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A 300-MHz digitally compensated SAW oscillator.

Research paper by W D WD Cowan, A R AR Slobodnik, G A GA Roberts, J H JH Silva

Indexed on: 01 Jan '88Published on: 01 Jan '88Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control



Abstract

A method for compensating for the inherent temperature sensitivity of surface-acoustic-wave (SAW) oscillators is described. Results for a 300-MHz digitally compensated SAW oscillator (DCSO) show a reduction of temperature-induced frequency variation from +/-125 parts per million to +/-1.4 parts per million over the temperature range of -23 to 75 degrees C. This is accomplished using simple digital circuitry and microprocessor control. The temperature-sensing scheme, using a SAW structure with two delay paths of different temperature sensitivity on the same AT-cut quartz substrate, virtually eliminates thermal resistance and time-constant problems. Advantages over ovenized systems include fast warmup; reduced size, weight, and power dissipation; low cost potential; and the ability to compensate for other sources of frequency drift.