Baseband Equivalent Volterra Series for Behavioral Modeling and Digital Predistortion of Power Amplifiers Driven With Wideband Carrier Aggregated Signals

This paper presents a new baseband equivalent (BBE) Volterra-series model suitable for the behavioral modeling and linearization of wideband RF power amplifiers (PAs). Starting with passband Volterra series, and following a number of signal transformations, a discrete expression relating the envelopes of the output and input signals to the carrier frequency was derived. The new BBE Volterra series reduces the number of kernels, and hence, avoids resorting to the pruning approaches commonly applied in the literature to the classical low-pass equivalent (LPE) Volterra formulation. The proposed baseband Volterra series has similar modeling and linearization performance to the full classical LPE Volterra series. It also outperforms the pruned LPE Volterra models, which use a dynamic deviation reduction approach, in terms of both linearization performance and complexity. The proposed BBE Volterra series was successfully used to linearize different PAs (200-W LDMOS Doherty and 45-W broadband GaN PA) driven with wideband and intra-band carrier aggregated signals (mixed LTE and WCDMA signals).