Nonlinear behavior of an UHF quartz resonator in an oscillating system

Characterization of a quartz resonator operating at 553 MHz in a closed loop oscillating system has been performed under various drive levels to characterize its nonlinear behavior. The voltage and current were measured across the resonator using differential active probes and used to calculate the magnitude of the admittance under drive. Our results show that nonlinear resonator operation widens the bandwidth of low phase noise operation. At the low frequency end of the operating range, where overall phase noise is degraded, phase noise improvement is ~ 20dB. However, the overall phase noise levels do not improve significantly over the linear case.