Patent ID: 6686804
Filing Date: 2004-02-03
Classification: H03F,H03J,H03L

Abstract:
An apparatus to maintain a voltage-controlled oscillator (VCO) close to a desired operating point, the voltage-controlled oscillator (VCO) providing a variable frequency output that depends, in part on an analog control input signal, and in part on a capacitance connected to a capacitor input, the apparatus comprising:a switchable bank of capacitors connected to said capacitor input and having a switch input to provide a selectable range of operating frequencies for the VCO; a sensor connected to the control input of the VCO providing a measurement that varies as the magnitude of the control signal, the sensor providing an analog output; and a digital controller connected to the switch input and accepting the control signal magnitude indication, the controller accepting a digital input and providing control to the switchable capacitor bank to maintain the operating point of the VCO close to the desirable operating point; and an analog to digital converter (ADC) to convert the analog sensor output to the magnitude indication accepted by the digital controller.