HP Labs Technical Reports

An IC for Linearizing RF Power Amplifiers Using Envelope Elimination and Restoration

Su, David; McFarland, William

HPL-98-186

Keyword(s): RF power amplifier linearization; envelope elimination and restoration; switching power supply; delta modulation; envelope detector; limiter; variable gain amplifier

Abstract: This paper presents a monolithic CMOS implementation of an envelope elimination and restoration linearization system that improves the linearity of efficient RF power amplifiers. The linearization IC, which occupies 4.3 mm (super 2) when implemented in a 0.8-um CMOS technology, consists of a limiter, envelope detectors, and a delta-modulated switching power supply. This circuit was used to linearize AMPS (Advanced Mobile Phone System) cellular power amplifiers transmitting NADC (North American Digital Cellular) wave-forms. Measurements show that the linearized outputs meet the spectral mask and phase distortion requirements of NADC. The linearization system can improve the overall efficiency from 36% to 49%, while increasing the maximum linear output power from 26.5dBm to 29.5dBm.

21 Pages

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