WO2024114705A1

WO2024114705A1 - Receving circuit, receiving method and lidar

Info

Publication number: WO2024114705A1
Application number: PCT/CN2023/135241
Authority: WO
Inventors: Peijun Wang; Jianfeng Liu; Shaoqing Xiang
Original assignee: Hesai Technology Co., Ltd.
Priority date: 2022-11-29
Filing date: 2023-11-29
Publication date: 2024-06-06
Also published as: CN118113106A

Abstract

A receiving circuit includes a photoelectric device configured to receive a light signal and convert the light signal into a current signal; a current amplification module configured to output a current signal proportional to an amplitude of the current signal; a current-to-voltage conversion module configured to generate a voltage signal based on the proportional current signal and perform low-pass filtering on the voltage signal; an analog-to-digital conversion module configured to perform analog-to-digital conversion on the low-pass filtered voltage signal to generate a digital signal; and a digital high-pass filter module configured to perform digital high-pass filtering on the digital signal and output a measurement signal.

Description

RECEVING CIRCUIT, RECEIVING METHOD AND LIDAR

CROSS-REFERENCE TO RELATED APPLICATION (S)

This application claims priority to Chinese Patent Application No. 202211509124.3, filed on November 29, 2022, the content of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

This disclosure relates to technical field of electric circuit, in particular to a receiving circuit, a receiving method and a LiDAR.

BACKGROUND

An avalanche photodiode (APD) is a highly sensitive semiconductor electronic device. APD can convert light into electricity through photoelectric effect. By applying a high reverse bias voltage, an internal current gain effect would occur in APD due to impact ionization, for example, an avalanche effect. A single photon avalanche diode (SPAD) or silicon photomultiplier (SiPM) is an APD that operates in Geiger mode. Theoretically, the gain of SPAD or SiPM can reach over a million times the gain of APD. Both SPAD and SiPM are silicon-based weak light detectors with excellent photon number resolution and single photon detection sensitivity, which have high gain and good timing resolution, as well as advantages such as low operating voltage and insensitivity to magnetic fields.

A LiDAR ranging system can include a transmitter and a receiver. The transmitter can generate and emit laser pulses. The laser pulses reach the measured object and are reflected by the measured object. Laser pulse echo signals are generated, which can be received by the receiver. The receiver can include a photoelectric device. A photoelectric device widely used in the field of LiDAR includes APD, SPAD, SiPM, or the like. The photoelectric device generates current pulses proportional to the received light signals. The photoelectric device operates at a higher bias voltage, and the measurement signal output by the photoelectric device is superimposed on this bias voltage. For example, if the bias voltage is 12V, all received measurement signals fluctuate based on the 12V bias voltage. For instance, if a negative pulse with an amplitude of 0.1V is received, it is superimposed on the 12V, resulting in a voltage peak of 11.9V. Therefore, the voltage of the output signal of the photoelectric device is relatively high, such as 3V-12V. However, the receiving circuit that processes the output signal of the photoelectric device operates at a lower voltage, such as 1V- 3V. A high-to-low voltage conversion is performed on the output signal.

Referring to FIG. 1, based on a receiving circuit 100, the photoelectric device SiPM senses external light signals and generates a corresponding current signal, namely the measurement signal. The light signals can include both an ambient light signal, and an echo light signal generated by reflection of a detection beam upon being incident on the measured object. Therefore, the measurement signal can include an ambient light component signal corresponding to the ambient light and an echo light component signal corresponding to the echo light signal. In the existing receiving circuit, to process the ambient light signal and the echo signal, the measurement signal is divided into two parts: one is converted into a voltage signal through a resistor and converted into a low voltage signal suitable for subsequent processing through a high-to-low voltage converter, the low voltage signal is input to an ambient light processing module for processing to obtain an ambient light component signal; the other one passes through a high-pass filter (HPF) for quenching recovery shaping, DC or low frequency signals including an ambient light interference signal are filtered out, the filtered signal is input to the echo signal processing module to obtain an echo light component signal. Finally, both the ambient light component signal and the echo component signal are input to an FPGA for processing to obtain required information, such as a distance between the measured object and the laser receiver system, the type of the measured object, or the like.

The frequency bandwidth of the measurement signal is relevant to adjustments of parameters of the photoelectric device, such as parasitic characteristics including SiPM recovery time, or the like. Different parameters result in different frequency bandwidth ranges of the measurement signal, the frequency bandwidth can be at high frequency or at low frequency. The frequency bandwidth range with optimal performance can be located based on the parasitic characteristics of the photoelectric device used, such as 50M-100MHz, 50M-80MHz, 70M-100MHz, etc. However, using a high-pass filter in the existing receiving circuit has the following problems: due to the requirement for quenching recovery shaping, the cutoff frequency of the high-pass filter module is set relatively high, such as 80Hz, allowing frequencies above 80Hz to pass. However, if the frequencies of the measurement signal are concentrated in a medium-to-low frequency range, such as 50M-100MHz, a considerable portion of the measurement signal are filtered out, resulting in more noises and a significant attenuation of the energy of the measurement signal, which is already weak. The system′s signal-to-noise ratio is deteriorated. Alternatively, larger power consumption is required to achieve the same performance, which results in a larger chip area that cannot be reduced. Besides, the existing high-to-low voltage conversion circuit is relatively complex and has significant DC offset. For example, if the voltage of the theoretical output signal is 1V, it may become 1.1V or even higher due to DC offset, and thus there may be an error of 10%or even greater, leading to a large error in the obtained ambient light component signal.

SUMMARY

This disclosure provides a circuit, a method and a device that implements high-to-low voltage conversion and low-pass filtering using a current mirror and a current-voltage converter or a current-voltage conversion module. The circuit structure is simplified, and the number of high voltage devices to be used is reduced, thereby improving the reliability and integration of the receiving circuit, and reducing chip area.

An aspect of this disclosure provides a receiving circuit for a light detection and ranging system, comprising: a photoelectric device, a current amplification module, a current-to-voltage conversion module, an analog-to-digital conversion module and a digital high-pass filter module, wherein, the photoelectric device is configured to receive a light signal and convert the light signal into a current signal, wherein the light signal comprises an ambient light signal and an echo light signal generated by reflection of a detection beam upon being incident on a target object; the current amplification module is configured to output, based on the current signal, a proportional current signal that is proportional to an amplitude of the current signal; the current-to-voltage conversion module is configured to generate a voltage signal based on the proportional current signal and perform low-pass filtering on the voltage signal; the analog-to-digital conversion module is configured to perform analog-to-digital conversion on the low-pass filtered voltage signal to obtain a digital signal corresponding thereto; and the digital high-pass filter module is configured to perform digital high-pass filtering on the digital signal and output a measurement signal.

Optionally, the receiving circuit further comprises a driver module, wherein the driver module is configured to receive and amplify the low-pass filtered voltage signal output by the current-to-voltage conversion module and drive the analog-to-digital conversion module.

