Abstract

An integrated receiver-TDC (time-to-digital converter) chip set is developed for pulsed time-of-flight (TOF) laser rangefinding. The receiver detects the current pulse from the optical detector and produces a timing mark for the TDC. The receiver uses time mode walk error compensation scheme achieving <+/-2.5 mm residual timing walk error within a dynamic range of ~1:40,000. The multi-channel TDC measures the time position, width and rise time of the echo pulses simultaneously with ~ 10 picosecond (ps) precision. Both chips are manufactured in 0.35-µm complementary metal-oxide semiconductor (CMOS) technology. The functionality of the chip set was demonstrated in a laser radar platform using 12 W and 3-ns optical pulses produced by a laser diode. A measurement accuracy of ~+/-3 mm was achieved with non-cooperative targets at a distance range of a few tens of metres within an amplitude range of received echoes of 1:40,000.