56 MHZ piezoresistive micromechanical oscillator

A fully functional oscillator has been developed, based on a resonator with an electrostatic-to-piezoresistive transduction. Both resonator and amplifier IC have been processed on a SOI wafer with identical SOI layer thickness of 1.5 μm. The resonator is a bulk-acoustic ‘dogbone’ design, for which an extended electrical model is presented. At an oscillation frequency of 56.1 MHz the oscillator consumes 6.1 mW and reaches a phase noise of −102 dBc/Hz at 1 kHz offset from carrier.