Highly efficient multiband and broadband power amplifiers for modern RF transmitters

This dissertation deals with the development and implementation of novel architectures and concepts as efficiency enhancement techniques for multiband and broadband RF power amplifiers, which are crucial for multiband/ multimode or software-defined, high-speed modern wireless communications. The concurrent multiband Doherty power amplifier in this work is the first efficiency enhancement architecture ever proposed for more than two bands. What makes it possible is the realization of multiband passive components, especially the impedance inverter network. The design concept has been validated with the implementation of concurrent triband and quadband Doherty PAs. The sequential power amplifi er with Doherty-type active load modulation (SPA-D) has also been devised as a wideband solution to reduce energy consumption of wireless transmitters. The SPA-D concept exploits a specific load modulation region that has, so far, not been used in the Doherty PA to approximate the sequential behavior as found in the broadband sequential power amplifi er (SPA) by adopting a new output combiner. The PA provides a highly efficient amplifi cation for wideband modulated signals of large crest factor imposed by modern wireless systems, such as WCDMA, LTE etc. The concept is also extended to 3-way architecture for larger output power back-off of up to14 dB. Both multiband and broadband effi ciency enhancement architectures are suited for a wide range of applications from low to high power and from wireless LAN, 3G, 4G, and 5G mobile communication systems, Terrestrial Digital Video Broadcasting (DVB-T) all the way to Radar.