Optionally, the driver module comprises a multiplexer and a buffer, the multiplexer is configured to perform gating on a plurality of the low-pass filtered voltage signals, select at least one low-pass filtered voltage signal and output the selected low-pass filtered voltage signal to the buffer; and the buffer is configured to receive and amplify the selected low-pass filtered voltage signal and drive the analog-to-digital conversion module.

Optionally, the photoelectric device comprises one or more of an avalanche photodiode, a single photon avalanche diode, and a silicon photomultiplier.

Optionally, the current amplification module comprises a current mirror circuit.

Optionally, the current mirror circuit comprises a first PMOS transistor and a second PMOS transistor, a source of the first PMOS transistor is coupled to a source of the second PMOS transistor and a supply voltage, a gate of the first PMOS transistor is coupled to a drain of the first PMOS transistor and receives the current signal output by the photoelectric device; and a drain of the second PMOS transistor outputs the proportional current signal.

Optionally, the current-to-voltage conversion module comprises a resistance-capacitance circuit.

Optionally, the resistance-capacitance circuit comprises an adjustable resistor and an adjustable capacitor; a first terminal of the adjustable resistor is coupled to a first terminal of the adjustable capacitor and an output terminal of the current amplification module, the adjustable resistor is configured to convert the proportional current signal into the corresponding voltage signal, and a second terminal of the adjustable resistor and a second terminal of the adjustable capacitor are grounded.

Optionally, the receiving circuit further comprises an electrostatic protection module configured to eliminate electrostatic interference in the current signal output by the photoelectric device, and input the current signal in which the electrostatic interference is eliminated to the current amplification module.

Optionally, the receiving circuit further comprises a direct current calibration module, wherein the direct current calibration module is configured to provide negative feedback to a signal input to the receiving circuit based on a DC component in the signal, so as to mitigate interference from the ambient light signal.

Optionally, the direct current calibration module is coupled between an input terminal of the analog-to-digital conversion module and an output terminal of the analog-to-digital conversion module; or the direct current calibration module is coupled between an input terminal of the driver module and the output terminal of the analog-to-digital conversion module; or the direct current calibration module is coupled between the input terminal of the driver module and an output terminal of the digital high-pass filter module; or the direct current calibration module is coupled between the input terminal of the analog-to-digital conversion module and the output terminal of the digital high-pass filter module.

Optionally, the direct current calibration module comprises a digital signal processor and a first adjustable current source, wherein, an input terminal of the digital signal processor is used as an input terminal of the direct current calibration module and an output terminal of the digital signal processor is coupled to an input terminal of the first adjustable current source, and one terminal of the first adjustable current source is used as an output terminal of the direct current calibration module; the digital signal processor is configured to calculate an DC component corresponding the ambient light and output a digital instruction to the first adjustable current source based on the DC component; and the first adjustable current source is configured to output, based on the digital instruction, a DC current corresponding to the digital instruction.

Optionally, the direct current calibration module is coupled between an input terminal of the driver module and an output terminal of the driver module.

Optionally, the direct current calibration module comprises an integrator, a second analog-to-digital converter, and a second adjustable current source; wherein, an input terminal of the integrator is coupled to the output terminal of the driver module, an output terminal of the integrator is coupled to the second analog-to-digital converter, an output terminal of the second analog-to-digital converter is coupled to an input terminal of the second adjustable current source, and one terminal of the second adjustable current source is coupled to the input terminal of the driver module; the integrator is configured to perform an integral operation on an analog signal output by the driver module and input an accumulated voltage signal obtained from the integral operation to the second analog-to-digital converter; the second analog-to-digital converter is configured to obtain a DC component corresponding to the ambient light based on the accumulated voltage signal and output a digital instruction to the second adjustable current source based on the DC component; and the second adjustable current source is configured to output, based on the digital instruction, a DC current corresponding to the digital instruction.

Optionally, the receiving circuit further comprises a processor module, wherein the output terminal of the second analog-to-digital converter is coupled to the processor module; and the processor module is configured to calculate ambient light information based on the DC component output by the second analog-to-digital converter.

Optionally, the receiving circuit further comprises a processor module, wherein an output terminal of the digital high-pass filter module is coupled to the processor module; the processor module is configured to analyze the measurement signal to determine one or more characteristics of the target object, and/or the processor module is configured to analyze the measurement signal to determine ambient light information.

An aspect of this disclosure provides a receiving method for light detection and ranging, comprising: converting a light signal into a current signal, wherein the light signal comprise an ambient light signal and an echo light signal generated by reflection of a detection beam upon being incident on a target object; outputting, based on the current signal, a proportional current signal that is proportional to an amplitude of the current signal; generating a voltage signal based on the proportional current signal and performing low-pass filtering on the voltage signal; performing analog-to-digital conversion on the low-pass filtered voltage signal to obtain a digital signal corresponding thereto; and performing digital high-pass filtering on the digital signal and outputting a measurement signal.

Optionally, the receiving method further comprises providing negative feedback to the low-pass filtered voltage signal based on a DC component in the digital signal or the voltage signal, so as to mitigate interference from the ambient light signal.

Optionally, the receiving method further comprises analyzing the measurement signal to determine one or more characteristics of the target object, and/or analyzing the measurement signal to determine ambient light information.

An aspect of this disclosure provides a LiDAR, comprising the receiving circuit describe above.

An aspect of this disclosure provides a terminal device comprises: LiDAR described above and a connector, configured to connect the LiDAR and the terminal device. Optionally, the terminal device includes a vehicle, a drone or a robot.

An aspect of this disclosure provides a circuit of a light detection and ranging system. The circuit including: a photoelectric device, a current amplifier, a current-to-voltage converter, an analog-to-digital converter and a digital high-pass filter. The photoelectric device configured to receive a light signal and convert the light signal into a current signal. The current amplifier configured to output a proportional current signal being proportional to an amplitude of the current signal, based on the current signal. The current-to-voltage converter configured to generate a voltage signal based on the proportional current signal and generate a filtered voltage signal by performing low-pass filtering on the voltage signal. The analog-to-digital converter configured to generate a digital signal by performing analog-to-digital conversion on the filtered voltage signal. The digital high-pass filter configured to output a measurement signal by performing digital high-pass filtering on the digital signal.

Optionally, the light signal includes an ambient light signal and an echo light signal generated by reflection of a detection beam incident onto a target object.

Optionally, the circuit includes a driver. The driver is configured to receive and amplify the filtered voltage signal, and drive the analog-to-digital converter.

Optionally, the driver includes a multiplexer and a buffer. The multiplexer is configured to gate a plurality of low-pass filtered voltage signals, select a low-pass filtered voltage signal, and output the low-pass filtered voltage signal to the buffer. The buffer is configured to receive and amplify the low-pass filtered voltage signal and drive the analog-to-digital converter.

