| 摘要 |
PURPOSE:To shorten the stabilizing time of an output circuit by providing a CCD output circuit with an initial charging circuit for charging/discharging a prescribed capacity element in a switched capacitor circuit and for setting up the operating point of an output amplifier to a prescribed level. CONSTITUTION:At the time of turning on a power supply VDD, the voltages of capacitors 16, 18 are boosted in accordance with a prescribed time constant and the output of an FF 13 is turned to 'H' at first. Since the output of an FF 14 is a difference period 'H' of the time constant, the output of a NAND circuit is turned to an 'L' level. Thereby, an analog switch 10 is turned on during the period and a capacitor C2 is rapidly charged up to the potential of a node Y through an FET 8 and a switch 10. Then, the output of the FF 14 is inverted to 'L', the output of the NAND circuit is turned to 'H', the switch 10 is turned off, and charging to the capacitor C2 is stopped. Then, normal operation is executed by a CCD transfer circuit 1 and switching elements 5, 6. Since the FET 8 or 9 is selected so that the potential of the node Y is made equal to that of the operating point of an optimum output signal S0 in accordance with the characteristics of the CCD transfer circuit 1 and initial charging is forcedly executed by a circuit 7, time required for starting stabilizing operation can be shortened.
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