Control automático de ganancia con baja intermodulación y alta eficiencia

Abstract

We present a novel approach for highly linear automatic gain control (AGC) of a HEMT small-signal amplifiers. The amplifier was implemented, with the transistor biased in the transition between the saturated and lineal operation regions. Gain control with low distortion is achieved by simultaneous adjustments of the gate to source (Vgs) and drain to source (Vds) voltages along the line where the second derivative of the transconductance (Gm3) has a null. We realized a comparative analysis of the performance of our proposal versus an amplifier designed following a traditional approach. With our approach we obtained a better performance in terms of intermodulation and power-efficiency, without an important reduction in the gain control range.