Patent ID: 7386065
Filing Date: 2008-06-10
Classification: H04L

Abstract:
1. A voltage controlled oscillator (VCO) device, suitable for use in a frequency shift keying (FSK) system, the VCO device comprising: a switching varactor unit, having a first terminal and a second terminal, wherein the switching varactor unit has at least a first diode and a second diode, the positive ends of the first diode and the second diode are commonly coupled to a node, and the node receives a frequency-selection voltage, such that the switching varactor unit produces a capacitance according to the frequency-selection voltage; a VCO core, having a first output terminal, a second output terminal complementary to the first output terminal, and an input terminal, wherein the switching varactor unit is coupled in parallel with the VCO core at the first output terminal and the second output terminal to produce a capacitance effect with respect to the capacitance, so as to adjust a frequency constant √{square root over (LC)} of the VCO core; and a frequency selection unit for outputting the frequency-selection voltage, wherein the frequency selection unit comprises: