| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce the leakage of a local signal included in a modulation signal before performing synchronous detection of a received modulation signal in a quadrature demodulator. <P>SOLUTION: The quadrature demodulator 1 includes a distribution phase unit 2 serving to distribute a received modulation signal to two, and to operate such that the two modulation signals have a 90° phase difference; first and second band filters 3, 4 for passing an FSK modulation signal component output from the distribution phase unit 2 and removing a leaking local signal component; a local oscillator 5 for outputting a local signal for quadrature demodulation; first and second multipliers 6, 7 for multiplying the modulation signal output from the first and second band filters 3, 4 and the local signal output for synchronous detection; and a first low pass filter 8 and a second low pass filter 9 for removing a high frequency component of the base band signal component subjected to the synchronous detection and outputting the base band signal from the FSK modulation signal. <P>COPYRIGHT: (C)2008,JPO&INPIT |
