Patent ID: 6226506
Filing Date: 2001-05-01
Classification: H03J,H03L,H04B

Abstract:
A frequency synthesizer having at least one variable frequency output, the output frequency varying as a capacitance within the synthesizer varies, comprising:a discretely variable capacitance circuit within the frequency synthesizer including a plurality of capacitor circuits, each capacitor circuit comprising:a capacitor coupled between a first node and a second node;a switch coupled between the second node and a third node to selectively couple the capacitor between the first node and the third node depending upon a digital signal applied to a control node for the switch; andmeans for controlling a voltage level on the second node by coupling the second node to a non-floating node so that the second node does not float when the switch is in an off state; anda multiple-bit digital control signal coupled to the plurality of control nodes of the switches to select an amount of capacitance provided by the discretely variable capacitance.