A Low-Voltage Temperature-Stable Micromechanical Piezoelectric Oscillator

We present a low-power 82 MHz reference oscillator that utilizes a temperature-stable thin- film piezoelectric-on-silicon resonator as the frequency-selective element. Low impedance micromachined resonators are designed and fabricated using an arraying technique. As a result, the transimpedance amplifier in the oscillator loop is reduced to a single active component (one transistor) and 3 resistors, which is very power-efficient (2.2 mW at 1.1 V supply). By employing the buried oxide layer of the SOI substrate as a part of the structural stack of the composite resonator, a very small (- 2 ppm/degC) temperature coefficient of frequency (TCF) is obtained for the oscillator.