Low phase noise, FBAR-based voltage controlled oscillator without varactor

A Colpitts voltage controlled oscillator (VCO) at 1.1 GHz is designed with a film bulk acoustic resonator (FBAR) as the frequency control element. The oscillator achieves an extremely low phase noise of -115 dBc/Hz at 10 kHz offset, which is 19 dB better than that of an LC oscillator. Voltage control of the oscillation frequency is obtained by applying a DC voltage on the FBAR, unlike a conventional VCO that uses a PN junction varactor (a significant noise contributor) to vary the oscillation frequency. The frequency tunability of the VCO is approximately -12 kHz/V between -5 V and +10 V.