Patent ID: 8922288
Filing Date: 2014-12-30
Classification: H03B,H03L

Abstract:
1. An oscillator circuit comprising: first and second resonator terminals for connecting to respective terminals of a resonator; a first inverting amplifier connected between the first and second resonator terminals in a first mode of operation; a back to back pair of second inverting amplifiers connected between the first and second resonator terminals in a second mode of operation; and a controller configured to compare an operational parameter of the oscillator circuit to a switchover threshold, and switch the oscillator circuit from the first mode of operation to the second mode of operation when the operational parameter exceeds the switchover threshold; wherein the operational parameter is the amplitude at a resonator terminal of the oscillator circuit; and wherein the controller comprises a detector configured to measure the operational parameter of the oscillator circuit; and wherein the controller further comprises a comparator configured to compare the measured operational parameter of the oscillator circuit with at least one target threshold in the second mode of operation; and the at least one target threshold comprises an upper target threshold and a lower target threshold; wherein the controller is configured to set at least one circuit parameter to cause the operational parameter to be between the upper and lower target thresholds; and the oscillator circuit is configured to set at least one of the circuit parameters to at least one preset value when switching the oscillator circuit from the first mode of operation to the second mode of operation; and the at least one preset value corresponds to those established during a previous operation of the oscillator circuit in the second mode of operation.