Prediction of acoustic resonator-stabilized oscillator sustaining stage phase noise characteristics from low Q resonator oscillator noise measurements

Measurement of the phase noise characteristics for a known, low-Q-value, LC oscillator allows accurate prediction of crystal/SAWR (surface-acoustic-wave resonator)-controlled oscillator near-carrier and noise floor performance, except that resulting from resonator short-term frequency instability. The low-Q oscillator white frequency noise levels (which are used to predict crystal oscillator noise floor level) are well above the noise contribution of all auxiliary measurement equipment. Excellent agreement between predicted and actual oscillator performance has been demonstrated using this technique for evaluation of oscillator configurations where resonator out-of-band impedance effects on output signal spectral performance are negligible. This approach should prove useful for the evaluation of the effects of sustaining stage amplifier gain compression and ALC diode bias circuit configurations on resultant oscillator flicker-of-frequency noise and noise floor performance