Dynamic biasing techniques for RF power amplifier linearity and efficiency improvement

Nowadays, mobile handsets have to deal with several challenges. First of all, a good efficiency is essential in order to save power and battery life-time. Then, to cater to multi-standards operation which provide very high data rates, strong linearity performances are mandatory, to the expense of transmit front-end efficiency. As RF Power Amplifiers (PAs) are the most power consuming components, this paper describes an approach of managing the efficiency-linearity trade-off by using dynamic biasing. The dynamic biasing allows a power control of the PA and is brought into play both with an open-loop solution and a closed-loop solution. The main purpose of the paper is to present a description of the circuits developed and their performances in terms of output power, linearity and efficiency. The reconfigurable PAs are dedicated to UMTS-WCDMA and WiFi/WiMAX standards.