Optionally, the photoelectric device includes at least one of an avalanche photodiode, a single photon avalanche diode, or a silicon photomultiplier.

Optionally, the current amplifier includes a current mirror circuit.

Optionally, the current mirror circuit includes a first PMOS transistor and a second PMOS transistor. A source of the first PMOS transistor is coupled to a source of the second PMOS transistor and a supply voltage. A gate of the first PMOS transistor is coupled to a drain of the first PMOS transistor. The gate of the first PMOS transistor is configured to receive the current signal. A drain of the second PMOS transistor is configured to output the proportional current signal.

Optionally, the current-to-voltage converter includes a resistance-capacitance circuit.

Optionally, the resistance-capacitance circuit includes an adjustable resistor and an adjustable capacitor, a first terminal of the adjustable resistor is coupled to a first terminal of the adjustable capacitor and an output terminal of the current amplifier. The adjustable resistor is configured to convert the proportional current signal into the digital signal. A second terminal of the adjustable resistor and a second terminal of the adjustable capacitor are grounded.

Optionally, the circuit includes an electrostatic protector. The electrostatic protector is configured to reduce electrostatic interference in the current signal and input the current signal to the current amplifier in response to reducing the electrostatic interference.

Optionally, the circuit includes a direct current calibrator, wherein the direct current calibrator is configured to provide negative feedback to a signal inputted to the circuit based on a DC component in the signal.

Optionally, the direct current calibrator is coupled between an input terminal of the analog-to-digital converter and an output terminal of the analog-to-digital converter.

Optionally, the direct current calibrator is coupled between an input terminal of the driver and the output terminal of the analog-to-digital converter.

Optionally, the direct current calibrator is coupled between the input terminal of the driver and an output terminal of the digital high-pass filter.

Optionally, the direct current calibrator is coupled between the input terminal of the analog-to-digital converter and the output terminal of the digital high-pass filter module.

Optionally, the direct current calibrator includes a digital signal processor and an adjustable current source. An input terminal of the digital signal processor functions as an input terminal of the direct current calibrator. An output terminal of the digital signal processor is coupled to an input terminal of the adjustable current source. A terminal of the adjustable current source functions as an output terminal of the direct current calibration module. The digital signal processor is configured to determine a DC component corresponding the ambient light and output a digital instruction to the adjustable current source based on the DC component. The adjustable current source is configured to output a DC current based on the digital instruction.

Optionally, the direct current calibrator is coupled between an input terminal of the driver and an output terminal of the driver.

Optionally, the analog-to-digital converter is a first analog-to-digital converter, and the direct current calibrator includes an integrator, a second analog-to-digital converter, and an adjustable current source. An input terminal of the integrator is coupled to the output terminal of the driver. An output terminal of the integrator is coupled to the second analog-to-digital converter. An output terminal of the second analog-to-digital converter is coupled to an input terminal of the adjustable current source. A terminal of the adjustable current source is coupled to the input terminal of the driver. The integrator is configured to perform an integral operation on an analog signal outputted by the driver and input an accumulated voltage signal determined from the integral operation to the second analog-to-digital converter. The second analog-to-digital converter is configured to determine a DC component corresponding to the ambient light based on the accumulated voltage signal and output a digital instruction to the second adjustable current source based on the DC component. The adjustable current source is configured to output a DC current based on the digital instruction.

Optionally, the circuit includes a processor. The output terminal of the second analog-to-digital converter is coupled to the processor. The processor is configured to determine ambient light data based on the DC component.

Optionally, the circuit includes a processor. An output terminal of the digital high-pass filter module is coupled to the processor. The processor is configured to determine a characteristic of the target object or the ambient light data based on the measurement signal.

This disclosure introduces a current signal into a low-pass filter by taking advantage of a proportional relationship between amplitudes of input current and output current of the current amplification module. Then, by using resistors in the current-voltage conversion module, there is no need to use an existing and commonly used high-to-low voltage conversion circuit with complex structure and larger DC-offset. This allows a current signal carrying the measurement signal to be converted from current domain to voltage domain, and to be converted into a low voltage suitable for subsequent processing. The circuit structure is simple, and the number of high voltage devices to be used is reduced, thereby improving the reliability and integration of the receiving circuit, and thus reducing chip area.

This disclosure uses a digital high-pass filter module to filter the digital signal output by the analog-to-digital converter, which facilitates the setting of the cutoff frequency of the digital high-pass filter through programming. This ensures that the cutoff frequency of the digital high-pass filter is compatible with the frequency range of the measurement signal output by the photoelectric device, thereby avoiding significant attenuation of the energy of the measurement signal and improving the system′s signal-to-noise ratio.

The electrostatic protection module in this disclosure can perform electrostatic protection when a transient high current is generated by the photoelectric device due to interference factors (such as electrostatic interference) , preventing damage to devices at subsequent stages.

The DC calibration module in this disclosure suppresses negative impact brought by ambient light interference signal when the ambient light interference signal is out of the operating range of the analog-to-digital conversion module, thereby improving signal processing capability of the receiving circuit and increasing the system′s signal-to-noise ratio.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are provided to understand this disclosure and form part of the specification. The drawings are used in conjunction with the embodiments of the present disclosure to explain this disclosure, which do not constitute limitation to this disclosure.

FIG. 1 shows a schematic diagram illustrating a structure of a receiving circuit.

FIG. 2 shows a schematic diagram illustrating a structure of an example receiving circuit, consistent with some embodiments of this disclosure.

FIG. 3 shows a schematic diagram illustrating an implementation of an example receiving circuit, consistent with some embodiments of this disclosure.

FIG. 4 shows a schematic diagram illustrating an implementation of an example receiving circuit, consistent with some embodiments of this disclosure.

FIGs. 5a to 5e show schematic diagrams illustrating structures of example receiving circuits, consistent with some embodiments of this disclosure.

FIG. 6 shows a schematic diagram illustrating an implementation of the example receiving circuit 501 of FIG. 5b.

FIG. 7 shows a schematic diagram illustrating an implementation of the example receiving circuit 504 of FIG. 5e.

FIG. 8 shows a waveform diagram illustrating a simulation result of the example receiving circuit 601 of FIG. 6.

FIG. 9 shows a flowchart illustrating an example method, consistent with some embodiments of this disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of this disclosure can increase the level of integration of the receiving circuit of LiDAR, can be adapted to different working environments, and can reduce the cost and complexity of LiDAR. The following embodiments of this disclosure are described for illustration instead of limiting. Some alternative embodiments can be implemented by using some of the aspects as described. For explanatory purposes, some example figures, materials and configurations are described for some embodiments.

This disclosure provides a receiving circuit, a receiving method, and a LiDAR. Some embodiments of this disclosure are described with the accompanying drawings.

