CN114625203A - A high-voltage bias circuit for single-photon avalanche diodes - Google Patents

Abstract

The invention discloses a high-voltage bias circuit of a single-photon avalanche diode, comprising: a dynamic high-voltage generating unit, a SPAD device and a front-end circuit unit, an optical pulse counting unit, and a counting rate comparison and judging unit. The dynamic high voltage generation unit is used to provide the SPAD device and the SPAD device of the front-end circuit unit with a dynamic bias voltage HV higher than its reverse breakdown voltage, so that the SPAD device and the SPAD device in the front-end circuit unit work in the Geiger mode, with Single-photon sensitivity, and receive the feedback output of the counting rate comparison and discrimination unit through the feedback input terminal Cont, the comparison result between the counting rate R of the optical pulse counting unit and the counting rate threshold, and the dynamic high voltage generating unit adjusts the dynamic bias voltage HV according to the comparison result. After the size is output, the photon detection efficiency of the SPAD device is changed, so that the optical pulse count rate R is always within a suitable range. The invention improves the tolerance of the laser radar receiver system to the background light and improves the dynamic range of the device.

Description

A high-voltage bias circuit for single-photon avalanche diodes

technical field

The invention belongs to the technical field of laser radar optical signal receiver systems, in particular to a high-voltage bias circuit of a single-photon avalanche diode.

Background technique

Lidar has the advantages of high resolution, strong resistance to active interference, high detection reliability, not affected by light, and large speed measurement range. It can detect three-dimensional images of the surrounding environment in real time, so that unmanned control equipment has a pair of bright " Eye". Single-photon detection in lidar ranging is a technology that obtains distance information by counting the received photons (the number of photons detected within a certain known measurement time). When it is on the detected target object, the target object reflects back the laser echo, and the laser echo is received by the single-photon avalanche photodiode (SPAD) working in Geiger mode and triggers avalanche breakdown to generate photocurrent, which is then paired by the front-end circuit. After the SPAD performs quenching reset and pulse compression, the voltage pulse signal is obtained, and then the time-of-flight information of the pulse is obtained by using a time-to-digital converter. Therefore, to make the SPAD device work, it is necessary to provide a high-voltage bias higher than the reverse breakdown voltage. The magnitude of the high-voltage bias often affects the photon detection efficiency of the SPAD device, so as to change the photon counting rate.

In the traditional scheme, the high-voltage bias circuit can only generate a fixed voltage, which limits the size of the over-bias voltage, and the dynamic range of the SPAD device is small. In practical applications, due to the existence of background light, the accuracy of laser echo signal reception will be affected, and some unnecessary photons will be introduced to trigger the SPAD device to work and generate current pulse signals, which will easily saturate the photon counting rate and cannot obtain accurate data. information on the number of photons in the laser echo.

SUMMARY OF THE INVENTION

In order to solve the above problems in the prior art, the present invention provides a high voltage bias circuit for a single photon avalanche diode. The technical problem to be solved by the present invention is realized by the following technical solutions:

A high-voltage bias circuit for a single-photon avalanche diode, comprising: a dynamic high-voltage generating unit, a SPAD device and a front-end circuit unit, an optical pulse counting unit, and a counting rate comparison and judging unit;

The clock input terminal CLK of the dynamic high voltage generation unit is connected to the output terminal of an external clock signal generation unit, the feedback input terminal Cont of the dynamic high voltage generation unit is connected to the output terminal of the counting rate comparison and determination unit, and the dynamic high voltage generation unit is connected to the output terminal of the count rate comparison and determination unit. The bias voltage output end of the high-voltage generating unit is connected to the input end of the SPAD device and the front-end circuit unit;

The output end of the SPAD device and the front-end circuit unit is connected to the input end of the optical pulse counting unit; the SPAD device and the front-end circuit unit are used to receive the photons in the echoes of the laser reflected from the target and output a voltage pulse signal;

The optical pulse counting unit counts the voltage pulse signal and converts the counting result into a digital signal, which is output from its OUT terminal, and the feedback output terminal of the optical pulse counting unit is connected to the input terminal of the counting rate comparison and discrimination unit;

Wherein, the dynamic high voltage generating unit is used to provide the SPAD device and the SPAD device of the front-end circuit unit with a dynamic bias voltage HV higher than its reverse breakdown voltage, so that the SPAD device and the SPAD device in the front-end circuit unit work In Geiger mode, and the feedback output of the counting rate comparison and determination unit is received through the feedback input terminal Cont, the comparison result between the counting rate R of the optical pulse counting unit and the counting rate threshold value is adjusted according to the comparison result. Output after the magnitude of the bias voltage HV.

