A Two-Port Nonlinear Dynamic Behavioral Model of RF PAs Subject to Wideband Load Modulation

This work presents a full two-port, i.e., double input-double output, behavioral modeling approach suitable for radio frequency power amplifiers (PAs) in the presence of dynamic load modulation (DLM). The formulation of the model, based on a first-order approximation of a modified Volterra series, accounts for the nonlinear distortion determined by large-signal operation under mismatched conditions, and also for the memory effects stimulated by a modulated PA input signal, or by the dynamic variations of the PA load. By following an exhaustive procedure defined in the frequency domain, the model of a general purpose commercial PA is extracted over 160 MHz of modulation bandwidth (BW) with nonlinear vector network analyzer measurements. Validation results under 20-MHz BW multisine excitation and injected 80-MHz BW multisine load modulation show improved prediction capabilities with respect to quasi-static or single-input descriptions, allowing for reliable system-level simulations in the presence of DLM.