直流和脉冲工作的VDMOS可靠性试验

基于恒定电应力温度斜坡法(CETRM),对工作于直流状态和脉冲状态下的VDMOS功率器件进行可靠性研究,考察了器件阈值电压、跨导以及导通电阻的退化情况,得出在两种工作状态下均是跨导为失效敏感参数。在直流工作状态下,VDMOS失效激活能为0.57~0.68 eV,寿命为7.97×105~1.15×107h;在脉冲工作状态下,VDMOS失效激活能为0.66~0.7 eV,寿命为4.3×105~4.6×106h。对跨导的退化机理进行了分析。     

A 2.1-6 GHz SiGe BiCMOS low-noise amplifier design for a multi-mode wideband receiver

正A wideband low-noise amplifier(LNA) with ESD protection for a multi-mode receiver is presented.The LNA is fabricated in a 0.18-μm SiGe BiCMOS process,covering the 2.1 to 6 GHz frequency band.After optimized noise modeling and circuit design,the measured results show that the LNA has a 12 dB gain over the entire bandwidth, the input third intercept point(IIP3) is -8 dBm at 6 GHz,and the noise figure is from 2.3 to 3.8 dB in the operating band.The overall power consumption is 8 mW at 2.5 V voltage supply.     

家庭网络中融合语音通信技术研究

在未来数字家庭中,宽带产品内融合无绳语音服务可以为用户提供更舒适的数字化生活体验。本文比较、分析了数字无绳语音业务融合型家庭宽带产品技术方案,给出了技术方案选择建议,并通过测试进行了验证。     

Numerical study on the short-circuit current in single layer organic solar cells with Schottkey contacts

The effects of the cathode operation voltage,the absorption coefficient,the carrier mobility,the temperature and the thickness of organic active layer on the short-circuit current density of single layer organic solar cells(OSCs) with Schottkey contacts are numerically studied.Quantitative dependences of the short-circuit current density on the respective parameters are obtained.The results show that a larger operation-voltage difference between the anode and the cathode,a higher carrier mobility as well as...     

Robust beamforming in cognitive radio

This letter considers the multi-antenna cognitive radio (CR) network, which has a single secondary user (SU) and coexists with a primary network of multiple users. Our objective is to maximize the service probability of the SU, subject to the interference constraints on the primary users (PUs) in the form of probability. Exploiting imperfect channel state information (CSI), with its error modeled by added Gaussian noise, we address the optimization for the beamforming weights at the secondary transmitter. In particular, this letter devises an iterative algorithm that can efficiently obtain the robust optimal beamforming solution. For the case with one PU, we show that a much simpler algorithm based on a closed-form solution for the antenna weights of a given power can be presented. Numerical results reveal that the optimal solution for the constructed problem provides an effective means to tradeoff the performance between the PUs and the SU, bridging the non-robust and worstcase based systems.     

基于无线传感器网络门禁系统研究

介绍了一种操作方便、运行可靠的智能型无线门禁系统,系统前端探测器与主机微处理器之间传送数据采用无线方式,克服了有线式门禁系统布线的困难,避免了布线后会影响美观性的缺陷。系统采用模块化的设计思想,通过微控制器控制无线模块nRF905进而实现对TCS3C-TCD42A所采集的数据进行无线收发。该系统成本低、实用、可靠、功能灵活多样,可广泛用于银行、仓库和家庭等重要场所。     

基于颜色的运动目标快速识别与跟踪

在自主式移动机器人对运动目标进行跟踪时,视觉系统主要完成目标的识别与跟踪,提高目标识别与跟踪的实时性和准确性是保证机器人跟踪顺利进行的关键。针对此提出了一种基于颜色色度Hs的向量判定算法,并运用这种算法结合动态窗口和螺旋扫描等技术,有效地提高了目标识别与跟踪的实时性和准确性。     

