| 摘要 |
PURPOSE:To reduce temperature dependency and to make a set level freely variable by comparing a detected current with a constant reference current and by controlling an input level with a current which corresponds to a comparison difference when the detected current is greater. CONSTITUTION:A signal from a signal source ES is supplied to an amplifier A1 through a capacitor C1 and a resistance R1, and the output of the amplifier A1 is supplied to an output terminal OUT and also supplied to a transistor (TR) Q6 and an amplifier B1 constituting a rectifying circuit Rec through a resistance R3. The detected current (i) of the rectifying circuit Rec is compared with a current I flowing through a current source circuit Is composed of TRs Q7 and Q8 and when i>I, a current i-I is outputted and, after integrated by a capacitor C, drives TRs Q1 and Q2. Then, a variable impedance circuit VI composed of TRs Q3, Q4, and Q5 connected to the collector of a TRQ2 is driven to exercise automatic level control. |
