Optimization of sub-0.1-μm offset Γ-shaped gate MHEMTs for millimeter-wave applications

We examine the effects of device scaling in both vertical and lateral dimensions for the metamorphic high electron mobility transistors (MHEMTs) on the DC and millimeter-wave electrical performances by using a hydrodynamic transport model. The well-calibrated hydrodynamic simulation for the sub-0.1-μm offset Γ-gate In_0.53Ga_0.47As/In_0.52Al_0.48As MHEMTs shows a reasonable agreement with the electrical characteristics measured from the fabricated 0.1 μm devices. We have calibrated all the parameters using the measurement data with various physical considerations to take into account the sophisticated carrier transport physics in sub-0.1-μm devices. Being simulated with these calibrated parameters, the optimum device performance is obtained at a source-drain spacing of 2 μm, a gate length of 0.05 μm, a barrier thickness of 10 nm and a channel thickness of 12 nm.     

Comparative studies on electronic transport due to the reduced dimensionality at the heterojunctions of GaAs/A1xGa(1−x)As and GaxIn(1−x)As/InP systems at low temperatures

Comparative studies on ac/dc mobility due to the reduced dimensionality of spatially confined low dimensional systems, at the heterojunctions of GaAs/A1_xGa_(1−x)As and Ga_xIn_(1−x)As/InP forming quasi-two dimensional (Q2D) and quasi-one dimensional (Q1D) systems have been made. The effect of various low temperature nonphonon scattering mechanisms such as ionized impurity, alloy disorder scattering and surface roughness scattering mechanisms; and phonon scattering mechanisms such as acoustic phonon via deformation potential and piezoelectric scattering mechanisms on the systems has been studied. It is found that the surface roughness scattering mechanism dominates in Q2D system whereas acoustic phonon scattering mechanism dominates in Q1D system due to which the nature and magnitude of the temperature dependent dc/ac mobility curves shows significant variation. Whereas, it is observed that the confinement does not change the nature of the frequency dependent real and imaginary parts of ac mobility curves. However, the mobility is found to be enhanced with effective mass and also due to the confinement, i.e. the mobility for Q1D system is higher than that for Q2D system.     

A fast seamless handover scheme and its CDT optimization for ping-pong type of movement

In mobile IPv6 networks, the ping-pong type of movement brings about frequent handovers and thus increases signaling burden. This letter proposes a fast seamless handover scheme where the access router keeps the mobile node＇s old reservation till the offline Count Down Timer （CDT） expires in order to reduce handover signaling and delay while the mobile node returns in a very short period of time. Based upon a poisson mobility model, an simple expression for CDT optimization is given out for the scheme to achieve the best cost performance of resource reservation.     

A low cost-low loss broadband integration of a CMOS transmitter and its antenna for mm-wave FMCW radar applications

A 60 GHz low-loss wideband interconnection of a CMOS transmitter and its antenna is presented in this paper. The integrated transmitter consists of an all-digital phase-locked loop (ADPLL) IC chip and a U-slot patch antenna connected through wire bonding and compensation matching circuit to operate in the 57–63 GHz frequency band. The system is implemented on a sandwiched printed circuit board (PCB) comprising FR4 to embed the ADPLL and the high-frequency Rogers laminate RO4350B for the antenna and the matching network. The matching circuit is designed in two configurations microstrip and grounded coplanar waveguide (GCPW) to compensate for the wire bond inductance. The capability and sensitivity of these two topologies considering the wire bond geometry variations are compared which points out that GCPW is more robust to wire bonding parasitic effects. Finally, the GCPW matching circuit is fabricated and interconnected to the ADPLL die and its performance is examined using hybrid simulation/measurement data.     

