A CMOS chip set for accurate pulsed time-of-flight laser range finding

Abstract

A laser rangefinder device based on pulsed time-of-flight (TOF) distance measurement techniques was constructed and tested. Key blocks of the system are the integrated receiver channel and the integrated time-to-digital converter (TDC) fabricated in a 0.35-um CMOS technology. The receiver-TDC chip set is capable of measuring the time position, rise time and pulse width of incoming optical pulses with ps precision in the amplitude range of more than 1: 50 000. The timing detection is based on leading edge detection in the receiver channel, and the amplitude-dependent timing error is compensated for by utilizing the multichannel TDC. A measurement distance of 100 m is achieved to a target with a reflectance of about 10% at the signal level of SNR = 6, with an optical output power and receiver aperture of 12 W and 18 mm, respectively.