Extended Cann model for behavioral modeling of envelope tracking power amplifiers

摘要

This paper deals with behavioral modeling of power amplifiers (PAs) for envelope tracking (ET) applications. In such a scenario, the power supply modulation brings in several additional challenges for the system design and, similarly, it becomes more difficult to obtain an accurate and general PA model. This work addresses these modeling challenges proposing a solution to improve model accuracy and generality including the modulated supply voltage Venv as an independent variable. The model typology proposed in this work is in the form of an equivalent baseband behavioral model and it is achieved extending the well-known Cann model. The Cann model is extended including the modulated supply voltage Venv as a new independent variable, enhancing the AM/AM model so that it can mimic PA memory effects and defining a dynamic nonlinear AM/PM function that can model the phase distortions introduced by the ET operation. The model performance is tested modeling data-sets acquired from an ET test bench including a commercial RFMD PA and an envelope modulator designed using a commercial IC from TI.