A BiCMOS Differential Amplifier and Timing Discriminator for the Receiver of a Laser Radar

A differential BiCMOS amplifier channel with gain control circuitry and a timing discriminator has been designed for a pulsed time-of-flight laser radar. The measured bandwidth of the amplifier channel is 160 MHz and its gain can be controlled with a variable R-2R ladder attenuator in 7 discrete steps from 0.44 to 23. A peak detector, used for gain control, can detect the peak of a single 10 ns pulse, the amplitude of which varies from 50 mV to 3.5 V. The timing discriminator produces accurately timed logic level pulses from noisy analog output pulses of the amplifier channel. The distance measurement result of the designed timing discriminator varies +/– 4 mm with an input amplitude range of 55 mV – 3.3 V. The single shot resolution with SNR = 250 is better than 6 mm. Measurement results suggest that a cm-level distance measurement accuracy can be realized using integrated ASICs.