Abstract: A gain-controlled amplifier with high dynamic range, useful in particular for frequencies in the GHz range, according to the invention comprises a bipolar or FET transistor (1) with an adaptive controlled feedback network (2) which may consist of one or a plurality of series connected diode(s) preferably PIN-diode(s). The transistor (1) and the controlling network (2, 3) can be operated at low voltages and current levels. Even for an operating frequency of 1 GHz and above, a gain control range of more than 20 dB can be obtained. Due to the feedback structure the linearity is enhanced especially for low gain values, and the controlled feedback does not degrade the noise figure. If used in an AGC loop circuit, the circuit current is increased for high input levels. Therefore the proposed circuit is suitable for battery powered receivers having input stages with automatic gain control.

Abstract: A gain-controlled amplifier with a high dynamic range, useful in particular for frequencies in the GHz range, according to the invention comprises a bipolar or FET transistor (1) with an adaptive controlled feedback network (2) which may consist of one or a plurality of series connected diode(s) preferably PIN-diode(s). The transistor (1) and the controlling network (2, 3) can be operated at low voltages and current levels. Even for an operating frequency of 1 GHz and above, a gain control range of more than 20 dB can be obtained. Due to the feedback structure the linearity is enhanced especially for low gain values, and the controlled feedback does not degrade the noise figure. If used in an AGC loop circuit, the circuit current is increased for high input levels. Therefore the proposed circuit is suitable for battery powered receivers having input stages with automatic gain control.