微带线不连续性对光电导开关非线性特性的影响

实验对自行研制的全固态同轴―微带型横向半绝缘砷化镓(SI-GaAs)光电导开关传输特性进行了研究：当偏置电压达到一定阈值时,普通开关进入了非线性锁定（Lock-on）工作模式;在相同实验条件下,当微带线出现不连续时,输出的电脉冲波形没有出现锁定现象;分别用空气击穿的流注模型和微带线等效电容机理分析了微带线不连续效应引起整个开关电路性能变化及抑制开关Lock-on效应的原因。     

射频微波晶体管的发展现状及分析

对当前各种类型射频微波晶体管的结构特点、性能和应用情况进行了分析和综述.对晶体管的发展历史进行了全面而细致的回顾,指明了今后射频微波晶体管的发展特点和发展趋势,得出了射频微波晶体管的选型原则.     

Highly (1 0 0)-oriented Pb(Zr0.20Ti0.80)O3/(Pb1−xLax)Ti1−x/4O3 multilayered thin films prepared by RF magnetron sputtering

The Pb(Zr_0.20Ti_0.80)O₃/(Pb_1−xLa_x)Ti_1−x/4O₃ (x = 0, 0.10, 0.15, 0.20) (PZT/PLT_x) multilayered thin films were in situ deposited on the Pt(1 1 1)/Ti/SiO₂/Si(1 0 0) substrates by RF magnetron sputtering technique with a PbO_x buffer layer. With this method, all PZT/PLT_x multilayered thin films possess highly (1 0 0) orientation. The PbO_x buffer layer leads to the (1 0 0) orientation of the multilayered thin films. The effect of the La content in PLT_x layers on the dielectric and ferroelectric properties of the PZT multilayered thin films was systematically investigated. The enhanced dielectric and ferroelectric properties are observed in the PZT/PLT_x (x = 0.15) multilayered thin films. The dielectric constant reaches maximum value of 365 at 1 KHz for x = 0.15 with a low loss tangent of 0.0301. Along with enhanced dielectric properties, the multilayered thin films also exhibit large remnant polarization value of 2P_r = 76.5 μC/cm², and low coercive field of 2E_c = 238 KV/cm.     

RF磁控溅射制备AZO透明导电薄膜及其性能

室温下采用RF磁控溅射技术在石英衬底E制备了多晶ZnO:Al(AZO)透明导电薄膜,通过XRD,AFM,AES,Hall效应及透射光谱等测试研究了RF溅射功率、氩气压强对薄膜的结构、电学和光学性能的影响.分析表明:在最优条件下(溅射功率为250W,氩气压强为1.2Pa时),180nm AZO薄膜的电阻率为2.68×10-3 Ω·cm,可见光区平均透射率为90%,适合作为发光二极管和太阳能电池的透明电极.所制备的AZO薄膜具有c轴择优取向,晶粒问界中的O原子吸附是限制薄膜电学性能的主要因素.     

具有微米/纳米复合粗化ITO的GaN基LED

Three types of textured indium-tin-oxide （ITO） surface, including nano-texturing and hybrid micro/nano-texturing with micro-holes （concave-hybrid-pattem） or micro-pillars （convex-hybrid-pattern）, were applied to GaN-based light-emitting diodes （LEDs）. The nano-texturing was realized by maskless wet-etching, and the micro-texturing was achieved by standard photolithography and wet-etching. Compared to LED chips with flat ITO surface, those with nano-pattern, concave-hybrid-pattern, and convex-hybrid-pattern exhibit enhancement of 11.3%, 15.8%, and 17.9%, respectively, for the light-output powers at 20 mA. The electrical performance has no degradation. Moreover, the convex-hybrid-pattern show higher light-output efficiency under small injection current, while the concave-hybrid-pattern exhibit better light-output efficiency at large injection current. The light- extraction efficiency is simulated by use of two-dimensional finite difference time domain method, and the numer- ical results are consistent with the experiments.     

