Patent ID: 7495514

Claim:
A low noise amplifier (LNA), comprising: a first-stage signal amplifier, comprising: a first transistor configured to receive a radio-frequency (RF) input signal at it gate; a second transistor outputting a first output signal at its drain; a first feedback circuit coupled between a source of the second transistor and the gate of the first transistor; and a second feedback circuit coupled between the gate and the drain of the second transistor; a second-stage signal amplifier, comprising: an output transistor having its gate coupled to the drain of the second transistor and having its drain outputting a second output signal according to the first output signal; and a third feedback circuit coupled between the drain and the gate of the output transistor; and a gain control unit comprising a first variable resistance device coupled to the source of the output transistor to change source degeneration of the output transistor.