FIG. 2 shows a schematic diagram illustrating a structure of an example receiving circuit, consistent with some embodiments of this disclosure. The receiving circuit 200 includes a photoelectric device 210, a current amplifier or amplification module 220, a current-to-voltage converter or conversion module 230, a driver or driver module 240, an analog-to-digital (ADC) converter or conversion module 250, a digital high-pass filter ( “DHPF” ) or DHPF module 260, and a processor or processor module 270.

FIG. 3 shows a schematic diagram illustrating an implementation of the example receiving circuit 300, consistent with some embodiments of this disclosure. The receiving circuit 300 includes a photoelectric device 310, a current amplifier or amplification module 320, a current-to-voltage converter or conversion module 330, a driver or driver module 340, an ADC converter or conversion module 350, a DHPF or DHPF module 360, and a processor or processor module 370. Some embodiments are described in detail in combination with FIG. 2 and FIG. 3 below.

With reference to FIGS. 2 to 3, the photoelectric devices 210 or 310 can be APD, SPAD, SiPM, or the like. The photoelectric device can receive a light signal and generate a current signal corresponding to the light signal. The light signal can include an ambient light signal and an echo light signal generated by reflection of a detection beam incident onto a target object. The current signal can include an ambient light component signal corresponding to the ambient light and an echo light component signal corresponding to the echo light signal.

For example, the current amplification modules 220 or 320 can include a current mirror circuit that can output a current signal proportional to the amplitude of the current signal based on the current signal. For example, the current signal outputted by the current amplification modules 220 and 320 can be approximately equal to its input current signal. The ratio coefficient of the current mirror circuit can be changed. For example, when the current signal is weak, a current mirror with an amplification ratio can amplify the weak current signal. When the current signal is strong, a current mirror with a reduced ratio can weaken the strong current signal. The current mirror circuit can be configured based on application environment of the LiDAR, configuration of the laser transmitting power, or the like. For example, a current signal outputted by a current mirror circuit used by the current amplification module 320 shown in FIG. 3 can approximately equal to the input current signal of the current mirror circuit.

With reference to FIGS. 2 to 3, the current signals outputted by the current amplification modules 220 or 320 are input to the current-to-voltage conversion modules 230 or 330, respectively. Each of the current-to-voltage conversion modules 230 and 330 can include a current-to-voltage converter, a current-to-voltage circuit, or the like. Each of the current-to-voltage conversion modules 230 and 330 can include a resistance-capacitance (RC) circuit. Each of the current-to-voltage conversion modules 230 and 330 can convert the current signal into a corresponding low voltage pulse signal through the RC circuit, for example, each of the current-to-voltage conversion modules can convert the current signal into a corresponding low voltage pulse signal through a resistor with a low ohm value in the RC circuit. The current signal can be converted from current domain to voltage domain, and converted into a low voltage value suitable for subsequent processing. Because pulse generated by the photoelectric device in response to the light signal can be fast (e.g., in an order of nanoseconds) , the slope of the pulse signal can be large. Subsequent analog-to-digital converters may miss some pulse signal due to the limitation of sampling frequency. The current-to-voltage conversion modules 230 and 330 in this disclosure can also perform low-pass filtering on the low voltage pulse signal, decreasing the slope of a pulse front edge in the input signal, and facilitating subsequent sampling by the analog-to-digital conversion module. The current-to-voltage conversion modules 230 and 330 can include a low-pass filtering modules. An analog-to-digital converter with low frequency can be used in the receiving circuit, thus reducing the cost.

It can be understood that the current-to-voltage conversion module can also be a tunable current-to-voltage conversion module. For example, the current-to-voltage conversion module can include an adjustable resistor and adjustable capacitor. The values of the adjustable resistor and adjustable capacitor can be adjusted to change the gain and bandwidth of the current-to-voltage conversion module.

Still referring to FIGS. 2 to 3, the low voltage signal obtained after low-pass filtering is input to the driver modules 240 or 340. The driver modules 240 or 340 can output the low voltage signal and drive the analog-to-digital conversion modules 250 or 350, respectively, in the subsequent stage. Because the impedance of RC in the current-to-voltage conversion modules 230 or 330 can be high, and because the input impedance of the analog-to-digital conversion modules 250 or 350 can be low, a direct connection between the analog-to-digital conversion modules 250 or 350 to the current-to-voltage conversion modules 230 or 330, respectively, can cause damage to the analog-to-digital conversion modules 250 or 350, respectively. In some embodiments, the driver modules 240 can be arranged between the analog-to-digital conversion modules 250and the current-to-voltage conversion modules 230. The driver modules 340 can be arranged between the analog-to-digital conversion modules 350 and the current-to-voltage conversion modules 330. The output signals of the driver modules 240 or 340 can be proportional to their input signal. The input impedances of the driver modules 240 or 340 can be large, and the driver modules can be directly connected to the current-to-voltage conversion modules 230 or 330, respectively. Driver modules 240, 340 can proportionally amplify the input signal. The amplification ratio can be 1 or more than 1. For example, the output voltage of the driver modules 240 or 340 can be equal to or greater than its input voltage. If the detection signal is weak, a driver with a large amplification ratio can be used to improve the signal processing capability.

Referring to FIG. 3, an output terminal of the photoelectric device 310 is coupled to an input terminal of the current amplification module 320. The current amplification module 320 can include a current amplification circuit or the like. For example, the current amplification module 320 includes a current mirror circuit. The current mirror circuit includes a first PMOS transistor M0 and a second PMOS transistor M1. A source of the first PMOS transistor M0 is coupled to a source of the second PMOS transistor M1 and a supply voltage VDD. A gate of the first PMOS transistor M0 is coupled to its drain. A drain of the second PMOS transistor M1 serves as an output terminal of the current mirror circuit and is coupled to an input terminal of the current-to-voltage conversion module 330. The current-to-voltage conversion module 330 includes a resistor R1 and a capacitor C1. A first terminal of the resistor R1 is coupled to the drain of the second PMOS transistor M1 and a first terminal of the capacitor C1. The second terminal of the resistor R1 and the second terminal of the capacitor C1 are both grounded. The driver module 340 includes a buffer, and an input terminal of the buffer is coupled to the first terminal of the capacitor C1.

With reference to FIGS. 2 to 3, each of the analog-to-digital conversion modules 250 and 350 can include an analog-to-digital converter. Each of the analog-to-digital conversion modules 250 and 350 can perform analog-to-digital conversion on the low-pass filtered voltage signals to obtain the corresponding digital signals, and output the corresponding digital signals to the digital high-pass filter modules 260 and 360, respectively. The analog-to-digital conversion modules 250 or 350 can sample the input voltage signals at a time frequency, convert each sampling value into a digital signal, and output the digital signal. By doing so, the outputted digital signal can reflect the value of the input voltage signal.

