| 摘要 |
PROBLEM TO BE SOLVED: To provide a time-constant switching circuit which suppresses characteristic deterioration, due to the parasitic capacity of a switch part varying the capacity value which determines the time constant. SOLUTION: The time-constant switching circuit 41 has an input 2 at one terminal of a resistance 1 and an output 3 at the other. To the output 3, switches 15a to 15d are connected in parallel. Capacitors 16a to 16d are connected to the other-end sides of the switches and are related so that C(16a)<C(16 b)<C(16c)<C(16d). Furthermore, a switch 18 is connected to the output 3 and switches 21a to 21d are connected to the other in parallel. Capacitors 22a to 22d are connected to the other-end sides of those switches and related with C(16d)<C(22a)<C(22b)<C(22c)<C(22d). When a small time constant is to be actualized, the parasitic capacity is made small by turning off the switch 18, so that time constant errors can be suppressed.
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