Signal level simulation method and device for APD linear laser radar receiving system

Abstract

The invention discloses a signal level simulation method and device for an APD linear laser radar receiving system, and the method comprises the steps: aided design of an APD device through device simulation, and extraction of the electrical characteristic data of the designed APD device; establishing an APD device equivalent circuit according to the electrical characteristic data; associating the APD device equivalent circuit to a front-end receiving circuit and performing circuit simulation to obtain the front-end receiving circuit meeting design requirements; associating the front-end receiving circuit to a radar receiving system and performing system simulation; and if the system simulation result does not meet the requirement, designing a radar receiving system in which the APD device, the front-end receiving circuit and the radar receiving system all meet the design requirement by continuously and jointly carrying out APD device simulation, circuit simulation and system simulation. Therefore, the problem of lack of connectivity and full coverage of a signal-level simulation whole process in simulation research of an APD linear laser radar receiving system at the present stage is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lidar, and particularly relates to a signal-level simulation method and device for a linear lidar receiving system based on an APD (Avalanche Photodiode). Background Art

[0002] Lidar technology is an information detection and acquisition technology developed on the basis of optoelectronic detection technology and electromagnetic radar technology. Lidar imaging technology is based on lidar technology, storing the information obtained by sensor measurement according to specific rules and converting it into a visual representation result, so as to accurately represent environmental information. Driven by strong market demand, imaging lidars of different systems have emerged and developed rapidly in various application backgrounds. Among them, the imaging lidar based on the linear-mode APD has emerged as an important development direction in the lidar technology field in the past decade or so because it is suitable for occasions that require fast and high-precision imaging of targets.

[0003] The development of a lidar imaging system is a complex process, involving multiple links such as system analysis, structural design, prototype manufacturing, and engineering applications. Among these links, the selection of system parameters and principle design is crucial and directly affects the imaging result of the system. If the parameters and principle design are unreasonable, not only the advantages of lidar imaging cannot be fully utilized, but the system may even fail to work properly. Therefore, in order to achieve the optimal parameter design and imaging control of the system, accurate system prediction and scientific performance evaluation are very necessary and urgent. In the fields of scientific research and engineering, simulation technology is an indispensable key tool in research and experiments. No matter how complex the system is, as long as the system model can be accurately established, the system can be comprehensively and deeply studied through simulation technology. Once the simulation model is established, it can be reused repeatedly and modified flexibly according to needs, which provides convenience for the update and optimization of the system. Relying on simulation technology, the system can be gradually corrected and corresponding decisions and measures can be taken accordingly, so that the system is under scientific management and control.

[0004] Based on this, the simulation work for lidar systems has been gradually emphasized and developed at the present stage. At the same time, with the rapid development of the computer industry, the demand for lidar digital simulation is also gradually catching up. In recent years, continuous progress has been made in the research on lidar simulation at home and abroad. Simulation research has become a basic prerequisite for the development of new lidar systems. It can not only provide system developers with predictions of system performance and optimization directions for system design, but also enable researchers to develop and verify application algorithms dedicated to specific systems through test data. Therefore, in-depth research on lidar simulation technology has important practical significance and broad development prospects.

[0005] At present, in the simulation of lidar receiving systems, usually after completing the design and simulation of the receiving circuit, research conclusions are drawn through the analysis of the circuit simulation results, or a prototype is directly built for result verification. For the detection device APD, an equivalent circuit is often extracted through a device parameterized model to be associated with the circuit design and simulation. However, this approach results in the simulation of the device or circuit only achieving independent simulation and design for their respective working processes and performance, such that the device or circuit cannot be fully verified before being applied to the prototype, leading to the designed device, circuit, and even the system being unable to meet the overall performance index requirements under actual application conditions, and it is difficult to conduct abnormal tests and error positioning, thereby increasing the design cycle and experimental costs. Summary of the Invention

[0006] To solve the above problems existing in the prior art, the present invention provides a signal-level simulation method and device for an APD linear lidar receiving system.

[0007] The technical problems to be solved by the present invention are achieved through the following technical solutions:

[0008] A signal-level simulation method for an APD linear lidar receiving system, comprising:

[0009] Auxiliary design of an APD device through device simulation, and extraction of electrical characteristic data of the designed APD device;

[0010] Establish an equivalent circuit of the APD device according to the electrical characteristic data; the equivalent circuit of the APD device includes: a reverse-biased APD element and a photocurrent equivalent circuit; the reverse-biased APD element is used to simulate the dark current output of the APD device according to the electrical characteristic data; the photocurrent equivalent circuit is used to simulate the photocurrent output of the APD device;

[0011] Associate the equivalent circuit of the APD device with the front-end receiving circuit of the lidar receiving system and perform circuit simulation to obtain a front-end receiving circuit that meets the design requirements;

[0012] Associate the front-end receiving circuit with the lidar receiving system and perform system simulation;

[0013] If the system simulation result does not meet the requirements, continue to jointly perform the APD device simulation, the circuit simulation, and the system simulation to design a lidar receiving system in which the APD device, the front-end receiving circuit, and the lidar receiving system all meet the design requirements.

[0014] Optionally, the auxiliary design of the APD device through device simulation includes:

[0015] Simulate the structure and process of the APD device to obtain the APD device model;

[0016] Use numerical calculation methods and physical models to analyze the electrical characteristics, optical characteristics, opto-electrical behavior, and internal physical state of the APD device model;

[0017] If the electrical characteristics, optical characteristics, opto-electrical behavior, and / or internal physical state do not meet the requirements, continue to simulate the structure and process of the APD device, and analyze the electrical characteristics, optical characteristics, opto-electrical behavior, and internal physical state of the APD device model to design an APD device that meets the design requirements.

[0018] Optionally, the front-end receiving circuit includes: the APD device equivalent circuit, a capacitive feedback transimpedance amplifier, a time discrimination circuit, and a time-to-amplitude conversion circuit; where,

[0019] The APD device equivalent circuit is used to simulate and output the photocurrent and dark current of the APD device; the photocurrent and dark current are respectively connected to the capacitive feedback transimpedance amplifier through two current-controlled current sources;

[0020] The capacitive feedback transimpedance amplifier is used to output an intensity detection signal according to the photocurrent and dark current;

[0021] The time discrimination circuit is used to perform time discrimination according to the intensity detection signal to obtain a time discrimination signal;

[0022] The time-to-amplitude conversion circuit is used to output an analog voltage quantity according to the time discrimination signal; the analog voltage quantity is used to characterize the flight time of the laser pulse; the laser pulse is characterized by the photocurrent.

[0023] Optionally, the photocurrent equivalent circuit includes: a pulse current source, a capacitor, and a resistor;

[0024] Wherein, the capacitor is connected in parallel with the pulse current source, one end of the resistor is connected to the pulse current source, and the other end is connected to the capacitive feedback transimpedance amplifier through a current-controlled current source; wherein, the current output by the pulse current source is used to simulate the photocurrent of the APD device.

