| 摘要 |
PURPOSE:To reduce the manufacturing cost, by applying the frequency of a local oscillator of a newly provided phase locked loop circuit to a main phase locked loop circuit, in a carrier reproducing circuit for a demodulation circuit of a digital signal receiver. CONSTITUTION:The 2nd phase loop circuit consisting of an amplifier 21, a low- frequency filter 22, a voltage-controlled quartz oscillator 23, and a mixer 24, is added, and the frequency of the voltage-controlled quartz oscillator 23 is given to a main phase locked loop circuit including a voltage controlled quartz oscillator 5' as a local oscillation frequency. Thus, the frequency in the loop including a base band processing circuit 2 gradually approaches an average frequency of an input singal S, and the main phase locked loop circuit can stably be drawn into the carrier frequency. |
