Fabrication of miniaturized Si-based electrocatalytic membranes

The increasing interest for lightweight and portable electronic systems, cellphones and small digital devices is driving technological research towards integrated regenerating power sources with small dimensions and great autonomy. Conventional batteries are already unable to deliver power in ever smaller volumes while maintaining the requirements of long duration and light weight. A possible solution to overcome these limits is the use of miniaturized fuel cells. The fuel cell offers a greater gravimetric energy density compared to conventional batteries. The micromachining technology of silicon is an important tool to reduce the fuel cell structure to micron sizes. The use of silicon also gives the opportunity to integrate the power source and the electronic circuits controlling the fuel cell on the same structure. This article reports preliminary results concerning the micromachining process for fabricating a silicon-based electrocatalytic membrane for miniaturized Si-based proton-exchange membrane (PEM) fuel cells.     

Low-loss inductors built on PECVD intrinsic amorphous silicon for RF integrated circuits

The quality factor (Q) of inductors on silicon (Si) is limited by the series resistance of the metal at low frequency and by the substrate resistivity at high frequency. Oxide is generally used to isolate the useful signal of the inductor from the lossy substrate. However, stoichiometric silica (SiO2) is processed at a high temperature, which eliminates the possibility of post-CMOS integration. By contrast, plasma enhanced chemical vapour deposition (PECVD) amorphous Si can be deposited at a low temperature and is easily integrated with most Si-based processes. Intrinsic amorphous hydrogenated silicon (i-a-Si:H) also displays low conductivity. In this work, i-a-Si:H deposited at a low temperature (250?) is used in a novel approach as the isolation material for planar inductors on Si for RF integrated circuits. An improvementof more than 50% in Q is measured when 1.5 μm i-a-Si:H film is deposited on the Si substrate prior to fabrication of the inductor. This result demonstrates the influence of i-a-Si:H film on the RF performance of an inductor. Intrinsic a-Si:H is shown to be a promising material for the isolation of RF devices on low-resistivity Si.     

New structures of polyphase claw-pole machines

New structures of motor magnetic circuits can be realized by use of the soft magnetic composites. This paper presents new claw-pole motors with a polyphase winding and a standard cylindrical rotor which use these isotropic materials. A division of the stator magnetic circuit into three parts and the use of a centralized-concentrated winding with a small number of coils simplify the production process, the mechanical assembly, and the winding realization. With these special stator geometries, the electromagnetic, mechanical and thermal functions are integrated into the same stator parts. This integration is much better than in a classical two-dimensional (2-D) structure using a laminated material. There is no end winding and the copper volume can be minimized. The size of the additional parts which are necessary for the bearing housings and the mechanical fixation of the rotor are reduced. These structures can be equipped with an integrated cooling system, with efficient air convection or water circulation. This paper describes the design approach of these original structures. It demonstrates that such three-dimensional (3-D) structures can be derived from their equivalent 2-D structures with a concentrated winding. The concept and the design approach are validated by the realization and the comparative experimental tests of two prototypes with a 3-D and its equivalent 2-D structure.     

Solid-state microsensors for cortical nerve recordings

The author discusses the application of solid-state microsensors and recording microprobes in acquiring neural signals. The combination of precision photolithographic techniques afforded by integrated circuit techniques, and the exacting micromachining capabilities available in silicon enable one to implement biomedical sensors that are smaller, more reproducible, and much more capable in terms of their functionality and signal processing capabilities than their predecessors     

开关变换器中阵列式平面集成磁件的磁集成研究

阵列式磁芯结构使矩阵变压器具有多个磁路,本文以矩阵变压器的多磁路为基础,从磁路和电路的结合出发,提出在矩阵变压器上通过电路的有效组合并利用解耦集成方法集成电感,形成阵列式解耦集成磁件基本单元,并从整体磁路的角度分析了其解耦集成原理,给出其基本单元等效电路并进行了仿真。通过将该解耦集成磁件平面化,形成了阵列式平面集成磁件。将阵列式平面集成磁件应用到带变压器隔离的Cuk变换电路的实验研究表明,阵列式平面集成磁件的平面化和阵列式结构使其达到了轻、小、薄的目的,并降低了损耗,并证明本文提出的阵列式平面集成磁件具有良好的性能。     