[0025] Optionally, the circuit simulation includes:

[0026] Design and simulate the APD device equivalent circuit, the capacitive feedback transimpedance amplifier, the time discrimination circuit, and the time-to-amplitude conversion circuit respectively, so that the electrical characteristics of the APD device equivalent circuit, the capacitive feedback transimpedance amplifier, the time discrimination circuit, and the time-to-amplitude conversion circuit all meet the design requirements;

[0027] Combine the equivalent circuit of the APD device, the capacitive feedback transimpedance amplifier, the time discrimination circuit, and the time-amplitude conversion circuit into the front-end receiving circuit, and perform transient simulation on this front-end receiving circuit;

[0028] If the transient simulation result does not meet the requirements, continue to design and simulate the equivalent circuit of the APD device, the capacitive feedback transimpedance amplifier, the time discrimination circuit, the time-amplitude conversion circuit, and / or the front-end receiving circuit to design a front-end receiving circuit that meets the design requirements.

[0029] Optionally, the system simulation includes: a pixel module, a batch simulation module, and an imaging module;

[0030] The pixel module includes an input module, the front-end receiving circuit, and an output module;

[0031] The input module is used to read the echo data information from a pre-written first Matlab script, and according to the echo data information, use a piecewise linear current source to simulate the pulse current source in the photocurrent equivalent circuit to generate the photocurrent;

[0032] The front-end receiving circuit is used to output the intensity detection signal and the analog voltage quantity;

[0033] The output module is used to process the intensity detection signal and the analog voltage quantity into simulation data and output the simulation data;

[0034] The batch simulation module is used to batch call the pixel module according to the number of array pixels to obtain the simulation data of each pixel;

[0035] The imaging module is used to output the distance map and the intensity map as the system simulation result according to the simulation data of each pixel.

[0036] Optionally, the method further includes:

[0037] Obtain a second Matlab script; a mathematical fitting relationship of the influence of circuit element parameter changes on the system simulation result is set in the second Matlab script;

[0038] While the batch simulation module calls the pixel module, call the second Matlab script according to the circuit element parameters of the pixel module, so as to reflect the influence of the circuit element parameters of the pixel module on the pixel module in the simulation data of the pixel module;

[0039] The system simulation result further includes: the imaging non-uniformity of the distance map and the intensity map.

[0040] The present invention also provides a signal-level simulation device for an APD linear lidar receiving system, including:

[0041] A device simulation module, configured to assist in designing an APD device through device simulation and extract electrical characteristic data of the designed APD device;

[0042] An APD device equivalent circuit; the APD device equivalent circuit is established according to the electrical characteristic data; the APD device equivalent circuit includes: a reverse-biased APD element and a photocurrent equivalent circuit; the reverse-biased APD element is used to simulate the dark current output of the APD device according to the electrical characteristic data; the photocurrent equivalent circuit is used to simulate the photocurrent output of the APD device;

[0043] A circuit simulation module, configured to associate the APD device equivalent circuit with the front-end receiving circuit of the lidar receiving system and perform circuit simulation to obtain a front-end receiving circuit that meets the design requirements;

[0044] A system simulation module, configured to associate the front-end receiving circuit with the lidar receiving system and perform system simulation; wherein, if the system simulation result does not meet the requirements, by continuously jointly invoking the device simulation module, the circuit simulation module, and the system simulation module, a lidar receiving system is designed in which the APD device, the front-end receiving circuit, and the lidar receiving system all meet the design requirements.

[0045] Optionally, the device simulation module is specifically configured to:

[0046] Simulate the structure and process of the APD device to obtain an APD device model;

[0047] Use numerical calculation methods and physical models to analyze the electrical characteristics, optical characteristics, opto-electrical behavior, and internal physical state of the APD device model;

[0048] Wherein, if the electrical characteristics, optical characteristics, opto-electrical behavior, and / or internal physical state do not meet the requirements, by continuously simulating the structure and process of the APD device and analyzing the electrical characteristics, optical characteristics, opto-electrical behavior, and internal physical state of the APD device model, an APD device that meets the design requirements is designed.

[0049] Optionally, the front-end receiving circuit includes: the APD device equivalent circuit, a capacitive feedback transimpedance amplifier, a timing discrimination circuit, and a time-to-amplitude conversion circuit;

[0050] Wherein, the APD device equivalent circuit is used to simulate and output the photocurrent and dark current of the APD device; the photocurrent and dark current are respectively connected to the capacitive feedback transimpedance amplifier through two current-controlled current sources;

[0051] The capacitive feedback transimpedance amplifier is used to output an intensity detection signal according to the photocurrent and dark current;

[0052] The moment discrimination circuit is used to perform moment discrimination according to the intensity detection signal to obtain a moment discrimination signal;

[0053] The time-to-amplitude conversion circuit is used to output an analog voltage according to the moment discrimination signal; the analog voltage is used to characterize the flight time of the laser pulse; the laser pulse is characterized by the photocurrent.

[0054] The signal-level simulation method for the APD linear lidar receiving system provided by the present invention forms a complete signal-level simulation method for the APD linear lidar receiving system, successfully establishes the association between the device level, circuit level and system level in the simulation, realizes the full-process simulation, and can be used for modeling and analyzing the entire optoelectronic imaging link of the lidar receiving system, simulating the imaging effect under the design of specified devices, circuits and systems, and providing a reference for the design of a real prototype. The simulation link established by the present invention can perform specific and accurate simulation work at each simulation level according to requirements, including process design and multi-aspect characteristic simulation of devices, circuit structure design and parameter optimization, system signal processing design, etc. At the same time, the simulation work at each level is reasonably associated by combining the actual physical principles and the functions of simulation tools. The association of the simulation in the present invention is based on the simulation work at each level and retains the simulation information at each level as comprehensively as possible. It can simulate and verify the structure design and parameter configuration of the detector, circuit and system at the overall machine application performance level, can comprehensively consider the influence of various factors such as the design, process and parameters of each part and optimize them, can realize the injection of various errors and the simulation of abnormal states, reduces the verification cost by getting rid of the limitation of hardware test equipment, allows precise control of the design at each level of the system to improve the verification efficiency, and can more intuitively reflect the performance of the prototype under specific application conditions by accessing the analog laser echo signal in the system-level simulation.

