| 摘要 |
PURPOSE:To prevent generation of demodulation noise of an FM modulation signal with a discontinuous phase by detecting a dropout of the FM demodulation circuit by a hold circuit depending on an amplitude of the FM modulation signal and phase information. CONSTITUTION:The PLL demodulation circuit is made up of a phase comparator 4, a voltage controlled oscillator 5 and a low pass filter 6, and a 1st output of a phase shifter 9 divides an output of the voltage controlled oscillator 5 to 1st and 2nd outputs whose phase differs by 90 deg. is fed to the phase comparator 4 to implement PLL demodulation. The 2nd output is fed as a clock signal input to a balanced modulator 10 receiving an FM modulation signal, and an output of the low pass filter 6 is extracted as an output of a sample-and-hold circuit 7 sampling-and-holding in response to the output of a balanced modulator 10. |
