Linearity improvement of RF power amplifiers using a simple high-order predistorter for WCDMA applications

A simple high-order predistorter to cancel the 3
^rd
- and 5
^th
-order intermodulation (IM3 and IM5) components of RF power amplifiers is proposed. The IM3 and IM5 components are cancelled out simultaneously by using their identical magnitude and phase difference in the predistorter and power amplifier. For experimental verification, a high-order predistorter has been implemented and tested with a 45-W class-AB power amplifier at wide-band code division multiple access (WCDMA) band of 2.11–2.17 GHz. The measured results show the significant cancellation of IM3 and IM5 components for a two-tone test and the notably improved adjacent channel leakage ratio (ACLR) for four-carrier WCDMA applications over a wide range of output power levels.