An integrated laser radar receiver with resonance-based timing discrimination

An integrated receiver channel for a pulsed time-of-flight laser range finder has been designed and tested. The timing discrimination is realised by converting the received unipolar pulse to a bipolar waveform immediately after the photodetector using a parallel resonant circuit. This minimises the timing errors caused by the nonlinearities of the gain blocks and a wide dynamic range can be achieved without gain control. A comparator is used to detect the timing point, i.e., the zero crossing of the bipolar pulse. The walk error of the receiver is 74 ps, or 11 mm in distance, over a dynamic range of 1:1280 using a laser pulse with half-value width of 6 ns. The minimum usable input signal is 1.9 μA.