​​of multiple quenching resistors can be set accordingly to meet the above ratio relationship. The photodetector is made to work under the required operating voltage and overvoltage conditions, and the output electrical signal does not exceed the voltage limit of the readout circuit, etc., which can not only ensure the performance of the photodetector, but also ensure the working safety of the subsequent circuit.

[0119] In some embodiments, a first voltage-applying terminal is provided at one end of the quenching circuit away from the photodetector, which is suitable for loading a first power supply voltage; a second voltage-applying terminal is provided at one end of the photodetector away from the quenching circuit, which is suitable for loading a second power supply voltage; wherein the difference between the first power supply voltage and the second power supply voltage is the working voltage of the photodetector. Through the first voltage-applying terminal and the second voltage-applying terminal, a reverse bias voltage can be applied to both ends of the photodetector as its working voltage, and the working voltage exceeds the avalanche breakdown voltage of the photodetector. The photodetector works in Geiger mode and can obtain extremely high gain.

[0120] In some embodiments, the quenching circuit further includes a signal output terminal adapted to output an electrical signal, and the signal output terminal is disposed between the plurality of quenching resistors.

[0121] When the photodetector is triggered to avalanche and avalanche breakdown occurs, the photodetector is turned on, and by setting the signal output terminal between multiple quenching resistors, the maximum value of the output electrical signal is less than the voltage value loaded on the first voltage-applying terminal through the voltage-dividing effect of the quenching resistors. In some embodiments, the first supply voltage loaded on the first voltage-applying terminal is less than the overvoltage of the photodetector, so that the maximum voltage corresponding to the electrical signal output by the photodetector is less than the overvoltage of the photodetector.

[0122] In some embodiments, at least one quenching resistor is disposed on the light detection chip.

[0123] The working voltage is loaded at both ends of the photodetector, and the maximum voltage between the photodetector and the quenching circuit is the difference between the working voltage and the avalanche breakdown voltage, that is, the overvoltage. By setting at least one quenching resistor on the photodetection chip, the voltage change between the photodetector and the quenching circuit will not affect the readout chip. The signal output end is set between multiple quenching resistors to ensure that the maximum voltage at the signal output end is less than the overvoltage. When the overvoltage of the photodetector exceeds the ability of the readout chip to read the voltage, the maximum voltage of the electrical signal output by the signal output end can still not exceed the working voltage threshold of the readout chip, ensuring the normal operation of the readout chip.

[0124] As an optional implementation, the quenching circuit includes a first quenching resistor and a second quenching resistor, and the first quenching resistor, the second quenching resistor and the first end of the photodetector are connected in sequence.

[0125] Continue to combine references Figures 2 to 4 The optical detection device M may further include: a quenching circuit 12, which is used to control the working state of the optical detector 11 and output the electrical signal.

[0126] As an optional implementation, continue to combine reference Figures 2 to 4 The quenching circuit 12 may include: a first quenching resistor R1, a second quenching resistor R2 and a signal output terminal S0, and the photodetector 11 may be provided with: a first terminal 11a and a second terminal 11b; wherein the first quenching resistor R1, the second quenching resistor R2 and the first terminal 11a of the photodetector 11 are connected in sequence, the signal output terminal S0 is provided between the first quenching resistor R1 and the second quenching resistor R2, and the signal output terminal S0 is connected to the readout circuit.

[0127] Specifically, after the photodetector converts the optical signal into an electrical signal, the quenching circuit outputs the corresponding electrical signal to the readout circuit of the readout chip through the signal output terminal, wherein, after voltage division processing by the quenching circuit, the electrical signal output by the signal output terminal to the readout circuit of the readout chip is different from the voltage corresponding to the electrical signal at the first end of the photodetector.

[0128] As an optional implementation manner, the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage is determined by the resistance values ​​of the first quenching resistor and the second quenching resistor.

[0129] The maximum range or maximum value of the overvoltage can be determined based on the application scenario's limitation on the maximum voltage of the output electrical signal and the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage. By setting the resistance value of the first quenching resistor and / or the second quenching resistor, the size of the above ratio can be adjusted to obtain the maximum overvoltage value that meets the application requirements.

[0130] In some embodiments, the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage is: the ratio of the resistance value of the first quenching resistor to the sum of the resistance values ​​of the first quenching resistor and the second quenching resistor.

[0131] For example, when the maximum voltage corresponding to the electrical signal limited by the application scenario is low, and the photodetector needs to operate under a higher overvoltage, the resistance of the first quenching resistor can be reduced, and / or the resistance of the second quenching resistor can be increased to reduce the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage. Thus, when the maximum voltage corresponding to the electrical signal is determined, the overvoltage can take a larger range, and the photodetector can operate under a higher operating voltage. The influence of the output electrical signal on the operating voltage of the photodetector can be further reduced, thereby adjusting the performance of the photodetector, for example, obtaining a higher detection efficiency.

