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本文叙述了用一对差动连接的晶体管作为基本放大器单元的自动增益控制宽带放大器,并提供一附加的晶体管线路,使得放大器的增益成为两晶体管直流偏置电流之比的函数。与两个偏流之比成正比的增益函数能使放大器的增益按双曲线或线性变化。此外,噪声分量以及输出直流分量的变化可通过从外加输入电流中减去一直流分量而实现最小化,该直流分量为放大器最小增益时的输入电流的直流分量减去其值为放大器增益函数的直流分量。
This article describes an automatic gain controlled wideband amplifier using a pair of differentially connected transistors as the basic amplifier unit and provides an additional transistor line to make the gain of the amplifier a function of the ratio of the DC bias currents of the two transistors. A gain function proportional to the ratio of the two bias currents allows the gain of the amplifier to vary hyperbola or linearly. In addition, the variation of the noise component and the output DC component can be minimized by subtracting a DC component from the applied input current, which is the DC component of the input current at the amplifier minimum gain minus its value as a function of the amplifier gain DC component.