Current Comparator with SiGe BiCMOS Input Stage for Photon-Counting LiDAR Applications

Abstract

A current-mode photon-counting circuit is proposed for long-range LiDAR applications to interface with a microchannel plate (MCP) photomultiplier tube (PMT). Based on the idea of a current-mode comparator, the proposed topology combines a BiCMOS regulated cascode current buffer together with a CMOS current comparator. The circuit accepts two input current signals, the photodetector current and a user-adjustable threshold current, and outputs a 1.8-V digital signal depending on the polarity of the difference current. Designed and characterized in a 180-nm SiGe BiCMOS process, the proposed design provides a 50-Ω input impedance up to 2-GHz and can detect 8-uA current pulses with widths of 300-ps FWHM at a count rate of 1-GHz. The solution also offers a low static power consumption of 4.07mW/channel dissipated from a 2.5-V and 1.8-V dual supply.