| 摘要 |
PURPOSE:To eliminate a tracking error over the entire region of a receiving band, by controlling the oscillating frequency of an oscillator having the correlation with a high frequency amplifying circuit and then controlling the tuning frequency of said amplifying circuit. CONSTITUTION:The signal induced at an antenna 1 is amplified by a high frequency amplifying circuit 2 and then fed to a mixing circuit 3 along with the oscillating output of a local oscillating circuit 4. Thus the intermediate frequency signal is extracted. The circuit 4 forms the 1st PLL circuit 50 along with a programmable frequency divider 5, a phase comparator 6, a reference frequency oscillator 7 and a loop filter 8. The oscillator 7 is used also for a reference frequency oscillator of the 2nd PLL60 which consists of an oscillator 61, a programmable frequency divider 65, a phase comparator 66 and a loop filter 68. The oscillating output of the oscillator 61 and the tuning frequency of the circuit 2 are controlled by the PLL60. |
