基于四螺旋梁-质量块的MEMS压电能量采集器北大核心

设计了一种四螺旋悬臂梁-质量块结构的压电能量采集器,将环境振动能转换为电能。采用有限元分析软件（COMSOL Multiphysics）建立结构模型,仿真结构固有频率,计算不同振动频率下器件的位移、应力、应变和电势以及不同加速度下的电压输出,仿真得到结构的一阶谐振频率为102 Hz,为后期测试提供指导。利用溶胶-凝胶工艺完成锆钛酸铅（PZT）压电薄膜的制备,通过微电子机械系统（MEMS）工艺和引线键合工艺完成器件结构制造,将四个螺旋梁上的压电单元串联以实现输出最大化。性能测试结果表明：器件固有频率为110 Hz,输出电压随加速度的增大而线性增大,3g加速度下输出电压峰峰值为140 m V。     

基于压电效应的MEMS振动式微能源器件

设计了一种硅基压电功能材料的四悬臂梁-中心质量块结构MEMS振动式微能源器件,可将环境振动能量有效转化为电能。采用溶胶-凝胶法制备硅基锆钛酸铅(PbZr0.53Ti0.47O3,PZT)压电功能薄膜,经干/湿法刻蚀和溅射沉积等MEMS工艺实现器件功能结构的制备。研制的器件整体结构尺寸为7 000μm×7 000μm×300μm,单个PZT压电单元面积为0.149 6 mm2。将悬臂梁上4个压电单元串联以实现输出最大化,测试结果表明,器件的谐振频率为300 Hz,适于低频振动环境;输出电压在一定范围内随加速度增加而增大;在加速度为10 g时压电单元单位面积输出电压达1.19 mV/mm2。     

振动能量拾取MEMS压电式微能源研究

设计并制作了一种"四悬臂梁-中心质量块"结构的振动能量拾取微机电系统(MEMS)压电式微能源,实现了环境振动能量向电能的转换。首先利用溶胶-凝胶工艺完成锆钛酸铅(PbZrxTi1-xO3,PZT)压电薄膜的异质集成制备;然后通过MEMS工艺和引线键合技术进行器件基础结构的集成制造;最后借助振动测试系统对该器件的各项输出性能进行测试。测试结果表明,8Hz谐振频率工作状态下,该压电式微能源器件的输出电压峰-峰值随着加速度激励的增加呈线性增大,当加速度激励为10 m/s2时,该能量采集器件的输出电压峰-峰值为82.4mV。在器件两端加载2.0 MΩ的负载时,器件输出功率密度达最大值(为2.074 3μW/cm3)。     

微型压电能量采集器的仿真、制造与测试

理论分析得到微悬臂梁式压电能量采集器的设计准则.采用一种新颖的制造工艺,将高性能压电陶瓷锆钛酸铅(PZT)块材与硅片在540 ℃高温下键合1 h后,减薄并切割成形成压电悬臂梁.使用ANSYS软件进行仿真,得到了器件的固有频率、尖端位移和电压输出的频率响应.设计一套振动能量采集器测试装置,并对器件进行测试.测试结果表明,所制得的器件固有频率为2 580 Hz,在10 m/s2的正弦加速度激励下,其输出峰-峰值电压达1.58 V,测试结果与仿真分析基本吻合.     

压电式十字型MEMS矢量仿生水听器的设计和研究

设计并研究了基于压电效应的微机电系统(MEMS)仿生结构的三维矢量水声传感机理,包含基础结构的建模、定向探测分析,器件制备的基础研究及其相关测试。通过Ansys 15.0对器件进行了静态位移分布和应力分析仿真,借助扫描电镜和原子力显微镜对锆钛酸铅(PZT)压电薄膜进行了观察,对器件进行了扫频测试和指向性测试,谐振频率约为500Hz,输出电压峰-峰值为280mV。它对促进现代水声传感技术的发展和解决对液体环境中微弱信号的高精度定位、识别、探测等技术难题具有一定的科学和实用价值。     

