Patent ID: 6501307
Filing Date: 2002-12-31
Classification: H03K,H04B

Abstract:
A clock modulator for spreading a frequency spectrum of an input clock to generate an output clock with a varying frequency comprising:an input buffer, receiving the input clock, for driving an intermediate node; an output buffer, receiving the intermediate node, for driving the output clock; a load capacitor; a load switch for connecting the load capacitor to the intermediate node in response to a control signal and for disconnecting the load capacitor from the intermediate node in response to an inverse of the control signal; and a sequencer, responsive to the input clock, for sequencing the control signal through a predetermined sequence of states; wherein a clock period of the output clock is extended when the load switch connects the load capacitor to the intermediate node in response to a change in state of the control signal; wherein the clock period of the output clock is reduced when the load switch disconnects the load capacitor from the intermediate node in response to a change in state of the control signal, whereby frequency is modulated by extending the clock period when the load capacitor is connected, and reducing the clock period when the load capacitor is disconnected.