[0055] The following will further elaborate on the present invention in conjunction with the accompanying drawings. Brief Description of the Drawings

[0056] Figure 1 is a schematic flowchart of a signal-level simulation method for an APD linear lidar receiving system provided by an embodiment of the present invention;

[0057] Figure 2 is a simplified flowchart of a signal-level simulation method for an APD linear lidar receiving system provided by an embodiment of the present invention;

[0058] Figure 3 shows a schematic diagram of defining the region, electrodes and doping distribution of a device in the simulation software Silvaco;

[0059] Figure 4(a) exemplarily shows the electric field characteristics obtained from device simulation;

[0060] Figure 4(b) exemplarily shows the conduction band energy obtained from device simulation;

[0061] Figure 4(c) exemplarily shows the voltage - current curve obtained from device simulation;

[0062] Figure 4(d) exemplarily shows the effective photocurrent under different light intensities obtained from device simulation;

[0063] Figure 5 Shows the software interface for extracting electrical characteristic data in the Model Editor;

[0064] Figure 6 Shows the SPICE model and component model of the APD device simulated in the present invention;

[0065] Figure 7(a) shows the front - end receiving circuit simulated in the present invention;

[0066] Figure 7(b) shows the result graph of the circuit simulation transient simulation in the present invention;

[0067] Figure 8 Shows the schematic diagram of the system simulation in the present invention;

[0068] Figure 9 Shows the PSpice - Simulink co - simulation model;

[0069] Figure 10 Shows the obtained device structure from the simulation in the present invention;

[0070] Figure 11 Shows the obtained system simulation result from the simulation in the present invention. Detailed implementation manners

[0071] The present invention will be further described in detail below in conjunction with specific embodiments, but the implementation manners of the present invention are not limited thereto.

[0072] At present, in the simulation of lidar receiving systems, there is no complete system simulation link that closely and reasonably combines the simulation work at the device, circuit, and system levels. There is a lack of penetration and full coverage of the entire process of system signal processing at the simulation level, and it is impossible to reflect the compatibility of the designs at each level with the overall system or the impact on the overall system performance at the simulation stage. Only independent simulations and designs for their respective working processes and performance are achieved, lacking the process of verifying and optimizing the designs of devices, circuits, or systems by placing them into the whole machine simulation and the laser signal input simulation scenario at the simulation stage, making it difficult to conduct abnormal tests and error localization. At the same time, it is also difficult to balance simulation accuracy and speed in system simulation, and a comprehensive and accurate reference cannot be provided at the simulation stage. In addition, the solution cannot be fully verified before the prototype is produced, which leads to the designs of devices, circuits, or systems not meeting the requirements of the overall machine performance indicators under actual application conditions, and further increases the design cycle and experimental costs.

[0073] To solve the problem of the lack of penetration and full coverage of the entire process of signal-level simulation in the current simulation research on APD linear lidar receiving systems, the embodiments of the present invention provide a signal-level simulation method for APD linear lidar receiving systems, which is used to conduct imaging tests at the simulation level to accurately reflect the performance of the real prototype, can be used for modeling and analyzing the entire optoelectronic imaging link of the lidar receiving system, simulate the imaging effects under the designs of specified devices, circuits, and systems, and provide a reference for the design of the real prototype.

[0074] See Figure 1 and Figure 2 As shown in, the signal-level simulation method for APD linear lidar receiving systems provided by the embodiments of the present invention includes the following steps:

[0075] S10. Assist in designing APD devices through device simulation and extract the electrical characteristic data of the designed APD devices.

[0076] In this step, assisting in designing APD devices through device simulation includes:

[0077] (1) Simulate the structure and process of the APD device to obtain the APD device model.

[0078] Specifically, use simulation software (such as Silvaco) to define the regions, electrodes, and doping distributions of the device (such as Figure 3 ), and can also simulate key process steps such as ion implantation, diffusion, etching, deposition, photolithography, and oxidation according to needs to obtain the expected device structure and corresponding device parameters.

[0079] It should be noted that the simulation software for APD device simulation is not limited to Silvaco. As long as it can perform device process simulation to obtain the expected device structure and extract the electrical, optical, and optoelectronic characteristics of the device based on this, it is sufficient.

[0080] (2) Use numerical calculation methods and physical models to analyze the electrical characteristics, optical characteristics, optoelectronic behavior, and internal physical states (such as concentration distribution, potential distribution, conduction band energy, etc.) of the APD device model.

[0081] After completing the above simulations of the structure and process of the APD device, use numerical calculation methods and physical models to analyze various device characteristics of the APD device model, such as electrical characteristics, optical characteristics, optoelectronic behavior, and internal physical states, to determine whether the device design meets the requirements. If it meets the requirements, the APD device simulation link is completed; if not, proceed to step (3).

[0082] Among them, numerical calculation methods such as Newton iteration method, Gummel iteration method, etc., and physical models such as Fermi-Dirac statistical model, mobility model, Shockley-Read-Hall recombination model, etc.

[0083] Figure 4(a) exemplarily shows the electric field characteristics obtained from device simulation, and Figure 4(b) exemplarily shows the conduction band energy obtained from device simulation; Figure 4(c) exemplarily shows the voltage-current curve obtained from device simulation, and Figure 4(d) exemplarily shows the effective photocurrent under different light intensities obtained from device simulation.

[0084] (3) If the electrical characteristics, optical characteristics, optoelectronic behavior, and / or internal physical states do not meet the requirements, continue to simulate the structure and process of the APD device, and analyze the electrical characteristics, optical characteristics, optoelectronic behavior, and internal physical states of the APD device model to design an APD device that meets the design requirements.

[0085] Here, if the electrical characteristics, optical characteristics, optoelectronic behavior, and / or internal physical states do not meet the requirements, continuously adjust and optimize the structure and process of the APD device and conduct simulation and analysis until an APD device that meets the design requirements is designed.

[0086] In this step S10, device process factors such as regions, electrodes, doping profiles, material parameters, and key process steps (ion implantation, diffusion, etching, deposition, photolithography, oxidation, etc.) are designed. And through multi-faceted device characteristic simulations, the circuit SPICE model of the device is extracted and the circuit element model of the device is packaged. Therefore, the lack of the device process design link can be effectively avoided. At the same time, it is possible to accurately predict various internal and external characteristics such as geometric parameters, potential distribution, and conduction band energy in the device structure, optimize the design parameters to achieve the best combination in all aspects, make the simulation analysis of the device more comprehensive, and thus the simulation work of the device part can be more detailed and reliable. By simulation to replace the costly selection experiment, the development cycle can be shortened and the yield can be increased.

[0087] After designing the APD device that meets the design requirements, electrical characteristic data such as the I-V characteristic, C-V characteristic, frequency characteristic, reverse breakdown characteristic, etc. of the APD device are extracted in the Model Editor for subsequent circuit simulation. Figure 5 The software interface for extracting electrical characteristic data in the Model Editor is shown.

