A 50ppm 600MHz frequency reference utilizing the series resonance of an FBAR

A 600MHz thin film bulk-acoustic wave resonator (FBAR)-based differential oscillator fabricated in a 0.13μm CMOS process is presented. The oscillator employs a crosscoupled pair with an FBAR resonator tank providing high Q source degeneration to realize frequency oscillation at the series resonance. The measured phase noise is -126 and -150dBc/Hz at 10kHz and 1MHz frequency offsets respectively; the integrated RMS jitter from 10kHz to 20MHz is 50fs. The oscillator achieves a frequency drift of 50ppm over the temperature range from 25 to 110 °C, providing the potential for quartz replacement in some applications. The figure-of-merit (FOM) of the oscillator is 214dB.