Video signal amplifier circuit

Abstract

PURPOSE: To prevent unsharpened waveform of a signal due to clipping by adopting a differential amplification system for a comparator of a clip circuit. CONSTITUTION: The comparator 3' of the clip circuit 2 is of differential amplifier form. That is, a collector of a transistor (TR) Q5 of emitter connection is connected to an output terminal of an amplifier 1, that is, a base of a TR Q4 via a resistor R 6 and a collector of the other TR Q6 is connected to a power supply Vcc. Moreover, a PNP TR Q7 is connected between the base of the TR Q4 and a grounding terminal, and the base is connected to the collector of the TR Q5. An output voltage of the TR Q4 is fed to the base of the TR Q5 while being divided by resistors R 4 , R 5 and a clip reference voltage V o is fed to the base of the TR Q6 from a constant voltage circuit 7. COPYRIGHT: (C)1988,JPO&Japio

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    US-6023305-AFebruary 08, 2000Matsushita Electric Industrial Co., Ltd.Primary color video signal output circuit