Patent ID: 7839216

Claim:
A power amplifier device, comprising: an input port that receives an RF signal to be amplified in power; an output port that outputs the RF signal that is amplified in power; a plurality of cells electrically coupled to amplify the received RF signal, each of the cells having a first end coupled to the input port and a second end coupled to the output port and comprising one or more banks of transistors; a bias circuit that provides a bias signal to turn on at least one bank of transistors in the plurality of cells and maintains a bias at the at least one bank during amplification of the RF signal; an RF signal detector circuit that detects the RF signal to produce a detected voltage; and a bias control circuit that receives the detected voltage, produces control signals based on the detected voltage, and supplies, respectively, the control signals to the banks of transistors other than the at least one bank of transistors that is biased on, to control an output current to increase with an increase in the control signals, wherein the cells, the bias circuit, the RF signal detector circuit and the bias control circuit are configured to increase an output power associated with the output current to increase a linear region and efficiency at a power back-off condition.