Patent ID: 7737797

Claim:
A controllable oscillating system for generating a differential oscillating signal, comprising: an oscillating circuit, comprising: a controllable resonator; a cross-coupling driving device, coupled to the controllable resonator, for driving the controllable resonator to generate the differential oscillating signal; and a current source, coupled to the cross-coupling driving device, for providing a first current; and a current adjusting device, coupled to the cross-coupling driving device, for selectively adjusting currents passing through the cross-coupling driving device according to at least a specific voltage level corresponding to the differential oscillating signal, wherein the current adjusting device is arranged to adjust the currents passing through the cross-coupling driving device when the specific voltage level falls in a predetermined range, and stop adjusting the currents when the specific voltage level does not fall in the predetermined range; and the predetermined range is between a first reference value and a second reference value lower than the first reference value.