Gain control circuit for controlling operation of a variable-gain amplifier or the like

摘要

A gain control circuit includes a first path block for a gain control voltage and a second path block for a reference voltage. The first path block includes a voltage-current linear conversion unit for outputting a current which is proportional to a gain control voltage Vctrl, and which is inversely proportional to a resistivity, and also includes a temperature characteristic compensation unit for mirroring the current output by the voltage-current linear conversion unit and outputting a current Ictrl which is proportional to the gain control voltage Vctrl and an absolute temperature, and which is inversely proportional to the resistivity. The second path block has the same construction as the first path block except that it receives a reference voltage Vref and outputs a current Iref. The current Ictrl and the current Iref are supplied to a variable- gain cell so as to produce a voltage gain Av not affected by a variation in temperature.