| 摘要 |
PURPOSE:To attain independent and wide setting of a time constant and rate of change of the time constant respectively by charging/discharging a capacitor with a synthesized current between a constant current and a variable current resulting from a control voltage. CONSTITUTION:A charging current I1 to the capacitor 32 is a current I-i being a current I flowing via a resistor 34 substrate by a current (i) flowing via a resistor 42 and a transistor 41. The current I is selected larger than the current (i), the time constant is decided mainly by the current I, which is set by a resistance value of the resistor 34. The time constant is changed by varying the current (i) and the current (i) is varied by varying the control voltage BVR fed to a terminal 35. Further, the rate of change of the current (i) with respect to the change in the voltage VVR depends on the resistance value of the resistor 42. Thus, the rate of change of the time constant changed by varying the voltage VVR is decided dependently of the time constant mainly and the time constant and its rate of change are selected over a wide range.
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