An Adaptive Threshold Analog Front-End Circuit for Direct ToF LiDAR

The analog front-end (AFE) circuit of the light detection and ranging (LiDAR) receivers need to provide time-of-flight (ToF) when the laser echo arrives. Accurate ToF is crucial for the ranging accuracy of LiDAR receivers. However, targets with different reflectivity will give different timing results even at the same distance due to the light intensity. This paper proposes an AFE circuit for LiDAR receiver. This AFE circuit can adaptively adjust the threshold based on photocurrent to reduce walk error under different light intensities. Proposed AFE is implemented in 55nm CMOS process. Simulation results show that within the photocurrent range of 3 to 20 uA, the timing error is less than 0.8 ns.