A low-noise FBAR-CMOS frequency/phase discriminator for phase noise measurement and cancellation

A sensitive low-noise frequency/phase discriminator and its applications in phase noise measurement and phase noise cancellation are presented. The discriminator uses a high quality factor thin Film Bulk Acoustic Resonator (FBAR) in a notch filter configuration with common-mode traps to reduce the low-frequency noise up-conversion. The performance of the notch filter, the discriminator transfer function, output noise, and phase noise floor are measured and compared with simulations. A feed-back feed-forward phase noise cancellation scheme is proposed based on the frequency/phase discriminator. Two chips were fabricated in 0.13 μm CMOS technology integrating the discriminator and the phase noise cancellation schemes, respectively. The 1.5 GHz discriminator shows phase noise floor of -128 dBc/Hz at 20 kHz,-142 dBc/Hz at 100 kHz, -162 dBc/Hz at 1 MHz and-166 dBc/Hz at 4 MHz, while consuming 26 mW of power. The measured phase noise of the feedback cancellation circuitry reaches the phase noise floor of the discriminator, verifying the proposed concepts.