A 3-dimensional modified vernier time-to-digital converter for lidar sensors

This paper presents a three-dimensional (3-D) modified Vernier time-to-digital converter (MV-TDC) for the applications of light detection and ranging (LiDAR) sensors. The proposed 3-D MV-TDC combines a 2-D modified Vernier TDC and a delay-lock loop (DLL) that is preceded by an XOR and an edge-detector as its input circuitry, so that the former provides 4-bit coarse digital codes while the latter generates 4-bit fine codes during the high-state of DLL that is maintained only between each rising edge of START and STOP pulses. Then, the measured detection range of a LiDAR sensor can be represented by an 8-bit digital code. The proposed 3-D MV-TDC were implemented in a 0.13-μm CMOS process, demonstrating the measured dynamic range of 43.2 dB that corresponds to the detection range of 18.8 centimeters~28.6 meters. The chip dissipates 2.9 mW from a single 1.2-V supply, while its core occupies the area of 0.37 x 0.89 mm².