A Received Signal Quality Evaluation Model for SPAD-Based LiDAR Receivers and Its Verification

In light detection and ranging (LiDAR) applications, the received signal is typically a series of echo patterns, and each pattern contains a predefined echo and a monitoring window with a random duration that depends on the time of flight of the optical signal. Therefore, bit error rate (BER) can not be directly applied to evaluate the quality of the received signal. In this letter, a received signal quality evaluation model is proposed for LiDAR receivers that are built with single-photon avalanche diodes (SPADs). The evaluation model is designed based on the normalized histogram of the received signal and two sigmoid weighting functions containing the extracted distribution information of the histogram. The advantage of the proposed model is that quantitative evaluation can be made among different histograms to compare the received signal quality of SPAD-based LiDAR receivers. To verify the proposed model, experiments are performed with an integrated SPAD-based LiDAR receiver fabricated in a standard 180 nm CMOS process. Experimental results demonstrate the effectiveness of the proposed model. The proposed model can be employed as a performance metric as well as a status indicator for performance optimization in SPAD-based LiDAR receivers.