压电式发电的悬臂梁结构参数分析

针对如何提高悬臂梁压电式发电效率的问题,通过所建立的压电转换模型,分析了结构参数对输出电压的影响,在设计悬臂梁的结构参数时,尽量在结构强度允许的条件下,选择大的附加质量块与压电双晶片宽度,是获得较大输出电压的重要方法.分析还表明,虽然压电双晶片的长度lb对输出电压影响较大,为满足压电发电装置的微型化要求,在设计中参数限制了lb的选取范围.在低频工作区,参数附加质量块与悬臂梁沿x轴方向上的接触长度lm、压电陶瓷层的厚度tc对输出电压作用较弱.经设计与搭建的实验平台及测试系统,进行了测试结果与仿真分析相比较,结果表明理论分析是可信的.     

MEMS压电-磁电复合式振动能量采集器

具有高能量输出密度的自我供电振动能量采集技术有着迫切的应用需求,是智能化MEMS器件系统发展的重要方向。研究了一种可将外界环境振动能转化为电能的MEMS压电-磁电复合振动能量采集器,其综合了压电发电和磁电发电的优势,为新型MEMS供电研究提供了新思路。利用溶胶-凝胶工艺完成锆钛酸铅(PZT)压电功能薄膜的制备,采用MEMS加工技术完成器件四悬臂梁-中心质量块基础结构的设计和制作,结合集成封装技术实现微结构与永磁铁的微组装。测试结果表明:在一阶谐振频率247 Hz,10 g加速度激励的振动状态下,器件压电部分压电敏感单元与磁电部分电感线圈的单位体积最大有效输出电压分别为2.066×107和5.002×106 mV/cm3。     

压电单晶悬臂梁的输出电压测试分析

通过有限元分析软件ANSYS对压电单晶悬臂梁进行仿真分析,再经实验,研究了基板材质、粘结胶、激振力加速度和激振频率对输出电压的影响.结果表明,弹性模量较大的基板能提高输出电压,采用不导电胶比导电胶的输出电压大;压电悬臂梁对激振频率有很好的选择性,当频率为33 Hz时,输出电压为25.3 V;这有助于优化器件结构,设计出...     

低频压电式MEMS振动能量采集器研究

设计了一种低频压电d31模式的"八悬臂梁-中心质量块"结构微机电系统(MEMS)振动能量采集器,实现环境振动能量向电能的转换。首先利用溶胶-凝胶工艺实现PZT压电薄膜的异质集成制造,单个锆钛酸铅(PZT)压电敏感单元的有效尺寸为935μm×160μm×1.5μm;然后通过MEMS加工工艺完成器件微结构的加工制造,器件结构有效体积为9.936×10~(-4)cm~3;最后借助振动测试系统对该器件的各项输出性能进行测试。测试结果表明,谐振频率为60Hz、加速度激励为1g(g=9.8m/s~2)时,该能量采集器的输出电压峰-峰值为232mV。在其两端加载3.0 MΩ的负载时最大输出功率为6×10~(-4)μW,输出功率密度为0.604μW/cm~3,PZT压电敏感单元有效面积下的输出功率密度为0.025μW/cm~2。     

用于能量收集器的不锈钢基PZT厚膜制备研究

采用了溶胶 凝胶技术在不锈钢基体上制备了厚为10 μm、结构致密的锆钛酸铅(PZT)厚膜。研究了不同退火条件对厚膜结晶状况的影响,X射线衍射分析表明,采用700 ℃退火处理20 min后得到了PZT厚膜的纯钙钛矿相结构。厚膜的电学性能测试结果显示,厚膜的剩余极化强度（Pr）为7.5 μC/cm2, 矫顽场强（Ec）为7.2 V/μm,压电常数（d33）为73 pC/N。设计制作了长20 mm、宽4 mm的压电悬臂梁结构振动能量收集器。输出性能测试结果显示,振动频率为95 Hz,采集器输出电压最高,输出电压值为862 mV。     

Design and implementation of UWB CMOS LC filters LNA for carrier less impulse radio receivers

