| 摘要 |
PURPOSE:To erase a ripple component which appears at a couple of differential amplifiers which mix switching signals with a stereophonic composite signal and to erase a ripple component and perform stable stereophonic demodulation by adding a inversional phase ripple component to the ripple component. CONSTITUTION:The couple of differential amplifiers 2 and 14 are supplied with switching signals from terminals 14' and 16 and operating currents are controlled by the stereophonic composite signal. Therefore, the amplifier 2 is supplied with a signal from a signal source 36 through a voltage-current converting circuit 38 and current inverting circuits 40 and 42, and the amplifier 14 is supplied with it through current inverting circuits 42 and with a reference constant current from a constant current circuit 46 through current inverting circuit 48 and 50. Outputs of the amplifiers 2 and 14 appear at terminals 32 and 34 through current inverting circuits 20 and 22. A ripple erasing circuit 120 generates the ripple component inverted in phase to the ripple component generated by the circuits 20, 22, 40, 44, and 48 and the negative-phase ripple component is subtracted from outputs of the circuits 20 and 22 to cancel the ripple component. |
