Factors influencing assessment in a TDC-based ranging system

Light detection and ranging (LiDAR), based on a time-to-digital converter (TDC) is an important technique for measuring the distance between a laser transmitter and its target. It is known that by decreasing the probability of trigger error, ranging precision will be improved. Based on a lab-designed APD detection circuit, noise analysis was deduced. Based on statistics and probability theory, the relationships among the probability of noise trigger error, reference voltage and noise were established. Then a given desired error probability (estimated via theoretical time jitter), the reference voltage of a TDC-based ranging system, can be properly designed based on the root mean square (RMS) noise. Extensive simulation and experimental results indicated that the reference voltage involved in a lab-scale TDC-based ranging system should be set to larger than five times RMS noise for an acceptable error probability of 0.01%. Thus, reasonable circuit parameter design can decrease time jitter, reduce the likelihood of noise trigger error, and further improve the ranging precision of a LiDAR system.