A Novel Cost-Effective and Programmable VLSI Architecture of CAVLC Decoder for H.264/AVC

This paper proposes a novel cost-effective and programmable architecture of CAVLC decoder for H.264/AVC, including decoders for Coeff_token, T1_sign, Level, Total_zeros and Run_before. To simplify the hardware architecture and provide programmability, we propose four new techniques: a new group-based VLD with efficient memory (NG–VLDEM) for Coeff_token decoder, a novel combined architecture (NCA) for level decoder, a new group-based VLD with memory access once (GMAO) for Total_zeros decoder and a new VLD architecture based on multiplexers instead of searching memory (MISM) for Run_before decoder. With the above four techniques, the proposed CAVLC decoder can decode every syntax element within one clock cycle. Synthesis result shows that the hardware cost is 3,310 gates with 0.18 μm CMOS technology at a clock constrain of 125 MHz. Therefore, the proposed design is satisfied for real-time applications, such as H.264/AVC HD1080i video decoding.

检测热水锅炉能耗和排污量的新型智能仪器

用传统方法检测热水锅炉使用中的污染物排放量存在很多缺点，而研究证明采用间接计算的方法是可行的。文章阐述了热水锅炉的煤耗量与其水耗量之间存在的比例关系，并叙述了比例系数的三种求法。据此理论已研制出能检测能耗与污染物排放量的新型仪器。     

一种基于DSP语音信号线性与非线性量化相互转换的新方法

文中首先对A律对数PCM的基本原理及算法进行了讨论,提出一种基于分段映射法实现A律对数PCM压缩和解压缩编码的方法,设计并实现了以TMS320VC5416为核心的语音压缩系统,并给出实现的具体原理框图.采用该方法可避免很复杂的对数和反对数计算,使信号处理速度快,同时也克服了传统的查表法要求有较大的存储空间的缺点,是一种比较好且实用的方法.     

Hybridized Nanowires and Cubes: A Novel Architecture of a Heterojunctioned TiO2/SrTiO3 Thin Film for Efficient Water Splitting

A unique morphology of SrTiO₃ nanocubes precipitated on TiO₂ nanowires is successfully synthesized in the form of a thin‐film heterojunctioned TiO₂/SrTiO₃ photocatalyst using facile hydrothermal techniques. The formation mechanisms of the synthesized photocatalysts are meticulously studied and described. Growth of SrTiO₃ single crystal nanocubes (≈50 nm in width) on anatase polycrystalline nanowires follows an in situ dissolution‐precipitation pathway. This is consonant with the classic LaMer model. By analyzing the results of field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), X‐ray diffraction (XRD), energy dispersive X‐ray (EDX) spectroscopy, X‐ray photoelectron spectroscopy (XPS), and UV‐vis spectrophotometry, a comprehensive structural and morphological characterization of the photocatalysts is established. FESEM images reveal that the anatase film comprises mainly of nanowires bristles while the tausonite film is primarily made up of nanocube aggregations. In comparison to the respective pristine semiconductor photocatalysts, the heterostructured photocatalyst demonstrates the highest efficiency in photocatalytic splitting of water to produce H₂, 4.9 times that of TiO₂ and 2.1 times that of SrTiO₃. The enhanced photocatalytic efficiency is largely attributed to the efficient separation of photogenerated charges at heterojunctions of the two dissimilar semiconductors, as well as a negative redox potential shift in the Fermi level.     

A Novel Photocathode Material for Sunlight‐Driven Overall Water Splitting: Solid Solution of ZnSe and Cu(In,Ga)Se2

Thin films of a solid solution of ZnSe and CuIn_0.7Ga_0.3Se₂ ((ZnSe) _x (CIGS) _1–x ) are prepared by co‐evaporation. Structural characterization reveals that the ZnSe and CIGS form a solid solution with no phase separation. (ZnSe)_0.85(CIGS)_0.15‐based photocathodes modified with Pt, Mo, Ti, and CdS exhibit a photocurrent of 7.1 mA cm^?2 at 0 V_RHE, and a relatively high onset potential of 0.89 V_RHE under simulated sunlight. A two‐electrode cell containing a (ZnSe)_0.85(CIGS)_0.15 photocathode and a BiVO₄‐based photoanode has an initial solar‐to‐hydrogen conversion efficiency of 0.91%, which is one of the highest values reported for a photoanode–photocathode combination. Thus, (ZnSe)_0.85(CIGS)_0.15 is a promising photocathode material for efficient photoelectrochemical water splitting.