PURPOSE: To attain setting of a coefficient by 1% step by using in common a capacitor for setting a coefficient of 1% step and 10% step and using further a capacitor ratio and a switched capacitor type voltage divider together.
CONSTITUTION: A circuit I is the switched capacitor circuit (equivalent resistance) corresponding to a feedback resistor to connect the circuits in parallel thereby preventing an opeational amplifier circuit from being in an open loop. Moreover, a circuit A is a voltage divider decreasing an output voltage of a circuit IV setting the coefficient by 1% step to 1/10. In selecting the capacitor ratio of capacitors C21, C22 and coefficient setting capacitors C11∼C110 in the circuit I as 10:1, the output voltage V0 becomes V0=(total capacitance of capacitors selected in the C11∼C110/C21 or C22) (1/10 of VIN+VIN) and since the C21 and C22 have a capacitance value being 10 times the C11∼C110, the coefficient setting by 1% step is attained.
KIDO MITSUYASU
KUDOU HIROYUKI
