Single-Resonator Dual-Frequency Thin-Film Piezoelectric-on-Substrate Oscillator

This paper reports on the design and implementation of a sub-milliwatt dual-frequency oscillator that utilizes two high-Q acoustic modes of an AIN-on-Si microresonator. While operating in atmospheric pressure, the microresonator shows Q_unloaded of 7100 at 35.5 MHz, and 4000 at 105.7 MHz corresponding to the first- and the third-order width-extensional resonance modes. The measured Q_unloaded is improved to 10100 in vacuum for the first-order resonance mode. The phase-noise of a two-transistor oscillator circuit using this resonator at 1 kHz offset from the carrier is -94 dBc/Hz and -88 dBc/Hz, for the low and high frequency modes, respectively, with a far from carrier noise of -143 dBc/Hz.