Patent ID: 7427899

Claim:
A variable segment oscillator comprising: an oscillator having a plurality of segments; a frequency determination circuit operable to receive a first signal which is outputted from the oscillator, thereby detecting operating frequency information of the oscillator from the first signal; a segment determination circuit operable to receive a second signal indicative of an expected operating frequency, and to generate a segment selection signal based on the operating frequency information of the oscillator which is detected by the frequency determination circuit; and a segment selection circuit operable to cause the oscillator to perform an operation at a particular segment among the plurality of segments based on the segment selection signal, wherein every time the expected frequency characteristic is changed to update the second signal, the following processing is executed: 1) the segment selection circuit causes the oscillator to operate at an initial segment, and receives operating frequency information indicative of an operating frequency F 1 of the oscillator from the frequency determination circuit; 2) the segment selection circuit causes the oscillator to operate at a segment adjacent to the initial segment, and receives operating frequency information indicative of an operating frequency F 2 of the oscillator from the frequency determination circuit; 3) the segment determination circuit calculates a frequency difference (=F 2 −F 1 ) between the adjacent segments, which is defined as a first frequency difference; 4) the segment determination circuit calculates a frequency difference (=F expect−F 1 ) between an expected operating frequency F expect and the operating frequency F 1 of the oscillator at the initial segment, which is defined as a second frequency difference; and 5) the segment determination circuit divides the second frequency difference (F expect −F 1 ) by the first frequency difference (F 2 −F 1 ), and receives the segment selection signal based on a result of the division.