Dynamic biasing in SiGe HBT for wideband step envelope tracking power amplifiers

This article investigates the use of reconfigurable class‐AB power amplifiers in wideband step envelope tracking (SET) architectures. The experimental results are related to a SiGe‐HBT power‐device prototype in which a dynamic switching capability has been integrated. The SET architecture is complemented by a digital predistortion algorithm and the resulting structure (circuit plus algorithm) is analyzed at system level. As a result, the SiGe prototype is capable to provide 20 dBm total output power with EVM = 5.1%. In the case of 802.11g and WCDMA signals the proposed approach gives a relative average PAE enhancement in excess of 46% with respect to traditional class‐AB RF power amplifiers. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.