| 摘要 |
PURPOSE:To stabilize a level of a transmission signal with simple circuit constitution by providing an output circuit obtaining a DC component reproduction output signal and an operational amplifier through the comparison between its output signal and a 1st reference voltage so as to stabilize the DC component reproduced output signal. CONSTITUTION:A composite video signal Vin is applied to one terminal of a coupling capacitor C1 and the other terminal of the coupling capacitor C1 is connected to an output terminal of an operational amplifier 3. A 1st reference voltage Vref is fed to a noninverting input terminal of the operational amplifier 3 and the voltage of the other terminal of the coupling capacitor C1 is fed back to an inverting input terminal of the operational amplifier 3. The voltage at the other terminal of the capacitor C1 and a 2nd reference voltage Va are compared by a voltage comparator 2, a switch means is controlled by the output of the voltage comparator to control the operating state and the nonoperating state of the operational amplifier 3 and the DC component reproduced output is obtained from the other terminal of the capacitor C1. Thus, an output signal corresponding to the level change in the input signal Vin is obtained and the reference level of the output signal is stabilized by the signal processing circuit with simple circuit constitution.
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