Design Of Signal Processing Circuit For HgCdTe APD

As an advanced three-dimensional imaging technology,laser radar technology has important applications in remote sensing,automatic drive,biomedical imaging and other fields.The HgCdTe APD device has important applications as a high-performance photodetector on Lidar.High-precision,wide-range,high-speed detection of laser radar is the focus of future laser radar research.Based on the in-depth analysis of the HgCdTe APD principle and time-of-flight-range principle,this paper proposes a circuit implementation scheme for a lidar receiver based on HgCdTe-APD.The main performance parameters of the HgCdTe APD receiver circuit are researched in detail.The factors affecting the performance of the receiver circuit are analyzed,and the key technologies to improve the performance of the receiver circuit of the TOF are proposed.The main achievements and innovations of this paper are as follows:1.Summarizes the history of Lidar development.The basic principle of threedimensional image acquisition is analyzed,and the main implementation scheme of three-dimensional imaging technology is summarized and the advantages and disadvantages of each scheme are compared.2.The main methods of time-of-flight measurement were studied.A detailed study of the laser signal receiver circuit based on time-of-flight was conducted.The difference between the linear mode APD distance information measurement circuit and the Geiger mode distance information measurement circuit was compared.The key points and difficulties in implementing the high-performance TOF laser signal receiver circuit of the linear mode APD are analyzed.The realization method of high-performance time measurement circuit is summarized and analyzed,and the realization method of highprecision,wide-range and low-power time measurement circuit is proposed.3.An implementation scheme for a three-dimensional imaging circuit system based on HgCdTe APD was proposed.The basic principle and structure of HgCdTe APD were analyzed.The main sources of noise for the HgCdTe APD detector were analyzed.A high voltage adjustable bias power supply suitable for HgCdTe APD is designed.The actual test results show that the adjustable range of the high voltage bias power supply is 0-15 V,and the minimum adjustable step length is 4mV.A transimpedance current signal amplification circuit was designed according to the characteristics of HgCdTe APD light current signal.A transimpedance amplifier was tested by simulating the optical signal current response of the APD.The results showed that the signal-to-noise ratio of the transimpedance amplifier exceeded 20,but the overall noise was high.The laser irradiation of the HgCdTe APD shows that the circuit works normally and the bandwidth exceeds 10 M.The relationship between the laser echo signal and the APD response current was analyzed,and a low-error time discrimination circuit was designed.The simulation results show that the constantproportional-time discrimination circuit can reduce the time discrimination error.4.According to the actual situation,select a time measuring circuit and the control circuit of the time measurement unit is designed.And for the entire system designed power and test auxiliary circuit.The circuit design and simulation are completed,which ensures the correctness of the design.Based on this,the design and manufacture of the circuit layout are completed.The performance of the analog side circuit,the pure digital time measurement circuit and the overall system circuit was tested separately.The experimental results show that there is a high constant noise in the analog-side circuit,and the pure-digital time unit realizes high-precision and wide-range measurement.The system circuit can quickly detect the echo signal,the time measurement range reaches 200?s,and the ns-level time measurement accuracy is achieved in the 250 ns range.The main error sources of the system are analyzed,including fixed delay errors and nonfixed delay errors.The formation mechanism of non-fixed delay error is studied,and the reason for the formation of non-fixed delay is proposed.The actual results and analysis show that the scheme has reference significance for improving the measurement accuracy and detection distance of laser signal receivers,and tests the rationality of the scheme,and the scientific and innovative design.