PURPOSE: To vary easily an input/output voltage coefficient by a switched capacitor by controlling the number of transmission and the sampling of an input voltage by capacitors different from the capacitance ratio via a switch for varying the control speed.
CONSTITUTION: An input voltage from a terminal 98 is sampled by a switched capacitor comprising switches 11, 12, 21, 31, 41, 32, 42 and capacitors 111, 122 of different capacitances and the result is fed to an inverting input terminal 97 of an operational amplifier 97. Then an output voltage is generated from a terminal 99 via an integration capacitor 100 brought into the initial state by switches 01, 02 and a capacitor 101. The operating speed of the switches 11, 12, 21, 22, 31, 32, 41, 42 applying input/output control of the capacitors 111, 122 is controlled within the operating period of the switches 01, 02 to change the switching number of times, then the output voltage is changed and the switched capacitor is used to apply fine adjustment of the input/output voltage coefficient having the input/output voltage ratio easily.
AKITAKE ISAO
MATSUMOTO SHUZO
HANABUSA HIRONORI
HITACHI VIDEO ENG
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