TCAD assisted design of the Doherty Power Amplifier

Nonlinear physics-based TCAD simulations based on the Harmonic Balance technique represent an important tool to link the performance of microwave circuits to the active device fabrication technology (Guerrieri et al., 2016 [1,2]). While nonlinear TCAD simulations were previously limited to the analysis of circuits including a single device, starting from Guerrieri et al. (2022) they have been extended to circuits with multiple interacting devices. This work, further extending Guerrieri et al. (2022), shows a complete example of the design of a Doherty Power Amplifier fully assisted by TCAD nonlinear simulations. The analysis allows for a complete inspection of the internal physical variables of the DPA, including carrier concentrations and electrostatic potential, making it possible to verify the correct operation of the main and auxiliary devices. The proposed DPA, exploiting a GaAs MESFET technology, achieves 30 dBm output power at 12 GHz with peak Power Added Efficiency (PAE) of 52% at 6 dB Output Power Back-off (OBO) and 5 dB gain. The reported results show that the power split ratio between the MAIN and AUX amplifier can be used to achieve a good compromise between linearity and efficiency.