| 摘要 |
PROBLEM TO BE SOLVED: To omit and freely adjust an external element without any inconvenience. SOLUTION: An FM demodulator 10 is provided with an S generation means 3 formed of a circuit including an active equivalent inductance circuit (element) 5 and giving the S-shaped phase characteristic of 1:1 to each frequency component of an input FM signal, a phase comparing means (90 deg. phase-shifting circuit 4, a phase comparator 4) comparing this output signal and an input FM signal to obtain a phase error signal as a comparing result 8, and a control signal generating means 7 obtaining a control signal 6 adjusting the inductance value of an active equivalent inductance circuit 5 so as to pulling the central frequency of the S-shaped phase characteristic into the central frequency from this phase error signal. Thus, the fear of the deterioration of output distortion, the deterioration of S/N or obstruction to another circuit is eliminated to omit the external element and to freely adjust the element.
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