The design and the implementation of Ultra-wide-band (UWB) CMOS LC filter LNA for Ultra Wide Band carrier less Impulse Radio receivers is presented. Architectures for both single ended and differential ended LNA are proposed for small fractional bandwidths such as the ECC frequency band and for large fractional bandwidths such as FCC frequency band. Simple guidelines to achieve large voltage gain and low noise figure are given. The implementation in standard CMOS technologies in the context of integrated receivers is discussed and simple layout rules allowing reliable designs are proposed. Several LNA prototypes for different fractional bandwidths have been fabricated in a 0.13 μm CMOS technology. Measurement results agree well with the simulations.     

An integrated IF amplifier

An IF amplifier that provides a temperature insensitive Q (adjustable independently of center frequency) of 50 at a center frequency of f/SUB 0/ of 1 MHz, over a 100/spl deg/C temperature range is presented. The design also features supply independent biasing, input and output buffering, a 40-dB (automatic gain control) range and a center frequency voltage gain of up to 60 dB. Results obtained from computer simulations, discrete, and integrated prototypes are compared.     

Low-Voltage MOS Translinear Analog Signal Processing

Different design procedures to operate MOS translinear loops at low supply voltage are presented. They utilize innovative biasing strategies based on flipped voltage followers and floating batteries. An alternate topology based on coupled negative feedback loops is also introduced. Simulation and measurement results for various test chip prototypes validate the proposed techniques and allow comparison among them.     

双斜槽式纵扭转换型超声波电机的实验研究

研制了两台双斜槽结构(A型和B型)的纵扭模态转换型超声波电机样机,针对其输出特性进行了对比实验研究。通过激光转速表测量了电机样机的输出转速,分析了工作频率、驱动电压、预压力对电机样机的输出转速的影响。实验结果表明:斜槽结构是影响这种模态转换型超声波电机输出特性的关键因素。在相同谐振频率37.7kHz,工作电压100V和预压力0.21N下,A型双斜槽电机样机的最高转速为87r/min,B型双斜槽电机样机的最高转速为135r/min。     

A cascade boost-switched-capacitor-converter - two level inverter with an optimized multilevel output waveform

Two structures, a switched-capacitor (SC)-based boost converter and a two-level inverter, are connected in cascade. The dc multilevel voltage of the first stage becomes the input voltage of the classical inverter, resulting in a staircase waveform for the inverter output voltage. Such a multilevel waveform is close to a sinusoid; its harmonics content can be reduced by multiplying the stage number of the SC converter. The output low-pass filter, customary after a two-level inverter, becomes obsolete, resulting in a small size of the system, as the SC circuit can be miniaturized. Both stages are operated at a high switching frequency, resulting in a high-frequency inverter output, as required by some industrial applications. A Fourier analysis of the output waveform is performed. The design is optimized with reference to the nominal duty-cycle for obtaining the minimum total harmonic distortion. Simulations and experiments on two prototypes, one with a five-level output and one with a seven-level output, confirm the theoretical analysis.     

Ultra-low-Voltage high-performance CMOS VCOs using transformer feedback

A transformer-feedback voltage-controlled oscillator (TF-VCO) is proposed to achieve low-phase-noise and low-power designs even at a supply below the threshold voltage. The advantages of the proposed TF-VCO are described together with its detailed analysis and its cyclo-stationary characteristic. Two prototypes using the proposed TF-VCO techniques are demonstrated in a standard 0.18-/spl mu/m CMOS process. The first design using two single-ended transformers is operated at 1.4 GHz at a 0.35-V supply using PMOS transistors whose threshold voltage is around 0.52 V. The power consumption is 1.46 mW while the measured phase noise is -128.6 dBc/Hz at 1-MHz frequency offset. Using an optimum differential transformer to maximize quality factor and to minimize the chip area, the second design is operated at 3.8 GHz at a 0.5-V supply with power consumption of 570 /spl mu/W and a measured phase noise of -119 dBc/Hz at 1-MHz frequency offset. The figures of merits are comparable or better to that of other state-of-the-art VCO designs operating at much higher supply voltage.     

