Output circuit for a CCD with a D.C. restoration circuit integrated together with the CCD in a monolithic semiconductor chip

摘要

An amplification MOSFET in a source ground form receives at its gate an output signal of a source-follower circuit through a second capacitor. The source-follower circuit, on the otherhand, receives a voltage of a first capacitor which receives a signal charge. A predetermined bias voltage is supplied to the gate of the amplification MOSFET through a switch device while the signal charge of the first capacitor is reset. According to this structure, the second capacitor can transmit only the signal component and the voltage signal itself can be amplified by the source ground type amplification MOSFET. The amplification MOSFET can be biased to its optimum operation point by the switch device during the reset period of the first capacitor; hence, sensitivity can be substantially improved with a simple circuit structure.