Patent ID: 8228130

Claim:
An oscillator comprising: (a) oscillator circuitry including an amplifying circuit having first and second outputs and also including a resonator having a first terminal for receiving a bias signal; (b) a comparator having first and second inputs coupled to the first and second outputs, respectively, of the amplifying circuit for producing first and second clock signals which indicate the timing of positive and negative phases of a differential output signal produced by the amplifying circuit; (c) a synchronous rectifier having first and second inputs coupled to receive first and second output signals that are produced in response to the first and second outputs of the amplifying circuit, the synchronous rectifier having first and second clock inputs coupled to receive the first and second clock signals, respectively; (d) a switched capacitor notch filter having an input coupled to an output of the synchronous rectifier, the switched capacitor notch filter having first and second clock inputs coupled to receive the first and second clock signals, respectively; and (e) a control current generator having an input coupled to an output of the switched capacitor notch filter, for generating a control current which controls the transconductance of the amplifying circuit.