Abstract: Class A gain control systems having extremely good linearity and wide dynamic range, and suitable for monolithic integration, are described in embodiments realizing several classical multiplier functions such as voltage controlled attenuators, exponentially controlled multipliers and four quadrant multipliers. Two identical current steering circuits, each comprising a matched, emitter coupled pair of transistors, or effective transistors, are fed from an actively linearized input circuit which derives the required well balanced signals from a single ended or balanced input source, and current mirror circuits are used to subtract unwanted common mode products from the output signals.

Abstract: A voltage controlled attenuator having extremely wide dynamic range and having low distortion is achieved by limiting the current density in each unit area of the transistors to minimize the current noise and by utilizing high current sources to minimize the noise voltage. A pair of compound gain cells having low current densities are each directly fed by a linearized current source. The gain cells are controlled by a single gain control voltage and feed a pair of linearized buffer amplifiers for minimizing loading on the gain cells. The output of the buffer amplifiers feed a differential output amplifier for generating an output signal that eliminates the effect of the control voltage in the output signal and any DC shift caused by changes in control voltage and nulls remaining distortion products.