Amplifiers

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Upcoming generations of radio access standards are placing high demands on the RF transmit chain, requiring significant improvements in size, integration, and functionality while improving power efficiency for multimode wireless devices. To date, trends in RF integration have been to add redundant circuits to accommodate new standards, packing more complexity into the circuit, and then shrinking it. However, this approach often requires a necessary compromise in performance and yield, with physical limits in terms of overall size reductions. A new approach is needed that incorporates a streamlined architecture to accommodate the additional levels of complexity due to multimode functionality, while improving efficiency, yield, and size, and meeting regulatory compliance.

In this paper, Part 3 of our three-part series on 3G/4G multimode handsets, the authors will examine the fundamental challenges engineers face when designing front ends to be multi-band and multi-standard across different modulations.

This article is targeting on a technology of adjustable DC-DC converters, which can be implemented with GSM-GPRS-EDGE power amplifiers, as it is already widely used in CDMA/WCDMA handsets. Simulations show why this has not been used so far and how important the battery average consumption savings could be, with this low complexity technology used instead of a polar-loop architecture, which is under high effort recently in many companies.