In an embodiment of the present invention, the dynamic high voltage generating unit includes a four-phase clock control module, a charge pump boosting module, an operational amplifier module and a resistor divider tap module;

The clock input terminal of the four-phase clock control module is connected to the output terminal of the clock signal generating unit, and the four output terminals of the four-phase clock control module are respectively connected to the four input terminals of the charge pump boosting module. , the four-phase clock control module is used to convert the clock signal CLK generated by the clock signal generating unit into four-phase clock outputs, so as to control the boosting process of the charge pump boosting module;

The fifth input end of the charge pump boosting module is connected to the output end of the operational amplifier module, and the bias voltage output end of the charge pump boosting module is connected to the input of the SPAD device and the front-end circuit unit The terminal is connected to the first input terminal of the resistor divider tap module;

The non-inverting input terminal of the operational amplifier module is connected to the reference level VP, and the inverting input terminal VN of the operational amplifier module is connected to the third input terminal of the resistor divider tap module;

The feedback input terminal Cont of the resistor divider tap module is connected to the output terminal of the counting rate comparison and determination unit.

In an embodiment of the present invention, the dynamic bias voltage HV is represented by the following formula:

HV=(N+1)×VOUT(1)

Wherein, N represents the number of stages of the unit charge pump in the charge pump boosting module, and VOUT represents the voltage of the output terminal of the operational amplifier module.

In an embodiment of the present invention, the ratio of the reference level VP of the non-inverting input terminal of the operational amplifier module (130) to the dynamic bias voltage HV is:

Wherein, x is controlled according to the digital signal of the comparison result received by the feedback input terminal Cont.

In an embodiment of the present invention, it can be obtained according to formula (1) and formula (2):

The dynamic bias voltage HV satisfies:

(N+1)×VOUT _min ≤HV≤(N+1)×VOUT _max (4)

Wherein, VOUT _min and VOUT _max respectively represent the lowest voltage value and the highest voltage value of the output terminal voltage VOUT of the operational amplifier module limited by the swing.

Beneficial effects of the present invention:

The invention can set the highest and lowest series rate thresholds of the system according to the intensity information of the background light, compare and judge the current counting rate and the rated threshold counting rate through the counting rate comparison and judgment unit, and feed back the comparison result to the dynamic high voltage generating unit. The size of the dynamic bias voltage HV is adjusted to change the reverse bias voltage of the SPAD device, thereby changing the photon detection efficiency of the device. When the background light intensity changes, the photon counting rate during the laser echo detection process is changed. In the required range, it is not easy to reach saturation, so the accurate photon number information of the laser echo can always be obtained, the tolerance of the lidar receiver system for the background light is improved, and the dynamic range of the device is improved.

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

Description of drawings

1 is a schematic structural diagram of a high-voltage bias circuit of a single-photon avalanche diode provided by an embodiment of the present invention:

2 is a schematic structural diagram of a dynamic high pressure generating unit provided by an embodiment of the present invention:

FIG. 3 is a feedback flow chart of a high-voltage bias circuit system of a single-photon avalanche diode according to an embodiment of the present invention.

Detailed ways

The present invention will be described in further detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

Example 1

Referring to FIG. 1 , a high-voltage bias circuit for a single-photon avalanche diode includes: a dynamic high-voltage generating unit 100 , a SPAD device and a front-end circuit unit 200 , an optical pulse counting unit 300 , and a counting rate comparison and determination unit 400 .

The clock input terminal CLK of the dynamic high voltage generation unit 100 is connected to the output terminal of the external clock signal generation unit, the feedback input terminal Cont of the dynamic high voltage generation unit 100 is connected to the output terminal of the counting rate comparison and determination unit 400, and the dynamic high voltage generation unit 100 The bias voltage output terminal is connected to the SPAD device and the input terminal of the front-end circuit unit 200 .

