Patent ID: 6768387
Filing Date: 2004-07-27
Classification: H03K,H03L

Abstract:
A voltage controlled oscillator circuit, comprising:a first node connected to a first power source having a first voltage; a second node connected to a second power source having a second voltage; a first MOS transistor; an oscillator arranged between the first node and a third node; and a first capacitive element arranged between the first node and the third node; a second capacitive element; and a node connected to the second capacitive element; wherein an oscillation frequency of the oscillator is controlled by connecting a source of the first MOS transistor to the second node, connecting a drain of the first MOS transistor to the third node, applying an analog control signal to a gate of the first MOS transistor, and changing a frequency of a high level and a low level of a digital control signal; and connection to and disconnection from the second capacitive element are selected according to the digital control signal.