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 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.