CMOS TDC Design for LiDAR Signal Processing

In this paper, a high-precision two-step time-to-digital converter (TDC) for LiDAR systems is proposed, which aims to solve the constraint between resolution and measurement range of traditional TDC. The design is based on the SMIC 55 nm CMOS process. It expands the measurement range by utilizing a gated ring oscillator (GRO)-based TDC as the coarse unit of the two-stage TDC; At the same time, the TDC and the time amplifier (TA) based on the Vernier ring oscillator (VRO) are used as the fine quantization units to improve the resolution. The simulation results show that the proposed TDC achieves the resolution of 6.5 ps and the measurement range of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.06 \mu ~\mathrm{s}$</tex>, and achieves the power consumption of 6.3 mw. The two-step TDC not only takes into account the resolution and measurement range under high linearity, but also is suitable for the LiDAR systems that require high-precision time-of-flight (ToF) measurement, which provides the new technical support for the development of LiDAR technology and has important theoretical significance and practical application.