Oscillator PM-noise reduction from correlated AM-noise
Archita Hati, Craig W. Nelson, David A. Howe
We demonstrate a novel technique for reducing the phase modulation (PM) noise of an oscillator in steady state as well as under vibration. It utilizes correlation between PM noise and amplitude modulation (AM) noise that can originate from the oscillator's loop components. A control voltage proportional to the correlated AM noise is generated and utilized in a feed-forward architecture to correct for the steady state as well as vibration induced PM noise. An improvement of almost 10 - 15 dB in PM noise is observed over almost one decade of offset frequency for a 635 MHz quartz MEMS oscillator. Under vibration this corresponds to more than a factor of five reduction in vibration sensitivity.
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control