Empowering GaN-Si HEMT Nonlinear Modelling for Doherty Power Amplifier Design

New system architectures oriented to more and more challenging performance for the next generations of mobile devices demand for an accurate design of integrated circuits. The power amplifier is one of the most critical components in an RF system and the need for high performance has focused the designer attention to complex architectures, such as the Doherty power amplifier (DPA). In its most common implementations, the design requires transistor models showing high-accuracy levels under different classes of operation. In this work, we investigate the possibility of achieving the required level of accuracy for the transistor current-generator model using a set of measurements performed under the different classes of operation that mimic realistic device operation and use them for the model optimization. The developed approach is fully validated on a 28-GHz MMIC DPA, showing good agreement with the measured results.