Power Amplifiers Linearization Based on Digital Predistortion with Memory Effects Used in CDMA

Efficient RF power amplifiers used in third generation systems require linearization in order to reduce adjacent channel inter-modulation distortion, without sacrificing efficiency. Digital baseband predistortion is a highly cost-effective way to linearize Power amplifiers (PAs), but most existing architectures assume that the PA has a memoryless nonlinearity. For wider bandwidth applications such as wideband code-division multiple access (WCDMA) or wideband orthogonal frequency-division multiplexing (W-OFDM),PA memory effects can no longer be ignored. In this paper we proposed a new technique for adaptation of digital predistorter that considers memory effects in power amplifiers. This new technique is validated by using a 1.9 GHz 85 W LDMOS power amplifier and various signals such as 3-carrier CDMA and IS95 CDMA.