A Dual-Ring Breath-Mode MEMS-Based 10.00 MHz GPS-Disciplined Reference Oscillator

The frequency stability of reference oscillators (ROs) is a key performance limiter for all applications that require a timing or frequency reference, including precision sensors, inertial navigation systems, and radio frequency (RF) transceivers. This work demonstrates a GPS-disciplined MEMS RO based on injection locking of a ∼10.00 MHz MEMS-referenced oscillator (breath-mode dual ring resonator and custom single-chip CMOS feedback amplifier) to a GPS-disciplined crystal oscillator. The RO has excellent intrinsic short-term stability due to the high quality factor of the resonator ($Q\approx 85,000$ at a polarization voltage of 19 V). Stability was further optimized by using the programmable phase shift provided by the amplifier, which revealed the existence of a well-defined maximum stability point (MSP). In addition, long-term frequency fluctuations of the unlocked RO were significantly reduced by using an oven and active temperature compensation loop.