| 摘要 |
PROBLEM TO BE SOLVED: To warrant a normal operation by setting differently an AGC time constant in the case of attack and recovery and easily making a dynamic range of an AGC wide so as to suppress level fluctuation to become a prescribed value quickly. SOLUTION: When a difference voltageΔVL resulting from subtracting a reference voltage V0 from a voltage VL denoting a detection level is positive, a rectifier amplifier circuit 12 amplifies the difference voltage and an integration circuit 14 gives a primary delay with a time constantτ1 to generate a voltage V1. When the difference voltageΔVL is negative, a rectifier amplifier circuit 13 amplifies the difference voltageΔVL and an integration circuit 15 gives a primary delay of a time constantτ2 (>τ1) to generate a voltage V2. The voltage V1 or V2 is added to a reference voltage VS at an adder circuit 6 and the sum controls a gain of a voltage controlled attenuator 1.
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