| 摘要 |
An FM stereo demodulator comprising a switching signal generator for providing four asymmetrical square wave switching signals whose phase differences from the subcarrier of the FM stereo composite signal are respectively 0 DEG , 90 DEG , 180 DEG , and 270 DEG and whose frequencies are the same as the frequency of the subcarrier; four switching circuits for respectively switching the FM stereo composite signal using the four switching signals; and an undesired-beat cancellation circuit for producing left and right audio signals from the respective output signals of the four switching circuits by cancelling the undesired beat signals in the audio frequency zone, produced by the second harmonic component of the subcarrier and SCA signals contained in the FM stereo composite signals.
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