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

TLDR: A laser rangefinder device based on pulsed time-of-flight (TOF) distance measurement techniques was constructed and tested and 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.

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.

Figures

Fig. 5. The block diagram of the TDC.

Fig. 1. Pulsed TOF laser rangefinder.

Fig. 4. Simplified block diagram of the receiver IC.

Fig. 3. Principle of timing walk compensation based on the measurements of pulse width and rise time.

Fig. 2. Optical pulse shape (905D1S2J03Y with MOS pulse driver) of the transmitter recorded with a 25 GHz optical measuremnt head.

Fig. 6. TDC measurement core based on counter and 2-level interpolation.

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In this paper, a laser rangefinder device based on pulsed time-of-flight ( TOF ) distance measurement techniques was constructed and tested.