In this embodiment, the dynamic high voltage generating unit 100 is used to provide the SPAD device and the SPAD device of the front-end circuit unit 200 with a dynamic bias voltage HV higher than the reverse breakdown voltage of the SPAD device, so that the SPAD device and the front-end circuit unit 200 The SPAD device works in the Geiger mode, has the sensitivity of single-photon triggering, and can output a digital signal to the feedback input terminal Cont of the dynamic high voltage generation unit 100 through the counting rate comparison and judgment unit 400, and adjust the dynamic bias within a certain dynamic range. The size of the voltage HV can adapt to the influence of the background light, improve the tolerance of the background light, and increase the dynamic range of the device.

The output end of the SPAD device and the front-end circuit unit 200 is connected to the input end of the optical pulse counting unit 300 . In this embodiment, the SPAD device is used to receive photons in the echoes reflected by the laser from the target. Under the high voltage bias of the dynamic bias voltage HV, the SPAD device is in the Geiger mode and has single-photon sensitivity. Trigger avalanche breakdown to generate a large amount of photocurrent, which is quenched, reset, pulse compression and other processes through its front-end circuit, so that a voltage pulse signal with appropriate pulse width is generated after a photon detection process is completed, and the voltage pulse signal is output to the pulse count. The cell counts photon-triggered voltage pulses.

The optical pulse counting unit 300 counts the voltage pulse signal and converts the counting result into a digital signal, which is output from its OUT terminal. In this embodiment, it is used to process the voltage pulse signals generated by the SPAD device and the front-end circuit unit 200, and count the voltage pulses triggered by the photons received during the laser echo receiving process per unit time, and obtain the received and generated voltage pulses per unit time. The total number of photons generating voltage pulses is converted into a digital signal and output from the OUT terminal, and the information of the current counting rate R is transmitted to the counting rate comparison and determination unit 400 through the feedback output terminal.

The counting rate comparison and judging unit 400 is configured to preset the maximum counting rate threshold _Rmax and the minimum counting rate threshold _Rmin according to the background light information in the working environment, and compare the counting rate R of the optical pulse counting unit 300 with the maximum counting rate threshold _Rmax and the maximum counting rate threshold Rmax. The minimum counting rate threshold R _min is compared and judged, and the result is output to the feedback input terminal Cont of the dynamic high voltage generating unit 100 through the output terminal to adjust the size of the dynamic bias voltage HV, thereby changing the photon detection efficiency of the SPAD device to adjust the optical pulse. The size of the counting rate R of the counting unit 300 enables the counting rate R of the optical pulse counting unit 300 to be within the range of the highest counting rate threshold _Rmax and the lowest counting rate threshold _Rmin under the current background light, which improves the system’s ability to deal with background light. tolerance.

Wherein, the dynamic high voltage generating unit 100 is used to provide the SPAD device and the SPAD device of the front-end circuit unit 200 with a dynamic bias voltage HV higher than its reverse breakdown voltage, so that the SPAD device and the SPAD device in the front-end circuit unit 200 work at Geiger mode, and receive the comparison result of the counting rate R of the optical pulse counting unit 300 and the counting rate threshold, which is fed back and output by the counting rate comparison and judging unit 400 through the feedback input terminal Cont, and dynamically adjust the size of the dynamic bias voltage HV according to the comparison result. output later.

The dynamic high voltage generation circuit of this embodiment can compare and determine the current count rate and the rated threshold count rate through the counting rate comparison and determination unit 400 according to the intensity information of the background light, and feed back the comparison result to the dynamic high voltage generation unit 100 to determine the dynamic bias. The magnitude of the voltage HV is adjusted to change the reverse bias voltage of the SPAD device, thereby changing the photon detection efficiency of the device. When the background light intensity changes, the photon counting rate during the laser echo detection process is at the required level. It is not easy to reach saturation in the range, so the accurate photon number information of the laser echo can always be obtained, which improves the tolerance of the lidar receiver system for the background light and improves the dynamic range of the device.

In a feasible implementation manner, the voltage value of the dynamic bias voltage HV is greater than 16V and less than or equal to 20V.

Further, as shown in FIG. 2 , the dynamic high voltage generating unit 100 includes a four-phase clock control module 110 , a charge pump boosting module 120 , an operational amplifier module 130 and a resistor divider tap module 140 .

The clock input terminal of the four-phase clock control module 110 is connected to the output terminal of the clock signal generating unit, the four output terminals of the four-phase clock control module 110 are respectively connected to the four input terminals of the charge pump boosting module 120, and the four-phase clock control module The module 110 is used for converting the clock signal CLK generated by the clock signal generating unit into clock outputs of four phases, so as to control the boosting process of the charge pump boosting module 120 . Among them, the charge pump boosting module 120 has five input terminals.

