A variable gain transimpedance amplifier channel with a timing discriminator for a time-of-flight laser radar

An integrated receiver channel for a pulsed time-of-flight laser rangefinder has been designed. A considerable increase in the input dynamic range of the receiver has been achieved by placing a current buffer with variable attenuation between the external photodetector and the transimpedance preamplifier. The bandwidth of the receiver channel is 170 MHz and the maximum transimpedance 260 kΩ. The distance measurement accuracy is +/-5 mm, when the signal varies in the range from 1 to 750. The circuit was implemented in a 0.8 µm BiCMOS process.