PURPOSE: To eliminate the effect of capacitance added parasitically and to switch accurately the circuit characteristic of an IC circuit, by grounding the other end of a capacitive element constituting the circuit, one end of which is grounded with a capacitor via a switch and actuating the switch.
CONSTITUTION: Switched capacitors 21, 22 and 23 are connected between an input terminal 11 and an output erminal 12, capacitors 21∼23 are switched alternately with positive and negative output of a clock signal 19 to switch the circuit characteristics between the terminals 11 and 12. One end of a switch 25 of the capacitor 23 of this switching circuit is grounded, the other end of the switch 25 is grounded via a switch 29 to control it by a switch 9, the switch 9 is changed over to the LP position at the long time recording and reproducing mode, and the switch 29 is opened. A parasitic capacitance 46 of the capacitance 28 is eliminated from the circuit comprising the capacitors 21, 22 and a capacitor 5. In closing the switch 29, a parasitic capacitance 45 of the capacitance 5 is eliminated by the capacitors 22, 23.
KUWABARA KAZUMI
ITOIGAWA KEIICHI
KOBORI YASUNORI
NISHIJIMA HIDEO
HITACHI MICROCUMPUTER ENG