| 摘要 |
A stereo signal demodulator includes a switching circuit for separating the stereo composite signal into left and right signal components. A composite stereo signal is attenuated in a preset quantity and superimposed upon the left and right signal components after they are separated by the switching circuit. The superimposed signals cancel the crosstalk components, not by switching the composite signal, but only by attenuating the stereo composite signal in the preset quantity. Consequently, the attenuator for reducing the stereo composite signal can be provided separately from the switching circuit for the stereo demodulation. The switching circuit can then be driven by the entire power supply voltage without any DC potential loss caused by the attenuator. Moreover, there is no DC potential loss by the attenuator, and transistors of the stereo switching circuit can operate with a power voltage margin. The distortion-free dynamic range of the output can be widened and the separation factor can be enhanced. The bias voltage of the active elements is also raised, so that the distortion factor characteristics can be improved. The composite signal attenuated in the preset quantity is superimposed upon the demodulated left and right signal components. Thus, it is possible to eliminate the distortion in the attenuated composite signal, and especially to eliminate the distortion in the demodulated output signals.
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