Yonghao Jia

Multipole Modes Excitation of uncoupled dark Plasmons Resonators based on Frequency Selective Surface at X-band Frequency Regime

In this report, we theoretically and experimentally demonstrates that multipole modes could be excited effectively in dark plasmonic resonators without introducing any other bright resonators at microwave range based on a two-dimensional frequency selective surface (FSS) structure. These excited multipole resonances are closely related to the coupling strength between adjacent S-LSPs resonators (the periodicity of the FSS). The modes splitting effects and resonance frequencies of the excited multipole modes are regulated by changing the numbers of grooves and inner disk radius, both of which play significant roles in the excitation of the dark S-LSPs disk resonator at normal incidence. Moreover, the multipole resonances characteristics of dark S-LSPs resonators in the case of oblique incidence are also presented. Observation of such multipole resonances in dark S-LSPs without introducing extra bright resonance at normal/oblique incidence would find more potential applications in microwave and terahertz based sensors, plasmonic resonance devices and metamaterial devices.

A new Inter-electrode coupling capacitance extraction method for deep-submicron AlGaN/GaN HEMTs

The accurate extraction of inter-electrode coupling capacitances (IECCs) is a difficult but important issue in small-signal modeling of highly scaled transistors. In this paper, a new method of determining the IECCs for deep-submicron aluminium gallium nitride/gallium nitride (AlGaN/GaN) high electron–mobility transistors (HEMTs) is proposed. The method uses the pinch-off S-parameters under large drain bias to eliminate the influence of intrinsic capacitance on IECCs extraction, thereby determining the reliable starting value of IECCs. Compared with the conventional method, this method not only greatly reduces the parameter searching range in final value optimization but also avoids the non-physical extraction value for intrinsic parameters. Using this method, we build a small-signal model for a 0.15 μm gate-length GaN HEMT. The measured data show that this method has high precision and can be applied to the modeling of millimeter-wave GaN HEMTs.

A robust small-signal equivalent circuit model for AlGaN/GaN HEMTs up to 110 GHz

In this paper we present an accurate and robust small-signal equivalent circuit model(SSECM) for GaN/AlGaN HEMTs. To extend the operating frequency, a flexible equivalent circuit network for parasitic parameters is proposed. The equivalent circuit network is constructed by a number of (N) seriate equivalent resist, inductance and capacitance (Rn-Ln-Cn), which accounts for distribution effects of gate and drain feeding line. The number of seriate R-L-C can be chosen by the maximum operating frequency flexibly. As a result, we can get an accurate SSECM on certain frequency range with the minimum cost of extraction procedure and time. The proposed parasitic model has been added in the conventional SSECM and a GaN HEMT with gate length 0.1μm and 2×100μm is used for validation. The results show that the SSECM with N=2 and N=3 can well describe the scattering parameters with maximum frequency up to 66GHz and 110 GHz, respectively.

A ultra-wideband empirical large-signal model for AlGaAs/GaAs HEMTs

An accurate large-signal GaAs HEMT modeling is very important for microwave and millimeter wave power MMIC amplifier design. This paper presents a complete GaAs HEMT model suitable for ultra-wide band application. The model is realized with an improved drain current (Ids) formulation with self-heating and charge trapping modification. This large-signal GaAs HEMT modeling is validated for a wideband frequency from 12GHz to 40GHz and can predict fundamental output power, gain, and power added efficiency accurately.