New RF power amplifiers modeling and identification for wideband applications

This paper presents a new time-domain model of radio frequency power amplifiers (RFPA) for wideband applications. The proposed model identification requires a set of characterization procedures of a memory polynomial model with delay taps for a two-tone test. This first characterized model is described using amplitude AM/AM and phase AM/PM characteristics including delay and gain parameters, which is able to reproduce distortion sideband asymmetries. A two-tone signal with varying tone spacings is used to find the frequency response of parameters on each nonlinearity order. These response are used to estimate equivalent digital filters giving the final structure of a wideband model. The measurement tests on a Class AB -1.85 GHz RFPA from advanced semiconductor business with various multitone signals show that the proposed architecture describes PA nonlinearities and memory effects with a high level of accuracy.