Abstract: An interface circuit 13 is provided for a display apparatus 3 such as a television. The display apparatus 3 comprises a video signal processing circuit 8 for processing a composite video signal to derive color component signals having variable black and white levels; a linear amplifier 10 for amplifying the color component signals; and a display device 4 such as a CRT driven by the output of the linear amplifier 10. The interface circuit 13 is provided to interface the color component signals with a digital signal processor 14. The interface circuit 13 includes a modification circuit 22 arranged to perform a modification of voltage levels of the color component signals and to output the modified color component signals to the digital signal processor 14 via an A/D convertor 18.

Abstract: An audio amplifier circuit comprises a voltage-gain amplifier and a current-gain amplifier in series between an input node and an output node. Power supply lines are provided for providing power to the audio amplifier circuit. An outer negative feedback loop is provided around the current gain amplifier and the voltage gain amplifier, and an inner negative feedback loop is provided around the voltage gain amplifier. A first switch is provided for selectively connecting the power supply lines to the current-gain amplifier. A second switch is provided for selectively switching the inner negative feedback loop or the outer negative feedback loop to the voltage-gain amplifier. A control circuit is also provided to control the switches during power supply switching.

Abstract: An audio amplifier circuit comprising: a voltage-gain amplifier 16 and a current-gain amplifier 17 in series thereafter between an input node 11 and an output node 12; power supply lines 18 for supplying power to the audio amplifier circuit; an outer negative feedback loop 20 around the current-gain amplifier 17 and the voltage-gain amplifier 16; an inner negative feedback loop 20 around the voltage-gain amplifier 23; a first switch 27 for selectively connecting the power supply lines 18 to the current-gain amplifier 17; a second switch 28 for selectively switching the inner negative feedback loop 23 or the outer feedback loop 20 to the voltage-gain amplifier 16; and a control circuit 36, 37 arranged to control the switch during power supply switching.

Abstract: An interface circuit 13 is provided for a display apparatus 3 such as a television. The display apparatus 3comprises a video signal processing circuit 8 for processing a composite video signal to derive color component signals having variable black and white levels; a linear amplifier 10 for amplifying the color component signals; and a display device 4 such as a CRT driven by the output of the linear amplifier 10. The interface circuit 13 is provided to interface the color component signals with a digital signal processor 14. The interface circuit 13 includes a modification circuit 22 arranged to perform a modification of voltage levels of the color component signals and to output the modified color component signals to the digital signal processor 14 via an A/D convertor 18.