The fifth input end of the charge pump boosting module 120 is connected to the output end of the operational amplifier module 130, and the bias voltage output end of the charge pump boosting module 120 is connected to the input end of the SPAD device and the front-end circuit unit 200 and the resistor divider tap The first input terminal of the module 140 is connected; the output terminal of the charge pump boosting module 120 generates a dynamic bias voltage HV. The charge pump boosting module 120 uses the same charge pump structure of N stages to complete the boosting process, and finally generates a dynamic bias voltage HV, where the magnitude of the dynamic bias voltage HV is as follows:

HV=(N+1)×VOUT(1).

Wherein, N represents the number of stages of the unit charge pump in the charge pump boosting module, and VOUT represents the voltage of the output terminal of the operational amplifier module.

The non-inverting input terminal of the operational amplifier module 130 is connected to the reference level VP, and the inverting input terminal VN of the operational amplifier module 130 is connected to the third input terminal of the resistor divider tap module 140 . Using the "virtual short" characteristic of the operational amplifier, when the operational amplifier module 130 is working normally, the level of the inverting input terminal VN should be equal to the reference level VP of the non-inverting input terminal. The level of the input terminal is also equal to the reference level of the non-inverting input terminal.

The feedback input terminal Cont of the resistor divider tap module 140 is connected to the output terminal of the counting rate comparison and determination unit 400 . The resistor divider tap module 140 is composed of resistors in series, the highest level of the resistor string is the dynamic bias voltage HV, the lowest level is the ground potential, and taps through the transmission gate at different resistor dividers, wherein the feedback input terminal Cont The output terminal of the counting rate comparison and determination unit 400 is connected, and the position of the resistor divider tap is controlled and adjusted by the feedback input digital signal, while the third input terminal is connected with the resistor divider tap, and the level of the third input terminal is the operational amplifier module. The reference level VP of the non-inverting input of 130. Therefore, the ratio of the reference level VP of the non-inverting input terminal of the operational amplifier module 130 to the dynamic bias voltage HV of the highest level of the resistor string is controlled by the digital signal input from the feedback input terminal Cont, and VP is a fixed reference value. The ratio is as follows:

From Expression 1, it can be obtained that the voltage VOUT at the output terminal of the operational amplifier module 130 is expressed as follows:

It can be seen from the above expression that the dynamic high voltage generating unit 100 changes the size of the ratio x in Equation 2 by feeding back the digital signal input from the input terminal Cont, so as to change the size of the dynamic bias voltage HV, thereby realizing the generation of a dynamic high voltage value, However, the variation of the dynamic bias voltage HV has a certain range. Because it can be seen from equations (1) and (3) that the change of the dynamic bias voltage HV is realized by the change of the voltage VOUT at the output end of the operational amplifier module 130, and the voltage value of the voltage VOUT at the output end of the operational amplifier module 130 The size is limited by the output swing of the operational amplifier module 130 . If VOUT has a maximum value VOUT _max and a minimum value VOUT _min , the dynamic adjustment range of the dynamic bias voltage HV is as follows:

(N+1)×VOUT _min ≤HV≤(N+1)×VOUT _max (4).

Wherein, VOUT _min and VOUT _max respectively represent the lowest voltage value and the highest voltage value of the output terminal voltage VOUT of the operational amplifier module limited by the swing.

Thus, the dynamic high voltage generating unit 100 generates the dynamic bias voltage HV with a certain dynamic range.

For the single-photon avalanche photodiode SPAD, its avalanche process is divided into two parts: absorption of photons to generate original carriers, and excitation of avalanche state. In the actual working environment, the processes that can generate original carriers include: 1. The absorption of laser signal photons reflected by the target object; 2. The absorption of background light; 3. The absorption of internal hot carriers. We define the possibility that the device absorbs a single photon to cause avalanche breakdown as the Photon Detection Probability, PDP, to measure the sensitivity of the SPAD device, and the Photon Detection Efficiency, PDE, that is PDP and the pixel filling rate. product. The part of the bias voltage that exceeds the reverse breakdown voltage of the SPAD device is called over-bias voltage. The size of the PDP is proportional to the size of the over-bias voltage, and the size of the PDE is also proportional to the size of the over-bias voltage. If the over-bias voltage is constant, the number of original carriers that may trigger the avalanche breakdown of the SPAD device will change due to the change of the background light intensity during the process of receiving and counting the echoed photons of the lidar, and then avalanche breakdown will occur. The number of photons passing through changes, so that the background light will also introduce photons to generate voltage pulse signals into the optical pulse counting unit 300, causing the photon counting rate and the counting result of the optical pulse counting unit 300 to change, and even causing the counting rate to saturate.