[0088] S20. Establish an equivalent circuit of the APD device according to the electrical characteristic data; the equivalent circuit of the APD device includes: a reverse-biased APD element and a photocurrent equivalent circuit; wherein, the reverse-biased APD element is used to simulate the dark current output of the APD device according to the electrical characteristic data; the photocurrent equivalent circuit is used to simulate the photocurrent output of the APD device.

[0089] Specifically, in a circuit simulation software tool (such as the Model Editor of PSpice), the device circuit model of the equivalent circuit of the APD device is established using the extracted electrical characteristic data, including the SPICE model and the element model (as shown in the appendix Figure 6 ).

[0090] Referring to Fig. 7(a), the equivalent circuit of the APD device is shown in the upper left corner, including a reverse-biased APD element (RTAPD) and a photocurrent equivalent circuit. It should be noted that the specific circuit structure of the photocurrent equivalent circuit is not limited to that shown in Fig. 7(a), and the photocurrent equivalent circuit in Fig. 7(a) is only an example. In Fig. 7(a), the photocurrent equivalent circuit includes: a pulsed current source, a capacitor, and a resistor; wherein, the current output by the pulsed current source is used to simulate the photocurrent of the APD device, the capacitor is connected in parallel with the pulsed current source, one end of the resistor is connected to the pulsed current source, and the other end is connected to the front-end receiving circuit of the radar receiving system through a current-controlled current source as the main optoelectronic conversion element of the front-end receiving circuit.

[0091] Taking the Model Editor as an example, the device circuit model of the APD device is extracted by using the Model Editor tool, which specifically includes the following steps:

[0092] (2-1) Use Tonyplot to adjust the characteristic curves directly simulated by Silvaco to obtain the required forward I-V characteristic curve, reverse I-V characteristic curve, and C-V characteristic curve. Select File->Export in the upper left corner to export the curve data.

[0093] (2-2) Call the Model Editor module of Cadence. Select the File->New command in the upper right corner of the initial interface to create a new model file. Select Model->New and set the model type. After the settings are completed, the window will be displayed as a parameter extraction interface. Paste the data of the various characteristic curves simulated by Silvaco into the list of the corresponding parameter extraction interface. Select Tools->Extract Parameters in the top selection bar to extract the various SPICE parameters of the device. The parameters of the components included in the photocurrent equivalent circuit can be established based on the various SPICE parameters.

[0094] (2-3) Execute "File->Export to Capture Part Library" to obtain the device PSpice model file with the.lib suffix. Execute "File-Model Import Wizard[Capture]", and after modifying the default Capture library, it is completed to obtain the device component model file with the.olb suffix.

[0095] In this step S20, the PSpice Model Editor for extracting the device circuit model is relatively maturely developed, and it can quickly obtain the parameters of a model with high accuracy and in line with reality. The relationship established between the device equivalent circuit extracted based on these conditions at the device and circuit levels is also closer.

[0096] S30. Associate the APD device equivalent circuit with the front-end receiving circuit of the radar receiving system and perform circuit simulation to obtain the front-end receiving circuit that meets the design requirements.

[0097] Specifically, introduce the APD device equivalent circuit into the front-end receiving circuit in a circuit simulation software tool (such as PSpice), and then perform circuit simulation.

[0098] Among them, referring to Fig. 7(a), the front-end receiving circuit includes: an APD device equivalent circuit, a capacitive feedback transimpedance amplifier (CTIA), a time discrimination circuit, and a time-to-amplitude conversion circuit. The time-to-amplitude conversion circuit includes a ramp generation circuit, a buffer, and a sample-and-hold circuit. Vth represents the threshold voltage, Vramp_ref, Vcomp_ref, and Vref are different reference voltages respectively, V_RESET represents the reset signal, V_TAC is an analog voltage quantity, V_TIA is an intensity detection signal, and V_RAMP, Vmid, and V_COMP are the outputs of the corresponding connected operational amplifiers respectively.

[0099] In the front-end receiving circuit, the APD device equivalent circuit is used to simulate and output the photocurrent and dark current of the APD device; the photocurrent and dark current are respectively connected to the capacitive feedback transimpedance amplifier through two current-controlled current sources; the capacitive feedback transimpedance amplifier is used to output an intensity detection signal according to the photocurrent and dark current; the time discrimination circuit is used to perform time discrimination according to the intensity detection signal to obtain a time discrimination signal; the time discrimination signal output by the time discrimination circuit is transmitted to the sample-and-hold circuit by an inverter. The time-to-amplitude conversion circuit is used to output an analog voltage quantity according to the time discrimination signal; the analog voltage quantity is used to characterize the flight time of the laser pulse; the laser pulse is characterized by the photocurrent.

[0100] It should be noted that the specific circuit structures of the capacitive feedback transimpedance amplifier, the time discrimination circuit, the time-to-amplitude conversion circuit, and the entire front-end receiving circuit shown in Fig. 7(a) are not limited to the circuit implementation shown in Fig. 7(a), and the circuit implementation in Fig. 7(a) is only taken as an example.

[0101] Taking PSpice as an example, associating the APD device equivalent circuit with the front-end receiving circuit may include: adding the.lib file generated in step S20 to the Configured Files list on the simulation settings page of PSpice, and adding the just-generated.olb file on the component library page to complete the access of the device's circuit model in PSpice and complete the simulation association between the device and the circuit.

[0102] Then, circuit simulation is carried out, which may specifically include:

[0103] (3-1) Design and simulate the APD device equivalent circuit, the capacitive feedback transimpedance amplifier, the time discrimination circuit, and the time-to-amplitude conversion circuit respectively, so that the electrical characteristics of the APD device equivalent circuit, the capacitive feedback transimpedance amplifier, the time discrimination circuit, and the time-to-amplitude conversion circuit all meet the design requirements, including design requirements in aspects such as AC and DC characteristics, transient characteristics, and noise characteristics.

[0104] (3-2) Combine the APD device equivalent circuit, capacitive feedback transimpedance amplifier, time discrimination circuit, and time-to-amplitude conversion circuit into a front-end receiving circuit, and perform transient simulation on the front-end receiving circuit;

[0105] FIG. 7(b) exemplarily shows a result graph of a circuit simulation transient simulation. From top to bottom in the figure are: the pulse current source current signal, the reset signal, the intensity detection signal at the output end of the CTIA, the time discrimination signal at the output end of the time discrimination circuit, the ramp signal at the output end of the ramp generation circuit, and the analog voltage signal at the output end of the time-to-amplitude conversion circuit.

[0106] (3-3) If the transient simulation result does not meet the requirements, continue to design and simulate the APD device equivalent circuit, capacitive feedback transimpedance amplifier, time discrimination circuit, time-to-amplitude conversion circuit, and / or front-end receiving circuit to design a front-end receiving circuit that meets the design requirements.

