Advanced architectures for high-efficiency multi-mode, multi-band terminal power amplifiers

Ubiquitous mobile coverage is the responsibility of the mobile device at this time, since there is no single system type deployed worldwide. The widely varying signal types used by the deployed systems require a mobile device to be extremely flexible. This flexibility comes at a generally unacceptable cost when conventional linear RF techniques are used. Alternative architectures, based on polar signal processing, show promise in their ability to meet all requirements. These techniques are compared and contrasted, leading to the presentation of encouraging preliminary results for direct polar technology.