A 60-m Range 6.16-mW Laser-Power Linear-Mode LiDAR System With Multiplex ADC/TDC in 65-nm CMOS

Abstract

This paper presents a linear-mode light detection and ranging (LiDAR) analog front-end architecture with multiplex analog-to-digital converter/time-to-digital converter (ADC/TDC). An added voltage-to-time converter (VTC) and a reused TDC are simultaneously used to implement the ADC and TDC function, thus replacing discrete ADC and TDC, saving hardware cost and reducing power consumption. A three-stage inverter-based transimpedance amplifier (TIA) with ultra-low-power, low-noise and high/low gain mode (long/short range mode) is proposed to reduce its influence to optical signal-to-noise ratios (OSNR). The prototype TIA and ADC/TDC is fabricated in the 65-nm CMOS technology and integrated into the single-line APD-based LiDAR system. The receiver front-end of TIA and ADC/TDC only consumes 12.44-mW. The minimum detection current of the receiver front-end is less than 238 nA with bandwidth of 150MHz for long-range and weak-light detection. LiDAR achieves a measurement range of 60 m with a 70-klx direct sunlight and only 6.16 mW average laser power. Experimental results show that this architecture is suitable for low-cost multi-line integrated LiDAR applications compared to conventional architecture using ADC, TDC, ADC+TDC architecture.