| 摘要 |
PURPOSE:To lower distortion factor and to reduce crosstalk of a signal switching a subcarrier, by providing a negative feedback circuit to each of the 1st and 2nd amplifying means amplifying a composite signal. CONSTITUTION:A composite signal is applied via a transistor (TR)Q10 to the 1st amplifying TRQ2, where the signal is amplified and applied to main switching SWTRQ5, Q6 via a bias TRQ8, and subjected to time division with a 38-kHz subcarrier wave applied to the base of the TRQ5, Q6, and each output of left and right channel CHs is outputted to terminals Lout, Rout. The attenuated composite signal with resistors R1-R3 is amplified in the inverse phase with the output of the TRQ2 at the 2nd amplifying TRQ1 and applied to SWTRQ3 and Q4 via a bias TRQ7. Time division is obtained with the 38kHz subcarrier wave at the TRQ3, Q4 and the terminals Lout, Rout respectively have attenuated inverted phase right CH component and left CH component to cancel crosstalk at the TRQ5, Q6. The TRQ1, Q2 constitute a negative feedback by using resistors Rf2 and Rf1 to reduce the distortion factor. |
