Complete parasitic‐capacitance‐shell extraction of high‐frequency switch‐HEMT equivalent‐circuit model

This paper presents a new solution to a particular problem of high electron-mobility transistor (HEMT) equivalent-circuit modeling, that is, complete parasitic-capacitance-shell extraction of high-frequency single-gate and dual-gate switch-based HEMTs, which is very important to the accuracy of high-frequency HEMT switch models, but not important in the conventional common-source HEMT modeling for amplifier-applications. A full-wave electromagnetic (EM) analysis based method is proposed to analytically extract the complete parasitic-capacitance-shell of single-gate and dual-gate switch-based HEMTs. All the 6 parasitic capacitances of the single-gate switch-based HEMT and all the 10 parasitic capacitances of the dual-gate switch-based HEMT are extracted by linear equations. No resistance parameter is needed to calculate the capacitance-to-ground and the interelectrode-capacitance, and for the first time, all the 10 parasitic capacitances of the dual-gate switch-based HEMT are completely considered and analytically extracted. Then, a consistent and systematic modeling procedure of single-gate and dual-gate switch-based HEMT is verified. With the complete parasitic-capacitance-shells extracted, the accurate intrinsic model of the single-gate HEMT can be directly embedded into the parasitic-shell of the dual-gate HEMT. The predicted scattering parameters of the single-gate and dual-gate series switches fit well with the measurements up to 40 GHz, and accurate linear scalability are also found.