Patent ID: 8354883

Claim:
A power amplifier comprising: an envelope detector configured to detect an envelope of an input signal; a bias power generator including at least two transistors having opposite polarities and connected to each other in an inverter manner between a driving power terminal for supplying driving power having a preset voltage level and a reference bias power terminal for supplying preset reference bias power, the bias power generator configured to generate bias power varied according to a detection result from the envelope detector; and an amplifier configured to amplify the input signal according to a level of the bias power from the bias power generator, wherein the at least two transistors comprise at least a P-type metal-oxide-semiconductor field-effect transistor (MOSFET) and an N-type MOSFET, and the envelope detector includes: a first resistor having a first terminal and a second terminal, the first terminal of the first resistor being connected to the driving power terminal; a first capacitor having a first terminal and a second terminal and connected to the first resistor in parallel, the first terminal of the first capacitor being connected to the driving power terminal; and a first N-type MOSFET having a drain connected to the second terminal of the first resistor and the second terminal of the first capacitor, a source connected to a ground, and a gate for receiving the input signal.