An integrated wide-band variable-gain amplifier with maximum dynamic range

Abstract

The design of an integrated wide-band variable-gain amplifier with maximum dynamic range is approached by considering three basic bipolar transistor configurations from which all others can be derived. The analysis of noise and of distortion shows the importance of transistor base resistance in all three circuits. On the basis of these analyses, one configuration is shown to yield maximum dynamic range, and this configuration is then used as the basis for the development of a new circuit called the improved automatic-gain control (agc) amplifier. A unique biasing scheme allows a considerable reduction in distortion and noise, together with a significant increase in bandwidth compared with conventional circuits.