TCAD simulation of microwave circuits: The Doherty amplifier

Analysis of Doherty Power Amplifier Matching Assisted by Physics-Based Device Modelling

“…In this work, we have shown that our in-house mixed-mode drift-diffusion TCAD simulator [29], recently extended to simulate microwave circuits including multiple active devices [30], is an effective tool to investigate the optimum design of Doherty amplifiers. We have presented, for the first time, a comprehensive analysis of a GaAs Doherty amplifier, focusing in particular on the input matching and the resulting DPA gain.…”

“…In this work, we address the design of a GaAs Doherty power amplifier at 12 GHz, exploiting two MESFET devices of identical periphery (1 mm), 0.5 µm gate length and 1 µm gate-drain spacing; see [30] for details. The device output and transcharacteristics are shown in Figure 1.…”

“…For TCAD simulations, the external network has been converted into a passive 2-port described by its equivalent 2 × 2 Z matrix, as shown in Figure 3. The two MESFETs with their independent grids have been merged into a unique mesh, equivalent to a 6-terminal device with approximately 6500 grid nodes overall [30]. The two devices interact only through the external network since Neumann boundary conditions ensure isolation at the GaAs level.…”

“…A first demonstration of the TCAD simulation of the Doherty stage of Figure 3 in low-frequency conditions was given in the pioneering paper [30], where a preliminary analysis could identify the AUX optimum bias for class C operation, shown in Figure 1 (blue marks), corresponding to V GS = −5 V. The same is adopted in this work.…”