Therefore, the lidar receiver plays a decisive role in the performance of the lidar system. Among them, the tolerance of the background light and the dynamic range of the detection device are the important performance indicators of the front-end circuit of the lidar receiver.

In the present invention, the highest and lowest thresholds of the photon counting rate of the system are set according to the intensity information of the background light, and a digital signal is generated after judging the counting rate and the high and low thresholds in the counting rate comparison and judging unit 400, and the feedback is input to the dynamic high voltage generating unit The feedback input terminal Cont of 100 performs feedback adjustment. In the dynamic high voltage generating unit 100, the feedback input terminal Cont controls the ratio of the reference level VP of the non-inverting input terminal of the operational amplifier module 130 to the dynamic bias voltage HV. The above formula 4 realizes the dynamic bias voltage HV within a certain dynamic range. Variety. The size change of the dynamic bias voltage HV changes the size of the over-bias voltage of the SPAD device, thereby changing the PDP and PDE of the SPAD device, so that the photon counting rate of the optical pulse counting unit 300 is within the range of high and low thresholds, that is, in a current background. The ideal value in the working environment of the light conditions to adapt to the influence of the background light and improve the tolerance of the lidar receiver system for the background light.

Please refer to FIG. 3. FIG. 3 is a feedback flow chart of a high-voltage bias circuit system of a single-photon avalanche diode provided by an embodiment of the present invention. The workflow of the entire system is as follows:

In a laser detection work, the maximum count rate threshold R _max and the minimum count rate threshold R _min of the photon pulse counting unit are firstly set according to the intensity information of the background light. After the laser is emitted to the target, the dynamic high voltage generation circuit of the SPAD device To start working, firstly, the dynamic high voltage generating unit 100 generates an initial bias voltage (the voltage value of the initial bias voltage is a preset value) to provide the reverse bias voltage of the SPAD device, so that it works in the Geiger mode and has a single photon The sensitivity of triggering, the photons in the echo reflected by the laser from the target object irradiate the SPAD device and the SPAD device of the front-end circuit unit 200 to trigger avalanche breakdown to generate photocurrent, and after passing through the SPAD device and the front-end circuit of the front-end circuit unit 200, a voltage is generated The pulse signal is input to the photon pulse counting unit, and the voltage pulse signal is counted. During the counting process, the current counting rate R is fed back to the counting rate comparison and judging unit 400, and compared with the highest counting threshold R _max , if R>R _max , Then, the dynamic high voltage generation unit 100 is controlled by the feedback signal to reduce the initial bias voltage and output the dynamic bias voltage HV to reduce the PDE of the SPAD device, thereby reducing the current counting rate R, and continue to feed back the current counting rate R to the counting rate. Compare and determine unit 400, reduce the dynamic bias voltage HV and output it until R<_Rmax; then compare the current counting rate R with the minimum counting rate threshold _Rmin , if R< _Rmin , control the dynamic high voltage through the feedback signal The generating unit 100 increases the dynamic bias voltage HV to increase the PDE of the SPAD device, thereby increasing the current counting rate R, until R>R _min and ending the comparison and determination of the counting rate. The above process is continuously performed during the receiving process to ensure that The counting rate R is always kept within the range of R _min < R < R _max , that is, in the presence of the current background light, the counting rate is always kept within the ideal range to improve the background light tolerance and the dynamic range of the device. Purpose.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", " rear, left, right, vertical, horizontal, top, bottom, inside, outside, clockwise, counterclockwise, etc., or The positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, Therefore, it should not be construed as a limitation of the present invention.

