US Patent 11156897 Enhanced stability oscillators using a phononic comb

A method and apparatus for enhancing the stability of an oscillator circuit by generating a comb of frequencies in a non-linear resonator member in response to a drive frequency, the oscillator circuit including a voltage controlled oscillator which is locked to a particular tooth of the comb of frequencies produced by the non-linear resonator member at a drive frequency for which the absolute value of the first derivative of the drive frequency versus said comb frequency is greater than 1, and wherein the second voltage controlled oscillator is coupled with a phase locked loop circuit which controls the locking of the second voltage controlled oscillator to said particular tooth of the comb of frequencies.