Impact of Wave Propagations on Figures of Merit in Millimeter-Wave Transistors

The effects of wave propagations on gain and cut-off frequency of millimeter-wave transistors are studied based on a new modeling approach. This model is developed based on the electron transport in semiconductor layers and transmission line properties of the electrodes in high-frequency transistors. In this approach, no small- or large-signal equivalent circuit is required for the analysis of the device. The electrodes of the transistor are considered as coupled multi-conductor transmission lines to represent the effect of non-uniform voltage and current distributions along the gate and drain conductors. A finite-difference time-domain solver is utilized to solve the governing equations of the distributed model. The achieved excellent agreement between the simulation and measurement results for a fabricated GaN-HEMT over a broad frequency range validates the accurate performance of the wave-electron-transport model in finding the figures of merit in W-band and beyond.