Still referring to FIGS. 2 to 3, each of the digital high-pass filter modules 260 and 360 can include a digital high-pass filter. Each of the digital high-pass filter modules 260 and 360 can perform digital high-pass filtering on the digital signal to cut off a tail of the signal to obtain a measurement signal. The cutoff frequency of the digital high-pass filter can be configured by programming. The cutoff frequency of the digital high-pass filter can be adjusted based on the frequency bandwidth range corresponding to parameters of the photoelectric device adapted by the receiving circuit. By doing so, the cutoff frequency of the digital high-pass filter can be compatible with the frequency range of the measurement signal output by the photoelectric device, thereby mitigating the problem of filtering out a large part of the measurement signal when the cutoff frequency is high and the frequencies of the measurement signal are concentrated in a medium-to-low frequency range, and thus improving the system′s signal-to-noise ratio. The tail of a signal in this disclosure refers to a falling edge of the signal (e.g., a pulse signal) . The tail generated by the echo signal can be long (e.g., the falling edge falls slowly) and take a long time to return to a reference voltage. In such a scenario, a previous pulse signal to overlap with a subsequent pulse signal, thereby affecting the detection on the subsequent pulse signal. The digital high-pass filter modules 260 and 360 can cut off the tail of the signal. By doing so, falling of the falling edge of the pulse signal can be accelerated, improving the ability of signal detection. The digital high-pass filter modules 260 or 360 can include a digital high-pass filter, a digital high-pass filtering circuit, or the like.

Still referring to FIGS. 2 to 3, the measurement signals are sent to the processor modules 270 or 370 for calculation and processing. A measurement signal can include an ambient light component signal corresponding to the ambient light and an echo light component signal corresponding to the echo light signal. Each of the processor modules 270 or 370 can include any combination of any number of processors, application specific integrated circuits ( “ASICs” ) , field programmable gate arrays ( “FPGAs” ) , digital signal processors ( “DSPs” ) , or any other circuits that can process data. The processor modules 270 and 370 can analyze one or more characteristics of the measurement signal to determine a characteristic of the target object. For example, the characteristic of the target object can include a distance between the target object and the laser receiving system, a type of the target object, a reflectivity of the target object, a shape of the target object, or the like. The measurement signal received by the processor modules 270 and 370 can include an ambient light component signal corresponding to the ambient light and an echo light component signal corresponding to the echo light signal. The processor modules 270 and 370 can perform an integral operation on the measurement signal to obtain ambient light information. By reading sampling data of the pulse signal corresponding to the echo light signal, the processor modules 270 and 370 can determine (e.g., by calculation) the time when the pulse reaches the LiDAR, and determine time of flight in combination with the time when the LiDAR emits the detection beam. By doing so, the distance between the target object and the laser receiving system can be determined. The reflectivity information of the target object can be calculated based on an amplitude, a pulse width of the pulse signal, or the like. The outline information of the target object can be calculated based on the detection data of a plurality of photoelectric devices. In some embodiments, the type information of the target object can be determined through a recognition algorithm.

It should be noted that for the functions of various modules in the receiving circuit, the implementation mode of the receiving circuit is not limited to the examples described in this disclosure.

In some embodiments, a proportional relationship between the input current and output current of the current amplification module can introduce a current signal into the low-pass filter. The resistors in the current-to-voltage conversion module can be used instead of an existing and commonly used high-to-low voltage conversion circuit with complex structure and large DC-offset. In such scenarios, a current signal carrying the measurement signal can be converted from a current domain to a voltage domain, and be converted into a low voltage suitable for subsequent processing. By doing so, the circuit structure is simplified, and the number of high voltage devices to be used is reduced, thereby improving the reliability and integration of the receiving circuit, and thus reducing a chip area. Also, using a digital high-pass filter module can facilitate to set the cutoff frequency of the digital high-pass filter by programming. Doing so can make the cutoff frequency of the digital high-pass filter compatible with the frequency range of the measurement signal outputted by the photoelectric device, thereby avoiding significant attenuation of the energy of the measurement signal and improving the system′s signal-to-noise ratio.

FIG. 4 shows a schematic diagram illustrating an implementation of the example receiving circuit, consistent with some embodiments of this disclosure. The receiving circuit 400 includes a photoelectric device 410, an electrostatic protector or protection module 480 (e.g., an electrostatic discharge, or “ESD” ) , a current amplifier or amplification module 420, a current-to-voltage converter or conversion module 430, a driver or driver module 440, an analog-to-digital converter or conversion module 450, a digital high-pass filter or filter module 460, and a processor or processor module 470. Compared with the receiving circuit shown in FIG. 3, an electrostatic protection module 480 is further provided, and a multiplexer ( “MUX” ) is arranged in the driver module 440. The functions implemented by the photoelectric device 410, the current amplification module 420, the current-to-voltage conversion module 430, the analog-to-digital conversion module 450, the digital high-pass filter module 460, and the processor module 470 are consistent with those implemented by the corresponding modules in some above embodiments, such as the embodiments described in association with FIG. 2 and FIG. 3.

In FIG. 4, as an example, the electrostatic protection module 480 includes a protection resistor R0 and a diode D0 connected in parallel. An output terminal of the photoelectric device 410 is coupled to a first terminal of the resistor R0. A second terminal of the resistor R0 is coupled to a first terminal of the diode D0 and an input terminal of the current amplification module 420. A second terminal of the diode D0 is grounded. When the photoelectric device generates a transient high current due to interference factors (e.g., electrostatic interference) , the electrostatic protection module 480 can protect the circuit at the subsequent stage by shunting the transient high current through the diode D0. In some embodiments, the electrostatic protection module 480 can provide electrostatic protection by an electrostatic discharge.

With reference to FIG. 4, as an example, the driver module 440 includes a multiplexer (MUX) and a buffer. An output terminal of the current-to-voltage conversion module 430 is coupled to an input terminal of the multiplexer MUX. An output terminal of the multiplexer MUX is coupled to an input terminal of the buffer. The multiplexer can perform gating on a plurality of low-pass filtered voltage signals, select a low-pass filtered voltage signal, and output the selected low-pass filtered voltage signal to the buffer. The buffer can receive and amplify the selected low-pass filtered voltage signal, and drive the analog-to-digital conversion module 450. Because the receiving end of the LiDAR can include a plurality of photoelectric detectors, the plurality of photoelectric detectors can be arranged in rows, in columns, or in a two-dimensional array. In some embodiments, the photoelectric device 410 can include one or more photoelectric detectors. A plurality of photoelectric devices 410 can share one single receiving circuit, reducing the number of receiving circuits. To collect output signals from different photoelectric devices, the driver module 440 can include a multiplexer MUX. In such a case, the output signals of the plurality of photoelectric devices 410 can be gated one by one, and the selected output signal of the photoelectric device 410 can be transmitted to the buffer for further data processing. In some embodiments, the multiplexer MUX can be a 4-to-1 MUX, an 8-to-1 MUX, a 16-to-1 MUX, a 32-to-1 MUX, or any other types of multiplexer.

