| 摘要 |
PURPOSE:To obtain a carrier signal for demodulation which has a wide band, and is in phase with an equal in frequency to an input carrier signal by dividing the frequency the carrier signal for demodulation from a voltage-controlled oscillating circuit, making a phase comparison with a reference frequency, and feeding the resulting output back to a voltage-controlled oscillating circuit. CONSTITUTION:In a generating circuit 25 for a carrier signal for demodulation, a voltage-controlled oscillating circuit 21 generates a reference frequency signal by an output signal for demodulation. A voltage-controlled oscillating circuit 23, on the other hand, outputs the carrier signal for demodulation by a control signal. On the basis of a frequency-division-ratio setting signal, a variable frequency dividing circuit 24 divides the frequency of the carrier signal for demodulation, and a control signal which corresponds to a phase difference between the reference frequency signal and the output signal of the circuit 24 is outputted from a digital phase comparing circuit 22. |
