A Time-to-Digital Converter Employing a Voltage-Controlled Ring Oscillator with High Gain Linearity for LiDAR Applications

This paper presents a time-to-digital converter (TDC) employing a voltage-controlled ring oscillator (VCRO) with high gain linearity for light detection and ranging (LiDAR) applications. To eliminate the regulation dead zone during voltage control, a resistance tuning module incorporating dual NMOS transistors is proposed in the VCRO. Simulation results demonstrate that the VCRO's oscillation frequency is fully tunable from 446 MHz to 800 MHz across the full power supply range of 1.8V with high linearity, and the variation rate of the voltage control gain is maintained within 17.02%. Based on the VCRO, a 16-bit TDC is designed, which achieves a resolution spanning from 134 to 280 ps, a maximum range of 18 μs, and the power consumption is 3.5 mW.