A 2.5-GHz FBAR-Based Push-Pull Class-C Oscillator with Low Phase Noise

A 2.5 GHz low-phase noise push-pull class-C oscillator with a high-Q film bulk acoustic resonator (FBAR) is proposed in this paper. The LC-tank of the oscillator is replaced by a high-Q FBAR to obtain low phase noise. The frame structure of FBAR is used to obtain a high-Q factor resonator. Meanwhile, in the circuit implemented with FBAR, a common-mode voltage bias network is introduced into the oscillator, to ensure all transistors work in the saturation region. The class-C oscillator active part is designed in 130 nm CMOS technology. The phase noise of the FBAR-based push-pull class-C oscillator is -120.8 dBc/Hz@10kHz, the power consumption is 0.4 mW, and the figure-of-merit (FoM) is 232.7 at 10kHz offset frequency.