| 摘要 |
A frequency synthesizer includes a control circuit configured to generate a digital control signal; and a digitally controlled oscillator of which oscillation frequency changes according to the generated digital control signal. The control circuit includes an operational circuit configured to divide an integer portion of a numerical value representing a phase difference between a reference signal and an oscillation frequency signal of the digitally controlled oscillator into high-order bits and low-order bits including a redundant bit as an MSB, and two encoders configured to encode the high-order bits and the low-order bits to generate control signals. The digitally controlled oscillator includes two capacitive element groups having capacitance values controlled by the control signals. The oscillation frequency of the digitally controlled oscillator changes according to a total capacitance value of the two capacitive element groups. |