Nano-WO3 film modified macro-porous silicon（MPS） gas sensor

We prepared macro-porous silicon（MPS） by electrochemical corrosion in a double-tank cell on the surface of single-crystalline P-type silicon.Then,nano-WO₃ films were deposited on MPS layers by DC facing target reactive magnetron sputtering.The morphologies of the MPS and WO₃/MPS samples were investigated by using a field emission scanning electron microscope.The crystallization of WO₃ and the valence of the W in the WO₃/MPS sample were characterized by X-ray diffraction and X-ray photoelectron spectroscopy,respectively. The gas sensing properties of MPS and WO₃/MPS gas sensors were thoroughly measured at room temperature. It can be concluded that:the WO₃/MPS gas sensor shows the gas sensing properties of a P-type semiconductor gas sensor.The WO₃/MPS gas sensor exhibits good recovery characteristics and repeatability to 1 ppm NO₂.The addition of WO₃ can enhance the sensitivity of MPS to NO₂.The long-term stability of a WO₃/MPS gas sensor is better than that of an MPS gas sensor.The sensitivity of the WO₃/MPS gas sensor to NO₂ is higher than that to NH₃ and C₂H₅OH.The selectivity of the MPS to NO₂ is modified by deposited nano-WO₃ film.     

Electrochemical Deposition and Characterization of Thermoelectric Ternary (Bi x Sb1?x )2Te3 and Bi2(Te1?y Se y )3 Thin Films

Thermoelectric thin films of the ternary compounds (Bi _x Sb_1?x )₂Te₃ and Bi₂(Te_1?y Se _y )₃ were synthesized using potentiostatic electrochemical deposition on gold-coated silicon substrates from aqueous acidic solutions at room temperature. The surface morphology, elemental composition, and crystal structure of the deposited films were studied and correlated with preparation conditions. The thermoelectric properties of (Bi _x Sb_1?x )₂Te₃ and Bi₂(Te_1?y Se _y )₃ films, i.e., Seebeck coefficient and electrical resistivity, were measured after transferring the films to a nonconductive epoxy support. (Bi _x Sb_1?x )₂Te₃ thin films showed p-type semiconductivity, and the highest power factor was obtained for film deposited at a relatively large negative potential with composition close to Bi_0.5Sb_1.5Te₃. In addition, Bi₂(Te_1?y Se _y )₃ thin films showed n-type semiconductivity, and the highest power factor was obtained for film deposited at a relatively small negative potential, having composition close to Bi₂Te_2.7Se_0.3. In contrast to Bi₂Te_2.7Se_0.3 thin films, an annealing treatment was required for Bi_0.5Sb_1.5Te₃ thin films to achieve the same magnitude of power factor as Bi₂Te_2.7Se_0.3. Therefore, Bi₂Te_2.7Se_0.3 thin films appear to be good candidates for multilayer preparation using electrochemical deposition, but the morphology of the films must be further improved.     

A Polymer/Carbon‐Nanotube Ink as a Boron‐Dopant/Inorganic‐Passivation Free Carrier Selective Contact for Silicon Solar Cells with over 21% Efficiency

Traditional silicon solar cells extract holes and achieve interface passivation with the use of a boron dopant and dielectric thin films such as silicon oxide or hydrogenated amorphous silicon. Without these two key components, few technologies have realized power conversion efficiencies above 20%. Here, a carbon nanotube ink is spin coated directly onto a silicon wafer to serve simultaneously as a hole extraction layer, but also to passivate interfacial defects. This enables a low‐cost fabrication process that is absent of vacuum equipment and high‐temperatures. Power conversion efficiencies of 21.4% on an device area of 4.8 cm² and 20% on an industrial size (245.71 cm²) wafer are obtained. Additionally, the high quality of this passivated carrier selective contact affords a fill factor of 82%, which is a record for silicon solar cells with dopant‐free contacts. The combination of low‐dimensional materials with an organic passivation is a new strategy to high performance photovoltaics.