Consistent with embodiments of this disclosure, circuit protection function and multiplex gating function can provide electrostatic protection and reduce the number of the receiving circuits.

Due to the existence of ambient light interference in the system, when the ambient light is strong, intensity of the current signal outputted by the photoelectric device can increase. The ambient light interference signal can be a direct current ( “DC” ) component that can cause DC fluctuations in the signal input to the analog-to-digital conversion module because the signal includes the ambient light interference signal. This fluctuation can cause the signal input to the analog-to-digital conversion module to exceed its operating range, resulting in errors in data processing. To suppress the above-mentioned impact of ambient light interference signal, this disclosure further provides a direct current calibration module (e.g., a direct current cancellation module, or a DCC module) to perform assistant correction regarding the ambient light signal.

FIGs. 5a to 5e show schematic diagrams illustrating structures of example receiving circuits, consistent with some embodiments of this disclosure. Each of the example receiving circuits 500, 501, 502, 503, and 504 includes a photoelectric device 510, a current amplifier or amplification module 520, a current-to-voltage converter or conversion module 530, a driver or driver module 540, an analog-to-digital converter or conversion module 550, a digital high-pass filter or filtering module 560, a processor or processor module 570, and a direct current calibrator or calibration module 590. In some embodiments, the current amplifier or amplifier module 520 can be implemented as the current amplifier 320 in FIG. 3.

FIG. 6 shows a schematic diagram illustrating an implementation of the example receiving circuit 501 of FIG. 5b. FIG. 7 shows a schematic diagram illustrating an implementation of the example receiving circuit 504 of FIG. 5e. It should be noted that for functions of various modules in the receiving circuit, the implementation mode of the receiving circuit is not limited to the examples described in this disclosure.

Some embodiments are described in detail in combination with FIGs 5a-5e, FIG. 6 and FIG. 7. The photodetector 510, the current amplification module 520, the current-to-voltage conversion module 530, the analog-to-digital conversion module 550, the digital high-pass filter module 560, and the processor module 570 can be similar to the corresponding modules described in the above embodiments, such as the embodiments described in association with FIG. 2, FIG. 3, or FIG. 4.

Referring to FIG. 5a, a direct current calibration module 590 is coupled between an input terminal and an output terminal of the analog-to-digital conversion module 550. Referring to FIG. 5b, the direct current calibration module 590 is coupled between an input terminal of the driver module 540 and an output terminal of the analog-to-digital conversion module 550. Referring to FIG. 5c, the direct current calibration module 590 is coupled between the input terminal of the driver module 540 and an output terminal of the digital high-pass filter module 560. Referring to FIG. 5d, the direct current calibration module 590 is coupled between an input terminal of the analog-to-digital conversion module 550 and the output terminal of the digital high-pass filter module 560. Referring to FIG. 5e, the direct current calibration module 590 is coupled between an input terminal and an output terminal of the driver module 540. The direct current calibration module 590 can extract a signal from the output terminal of the analog-to-digital conversion module 550 or the output terminal of the digital high-pass filter module 560. The direct current calibration module 590 can also measure DC component in the signal. The direct current calibration module 590 can further provide negative feedback to the input terminal of the analog-to-digital conversion module 550 or the input terminal of the driver module 540 using the DC component. By doing so, at least part of impact brought by ambient light interference signals can be mitigated. The direct current calibration module 590 can include a direct current calibration circuit, a direct current calibrator, or the like.

Referring to FIG. 6, the receiving circuit 601 further includes a direct current calibration module 690 coupled between an input terminal of a driver module 640 and an output terminal of an analog-to-digital conversion module 650. The direct current calibration module 690 includes a digital signal processor 6910 and a first adjustable current source 6920. An input terminal of the digital signal processor 6910 is coupled to the output terminal of the analog-to-digital conversion module 650. An output terminal of the digital signal processor 6910 is coupled to an input terminal of the first adjustable current source 6920. A terminal of the first adjustable current source 6920 is grounded or connected to another low voltage source. Another terminal of the first adjustable current source 6920 is coupled to an input terminal of the driver module 640. The digital signal output by the analog-to-digital conversion module 650 can include DC signal generated by ambient light. The digital signal output by the analog-to-digital conversion module 650 can be inputted to the digital signal processor. The digital signal processor 6910 can perform an operation on the digital signal. For example, the digital signal processor 6910 can calculate an arithmetic average to obtain the DC component signal, and output a digital instruction to the first adjustable current source 6920 based on the DC component signal. The first adjustable current source 6920 outputs a DC current corresponding to the digital instruction based on the digital instruction. Because that a terminal of the first adjustable current source 6920 is grounded, that another terminal is coupled to the input terminal of the driver module 640, and that the current flowing through the first adjustable current source 6920 corresponds to the DC current generated by the ambient light, the DC component inputted to the driver module 640 from the current-to-voltage conversion module 630 can flow through the first adjustable current source, and the DC component can be partially or completely removed from the signal input to the driver module 640. The removal ratio can be configured by the digital signal processor 6910 (e.g., by setting a data mapping table in the digital signal processor 6910 to establish a certain mapping relationship between the ambient light DC signal and the output instruction of the digital signal processor 6910) . By adjusting the mapping relationship, the removal ratio can be adjusted. In this way, at least part of impact of the ambient light interference signal on the analog-to-digital conversion module 650 can be mitigated.

The direct current calibration module 690 includes a digital signal processor for processing digital signals. Therefore, the input terminal of the direct current calibration module 690 can be coupled to the output terminal of the analog-to-digital conversion module 650 or coupled to the output terminal of the digital high-pass filter module. In some embodiments, the direct current calibration module 690 can be used in the receiving circuits as shown in FIG. 5a to FIG. 5d.

In the receiving circuit 504 as shown in FIG. 5e, the direct current calibration module 590 is coupled between the input terminal of the driver module 540 and the output terminal of the driver module 540. However, because the output of the driver module is an analog signal, the direct current calibration module 690 cannot be applied to the receiving circuit shown in FIG. 5e.

