A SAWR oscillator vibration sensitivity and phase noise reduction technique using multiple resonators and RF outputs

Abstract

A technique previously described by the author for reduction of quartz crystal vibration sensitivity and phase noise has been modified and applied to the design of a UHF, SAWR oscillator. Use of four SAW resonators mounted in an in-plane orientation provides 3-axis vibration sensitivity cancellation. Because of variations in individual SAWR vibration sensitivity vector magnitude and direction, the cancellation is non-exact. However, a 14:1 reduction in vibration sensitivity has been achieved using resonators having fairly uniform, individual sensitivities in the range 44×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> to 55×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> per g. The novel oscillator loop circuitry consists of cascaded stages of SAWR/modular amplifier/power divider combinations, providing multiple, per-stage RF output signals whose noise phase floors are uncorrelated as a result of individual SAW resonator frequency selectivity