Meeting the Needs of Cellular Dual-Mode(EGPRS/3G) Power Amplifiers with aUnique J-PHEMT Process and NovelControl Architecture

Based upon a unique Junction-PHEMT device, a novel method of providing high efficiency PA power control for variable envelope modulation schemes is demonstrated for EDGE and WCDMA. The method of control allows for substantially higher efficiency levels under typical handset operating conditions than those of conventional linear power amplifiers, on a par with polar loop solutions, whilst avoiding the necessity for complex control loops. An immediate benefit of the approach includes the ability to add EDGE front-end capability to a GSM handset without incurring a significant size or component cost impact. Furthermore, the method of control aids the future prospect of single transmit strip multi-mode configurations (GSM/EDGE/WCDMA) in order to achieve considerable size and cost advantages.