Highly linear predistortion power amplifiers with phase-controlled error generator

Abstract

A simple predistortion technique to cancel the fifth-order intermodulation (IM5) as well as third-order intermodulation (IM3) components using a third-order predistorter (PD) is represented. The IM3 and IM5 components are cancelled out simultaneously by their same magnitude and phase difference in the PD and power amplifier (PA). Moreover, this phase difference is controlled by using the phase-controlled error generator in the PD. For experimental verification, a third-order PD has been implemented and tested in a 30-W class-AB PA at the wide-band code division multiple access (WCDMA) band of 2.11-2.17 GHz. Two-tone test results show that significant cancellation of the IM3 and IM5 components can be obtained. For a four-carrier WCDMA,application, significant adjacent channel leakage ratio improvement is achieved over a wide range of output power levels.