Amplifier with feedback to provide bias adjustment

摘要

An amplifier (1) having an amplifier transistor (Tr1) with a gate (G) and drain (D). A feedback circuit (2) couples the drain (D) to the gate (G). The feedback circuit (2) has a direct current blocking capacitor (C1) and low pass filter (R3,C2) with a rectifier (D1) therebetween. In use, radio frequency signals at the drain (D) are processed by the feedback circuit (2) to provide a direct current bias to the gate(G). This bias is dependent upon variations of the radio frequency signals at the drain (D).