Study of a 10 MHz MEMS oscillator with a TPoS resonator

This paper reports a low phase noise 10 MHz oscillator based on a lateral-extensional mode thinfilm piezoelectric-on-silicon (TPoS) resonator. A novel design of interdigital electrodes is introduced to improve both the insertion loss and quality factor of the resonator. The average quality factor gets improved by 43% by this method. The equivalent circuit model of the fundamental lateral-extensional mode is analysed. An oscillator is also designed and manufactured. The whole circuit includes a single common emitter BJT amplifier, LC network filter, a phase shifting unit and a MEMS resonator. Tuning the phase shifter in the feedback circuit, the MEMS resonator works at the best operating point while the phase shifting of the peripheral circuit is 900. With an operating input power around 0 dBm, the resonator is not driven at its bifurcation point. Little nonlinearity is observed in the output waveform. The phase noise is measured below -105 dBcifiz@l 00 Hz, -135 dBc/Hz@l kHz offset and the far-from-carrier noise reaches below -150 dBc/Hz. (C) 2017 Elsevier B.V. All rights reserved.