Patent ID: 7432773

Claim:
A current controlled variable frequency oscillator, comprising: an oscillator having a frequency determining circuit that changes frequency with changes in current thereto; a plurality of current sources; a plurality of first switches, each of the plurality of first switching when selected couples a respective one of the plurality of current sources to the frequency determining circuit of the oscillator, and when deselected decouples the respective one of the plurality of current sources from the frequency determining circuit of the oscillator, wherein the frequency determining circuit changes frequency based upon which ones of the plurality of current sources are coupled thereto; a plurality of second switches; and a buffer amplifier connected as a non-inverting amplifier and having a gain of substantially one, wherein an input of the buffer amplifier is coupled to the frequency determining circuit of the oscillator, and an output of the buffer amplifier is coupled to the plurality of second switches; wherein each of the plurality of second switches is coupled to a respective one of the current sources and couples the output of the buffer amplifier to the respective current source when the respective current source is not coupled to the frequency determining circuit of the oscillator through a respective selected one of the plurality of first switches such that each one of the plurality of current sources is at substantially the same voltage level as the frequency determining circuit.