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Oulun yliopiston väitöskirjat

INTEGRATED CMOS CIRCUITS FOR LASER RADAR TRANSCEIVERS, ACTA UNIVERSITATIS OULUENSIS C Technica 389

ISBN-13:	978-951-42-9544-7
Kieli:	englanti
Kustantaja:	Oulun yliopisto
Oppiaine:	Tekniikka, matematiikka
Painosvuosi:	2011
Sidosasu:	pehmeäkantinen
Sijainti:	Print Tietotalo
Sivumäärä:	126
Tekijät:	NISSINEN JAN

21.00 €

The main aim of this work was to design CMOS receiver channels for the integrated receiver chipof a pulsed time-of-flight (TOF) laser rangefinder. The chip includes both the receiver channel andthe time-to-digital converter (TDC) in a single die, thus increasing the level of integration of thesystem, with the corresponding advantages of a cheaper price and lower power consumption, forexample. Receiver channels with both linear and leading edge timing discriminator schemes wereinvestigated. In general the receiver channel consists of a preamplifier, a postamplifier and atiming comparator. Since a large systematic timing error may occur due to high variation in theamplitude of the received echo, a leading edge timing discriminator scheme with time domainwalk error compensation is proposed here, making use of the TDC already available in the chip tomeasure the slew rate of the pulse and using that information to evaluate the timing error. Thiscompensation scheme benefits from the fact that compensation can be continued even though thesignal is clipped in the amplitude domain, because the slew rate continues to increase even then. The receiver channel with leading edge detection and time domain walk error compensationachieved a compensated timing walk error of ±4.5 mm within a dynamic range of more than1:10000. The standard deviation in single shot precision was less than 25 mm with an SNR of morethan 20. The usability of the receiver channel in pulsed TOF laser rangefinders was verified bymaking actual time-of-flight measurements on a calibrated measurement track. The linearity of thereceiver chip was better than ±5 mm in a measurement range from 3 m to 21 m, with the dynamicrange of the receiver channel reaching more than 1:2000. An integrated CMOS laser diode pulser was also demonstrated to prove its functionality forgenerating ampere-scale peak current pulses through a low ohmic load and a laser diode. TheCMOS pulser achieved a peak current pulse with the amplitude of ~1 A, an optical pulse width of~2.5 ns and a rise time of ~1 ns with a 5 V power supply.

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