[0132] As an optional implementation, continue to combine reference Figures 2 to 4 The optical detection device M also includes: a first voltage-applying terminal S1, which is connected to an end of the first quenching resistor R1 away from the second quenching resistor R2, and is used to load a first power supply voltage; a second voltage-applying terminal S2, which is connected to the second end 11b of the optical detector 11, and is used to load a second power supply voltage, wherein the difference between the first power supply voltage and the second power supply voltage is the working voltage.

[0133] It should be noted that the configuration of the quenching circuit and the photodetector in the light detection device described in the embodiment of the present disclosure may adopt the configuration of the quenching circuit and the photodetector in any of the aforementioned embodiments.

[0134] In a specific implementation, the location of the first pressurizing end can be determined according to specific circumstances.

[0135] For example, refer to Figure 4 The first pressurizing end S1 may be provided on the light detection chip M1.

[0136] For example, in conjunction with reference Figure 2 and Figure 3 , the first voltage-applying terminal S1 may be provided in the readout chip M2. In some embodiments, the readout chip includes a CMOS circuit, and a power supply circuit may be provided in the readout chip to apply a first power supply voltage to the first voltage-applying terminal. A power supply voltage regulating circuit may also be provided in the readout chip to make the first power supply voltage adjustable. According to the needs of the actual application, the magnitude of the first power supply voltage is adjusted, thereby adjusting the magnitude of the operating voltage and the output voltage of the photodetector.

[0137] In some embodiments, a gating circuit may be provided in the readout chip, and when the photodetector needs to be gated, a first supply voltage is applied to the first voltage-applying terminal of the photodetector, so that the photodetector is in Geiger mode; when the photodetector does not need to be gated, the path for applying the first supply voltage to the first voltage-applying terminal may be disconnected, and the reverse bias voltage of the photodetector may be reduced to below the avalanche breakdown voltage, so as to prevent the photodetector from being falsely triggered to generate interference signals.

[0138] In a specific implementation, the location of the second pressurizing end can be determined according to specific circumstances.

[0139] For example, combined with reference Figures 2 to 4 , the second pressurizing end S2 can be arranged on the light detection chip M1.

[0140] For another example, the second pressure-applying end S2 may be disposed on the readout chip M2.

[0141] As a specific example, refer to Figure 4 The first pressurizing end S1 and the second pressurizing end S2 are both disposed on the light detection chip M1.

[0142] As another specific example, in conjunction with reference Figure 2 and Figure 3 The first pressurizing end S1 is provided at the readout chip M2, and the second pressurizing end S2 is provided at the light detection chip M1.

[0143] In a specific implementation, the location of the first quenching resistor may be determined according to specific circumstances.

[0144] For example, combined with reference Figure 3 and Figure 4 The first quenching resistor R1 can be provided in the light detection chip M1.

[0145] For example, refer to Figure 2 , the first quenching resistor R1 can be set in the readout chip M2.

[0146] In a specific implementation, the location of the second quenching resistor may be determined according to specific circumstances.

[0147] For example, combined with reference Figures 2 to 4 The second quenching resistor R2 can be provided in the light detection chip M1.

[0148] As a specific example, refer to Figure 3 and Figure 4 The first quenching resistor R1 and the second quenching resistor R2 are both arranged on the light detection chip M1.

[0149] By adopting the above technical solution, by arranging the first quenching resistor and the second quenching resistor on the light detection chip at the same time, the first quenching resistor and the second quenching resistor can be prepared using exactly the same process conditions, so that the first quenching resistor and the second quenching resistor have the same temperature coefficient of resistance changing with temperature, so that the k value can be kept stable within a larger temperature range, thereby stabilizing the voltage corresponding to the electrical signal output by the signal output end.

[0150] As another specific example, refer to Figure 2 The first quenching resistor R1 is arranged on the readout chip M2, and the second quenching resistor R2 is arranged on the light detection chip M1.

[0151] It can be understood that the above describes multiple embodiment schemes provided by the embodiments of the present disclosure, and the optional implementation methods and specific examples introduced in each embodiment scheme can be combined and cross-referenced with each other without conflict, thereby extending a variety of possible embodiment schemes, which can all be regarded as the embodiment schemes disclosed and disclosed by the present disclosure.

[0152] It should be noted that the “examples” or “embodiments” referred to in this specification refer to specific features, structures or characteristics that may be included in at least one implementation of the novel embodiments of the present disclosure. And in the description of this specification, the terms “first”, “second”, etc. are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined by terms such as “first”, “second”, etc. may explicitly or implicitly include one or more of the features. Moreover, the terms such as “first”, “second”, etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or to express importance. It is understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein.

[0153] Although the embodiments of the present disclosure are disclosed as above, the present disclosure is not limited thereto. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the scope defined by the claims.