[0107] Here, if the transient simulation result does not meet the requirements, the cause can be investigated first. If the investigation result shows that it is caused by the APD device, then continuously adjust and optimize the structure and process of the APD device, perform APD device simulation and analysis, and perform circuit simulation until the entire link from the APD device to the front-end receiving circuit meets the design requirements. If the investigation result shows that it is caused by inappropriate design of the circuit parameters, then continuously adjust and optimize the circuit parameters of the APD device equivalent circuit, capacitive feedback transimpedance amplifier, time discrimination circuit, and / or time-to-amplitude conversion circuit until the entire link from the APD device to the front-end receiving circuit meets the design requirements.

[0108] It should be noted that the simulation software for circuit simulation is not limited to PSpice. As long as it has basic circuit simulation functions, can extract and package the circuit model of the device according to the device simulation result to establish the APD device equivalent circuit, and can establish co-simulation with the system-level simulation software.

[0109] S40. Associate the front-end receiving circuit with the radar receiving system and perform system simulation.

[0110] Specifically, establish the simulation association between the circuit level and the system level through an interface tool (such as the PSpice Block module). Then, perform system simulation in the system simulation software, such as Figure 8 .

[0111] Among them, the system simulation includes: a pixel module, a batch simulation module, and an imaging module;

[0112] The pixel module includes an input module, a front-end receiving circuit, and an output module.

[0113] An input module for reading echo data information from a pre-written first Matlab script, and generating photocurrent by using a piecewise linear current source to simulate the pulsed current source in the photocurrent equivalent circuit according to the echo data information.

[0114] Specifically, the echo data information can be the optical echo energy-time data obtained in various application scenarios such as measured data, hardware-in-the-loop simulation, digital simulation, etc., which is converted into photocurrent data according to the optoelectronic characteristics obtained from device simulation, so as to generate photocurrent by using a piecewise linear current source to simulate the pulsed current source in the photocurrent equivalent circuit.

[0115] A front-end receiving circuit for outputting an intensity detection signal and an analog voltage quantity.

[0116] An output module for processing the intensity detection signal and the analog voltage quantity into simulation data and outputting the simulation data.

[0117] Specifically, the output module quantifies the final value of the intensity detection signal of each pixel to obtain the intensity simulation data of each pixel, and calculates the distance simulation data of each pixel according to the following formula for the analog voltage quantity of each pixel.

[0118]

[0119] Dis = c × TOF;

[0120] where TOF is the flight time of the laser pulse, V TAC is the analog voltage quantity, V ramp_ref is the reference voltage of the ramp generation circuit, α is the ramp voltage slope, Dis is the distance simulation data, and c is the speed of light.

[0121] In addition, the output module can also output the transient simulation results in the system simulation.

[0122] A batch simulation module for batch-calling pixel modules according to the number of array pixels to obtain the simulation data of each pixel;

[0123] An imaging module for outputting a distance map and an intensity map as the system simulation results according to the simulation data of each pixel.

[0124] Regarding the establishment of the simulation association between the circuit level and the system level, for example, open PSpice, select Tools - MATLAB - Set MATLAB Path to set the MATLAB installation path, and then select Tools - MATLAB - Co-simulation to open MATLAB, and the PSpice - Simulink co-simulation is automatically established. Save the Simulink simulation model (pixel module) in the same folder as the PSpice project, and find the PSpice Block in the Simulink library (Figure 9 In the color module), only when the co - simulation is correctly established can this module be found in the Simulink library and added to the Simulink project file to build a model, complete the simulation association between the circuit and the system. For example, Figure 9 . Figure 9 In it, "scope" represents waveform display, "Demux" represents signal demultiplexing, and "Solver Configuration" represents solver configuration, which is used to set and adjust the parameters of the solver in simulation, optimization, or numerical calculation software to control the behavior and performance of the solver. "Current Sensor" represents a current sensor, "out.time" is a program module for outputting V_TAC, and "out.inten" is a program module for outputting the intensity detection signal.

[0125] Then, perform system simulation to complete the input of echo data and the output of detection images (range map and intensity map).

[0126] Specifically, open the PSpice Block settings to select the input and output of the front - end receiving circuit, then add the corresponding input and output modules in the Simulink simulation model and connect them to the PSpice Block, and run the simulation to determine whether the correct co - simulation result can be obtained. Write the first Matlab script to read the echo data information (optical echo energy - time data) as input, call the Simulink simulation model in the Matlab script to perform batch simulation according to the number of array pixels to obtain the simulation data of each pixel, and perform simulation data processing in combination with the working timing and relevant parameter settings of the readout circuit to calculate the ranging values and echo intensity measurement values of each pixel, and then the range map and intensity map can be output.

[0127] It should be noted that the simulation tool for system simulation can be replaced, as long as it can access the circuit simulation file for co - simulation, and can perform operations such as input signal reading, data processing and output, and batch simulation to complete the simulation of the system signal processing process and the non - uniformity of the focal plane array.

[0128] S50. If the system simulation result does not meet the requirements, continue to jointly perform APD device simulation, circuit simulation, and system simulation to design a radar receiving system in which the APD device, front - end receiving circuit, and radar receiving system all meet the design requirements.

[0129] Here, if the system simulation results do not meet the requirements, the reasons can be investigated first. If the investigation results indicate that it is caused by the APD device, then by continuously adjusting and optimizing the structure and process of the APD device, and conducting APD device simulation and analysis, circuit simulation, and system simulation until the entire link from the device to the system meets the design requirements. If the investigation results indicate that it is caused by inappropriate design of circuit parameters, then by continuously adjusting and optimizing the circuit parameters of the APD device equivalent circuit, capacitive feedback transimpedance amplifier, time discriminator circuit, and / or time-amplitude conversion circuit, and conducting circuit simulation and system simulation until the entire link from the device to the system meets the design requirements. If the investigation results indicate that it is caused by improper system design, then by adjusting the system settings and conducting system simulation until the system meets the design requirements.

[0130] In summary, the present invention first uses semiconductor device simulation software to perform process and characteristic simulations on the APD, intuitively evaluate the influence of key process steps such as ion implantation, diffusion, etching, deposition, photolithography, and oxidation on the system performance, and cooperate with circuit simulation software to extract the circuit model of the device, so as to combine the APD device into the circuit simulation in the form of an equivalent circuit. Then, use circuit simulation software to build the circuit structure of the pixel front-end receiving circuit and conduct simulation, so as to combine the circuit part into the system simulation in the form of co-simulation. Finally, use simulation software to simulate the system signal processing flow and the non-uniformity of the focal plane array to receive the input signal, obtain the output result to complete the system simulation, and conduct analysis and evaluation to ensure the granularity of each level in the simulation, and at the same time reasonably associate the simulation work of each level in combination with the actual physical principle and the function of the simulation tool to form a full-system simulation link to achieve the full-process simulation from echo input to detection image output, taking into account the granularity of each simulation level and the integrity of the simulation work, and realizing the full-process simulation from echo input to detection image output.

