| 摘要 |
PROBLEM TO BE SOLVED: To configure a demodulation circuit that enables the feedback control of a local oscillation frequency over a wide frequency range exceeding the linear region of S-shaped curve characteristics in a detection circuit so that a local oscillator having low frequency stability can be used, and can reduce cost easily, and to configure a receiver having the demodulation circuit. SOLUTION: There are provided a mixer circuit 17 for mixing a local oscillation signal to an FSK signal to generate an IF signal; the detection circuit 11 for detecting the frequency of the IF signal; a DC component extraction circuit 12 for extracting a DC voltage component in a detection signal; a comparator 25 for comparing the DC voltage with a reference voltage; and an integrating circuit 26 for integrating the output signal of the comparator 25 to give a frequency control voltage signal to a local oscillation circuit 16. COPYRIGHT: (C)2007,JPO&INPIT
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