Patent ID: 8692620

Claim:
A power amplifier for receiving and amplifying a radio frequency (RF) input signal and outputting an amplified RF signal, the power amplifier comprising: an RF power amplification unit configured to amplify the RF input signal; a metal-oxide semiconductor field-effect transistor (MOSFET) configured as having a source supplied with a first direct current (DC) power, a gate that receives the RF input signal, and a drain connected to a power supply terminal of the RF power amplification unit; a power detection unit configured to detect an amplitude of the RF input signal and generate an envelope signal based on the detected amplitude; a supply voltage modulation control unit configured to determine a DC gate voltage of the MOSFET based on the envelope signal; and a bypass circuit including a first end connected to the drain of the MOSFET and a second end connected to the power supply terminal of the RF power amplification unit, wherein the MOSFET outputs a second DC power via the drain based on the DC gate voltage, the second DC power being lower than the first DC power, wherein the MOSFET amplifies the RF input signal based on a third DC power which has a magnitude substantially identical to a differential between the first DC power and the second DC power, and outputs an RF power via the drain thereof, and wherein the bypass circuit receives and rectifies the RF power output from the drain of the MOSFET, and supplies a recycled DC power to the power supply terminal of the RF power amplification unit responsive to the rectifying.