[0131] The present invention can perform simulation verification on the structural design and parameter configuration of detectors, circuits, and systems at the overall machine application performance level, support the input of simulated laser echoes based on a specific application background, and comprehensively consider and optimize factors such as the structural design and process factors of detection devices and circuit design factors. This full-link simulation method enables the simulation design of each part of the system to directly adapt to the overall performance indicators of the system rather than being carried out independently, can realize the injection of various errors and the simulation of abnormal states, reduces the verification cost by getting rid of the limitations of hardware test equipment, allows for precise control of the design at all levels of the system, improves the verification efficiency, and thus the simulation work can more directly reflect the overall performance of the system. At the same time, it can also quickly model complex systems, retain detailed models of devices and circuits in the simulation, and introduce complex control algorithms, shortening the simulation time and expanding the simulation function while ensuring the accuracy of circuit simulation. On this basis, system design simulation verification, performance prediction, rapid iteration of digital design, algorithm verification, etc. can be carried out to meet broader research needs and provide comprehensive and accurate references for the construction and experiments of physical prototypes.

[0132] The present invention can be used to model and analyze the entire optoelectronic imaging link of a lidar receiving system, simulate the imaging effects under the design of specified devices, circuits, and systems, and provide references for the design of real prototypes, thereby facilitating the development and application of APD linear radars in aspects such as target interception, target recognition, and driverless driving.

[0133] In one embodiment, the method of the present invention further includes the following steps:

[0134] (1) Obtain a second Matlab script; a mathematical fitting relationship of the influence of changes in circuit element parameters on the system simulation results is set in the second Matlab script;

[0135] (2) While calling the pixel module in the batch simulation mode, call the second Matlab script according to the circuit element parameters of the pixel module, so as to reflect the influence of the circuit element parameters of the pixel module on the pixel module in the simulation data of the pixel module;

[0136] Thus, the system simulation results in the present invention can also include: the imaging non-uniformity of the distance map and the intensity map.

[0137] Exemplarily, taking the non-uniformity simulation caused by the difference in the integration capacitance value of the CTIA circuit as an example, the specific operation steps include: determining the influence of the fluctuation of the CTIA integration capacitance value on the circuit simulation results (intensity detection signal and analog voltage quantity) through simulation in PSpice, fitting out the mathematical relationship and writing it as a second Matlab function script, calling this function to change the relevant values while calling the Simulink model, and controlling the change of the input parameters each time this function is called in the batch simulation to complete the non-uniformity simulation.

[0138] In this embodiment, while the pixel module is called by the batch simulation module, the second Matlab script is called according to the circuit element parameters of the pixel module, so that the influence of the circuit element parameters of the pixel module is reflected in the simulation data of the pixel module, thereby visually reflecting the differences in the circuit element parameters of different pixel modules in the imaging non-uniformity, and reflecting the imaging non-uniformity caused by the differences in the circuit element parameters among the pixels (each pixel corresponds to an array element module) in the imaging array (composed of multiple array element modules), realizing the non-uniformity simulation of the system.

[0139] Moreover, since the non-uniformity simulation in the present invention is carried out in the system-level simulation by means of co-simulation of PSpice and Simulink through batch simulation, rather than the existing method of directly building an array structure in the circuit-level simulation, a large number of repetitive simulation experiment settings and simulation operation loads are avoided, and the simulation time is shortened and the simulation function is extended while ensuring the accuracy of the circuit simulation.

[0140] The following is a specific simulation example of the present invention:

[0141] The present invention uses Silvaco developed by Silvaco Group, PSpice 17.4 developed by ORCAD, and MATLAB 2021b developed by Mathworks for simulation.

[0142] The simulation settings at each level in the experiment are as follows:

[0143] The device-level simulation is based on the Silvaco example project file OPTOELECTRONICS-optoex18-Reach Through APD (RTAPD) and is modified according to requirements;

[0144] The schematic diagram for the circuit-level simulation includes parts such as the APD device equivalent circuit, capacitive feedback transimpedance amplifier (CTIA), time discriminator circuit, and time-to-amplitude conversion circuit (TAC). The simulation test is completed through transient simulation, and the maximum simulation step size is 0.1 ns;

[0145] In the system-level simulation, the simulation settings of Matlab-Simulink follow the PSpice simulation configuration. The array size is set to 12×12. The non-uniformity variable selects the CTIA capacitance value. The input is the echo data simulated by the optoelectronic virtual reality scene, and the output is the simulated distance map and intensity map.

[0146] 2. Simulation content

[0147] According to the specific embodiments of the present invention, the associations of each simulation level are established, and device, circuit, and system simulations are carried out, where the device structure obtained from the simulation is as Figure 10 , and the system simulation result is as Figure 11 , Figure 11 , in which from left to right are the target scene, intensity map, and distance map in sequence.

[0148] The above examples can illustrate that the simulation link provided by the present invention covers the simulation work of each level of devices, circuits, and systems and the reasonable association of each simulation level, taking into account the granularity of each simulation level and the integrity of the simulation work, and can realize the full-process simulation from echo input to detection image output.

[0149] In summary, the present invention has carried out specific and accurate simulation work at each level such as the process design and multi-faceted characteristic simulation of devices, the circuit structure design and parameter optimization, and the system signal processing design, etc. At the same time, the simulation work at each level is reasonably associated by combining the actual physical principles and the functions of simulation tools. The establishment of the simulation association is based on the simulation work at each level and retains the simulation information at each level as comprehensively as possible. Therefore, the present invention can simulate and verify the structure design and parameter configuration of detectors, circuits, and systems at the overall machine application performance level, can comprehensively consider the influence of various factors such as the design, process, and parameters of each part and optimize them, can realize the injection of various errors and the simulation of abnormal states, breaks away from the limitations of hardware test equipment to reduce the verification cost, allows precise control of the design at each level of the system to improve the verification efficiency, and can make the performance of the prototype more intuitively reflected under specific application conditions by accessing the simulated laser echo signal in the system-level simulation. In addition, with the co-simulation of PSpice and Simulink, complex systems can be modeled quickly. Both the detailed models of circuit devices are retained in the simulation, and complex control algorithms can also be introduced, shortening the simulation time and expanding the simulation functions while ensuring the accuracy of circuit simulation.

