PURPOSE: To decrease the number of pins in circuit integration by mounting a switch for settings a coefficient and a resistor for setting 10% step coefficient to the outside of an integrated circuit in a coefficient circuit of a switched capacitor circuit.
CONSTITUTION: A resistor R for setting a coefficient and switches S1∼S10, S10∼S100 are mounted at the outside of the integrated circuit shown in an alternate long, and short dash line, a coefficient for addition for obtaining the coefficient setting of 1% step is built in the form of 10 switched capacitor adders, an input voltage V1 is added through the resistance division while respective output voltages (a) (for 10% step) and (j) (for 1% step) subjected to coefficient setting in 10% step in the ratio of 1:1 for the (a) and 10:1 for the (j), and the coefficient setting of 1% step is attained in total. The circuits 1, 2 are switched capacitors, which are of the same circuit constitution, but the capacitance of the circuit 2 is 1/10 to the capacitance of the circuit 1.
CHIBA TOMIO
KUDOU HIROYUKI
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