Receiver channel with resonance-based timing detection for a laser range finder

An integrated receiver channel for a pulsed time-of-flight laser range finder is presented. The receiver operates in a wide dynamic range without gain control. This is achieved by converting the received unipolar pulse to a bipolar waveform already after the optical detector before the signal is fed to amplifier blocks. Thus the nonlinearities of the amplifiers have the minimum effect on the timing point, which is located in the zero crossing of the bipolar pulse. A parallel resonant circuit is used to shape the pulse in the input of the channel, which consists of a cascade of limiting voltage amplifiers followed by a comparator. The measurements show that the receiver has a walk error of 74 ps in the dynamic range of 1:1280. This corresponds to 11 mm in distance. The minimum usable input signal is limited by the noise of the receiver and equals 1.9 mu A.