Design And Application Of Digital SiPM Chip Based On The Principle Of Pseudo-random Code Laser Ranging

The current mainstream laser ranging solutions include triangle ranging method,TOF ranging method,and amplitude modulated continuous wave(AMCW)ranging method.In the long-distance detection of the triangulation method,the detection error will increase geometrically,and in the case of direct sunlight,the reflected light spot will usually be submerged in the sunlight,causing the detector to be unable to extract the reflected light spot,thus making the instrument ineffective.The flying speed of light is extremely fast,so the TOF ranging solution requires a very fine clock circuit(usually ps level)and a very narrow pulse width laser emitting circuit(usually ns level),so the development difficulty and threshold are high.The AMCW ranging solution obtains the flight time of the light by measuring the phase difference between the emitted light and the returning light.The ability to resist external environmental interference or human intervention is poor,making it difficult to continue to achieve high precision and long distance in a complex and changeable environment.Precise ranging.The laser ranging system based on pseudo-random code uses FPGA to generate high-order pseudorandom number,and achieves the detection of target range through correlation demodulation,which has strong anti-interference ability.At the same time,it uses continuous wave modulated laser,which can achieve good measurement accuracy under the condition of low signal-to-noise ratio,ensure the single value of measurement,and has higher range resolution than single pulse ranging;The digital Si PM composed of single photon avalanche diode(SPAD)array is used as the photodetector,and the adder circuit network is used to realize the on-chip photon number accumulation.The whole process is a pure digital process,without additional analog-to-digital conversion module,which can reduce the quantization error and improve the detector bandwidth.In this paper,the SPAD device is simulated and the structural parameters of the SPAD device are determined.After the tape-out is completed,the optical and electrical characteristics of the selected SPAD device are tested to ensure that the SPAD device can work in the best state and lay the foundation for subsequent applications.Then,the Si PM chip is designed based on the SPAD device,and the FPGA is used at the same time to generate the clock signal needed by digital Si PM and generate the pseudorandom code to modulate the specific laser.On the basis of the above,build an optical system to test the ranging accuracy and ranging distance of the laser ranging system,and the results show that the ranging range about 100 meters level can be achieved with m-level resolution accuracy.Finally,the factors that affect the ranging accuracy and ranging range are analyzed.Among them,the working clock frequency of SPAD and the output optical power of the laser have the largest impact.Suggestions for improvement are put forward for higher accuracy and larger range of false Random code laser ranging provides the possibility.