New transistor behavioral model formulation suitable for Doherty PA design

• Autor(a) principal: Louro, João
• Data de Publicação: 2021
• Outros Autores: Belchior, Catarina, Barros, Diogo R., Barradas, Filipe M., Nunes, Luís C., Cabral, Pedro M., Pedro, José C.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/40308
• topic: Artificial neural network (ANN); Behavioral model; Doherty; Load modulation; Passive load-pull; Power amplifier

This work presents a new artificial neural network (ANN) model formulation for RF high-power transistors which includes the S-parameters of the active device. This improves the small-signal extrapolation capability, and the OFF-state impedance approximation, making it suitable for Doherty power amplifier (DPA) design. This extrapolation capability plays a key role in the correct Doherty load modulation prediction, since, at low power levels, the peaking PA is subjected to active loads that cannot be synthetized with a passive load-pull system, forcing the model to extrapolate. Thus, the proposed model formulation is able to solve the issues that are normally observed when ANN-based models are used in complex PA architectures as the Doherty PA. To validate the proposed behavioral model, a 700-W asymmetrical LDMOS DPA, centered at 1.84 GHz, was simulated and measured.