FIG. 7 shows a schematic diagram illustrating an implementation of the example receiving circuit 504 of FIG. 5e. The receiving circuit 704 further includes a direct current calibration module 790 coupled between the input terminal and the output terminal of the driver module 540. The direct current calibration module 790 includes an integrator 7910, a second analog-to-digital converter 7920, and a second adjustable current source 7930. An input terminal of the integrator 7910 is coupled to an output terminal of the driver module 740. An output terminal of the integrator 7910 is coupled to the second analog-to-digital converter 7920. An output terminal of the second analog-to-digital converter 7920 is coupled to an input terminal of the second adjustable current source 7930. A terminal of the second adjustable current source 7930 is grounded or coupled to another low fixed voltage. Another terminal of the second adjustable current source 7930 is coupled to an input terminal of the driver module 740. The integrator 7910 performs an integral operation on an analog signal output from the driver module 740 and inputs the accumulated voltage signal obtained by the integral operation to the second analog-to-digital converter 7920. The second analog-to-digital converter 7920 samples the accumulated voltage signal at a certain frequency and calculates the average to obtain a DC component corresponding to the ambient light. The second analog-to-digital converter 7920 outputs a digital instruction to the second adjustable current source 7930 based on the DC component determined by calculation. The second adjustable current source 7930 can output a DC current corresponding to the digital instruction based on the digital instruction. Because that terminal of the second adjustable current source 7930 is grounded, that another terminal is coupled to the input terminal of the driver module 740, and that the current flowing through the second adjustable current source 7930 corresponds to the DC current generated by the ambient light, the DC component inputted to the driver module 740 from the current-voltage conversion module 730 can flow through the adjustable DC source. By doing so, the DC component can be partially or completely removed from the signal input to the driver module 740. The removal ratio can be configured by the second analog-to-digital converter 7920 (e.g., by setting a data mapping table in the second analog-to-digital converter 7920 to establish a certain mapping relationship between the ambient light DC signal and the output instruction of the second analog-to-digital converter 7920) . By adjusting the mapping relationship, the removal ratio can be adjusted. In this way, at least part of impact of the ambient light interference signal on the analog-to-digital conversion module 750 can be mitigated.

Because the frequency of the ambient light can change slowly, a low frequency analog-to-digital converter can be used as the second analog-to-digital converter 7920 to sample the voltage signal at a long interval, which can provide accurate ambient light data as well. The overall cost of the system can be reduced.

For example, in the direct current calibration module 790 shown in FIG. 7, the output terminal of the second analog-to-digital converter 7920 is coupled to the input terminal of the processor. The ambient light signal can be transmitted to the processor 770. The processor 770 can perform further system adjustment based on this ambient light signal, such as altering the emission intensity of the laser or adjusting the detection efficiency of the photoelectric device.

By introducing the direct current calibration module, when the ambient light interference signal is out of the operation range of the analog-to-digital conversion module, the negative impact brought by ambient light interference signal can be suppressed, thereby improving signal processing capability of the receiving circuit and increasing the system′s signal-to-noise ratio.

FIG. 8 shows a waveform diagram illustrating the simulation result of the example receiving circuit 601 of FIG. 6. The upper graph in FIG. 8 illustrates the output voltage signal of the analog-to-digital converter 650, for example, the waveform of the voltage signal VA at point A in FIG. 6. The lower graph in FIG. 8 illustrates the output voltage signal of the digital high-pass filter 660, for example, the waveform of the voltage signal VB at point B in FIG. 6. The input-output function of DHPF can be y (t) =x (t) -0.5*x (t-10ns) . Assuming there are 295 units in a photoelectric device SiPM, traversing from 5 to 295 with a step size of 20 units, different curves from bottom to top are obtained correspondingly. For example, in the upper graph and the lower graph of FIG. 8, each curve represents a simulation result of a group of units in the SiPM. For example, in either the upper graph of the lower graph of FIG. 8, the bottom curve can represent a simulation curve of 5 activated units in the SiPM. A first curve above the bottom curve can represent a simulation curve of 25 activated units in the SiPM. A second curve above the first curve can represent a simulation curve of 45 activated units in the SiPM. The top curve can represent a simulation curve of 295 activated units in the SiPM. In FIG. 8, the lower curves represent the cases where fewer units are excited, where fewer photons are incident on the SiPM. The the upper curves represent the cases where more units are excited, where more photons are incident on the SiPM. By comparing the waveforms in the upper and lower graphs in FIG. 8, it can be seen that a signal that has not been processed by the digital high-pass filter (e.g., as represented by the upper graph) has significant tailing, and the tail of a previous pulse signal can have a large impact on the subsequent pulse signal. After passing through the digital high-pass filter, the signal tail can be cut off (e.g., as represented by the lower graph) , and the tail of the previous pulse signal can have a small impact on the subsequent pulse signal.

FIG. 9 shows a flowchart illustrating an example method, consistent with some embodiments of this disclosure. The method 900 can be used for a light detection and ranging system. The method 900 can also be applied to a LiDAR.

With reference to FIG. 9, the method includes the following steps. At step S901, a light signal is converted into a current signal. In some embodiments, the light signal can include an ambient light signal and an echo light signal generated by reflection of a detection beam incident onto the target object.

At step S902, a proportional current signal is output based on the current signal. The proportional current signal can be proportional to an amplitude of the current signal.

At step S903, a voltage signal is generated based on the proportional current signal, and low-pass filtering is performed on the voltage signal. At step S904, analog-to-digital conversion is performed on the low-pass filtered voltage signal to generate a digital signal corresponding to the digital signal. At step S905, digital high-pass filtering is performed on the digital signal, and a measurement signal is outputted.

Consistent with some embodiments of this disclosure, the receiving method 900 can further include a step of providing negative feedback to the low-pass filtered voltage signal based on the DC component in the digital signal or in the voltage signal. By doing so, interference from ambient light signals can be reduced.

Consistent with some embodiments of this disclosure, the method 900 can further include a step of analyzing the measurement signal to determine a characteristic of the target object. In some embodiments the method 900 can further include a step of analyzing the measurement signal to determine ambient light information.

In the drawings, some structural features or method features can be shown in a particular arrangement or order. However, it should be understood that such particular arrangement or order can change. In some embodiments, these features can be arranged in a manner or order different from that shown in the illustrative drawings. Additionally, inclusion of a structure feature or a method feature in a particular drawing does not imply that such a feature is necessary in all embodiments, and in some embodiments, such a feature can be omitted or combined with other features.

It should be noted that, in this disclosures, terms indicating a relationship such as "first" and "second" are merely used to distinguish one entity or operation from another, which do not necessarily require or imply any actual relationship or order between these entities or operations. Furthermore, the terms "comprise, " "include, " or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device not only includes a series of elements, but may also include other elements not explicitly listed or inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the statement "including one" does not preclude the existence of additional identical elements in a process, method, article, or apparatus that are the same as or similar to the one element.

The terms "or" and "and/or" describe an association relationship between associated objects, and represents a non-exclusive inclusion. For example, each of "A and/or B" and "A or B" can include: only "A" exists, only "B" exists, and "A" and "B" both exists, where "A" and "B" can be singular or plural. For another example, each of "A, B, and/or C" and "A, B, or C " can include: only “A” exists, only “B” exists, only “C” exists, “A” and “B” both exist, “A” and “C” both exist, “B” and “C” both exist, and “A, ” “B, ” and “C” all exist, where "A, " "B, " and “C” can be singular or plural. Although this disclosure has been described and illustrated in detail with reference to some embodiments of this disclosure, those skilled in the art should understand that various changes may be made in form and in detail without departing from the spirit and scope of this disclosure.

