Laser Radar Receiver Channel With Timing Detector Based on Front End Unipolar-to-Bipolar Pulse Shaping

An integrated receiver channel for a pulsed time-of-flight laser range finder is presented based on a timing discrimination principle in which the incoming unipolar detector current pulse is converted to a bipolar pulse at the front end of the receiver channel. Thus no optical or electrical gain control is needed within the dynamic range of the receiver, which according to measurements is 1:3000 with a timing walk error of plusmn 55 ps (plusmn 8 mm in distance). The minimum detectable input signal current is about 1.3 muA at an SNR of 10 with a bandwidth of 200 MHz. The circuit is realized in a 0.35 mum SiGe BiCMOS process and consumes 220 mW of power.