A wide-tuning digitally controlled FBAR-based oscillator for frequency synthesis

This paper presents a wide-tuning digitally controlled FBAR-based oscillator in a 0.18μm CMOS process. The oscillator is tuned with a digitally-switched capacitor array to achieve a tuning range of >7000ppm, an over eight-fold improvement over previously published low power FBAR-based VCOs. The high Q FBAR allows frequency tuning to be implemented with a switched-capacitor array with relatively large unit capacitors to achieve a sufficiently fine resolution for frequency synthesis. Our oscillator achieves a measured phase noise of -99dBc/Hz and -142dBc/Hz at 10kHz and 1MHz offsets respectively at a carrier frequency of 1.50GHz while consuming less than 4mW.