Claims

A receiving circuit for a light detection and ranging system, comprising:

a photoelectric device, a current amplification module, a current-to-voltage conversion module, an analog-to-digital conversion module and a digital high-pass filter module, wherein the photoelectric device is configured to receive a light signal and convert the light signal into a current signal, wherein the light signal comprises an ambient light signal and an echo light signal generated by reflection of a detection beam upon being incident on a target object;

the current amplification module is configured to output, based on the current signal, a proportional current signal being proportional to an amplitude of the current signal;

the current-to-voltage conversion module is configured to generate a voltage signal based on the proportional current signal and perform low-pass filtering on the voltage signal;

the analog-to-digital conversion module is configured to perform analog-to-digital conversion on the low-pass filtered voltage signal to generate a digital signal corresponding to the low-pass filtered voltage signal; and

the digital high-pass filter module is configured to perform digital high-pass filtering on the digital signal and output a measurement signal.
The receiving circuit of claim 1, further comprising a driver module, wherein the driver module is configured to receive and amplify the low-pass filtered voltage signal outputted by the current-to-voltage conversion module and drive the analog-to-digital conversion module.
The receiving circuit of claim 2, wherein the driver module comprises a multiplexer and a buffer, and wherein

the multiplexer is configured to gate a plurality of low-pass filtered voltage signals, select at least one low-pass filtered voltage signal, and output the selected at least one low-pass filtered voltage signal to the buffer; and

the buffer is configured to receive and amplify the selected at least one low-pass filtered voltage signal and drive the analog-to-digital conversion module.
The receiving circuit of any of claims 1 to 4, wherein the photoelectric device comprises at least one of an avalanche photodiode, a single photon avalanche diode, or a silicon photomultiplier.
The receiving circuit of any of claims 1 to 5, wherein the current amplification module comprises a current mirror circuit.
The receiving circuit of claim 5, wherein the current mirror circuit comprises a first PMOS transistor and a second PMOS transistor;

a source of the first PMOS transistor is coupled to a source of the second PMOS transistor and a supply voltage;

a gate of the first PMOS transistor is coupled to a drain of the first PMOS transistor and is configured to receive the current signal outputted by the photoelectric device; and

a drain of the second PMOS transistor is configured to output the proportional current signal.
The receiving circuit of any of claims 1 to 6, wherein the current-to-voltage conversion module comprises a resistance-capacitance circuit.
The receiving circuit of claim 7, wherein the resistance-capacitance circuit comprises an adjustable resistor and an adjustable capacitor;

a first terminal of the adjustable resistor is coupled to a first terminal of the adjustable capacitor and an output terminal of the current amplification module;

the adjustable resistor is configured to convert the proportional current signal into the digital signal; and

a second terminal of the adjustable resistor and a second terminal of the adjustable capacitor are grounded.
The receiving circuit of any of claims 1 to 8, further comprising: an electrostatic protection module, configured to reduce electrostatic interference in the current signal outputted by the photoelectric device, and input the current signal to the current amplification module in response to reducing the electrostatic interference.
The receiving circuit of any of claims 1 to 9, further comprising a direct current calibration module, wherein the direct current calibration module is configured to provide negative feedback to a signal inputted to the receiving circuit based on a DC component in the signal to mitigate interference from the ambient light signal.
The receiving circuit of claim 10, wherein the direct current calibration module is coupled between an input terminal of the analog-to-digital conversion module and an output terminal of the analog-to-digital conversion module; or

the direct current calibration module is coupled between an input terminal of the driver module and the output terminal of the analog-to-digital conversion module; or

the direct current calibration module is coupled between the input terminal of the driver module and an output terminal of the digital high-pass filter module; or

the direct current calibration module is coupled between the input terminal of the analog-to-digital conversion module and the output terminal of the digital high-pass filter module.
The receiving circuit of claim 11, wherein the direct current calibration module comprises a digital signal processor and a first adjustable current source, and wherein

an input terminal of the digital signal processor functions as an input terminal of the direct current calibration module,

an output terminal of the digital signal processor is coupled to an input terminal of the first adjustable current source,

a terminal of the first adjustable current source functions as an output terminal of the direct current calibration module,

the digital signal processor is configured to calculate an DC component corresponding the ambient light and output a digital instruction to the first adjustable current source based on the DC component, and

the first adjustable current source is configured to output, based on the digital instruction, a DC current corresponding to the digital instruction.
The receiving circuit of claim 10, wherein the direct current calibration module is coupled between an input terminal of the driver module and an output terminal of the driver module.
The receiving circuit of claim 13, wherein the direct current calibration module comprises an integrator, a second analog-to-digital converter, and a second adjustable current source; wherein

an input terminal of the integrator is coupled to the output terminal of the driver module,

an output terminal of the integrator is coupled to the second analog-to-digital converter,

an output terminal of the second analog-to-digital converter is coupled to an input terminal of the second adjustable current source,

a terminal of the second adjustable current source is coupled to the input terminal of the driver module,

the integrator is configured to perform an integral operation on an analog signal outputted by the driver module and input an accumulated voltage signal obtained from the integral operation to the second analog-to-digital converter,

the second analog-to-digital converter is configured to obtain a DC component corresponding to the ambient light based on the accumulated voltage signal and output a digital instruction to the second adjustable current source based on the DC component, and

the second adjustable current source is configured to output, based on the digital instruction, a DC current corresponding to the digital instruction.
The receiving circuit of claim 14, further comprising a processor module, wherein the output terminal of the second analog-to-digital converter is coupled to the processor module; and

the processor module is configured to calculate ambient light information based on the DC component output by the second analog-to-digital converter.
The receiving circuit of claim 1, further comprising a processor module, wherein an output terminal of the digital high-pass filter module is coupled to the processor module;

the processor module is configured to analyze the measurement signal to determine a characteristic of the target object, or

the processor module is configured to analyze the measurement signal to determine ambient light information.
A method for light detection and ranging, comprising:

converting a light signal into a current signal, wherein the light signal comprises an ambient light signal and an echo light signal generated by reflection of a detection beam upon being incident on a target object;

outputting, based on the current signal, a proportional current signal that is proportional to an amplitude of the current signal;

generating a voltage signal based on the proportional current signal and performing low- pass filtering on the voltage signal;

performing analog-to-digital conversion on the low-pass filtered voltage signal to obtain a digital signal corresponding thereto; and

performing digital high-pass filtering on the digital signal and outputting a measurement signal.
The method of claim 17, further comprising:

providing negative feedback to the low-pass filtered voltage signal based on a DC component in the digital signal or the voltage signal to mitigate interference from the ambient light signal.
The method of claim 17 or claim 18, further comprising:

analyzing the measurement signal to determine a characteristic of the target object; or

analyzing the measurement signal to determine ambient light information.
A LiDAR, comprising the receiving circuit of any of claims 1 to 16.