MEMS微拾振器制备工艺研究

采用微机电系统(MEMS)技术制作了悬臂梁式压电微拾振器,该技术主要包括:sol-gel法制备PZT压电膜、干法刻蚀、湿法化学刻蚀、UV-LIGA等工艺。研制的拾振器悬臂梁结构尺寸为:长2000μm,宽600μm,硅膜厚度12μm,PZT压电膜厚1.5μm,Ni质量块长600μm、高500μm。测试表明其固有频率为610Hz,适合低频振动源环境的应用。在1gn加速度谐振激励下,电压输出达562mV。     

Isolated DC-DC converters with high-output voltage for TWTA telecommunication satellite applications

Two alternatives for the implementation of an isolated DC-DC converter operating with a high output voltage and supplied by an unregulated low input voltage are presented in this paper. The proposed topologies are especially qualified for the implementation of travelling wave tube amplifiers (TWTA) utilized in telecommunication satellite applications due to their low mass and volume and their high-efficiency. The converters studied follow different principles and the main operational aspects of each topology are analyzed. A two-stage structure composed by a regulator connected in series with a ZVS/ZCS isolated DC-DC converter is the first topology proposed. The second topology studied is an isolated single-stage converter that continues being highly efficient even with a large input voltage variation. The experimental results obtained from two prototypes, implemented following the design procedures developed, are presented, verifying experimentally the characteristics and the analysis of the proposed structures. The prototypes are developed for an application requiring an output power of 150 W, a total output voltage of 3.2 kV and an input voltage varying from 26 V to 44 V. The minimum efficiency obtained for both converters operating at the nominal output power, is equal to 93.4% for the two-stage structure and equal to 94.1% for the single-stage converter.     

Lumped-Element Quadrature Power Splitters Using Mixed Right/Left-Handed Transmission Lines

This paper presents the design of lumped quadrature power splitters (LQPSs) based on unit cells of right-handed (RH) and left-handed (LH) synthetic transmission lines (TLs). The LQPSs include a lumped Wilkinson splitter, with phase-adjusting RH/LH TLs at the outputs. Two topologies, considered to be advantageous with regards to size and electric characteristics, are studied in detail. For these two, closed-form design equations are derived and the performances are analyzed by circuit simulations. The theory and simulation results are experimentally validated by monolithic-microwave integrated-circuit prototypes designed for a center frequency of 2.5 GHz. Both prototypes have performance that agree well with theory and design simulations. Within the frequency range of 2–3 GHz, the maximum amplitude and phase errors are less than 0.3 dB and 3$^circ$, respectively. All reflections and the isolation are better than$-$10 dB. The effective areas of the two prototypes are 900$, times,$700$mu$m$^2$and 720$, times,$520$mu$m$^2$, respectively.     

A New Technique for Design of Low-Profile, Second-Order, Bandpass Frequency Selective Surfaces

In this study, a new method for designing low profile frequency selective surfaces (FSS) with second-order bandpass responses is presented. The FSSs designed using this technique utilize non-resonant subwavelength constituting unit cells with unit cell dimensions and periodicities in the order of $0.15lambda _{0}$. It is demonstrated that using the proposed technique, second-order FSSs with an overall thickness of $lambda _{0}/30$ can be designed. This is considerably smaller than the thickness of second-order FSSs designed using traditional techniques and could be particularly useful at lower frequencies with long wavelengths. To facilitate the design of this structure, an equivalent circuit based synthesis method is also presented in this paper. Two bandpass FSS prototypes operating at X-band are designed, fabricated, and tested. A free space measurement setup is used to thoroughly characterize the frequency responses of these prototypes for both the TE and TM polarizations and various angles of incidence. The frequency responses of these structures are shown to have a relatively low sensitivity to the angle of incidence. Principles of operation, detailed design and synthesis procedure, and measurement results of two fabricated prototypes are presented and discussed in this paper.