Patent ID: 7477111
Filing Date: 2009-01-13
Classification: H03K

Abstract:
1. A digitally controlled oscillator, comprising: a ring oscillator composed of a plurality of delay circuits connected in a ring; a plurality of variable load capacitance circuits each connected to each node between adjacent delay circuits of the ring oscillator, for changing load capacitance according to an external control signal; and a control circuit for adjusting timing of the control signal that is inputted to the plurality of variable load capacitance circuits, by using a clock signal of one or more nodes of the ring oscillator, wherein the control circuit comprises a plurality of timing adjustment circuits each connected to each of the plurality of variable load capacitance circuits, for adjusting timing of the control signal that is inputted to each variable load capacitance circuit, by using the clock signal of the one or more nodes of the ring oscillator; and a delay circuit for delaying control signals outputted from the plurality of timing adjustment circuits by time selected by an externally inputted signal.