Patent ID: 7482888

Claim:
An oscillator circuit, comprising: A main oscillator generating an output frequency, said main oscillator including a resonator having a resonant frequency that is substantially equal to said output frequency while said circuit is operating in a stable condition; a tunable oscillator being AC coupled to said main oscillator and providing an input signal to said main oscillator, said input signal having a tunable frequency; a capacitor coupled to said main oscillator and to said tunable oscillator, said capacitor coupling in said input signal to said main oscillator so that said resonator receives energy at said resonant frequency while said input signal has minimal effect on said main oscillator when said main oscillator has reached said stable condition; compare and control circuitry including digital logic and frequency detectors, said compare and control circuitry being coupled to said main oscillator and to said tunable oscillator, said compare and control circuitry providing enable signals to said main oscillator and said tunable oscillator, said compare and control circuitry measuring and comparing said output frequency and said tunable frequency, said compare and control circuitry adjusting said tunable frequency until said tunable frequency of said input signal is adjusted so as to be substantially equal to said resonant frequency of said resonator.