MMICs in the millimeter-wave regime

On the basis of the current status of silicon based MMICs, it is possible to implement millimeter-wave SOC in silicon-based technologies that include the antenna, a medium-power amplifier, a transceiver, an LO (frequency synthesizer), and baseband circuits in a single chip. With certain interconnection schemes, such as flip-chip, to connect the chip to the substrate, it is also possible to integrate the best possible chips for a millimeter-wave communication system. Currently, CMOS is the best choice for the baseband circuits, while GaAs and InP MMICs can provide the best noise/power performance in the transceiver. High-efficiency antennas can be implemented directly on the packaging substrate. The SIP approach has the optimal combinations of the components for the best performance in a particular system. For example, a system in a package including CMOS baseband circuits, GaAs/InP-based transceiver, high-efficiency antenna, and high-power amplifier can achieve the best system characteristics. As we have discussed, the scope of SOC can be expanded along with more advanced MMIC fabrication technology and design techniques.     

A Silicon Micromachined f- θ Microlens Scanner Array by Double-Deck Device Design Technique

In this paper, we report an array of f- thetas microlens optical scanners developed for 3-D optical cross connect (OXC) system using the bulk-silicon micromachining technique. An electrostatic XY-stage mechanism for the 2-D lens scanner was designed to have a small footprint (2 mmtimes2 mm), compared with an integrated silicon lens (diameter 1 mm) due to the newly developed double-deck actuator design; all the mechanical parts (suspensions and frames) were made in the substrate layer of a silicon-on-insulator (SOI) wafer, and the electrostatic actuation mechanism (electrodes and electrical interconnection) was made in the SOI layer. A silicon lens was integrated on top of the XY-stage by transferring the spherical profile of a thermal-reflow photoresist pattern into the SOI layer by reactive-ion etching. The XY lens scanner was found to operate at lateral displacement of 19 mum in the X-directions and 23 mum in the Y-directions at drive voltages of 110 and 60 V, respectively. For an optical assembly of the OXC, we used additional lenses in a telescope formation to double the beam angle that was steered by the f- thetas microlens scanner by which the lens displacement could be designed to be smaller by a factor of 1/2     

Heterogeneous Wafer-Scale Circuit Architectures

This article has presented circuit architectures that allow for the 3D integration and on-wafer packaging through the concept of an Si interposer. The presented 3D integration schemes have allowed for the design and fabrication of a fully integrated receiver that performs at 10 GHz. High-Q passives and 3D interconnects allow for the design of low-cost, high-density circuits that also exhibit very high performance     

SG6849在单端反激式开关电源中的应用

SG6849芯片是SG(System General)公司生产的开关电源专用集成电路,使用该芯片设计小功率开关电源,可大大减少外围电路,降低成本,电路可靠性高,且可以不带副边反馈。详细介绍了SG6849芯片的工作原理,并基于此芯片设计了一个5.6W的单端反激式开关电源,给出了实验结果。     

Design and applications of silica-based planar lightwave circuits

Planar lightwave circuits (PLCs) are waveguide devices that integrate fiber-matched optical waveguides on silicon or glass substrate to provide an efficient means of interaction for the guided-wave optical signals, PLCs provide various important and functional devices for optical wavelength-division multiplexing, time-division-multiplexing systems, and subscriber networks. This paper reviews the recent progress and future prospects of PLC technologies including arrayed-waveguide grating multiplexers, optical add-drop multiplexers and hybrid optoelectronics integration technologies     

RF CMOS come of age

Radio-frequency integrated circuits (RFICs) in complementary metal-oxide semiconductors (CMOS) are developing a strong presence in the commercial world. They are dominant for applications such as wireless LAN and Bluetooth and are making inroads into areas such as global system for mobile communications (GSM) cellular transceivers and global positioning system (GPS) receivers. This article offers a brief retrospective on how RF circuits and systems in CMOS have evolved to their current state of the art, followed by perspective of what the future might hold for RF systems on a chip (SOC) in CMOS. It seems appropriate today, roughly ten years after the first publications reporting RF circuits in CMOS, to document the key developments and first reports of the circuit techniques and architectural innovations that are now in widespread use for the development of a new generation of RFICs.     

