PURPOSE: To obtain a filter that uses a small number of operational amplifiers by using the operational amplifiers in time-division mode.
CONSTITUTION: With clock 1 on, capacity element C5 is connected to operational amplifier A4 through switches SW15 and SW16 and with clock 2 on, capacity element C2 is connected to operational amplifier A4 through switches SW17 and SW18. While 1 is on and 2 is off, the output side of operational amplifier A4 is connected to the connection points of switches SW2 and SW6 by way of SW1 while the input side is connected to capacity element C4 and the connection point of switch SW12 via switch SW20 and further via switch SW5, and capacity element C5 is connected to operational amplifier A4 to charge capacity elements C1, C5 and C6 instantaneously while capacity elements C2 and C7 stay as they are. When the clocks are in the reversed states, the charge in capacity element C5 is unchanged and capacity elements C2, C4 and C7 are instantaneously charged to fixed values.
FUSHIMI SHIGEO
SHIDA SEIYA
NAKASHIMA MASAHIKO
