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Extensive studies have concluded that breakdown mechanisms in Gallium Nitride (GaN) High Electron Mobility Transistors (HEMT) can be improved by substrate reduction and the addition of field plate (FP) on their structures. A theoretical analysis of the FP effects on the HEMT is carried out by modeling the electric fields inside the structure. The electric field model is deduced by solving the potential...
In this paper, a reflective metasurface consists of 19 × 19 unit cells is designed, which can effectively convert general incident linear co-polarized wave to orbital angular momentum (OAM) with different modes. Using this reflective metasurface, we achieved OAM with mode 1, 2 and 3, and provides their phase and magnitude distribution in near field, as well as far field radiation pattern. Reflective...
“Acoustic angiography” is a super-harmonic contrast imaging technique, which is based on the fact that when excited with a moderate acoustic pressure near their resonance (2–4 MHz; around MI of 0.5–0.7) ultrasound contrast agents produce broadband content which extends well past 15 MHz. By detecting the higher order harmonic energy while transmitting at a low fundamental frequency, exquisite resolution...
I.H.P. SAW (Incredible High-Performance SAW) has a novel multi-layered structure to confine SAW energy in substrate surface area, and it shows extremely high quality (Q) factor, low temperature coefficient of frequency (TCF) and improved electromechanical coupling coefficient (K2). This paper introduces its mechanism of the high acoustic Q factor, both theoretically and experimentally, and its applications...
SAW filter technology includes different substrates, multilayered electrodes from Al, Cu, Pt, …, dielectric sublayers and over-layers, etc. Temperature compensated SAW filters have been developed that have performance competitive with FBARs. Traditional design tools, such those as based on COM models, demand experimental characterization of wave propagation parameters. FEM/BEM models cannot be easily...
A CRF/DMS filter is simulated using “Layers” software [1-2]. We analyze a few different CRF/DMS structures, including the 10-port CRF device with passband frequency close to 1842.5 MHz including 5 IDTs, 8 “gap IDTs” and 2 reflectors. This TC SAW structure has a thick SiO2 over layer covering 274 Cu electrodes on a 128° LiNbO3 substrate. In addition to the electrical network parameters for the filter,...
As compared to piezoelectric technology, MEMS technology employed for Capacitive Micromachined Ultrasonic Transducer (CMUT) fabrication provides increased compatibility with 3D packaging methods, enabling the possible development of advanced transducer-electronics multi-chip modules (MCM) for medical imaging applications. In this paper, an acoustically optimized 3D packaging method for the interconnection...
In this paper, a 2 × 8 elements ultra-wideband tightly coupled dipole antenna array is presented. The array is constructed by placing alternate dipole elements on the opposite sides of a substrate. The array is designed to operate in the FCC frequency band for ultra-wideband (3.1 GHz to 10.6 GHz) wireless communication. The mutual coupling between the elements in the proposed array is high and it...
The heat generated by self-propagating exothermic reaction can be used to melt solder and then join the components. However, the microstructure of self-propagating interconnects is different from those obtained through traditional soldering process for its unique thermal conditions. In this paper, a finite element model was established to simulate the temperature field of self-propagating joints at...
In this paper, a new packaging structure was proposed to reduce the heat accumulation of high-power UV-LEDs using silicone encapsulant with high thermal conductivity. The simulations for the thermal behavior of the traditional and proposed structures had been performed using finite element analysis (FEA). It was obtained that the improvement of temperature distribution was obviously enhanced as the...
Junction temperature of the IGBT chip is 200 °C. IGBT chip would be damaged by high temperature and long-time heating in reflow or nanosilver sintering process. Therefore, Al/Ni self-propagating foil was investigated as a heat source to bond IGBT chip and DBC substrate for a short affecting time and small thermal damage on the chips. In this paper, finite element method was used to simulate the soldering...
Small and high-precision piezoresistive pressure sensor based on graphene/hexagonal boron nitride (h-BN) heterostructures can be embedded in aircraft airborne equipment, allowing for potential application involving fault diagnosis, prognostics and health management. In this paper, the pressure-sensing characteristics of graphene/h-BN heterostructures membrane — the relationship between pressure and...
A new type of acoustic wave device based on buried waves is proposed. Characteristic to the device is that wave guidance is achieved through the use of heavy metal electrodes buried deep inside a piezoelectric substrate. Such as a structure can be realized, for example, with wafer-wafer bonding techniques. In this work, simulations are used to characterize devices consisting of platinum electrodes...
Design of unit cell of Microstrip Reflectarray Antenna (MRA) is one of important parameter. Using infinite array approach method, resonant element of MRA is observed in unit cell environment. The reflection phase curve helps to compare the different commercially available dielectric materials.
A novel suspended GeSn microstructure is demonstrated by selective etching of GeSn thin film on Ge. XRD and μ-Raman measurements show that the compressive strain in the GeSn thin film is effectively relaxed, and furthermore, unexpected tensile strain was introduced in the suspended GeSn.
A periodic frequency selective surface (FSS) having triple frequency band reject behaviour has been proposed with a square and two dodecagon shaped element. These three elements of the FSS unit cell are embedded on the FR-4 substrate, which acts as a triple band reject filter on the frequency band 1.8 GHz, 2.5 GHz and 5.5GHz to avoid the leakage of GSM, WiMax and WLAN signal outside the building....
This paper teaches the way to achieve an optimum substrate isolation in RF switch design thanks to Deep Trenches Isolation (DTI). The role of Deep Trench Isolation in substrate coupling around active blocks is analysed in link to its ability to break the conductive buried layers in the substrate. Then, an accurate modelling approach based on quasi-static approach developed for inhomogeneous substrate...
A novel and systematic methodology to predict the warpage of extremely thin packages is proposed. The geometrical and material inhomogeneities of both die and substrate are included in the prediction methodology. The inhomogeneous thermo-mechanical properties of dies due to the thermal incompatibility between silicon substrate and active/passive layers are inversely extracted from the Shadow Moiré...
The key role that underfill materials play in highly reliable, advanced flip chip organic packages has generated an increased focus on their behavior and structure. One such behavior relates to the observation of filler separation from the resin matrix which, to date, has been predominantly attributed to gravity or capillary flow. The phenomenon of silica filler separation is discussed in the context...
The Glass interposer is proposed as a superior alternative to organic and silicon-based interposers for 3D IC (Integrated Circuit) packaging and 2.5D TSV (Through Silicon Vias) package in the near future. The several attractive advantages such as excellent electrical isolation, better RF performance, better feasibility with CTE, could be fabricated with large size. However, the thin glass is extremely...
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