In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature. In the description of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

In the present invention, unless otherwise expressly specified and limited, the terms "installed", "connected", "connected", "fixed" and other terms should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection , or integrated; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of the two elements or the interaction relationship between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

In the present invention, unless otherwise expressly specified and limited, a first feature "on" or "under" a second feature may include the first and second features in direct contact, or may include the first and second features Not directly but through additional features between them. Also, the first feature being "above", "over" and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is level higher than the second feature. The first feature is "below", "below" and "below" the second feature includes the first feature being directly below and diagonally below the second feature, or simply means that the first feature has a lower level than the second feature.

In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be considered that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deductions or substitutions can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (5)

1. A high voltage bias circuit for a single photon avalanche diode, comprising: the device comprises a dynamic high-voltage generating unit (100), an SPAD device and front-end circuit unit (200), an optical pulse counting unit (300) and a counting rate comparison and judgment unit (400);

a clock input end CLK of the dynamic high-voltage generation unit (100) is connected with an output end of an external clock signal generation unit, a feedback input end Cont of the dynamic high-voltage generation unit (100) is connected with an output end of the counting rate comparison and judgment unit (400), and a bias voltage output end of the dynamic high-voltage generation unit (100) is connected with input ends of the SPAD device and the front-end circuit unit (200);

the output end of the SPAD device and front-end circuit unit (200) is connected with the input end of the optical pulse counting unit (300); the SPAD device and front-end circuit unit (200) is used for receiving photons in laser reflection echoes from a target and outputting a voltage pulse signal;

the optical pulse counting unit (300) counts the voltage pulse signals and converts counting results into digital signals, and the digital signals are output from an OUT end of the optical pulse counting unit, and a feedback output end of the optical pulse counting unit (300) is connected with an input end of the counting rate comparison and judgment unit (400);

the dynamic high voltage generating unit (100) is used for providing a dynamic bias voltage HV higher than a reverse breakdown voltage of an SPAD device of the SPAD device and front-end circuit unit (200), enabling the SPAD device in the SPAD device and the front-end circuit unit (200) to work in a Geiger mode, receiving a comparison result of a count rate R and a count rate threshold of the optical pulse counting unit (300) through the feedback input end Cont, and adjusting the magnitude of the dynamic bias voltage HV according to the comparison result to output the comparison result.

2. The high voltage bias circuit for a single photon avalanche diode according to claim 1, characterized in that said dynamic high voltage generation unit (100) comprises a four-phase clock control module (110), a charge pump boosting module (120), an operational amplifier module (130) and a resistance voltage division tap module (140);

the clock input end of the four-phase clock control module (110) is connected with the output end of a clock signal generation unit, four output ends of the four-phase clock control module (110) are respectively connected with four input ends of the charge pump boosting module (120), and the four-phase clock control module (110) is used for converting the clock signal CLK generated by the clock signal generation unit into clock outputs of four phases so as to control the boosting process of the charge pump boosting module (120);

a fifth input end of the charge pump boosting module (120) is connected with an output end of the operational amplifier module (130), and the bias voltage output end of the charge pump boosting module (120) is connected with input ends of the SPAD device and front-end circuit unit (200) and a first input end of the resistance voltage division tap module (140);

the non-inverting input end of the operational amplifier module (130) is connected with a reference level VP, and the inverting input end VN of the operational amplifier module (130) is connected with the third input end of the resistance voltage division tap module (140);

the feedback input end Cont of the resistance voltage division tap module (140) is connected with the output end of the counting rate comparison and judgment unit (400).

3. The high voltage bias circuit for a single photon avalanche diode according to claim 2, wherein said dynamic bias voltage HV is represented by the following formula:

HV＝(N+1)×VOUT (1)

wherein N represents the number of stages of a unit charge pump in the charge pump boosting module (120), and VOUT represents the voltage of the output end of the operational amplifier module (130).

4. The high voltage bias circuit for single photon avalanche diodes according to claim 3, characterized in that the ratio of the reference level VP of the non-inverting input of the operational amplifier module (130) to the dynamic bias voltage HV is:

wherein x is controlled in dependence on the digital signal of the comparison result received by the feedback input Cont.

5. The high voltage bias circuit for a single photon avalanche diode according to claim 4, characterized by the following equations (1) and (2):

the dynamic bias voltage HV satisfies:

(N+1)×VOUT_min≤HV≤(N+1)×VOUT_max (4)

wherein VOUT_minAnd VOUT_maxRespectively representing the minimum voltage value and the maximum voltage value of the output end voltage VOUT of the operational amplifier module limited by the swing amplitude.

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