Global Modeling of Millimeter-Wave Transistors: Analysis of Electromagnetic-Wave Propagation Effects

Abstract

In this study, the transmission line concept and the electron transport theory are consolidated in a global modeling approach, the wave-electron-transport (WET) model, to account for the physical phenomena in millimeter-wave devices. No equivalent circuit model is required to represent the innate properties of the device. Hence, the model is reliable for both small-and large-signal analyses. The electrodes of a transistor act as coupled multi-conductor transmission lines at millimeter-wave bands. The WET model consists of a device solver to obtain solutions for carrier-transport equations of the intrinsic device, and an electromagnetic solver (EM solver) to provide solutions for the governing transmission lines equations. As it is crucial to transfer data between these two solvers, an interface scheme is also developed and included in the WET model. The extrinsic parameters of the device are extracted using a novel systematic technique merely based on the physical structure of the transistor. In this paper, the modeling procedure is applied to a fabricated GaN-HEMT device. Power sweep analysis has verified the accuracy of the proposed model under both linear and non-linear operations. Non-uniform voltage distribution caused by traveling waves over the electrodes is elaborately discussed to demonstrate the necessity of incorporating distributed effects.INDEX TERMS Electromagnetic-wave propagations, millimeter-wave transistor, non-linear operations, transmission line concept, wave-electron-transport model.

Effects of Electrodes Layout on Performance of Millimeter-Wave Transistors

“…The capacitance is calculated using a conformal mapping technique, which includes adjustments to account for metallization thickness. The value of inductance is obtained through wave speed theory, assuming a quasi-TEM mode of propagation [1].…”

“…Millimeter-wave transistors are crucial components in the design of monolithic microwave integrated circuits (MMICs). However, nonphysical models used for these transistors have limited accuracy and are not predictive beyond their range of validation [1]. To overcome this limitation, it is essential to incorporate device physics into the modeling methodologies for high-frequency transistors.…”

Analysis of electromagnetic interaction between smooth and corrugated transmission lines by using a circuit model

“…We should point out that in order to accurately extract the circuit parameters of the millimetre-wave transistors, it is an inevitable trend to use the full-wave analysis. Recently, electromagnetic wave propagation effect on the electrodes of millimetre-wave transistors has been analyse by electromagnetic numerical methods [37,38]. The electrodes of a transistor act as the coupled multi-conductor transmission lines.…”