A 19-GHz Pulsed-Coherent ToF Receiver With 40-μm Precision for Laser Ranging Systems

Abstract

This letter presents a pulsed-coherent time-of-flight (ToF) receiver for a laser ranging system implemented in 28-nm CMOS process. The prototype is designed at 19-GHz carrier frequency with 6.8-ns pulsed modulation. A segmented coarse-fine ToF measurement is adopted to achieve high resolution and fast acquisition. The coarse ToF is recorded by detecting the pulse’s edge whereas the fine measurement is measured by coherent detection. The proposed post-edge detection with automatic gain control loop provides better suppression of walk error from 600 to 26 ps as compared to the rising-edge detection. Also, phase-invariant variable-gain amplifiers provide a low phase error of <± 1° across gain settings with 60-dB dynamic range. This letter can, based on the timing accuracy, achieve 40-µm precision with 1-MHz sampling rate.