A Switched-Capacitor Cross-Correlation-Based Time-of-Flight Design for Pulsed Chaos Lidar Systems

This work presents a time-of-flight module design for pulsed chaos lidar systems. With a mixed-signal architecture and 1-bit digitization, the proposed design evaluates the delay in time and the corresponding distance by calculating the cross-correlation function between the two signals. A 400-unit XOR array followed by a switched-capacitor summer is adopted that enables high-speed operations and supports a $\gt10-\mathrm{m}$ ranging dynamic range. A subsequent asynchronous loop-unrolled SARADC digitizes the cross-correlation result and generates a 4-bit output. The prototype IC with $28-\mathrm{nm}$ CMOS is evaluated using an in-house pulsed chaos lidar system. At 2 GS/s, experimental results demonstrate a maximum ranging error of 2.11 cm with $1 \sigma$ of 1.49 cm over a distance of 20 m. With a signal pulse width of 200 ns and a repetition period of $\mathbf{1 0}$ us, this work consumes 45.7 mW under a $0.9-\mathrm{V}$ supply.