| 摘要 |
PURPOSE:To apply phase locked type FM detection while using a voltage controlled oscillator by branching an input signal into two, inputting the one to a phase comparator via a transmission circuit whose transmission characteristic is varied, inputting the other directly and using a signal filtering the output of the phase comparator so as to change the characteristic of said transmission circuit. CONSTITUTION:The input is inputted to a phase comparator 103a via the 1st signal transmission circuit 101 from a terminal A and inputted to the phase comparator 103a via the 2nd signal transmission circuit 102. The capacitance of varactor elements D1, D2 is varied by a signal voltage inputted to a resistor R3 in the 2nd signal transmission circuit 102 to vary the frequency transmission characteristic. The output of the phase comparator 103a is inputted to a low- pass filter 104a and the output is fed back negatively to the 2nd signal transmis sion circuit 102 to compress the phase difference of the two inputs.
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