[0150] Based on the same inventive concept, the present invention also provides a signal-level simulation device for an APD linear lidar receiving system, including:

[0151] A device simulation module for assisting in the design of APD devices through device simulation and extracting the electrical characteristic data of the designed APD devices;

[0152] An equivalent circuit of the APD device; the equivalent circuit of the APD device is established according to the electrical characteristic data; the equivalent circuit of the APD device includes: a reverse-biased APD element and a photocurrent equivalent circuit; the reverse-biased APD element is used to simulate the dark current output of the APD device according to the electrical characteristic data; the photocurrent equivalent circuit is used to simulate the photocurrent output of the APD device;

[0153] A circuit simulation module, which is used to associate the equivalent circuit of the APD device with the front-end receiving circuit of the radar receiving system and perform circuit simulation to obtain a front-end receiving circuit that meets the design requirements;

[0154] A system simulation module, which is used to associate the front-end receiving circuit with the radar receiving system and perform system simulation; wherein, if the system simulation result does not meet the requirements, by continuously jointly calling the device simulation module, the circuit simulation module and the system simulation module, a radar receiving system in which the APD device, the front-end receiving circuit and the radar receiving system all meet the design requirements is designed.

[0155] Optionally, the device simulation module is specifically used for:

[0156] Simulate the structure and process of the APD device to obtain an APD device model;

[0157] Use numerical calculation methods and physical models to analyze the electrical characteristics, optical characteristics, opto-electrical behavior and internal physical state of the APD device model;

[0158] Wherein, if the electrical characteristics, optical characteristics, opto-electrical behavior and / or internal physical state do not meet the requirements, by continuously simulating the structure and process of the APD device and analyzing the electrical characteristics, optical characteristics, opto-electrical behavior and internal physical state of the APD device model, an APD device that meets the design requirements is designed.

[0159] Optionally, the front-end receiving circuit includes: an equivalent circuit of the APD device, a capacitive feedback transimpedance amplifier, a timing discrimination circuit, and a time-to-amplitude conversion circuit;

[0160] Among them, the equivalent circuit of the APD device is used to simulate and output the photocurrent and dark current of the APD device; the photocurrent and dark current are respectively connected to the capacitive feedback transimpedance amplifier through two current-controlled current sources;

[0161] The capacitive feedback transimpedance amplifier is used to output an intensity detection signal according to the photocurrent and dark current;

[0162] The timing discrimination circuit is used to perform timing discrimination according to the intensity detection signal to obtain a timing discrimination signal;

[0163] The time-to-amplitude conversion circuit is used to output an analog voltage according to the timing discrimination signal; the analog voltage is used to characterize the flight time of the laser pulse; the laser pulse is characterized by the photocurrent.

[0164] Optionally, the photocurrent equivalent circuit includes: a pulse current source, a capacitor and a resistor;

[0165] Among them, the capacitor is connected in parallel with the pulsed current source, one end of the resistor is connected to the pulsed current source, and the other end is connected to the capacitive feedback transimpedance amplifier through a current-controlled current source; wherein, the current output by the pulsed current source is used to simulate the photocurrent of the APD device.

[0166] Optionally, the circuit simulation module is specifically configured to:

[0167] Design and simulate the equivalent circuit of the APD device, the capacitive feedback transimpedance amplifier, the time discriminator circuit, and the time-to-amplitude conversion circuit respectively, so that the electrical characteristics of the equivalent circuit of the APD device, the capacitive feedback transimpedance amplifier, the time discriminator circuit, and the time-to-amplitude conversion circuit all meet the design requirements;

[0168] Combine the equivalent circuit of the APD device, the capacitive feedback transimpedance amplifier, the time discriminator circuit, and the time-to-amplitude conversion circuit into the front-end receiving circuit, and perform transient simulation on this front-end receiving circuit;

[0169] If the transient simulation result does not meet the requirements, continue to design and simulate the equivalent circuit of the APD device, the capacitive feedback transimpedance amplifier, the time discriminator circuit, the time-to-amplitude conversion circuit, and / or the front-end receiving circuit to design a front-end receiving circuit that meets the design requirements.

[0170] Optionally, the system simulation includes: a pixel module, a batch simulation module, and an imaging module;

[0171] The pixel module includes an input module, the front-end receiving circuit, and an output module;

[0172] The input module is configured to read echo data information from a pre-written first Matlab script, and according to the echo data information, use a piecewise linear current source to simulate the pulsed current source in the photocurrent equivalent circuit to generate the photocurrent;

[0173] The front-end receiving circuit is configured to output the intensity detection signal and the analog voltage quantity;

[0174] The output module is configured to process the intensity detection signal and the analog voltage quantity into simulation data and output the simulation data;

[0175] The batch simulation module is configured to batch call the pixel module according to the number of array pixels to obtain the simulation data of each pixel;

[0176] The imaging module is configured to output a distance map and an intensity map as the system simulation result according to the simulation data of each pixel.

[0177] Optionally, the above device further includes: a non-uniformity simulation module;

[0178] The non-uniformity simulation module is specifically configured to:

[0179] Obtain a second Matlab script; a mathematical fitting relationship of the influence of circuit element parameter changes on the system simulation result is set in the second Matlab script;

[0180] While the batch simulation module calls the pixel module, the second Matlab script is called according to the circuit element parameters of the pixel module, so that the influence of the circuit element parameters of the pixel module on the pixel module is reflected in the simulation data of the pixel module;

[0181] The system simulation result further includes: the imaging non-uniformity of the distance map and the intensity map.

[0182] It should be noted that for the device embodiments, since they are basically similar to the method embodiments, the description is relatively simple. For the relevant parts, please refer to the partial description of the method embodiments.

[0183] It should be noted that the terms "first", "second", etc. are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order different from those illustrated or described here. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present invention.

[0184] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0185] Although the present invention has been described in connection with various embodiments, those skilled in the art can understand and implement other variations of the disclosed embodiments by viewing the accompanying drawings and the disclosure during the implementation of the claimed invention. In the description of the present invention, the term "comprising" does not exclude other components or steps, the use of "a" or "an" does not exclude a plurality, and the meaning of "plurality" is two or more unless specifically defined otherwise. In addition, certain measures are described in different embodiments, but this does not mean that these measures cannot be combined to produce good results.

[0186] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited only to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as falling within the protection scope of the present invention.

Claims

1. A signal level simulation method for an APD linear laser radar receiving system, characterized in that: include: Design APD devices through device simulation and extract electrical characteristic data of designed APD devices; Establishing an APD device equivalent circuit according to the electrical characteristic data; The APD device equivalent circuit includes: a reverse biased APD element and a photocurrent equivalent circuit; the reverse biased APD element is used to simulate the dark current output of the APD device according to the electrical characteristic data; the photocurrent equivalent circuit is used to simulate the photocurrent output of the APD device; Associating the APD device equivalent circuit with the front-end receiving circuit of the radar receiving system and performing circuit simulation to obtain a front-end receiving circuit that meets the design requirements; Associating the front-end receiving circuit with a radar receiving system and performing system simulation; If the system simulation result does not meet the requirements, a radar receiving system is designed in which the APD device, the front-end receiving circuit and the radar receiving system all meet the design requirements by continuing to jointly perform the APD device simulation, the circuit simulation and the system simulation.

