Predistortion of a 100-W base station high-power amplifiers

Abstract

This article presents the design of a fifth-order RF predistorter for use in a base-station high-power amplifier (HPA).The predistorter uses two intermodulation (IM) signal generators, with identical configuration, to individually generate the third- and fifth-order inband intermodulation (IM3 and IM5) signals for cancellation of the third- and fifth-order intermodulation distortion products (IMDP3 and IMDP5) at the output of the HPA. The IM signal generators are constructed using two Schottky diodes as non-linear devices to generate the inband IM3 and IM5 signals. The proposed predistorter is designed and optimized using computer simulation. A hardware prototype is built and tested in a practical 100-W HPA using a standard IS-95 CDMA signal at 2.2 GHz. Measured results show that the spectral regrowth of the signal at the HPA output can be significantly suppressed over a wide range of output power levels. © 2011 Wiley Periodicals, Inc.