A Low-Power Multimode Eight-Channel AFE for dToF LiDAR

This paper presents a low-power multimode eight-channel analog front-end (AFE) circuit for direct time-of-flight (dToF) LiDAR applications. The proposed AFE features rich programmability in: a) Two operation modes, parallel mode and selectable mode to save power; b) Two coupling modes, anode and cathode coupling with photodiodes (PDs); c) Two gain modes, high-gain mode for PIN-PD and low-gain mode for APD. Correspondingly, several circuit design techniques have been proposed to support the programmability including: a) Reconfigurable TIA with awake/sleep state and high/low gain mode switching; b) Symmetrical pulse width control to match the pulse width of anode and cathode coupling and input over load protection; 3) Glitch reduction for channel switchover in selectable mode. Designed in 0.18-μm CMOS technology, the AFE achieves bandwidth of 180 MHz, transimpedance gain of 100 dBW, input-referred noise current of 2.1 pA/√ Hz and output swing of 1 V_pp,diff. The channel switchover time is around 10 ns in selectable mode. The channel power consumption is 50 mW in parallel mode and 11.4 mW in selectable mode.