2. The signal level simulation method of the APD linear laser radar receiving system according to claim 1 is characterized in that: The device simulation-assisted design of the APD device comprises: Simulate the structure and process of the APD device to obtain the APD device model; Analyzing the electrical properties, optical properties, photo-electric behavior and internal physical state of the APD device model using numerical calculation methods and physical models; If the electrical properties, optical properties, photoelectric behavior and / or internal physical state do not meet the requirements, an APD device that meets the design requirements is designed by continuing to simulate the structure and process of the APD device and analyzing the electrical properties, optical properties, photoelectric behavior and internal physical state of the APD device model.

3. The signal level simulation method of the APD linear laser radar receiving system according to claim 1 is characterized in that: The front-end receiving circuit includes: the APD device equivalent circuit, a capacitive feedback transimpedance amplifier, a time identification circuit and a time-amplitude conversion circuit; wherein, The APD device equivalent circuit is used to simulate the photocurrent and dark current of the output APD device; the photocurrent and dark current are connected to the capacitive feedback transimpedance amplifier through two current-controlled current sources respectively; The capacitive feedback transimpedance amplifier is used to output an intensity detection signal according to the photocurrent and dark current; The time identification circuit is used to perform time identification according to the intensity detection signal to obtain a time identification signal; The time-amplitude conversion circuit is used to output an analog voltage according to the moment identification signal; the analog voltage is used to characterize the flight time of the laser pulse; the laser pulse is characterized by the photocurrent.

4. The signal level simulation method of the APD linear laser radar receiving system according to claim 3 is characterized in that: The photocurrent equivalent circuit comprises: a pulse current source, a capacitor and a resistor; Wherein, the capacitor is connected in parallel to the pulse current source, one end of the resistor is connected to the pulse current source, and the other end is connected to the capacitive feedback transimpedance amplifier through a current-controlled current source; wherein, the current output by the pulse current source is used to simulate the photocurrent of the APD device.

5. The signal level simulation method of the APD linear laser radar receiving system according to claim 3 is characterized in that: The circuit simulation comprises: The APD device equivalent circuit, the capacitive feedback transimpedance amplifier, the moment identification circuit and the time-amplitude conversion circuit are designed and simulated respectively, so that the electrical characteristics of the APD device equivalent circuit, the capacitive feedback transimpedance amplifier, the moment identification circuit and the time-amplitude conversion circuit meet the design requirements; The APD device equivalent circuit, the capacitive feedback transimpedance amplifier, the time identification circuit and the time-amplitude conversion circuit are combined into the front-end receiving circuit, and transient simulation is performed on the front-end receiving circuit; If the transient simulation results do not meet the requirements, a front-end receiving circuit that meets the design requirements is designed by continuing to design and simulate the APD device equivalent circuit, capacitive feedback transimpedance amplifier, moment identification circuit, time-amplitude conversion circuit and / or the front-end receiving circuit.

6. The signal level simulation method of the APD linear laser radar receiving system according to claim 4 is characterized in that: The system simulation includes: a pixel module, a batch simulation module and an imaging module; The pixel module comprises an input module, the front-end receiving circuit and an output module; The input module is used to read echo data information from a pre-written first Matlab script, and generate the photocurrent by simulating the pulse current source in the photocurrent equivalent circuit using a piecewise linear current source according to the echo data information; The front-end receiving circuit is used to output the strength detection signal and the analog voltage; The output module is used to process the intensity detection signal and the analog voltage into simulation data and output the simulation data; The batch simulation module is used to call the pixel modules in batches according to the number of array pixels to obtain simulation data of each pixel; The imaging module is used to output a distance map and an intensity map as the system simulation result according to the simulation data of each pixel.

7. The signal level simulation method of the APD linear laser radar receiving system according to claim 6 is characterized in that: The method further comprises: Obtaining a second Matlab script; wherein the second Matlab script is provided with a mathematical fitting relationship of the influence of the change of circuit element parameters on the system simulation result; When the batch simulation module calls the pixel module, the second Matlab script is called according to the circuit element parameters of the pixel module, so that the influence of the circuit element parameters of the pixel module on the pixel module is reflected in the simulation data of the pixel module; The system simulation results also include: imaging non-uniformity of the distance map and the intensity map.

8. A signal level simulation device for an APD linear laser radar receiving system, characterized in that: include: A device simulation module is used to assist in the design of APD devices through device simulation and to extract the electrical characteristic data of the designed APD devices; APD device equivalent circuit; The APD device equivalent circuit is established according to the electrical characteristic data; the APD device equivalent circuit includes: a reverse biased APD element and a photocurrent equivalent circuit; the reverse biased APD element is used to simulate the dark current output of the APD device according to the electrical characteristic data; the photocurrent equivalent circuit is used to simulate the photocurrent output of the APD device; A circuit simulation module, used to associate the APD device equivalent circuit with the front-end receiving circuit of the radar receiving system and perform circuit simulation to obtain a front-end receiving circuit that meets the design requirements; A system simulation module is used to associate the front-end receiving circuit with the radar receiving system and perform system simulation; wherein, if the system simulation result does not meet the requirements, by continuing to jointly call the device simulation module, the circuit simulation module and the system simulation module, a radar receiving system is designed in which the APD device, the front-end receiving circuit and the radar receiving system all meet the design requirements.

9. The APD linear laser radar receiving system signal level simulation device according to claim 8, characterized in that: The device simulation module is specifically used for: Simulate the structure and process of the APD device to obtain the APD device model; Analyzing the electrical properties, optical properties, photo-electric behavior and internal physical state of the APD device model using numerical calculation methods and physical models; Among them, if the electrical properties, optical properties, photoelectric behavior and / or internal physical state do not meet the requirements, an APD device that meets the design requirements is designed by continuing to simulate the structure and process of the APD device and analyzing the electrical properties, optical properties, photoelectric behavior and internal physical state of the APD device model.

10. The APD linear laser radar receiving system signal level simulation device according to claim 8, characterized in that: The front-end receiving circuit includes: the APD device equivalent circuit, a capacitive feedback transimpedance amplifier, a time identification circuit and a time-amplitude conversion circuit; Wherein, the APD device equivalent circuit is used to simulate the photocurrent and dark current of the output APD device; the photocurrent and dark current are connected to the capacitive feedback transimpedance amplifier through two current-controlled current sources respectively; The capacitive feedback transimpedance amplifier is used to output an intensity detection signal according to the photocurrent and dark current; The time identification circuit is used to perform time identification according to the intensity detection signal to obtain a time identification signal; The time-amplitude conversion circuit is used to output an analog voltage value according to the time identification signal; The analog voltage quantity is used to characterize the flight time of the laser pulse; the laser pulse is characterized by the photocurrent.

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