Ultra-Low Phase Noise Crystal Oscillators

This paper describes, in general terms, the theory and design of ultra-low noise crystal oscillators based on SC cut crystal resonators operating at 10 MHz. These oscillators demonstrate -118 dBc/Hz at 1Hz and -147 dBc/Hz at 10 Hz offsets. The noise floor was <-160 dBc/Hz. To achieve this performance a feedback oscillator has been designed by optimizing the individual elements separately and then combining them to form the final oscillator. The parameters for the resonators, tuning networks, phase shifters and amplifiers were optimized both theoretically and experimentally.