一种低复杂度信道模拟器的设计

针对TD-LTE射频一致性测试系统专项的需求及通用信道模拟器设计周期长、复杂度高的现状,研究了影响无线信道特性的路径损耗、阴影衰落、多径多普勒效应和高斯白噪声等因素,并相应提出了一种新的计算正余弦函数方法和高斯白噪声产生方法。通过信道理论建模、Matlab链路搭建进行模型优化分析以及基于Xilinx公司Virtex-6芯片的模型FPGA实现,得到了一种简单有效的信道模拟器。实验表明,用TD-LTE基带信号作为激励,该信道冲激响应与Matlab理论值误差在2‰之内,且模型不涉及SCM、WINNER等模型天线方向图、多链路等高复杂度模块,说明该信道模拟器具有简便性和可靠性。     

压电微动平台的改进PI迟滞模型研究

为了建立既有较高精度又有较快运算速度的压电微动平台迟滞模型,对传统PI迟滞模型进行了改进研究。由于压电微动平台初载曲线前半升程斜率变化较大,而后半升程斜率变化较小,因此,采用非等分域值方法建立了其PI迟滞模型,通过求取所建模型与实测初载曲线误差的最小二范数辨识出了模型的相应参数,实验验证了所建模型的有效性。实验结果表明,在20.7μm的平台最大位移范围内,模型的最大误差为0.71μm,平均误差为0.23μm。     

Dual-band RF receiver for GPS-L1 and compass-B1 in a 55-nm CMOS

A fully integrated dual-band RF receiver with a low-IF architecture is designed and implemented for GPS-L 1 and Compass-Bl in a 55-nm CMOS process. The receiver incorporates two independent IF channels with 2 or 4 MHz bandwidth to receive dual-band signals around 1.57 GHz respectively. By implementing a flexible frequency plan, the RF front-end and frequency synthesizer are shared for the dual-band operation to save power consumption and chip area, as well as avoiding LO crosstalk. A digital automatic gain control （AGC） loop is utilized to improve the receiver＇s robustness by optimizing the conversion gain of the analog-to-digital converter （ADC）. While drawing about 20 mA per channel from a 1.2 V supply, this RF receiver achieves a minimum noise figure （NF） of about 1.8 dB, an image rejection （IMR） of more than 35 dB, a maximum voltage gain of about 122 dB, a gain dynamic range of 82 dB, and an maximum input-referred 1 dB compression point of about -36.5 dBm with an active die area of 1.5 × 1.4 mm2 for the whole chip.     

基于微纳电离的有毒有害气体传感器

为了有效避免有害气体浓度的超标对经济效益和人类生命财产安全造成损害,提出并设计了一种新型检测方法,通过对微纳电离型传感器进行一系列的测试,设计的传感器展现了较强的抗弯能力及较快的响应-恢复能力。在室温常压、相对湿度75%的实验条件下,对多个浓度的苯、甲苯气体展开了测试,并基于特征噪声强度识别气体的浓度,构建了对应的识别模型。实验结果表明：传感器对有害气体检测时的测量值和真实值的拟合度可达99%以上,体现了较高的检测精度,且在检测有害气体时传感器处于可逆电离平衡状态,重复性良好,不需要进行预热、安全无毒,因此适合于应用到苯类气体的检测中,能够满足效率、精度的要求,具备了一定的实用性。     

Ultraprecise 3D Printed Graphene Aerogel Microlattices on Tape for Micro Sensors and E-Skin

3D printed graphene aerogels hold promise for flexible sensing fields due to their flexibility, low density, conductivity, and piezo-resistivity. However, low printing accuracy/fidelity and stochastic porous networks have hindered both sensing performance and device miniaturization. Here, printable graphene oxide (GO) inks are formulated through modulating oxygen functional groups, which allows printing of self-standing 3D graphene oxide aerogel microlattice (GOAL) with an ultra-high printing resolution of 70 µm. The reduced GOAL (RGOAL) is then stuck onto the adhesive tape as a facile and large-scale strategy to adapt their functionalities into target applications. Benefiting from the printing resolution of 70 µm, RGOAL tape shows better performance and data readability when used as micro sensors and robot e-skin. By adjusting the molecular structure of GO, the research realizes regulation of rheological properties of GO hydrogel and the 3D printing of lightweight and ultra-precision RGOAL, improves the sensing accuracy of graphene aerogel electronic devices and realizes the device miniaturization, expanding the application of graphene aerogel devices to a broader field such as micro robots, which is beyond the reach of previous reports.