Claims

1. A quenching circuit for a photodetector, It is characterized in that used to control the working state of the photodetector, the photodetector being suitable for photoelectric conversion, and the working voltage of the photodetector being higher than the avalanche breakdown voltage of the photodetector; The quenching circuit quenches the photodetector after the photodetector avalanche breakdown and outputs a corresponding electrical signal, wherein a maximum voltage corresponding to the electrical signal is lower than a difference between the operating voltage and the avalanche breakdown voltage.

2. The quenching circuit according to claim 1, It is characterized in that The maximum voltage corresponding to the electrical signal is proportional to the overvoltage, wherein the overvoltage is the difference between the operating voltage and the avalanche breakdown voltage.

3. The quenching circuit according to claim 2, It is characterized in that It comprises a plurality of quenching resistors, and the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage is determined by the resistance values ​​of the plurality of quenching resistors.

4. The quenching circuit according to claim 3, It is characterized in that The quenching circuit is provided with a first voltage-applying end at one end away from the photodetector, suitable for applying a first power supply voltage; The end of the photodetector away from the quenching circuit is provided with a second voltage-applying end suitable for loading a second power supply voltage; The difference between the first power supply voltage and the second power supply voltage is the operating voltage.

5. The quenching circuit according to claim 3, It is characterized in that Also includes: The signal output terminal is suitable for outputting the electrical signal, and the signal output terminal is arranged between the multiple quenching resistors.

6. The quenching circuit according to claim 3, It is characterized in that The plurality of quenching resistors include: a first quenching resistor and a second quenching resistor; The first quenching resistor, the second quenching resistor and the photodetector are connected in sequence.

7. The quenching circuit according to claim 6, It is characterized in that The ratio of the maximum voltage corresponding to the electrical signal to the overvoltage is determined by the resistance values ​​of the first quenching resistor and the second quenching resistor.

8. The quenching circuit according to claim 7, It is characterized in that The ratio of the maximum voltage corresponding to the electrical signal to the overvoltage is: the ratio of the resistance value of the first quenching resistor to the sum of the resistance values ​​of the first quenching resistor and the second quenching resistor.

9. The quenching circuit according to claim 4, It is characterized in that The first supply voltage is less than the overvoltage.

10. The quenching circuit according to claim 1, It is characterized in that The photodetector is a single photon avalanche diode.

11. A light detection device, It is characterized in that include: The light detection chip includes a light detector, which is suitable for performing photoelectric conversion and outputting corresponding electrical signals; a readout chip, comprising a readout circuit, adapted to read out the electrical signal; The operating voltage of the photodetector is higher than the avalanche breakdown voltage of the photodetector, The maximum voltage corresponding to the electrical signal is lower than the difference between the operating voltage and the avalanche breakdown voltage.

12. The light detection device according to claim 11, It is characterized in that The maximum voltage corresponding to the electrical signal is proportional to the overvoltage, wherein the overvoltage is the difference between the operating voltage and the avalanche breakdown voltage.

13. The light detection device according to claim 12, It is characterized in that Also includes: A quenching circuit, used for controlling the working state of the photodetector and outputting the electrical signal; The quenching circuit includes a plurality of quenching resistors, and the ratio of the maximum voltage corresponding to the electrical signal to the overvoltage is determined by the resistance values ​​of the plurality of quenching resistors.

14. The light detection device according to claim 13, It is characterized in that The quenching circuit further comprises: A signal output terminal is suitable for outputting the electrical signal. The signal output terminal is arranged between the multiple quenching resistors and is connected to the readout circuit.

15. The light detection device according to claim 13, It is characterized in that At least one quenching resistor is disposed on the light detection chip.

16. The light detection device according to claim 13, It is characterized in that The plurality of quenching resistors include a first quenching resistor and a second quenching resistor, and the first quenching resistor, the second quenching resistor and the photodetector are connected in sequence; The quenching circuit further includes a signal output terminal adapted to output an electrical signal, wherein the signal output terminal is arranged between the first quenching resistor and the second quenching resistor.

17. The light detection device according to claim 16, It is characterized in that The second quenching resistor is arranged on the light detection chip.

18. The light detection device according to claim 17, It is characterized in that The readout chip further includes a first voltage-applying terminal connected to an end of the first quenching resistor away from the second quenching resistor and suitable for loading a first supply voltage.

19. The light detection device according to claim 17, It is characterized in that The light detection chip further includes a first voltage-applying terminal connected to an end of the first quenching resistor away from the second quenching resistor and suitable for loading a first supply voltage.

20. The light detection device according to claim 18 or 19, It is characterized in that The light detection chip further includes a second voltage-applying terminal connected to an end of the light detector away from the quenching circuit and suitable for loading a second supply voltage, wherein the difference between the first supply voltage and the second supply voltage is the operating voltage.

Images