A 250-MHz BiCMOS receiver channel with leading edge timing discriminator for a pulsed time-of-flight laser rangefinder

An integrated receiver channel of a pulsed time-of-flight (TOF) laser rangefinder for fast industrial measurement applications with the measurement accuracy of a few centimeters in the measurement range from ∼1 m to ∼30 m to noncooperative targets was developed. The receiver channel consists of a fully differential transimpedance amplifier channel, a peak detector, an rms meter and a timing discriminator. In this particular application there is no time to measure the received signal strength beforehand and it is not predictable from previous measurements, so a leading edge timing discriminator with a constant threshold voltage was used. The amplitude of the received pulse is measured with a peak detector and the amplitude information is used to compensate for the resulting walk error. The measured bandwidth of the receiver channel is 250 MHz, the maximum transimpedance 40kΩ and the input-referred noise ∼7pA/√Hz (C_photodiode=2 pF). The timing detection accuracy of the receiver is better than ±35 mm in a single-shot measurement in a dynamic range of 1:4000 and a temperature range of 0°C to +50°C.