Active integrated antennas

Even with microwave techniques, however, signal losses in materials and decreased gain and power from solid-state devices become significant obstacles to creating low-cost, high-frequency wireless systems. Perhaps the most dramatic effect occurs when a circuit component becomes a significant fraction of a wavelength. At this point it may begin to function well as an antenna. For microwave and mm-wave signals, this can occur with circuits that are only centimetres in size. With conventional circuit techniques, this radiation may cause drastic signal losses, spurious coupling between circuit elements, and radio interference with other. However, with new techniques, it is possible to create circuits that use these effects to advantage. Known as active integrated antennas, these circuits have sparked interest as possible solutions to problems in designing the next-generation wireless systems. Active integrated antennas are a combination of solid-state devices and circuits with printed antenna structures. They comprise integrated radio-system elements that are fabricated using inexpensive printed-circuit techniques     

基于LTCC/LTCF的数控YIG调谐激励器设计与实现

基于LTCC/LTCF复合集成技术,对包含DC-DC电源变换电路的YIG调谐数字激励器进行集成化设计。电路基板由LTCC和LTCF两种材料复合层叠而成。通过Maxwell 3D软件进行仿真设计,利用LTCF材料的磁特性,在基板内集成了DC-DC电源所需的电感器,取代了高度较高的表贴式电感。将电感仿真结果导入Durst Graffy软件,与其它电路元件一起进行布局布线,实现了YIG激励器的平面化设计。最后,通过多次烧结工艺试验,成功实现了YIG激励器电路基板样品的制作。预计组装完成后,激励器高度将缩减到约原先PCB电路的44%。     

Intimate monolithic integration of chip-scale photonic circuits

In this paper, we introduce a robust monolithic integration technique for fabricating photonic integrated circuits comprising optoelectronic devices (e.g., surface-illuminated photodetectors, waveguide quantum-well modulators, etc.) that are made of completely separate epitaxial structures and possibly reside at different locations across the wafer as necessary. Our technique is based on the combination of multiple crystal growth steps, judicious placement of epitaxial etch-stop layers, a carefully designed etch sequence, and self-planarization and passivation steps to compactly integrate optoelectronic devices. This multigrowth integration technique is broadly applicable to most III-V materials and can be exploited to fabricate sophisticated, highly integrated, multifunctional photonic integrated circuits on a single substrate. As a successful demonstration of this technique, we describe integrated photonic switches that consume only a 300 /spl times/300 /spl mu/m footprint and incorporate InGaAs photodetector mesas and InGaAsP/InP quantum-well modulator waveguides separated by 50 /spl mu/m on an InP substrate. These switches perform electrically-reconfigurable optically-controlled wavelength conversion at multi-Gb/s data rates over the entire center telecommunication wavelength band.     

A Hybrid Integrated Pulsewidth Modulator

A hybrid integrated circuit is described which generates two phase-shifted 20-kHz output pulse trains whose duty cycles are related to the amplitude of an applied input signal. The circuit was designed primarily for use in power conditioning schemes utilizing pulsewidth modulated signals for regulated dc-to-dc voltage conversion. Realization of this hybrid circuit has been accomplished with a beam-lead sealed-junction monolithic silicon chip and several tantalum thin-film resistors and capacitors which are bonded/ deposited on a ceramic substrate in the form of a 28-terminal dual-in line package (DIP).     

A 1–6 GHz analog radio frequency power driver in 90 nm complementary metal‐oxide semiconductor technology for wireless applications

One of the most challenging subsystems for integrated radio frequency (RF) complementary metal‐oxide semiconductor (CMOS) solutions is the power amplifier. A 1–6 GHz RF power driver (RFPD) in 90 nm CMOS technology is presented, which receives signals from on‐chip RF signal chain components at ?12 dBm power levels and produces a 0 dBm signal to on‐chip or off‐chip 50 Ω loads. A unique unit cell design is developed for the RFPD to offset issues associated with very wide multi‐fingered transistors. The RF driver was fabricated as a stand‐alone sub‐circuit on a 90 nm CMOS die with other sub‐circuits. Experimental tests confirmed that the on‐chip RFPD operates up to 6 GHz and is able to drive 50 Ω loads to the desired 0 dBm power level. Spur free dynamic range exceeded 70 dB. The measured power gain was 11.6 dB at 3 GHz. The measured 1 dB compression point and input third‐order intercept point (IIP3) were ?4.7 dBm and ?0.5 dBm, respectively. Also, included are modeling, simulation, and measured results addressing issues associated with interfacing the die to a package with pinouts and the package to a printed circuit test fixture. The simulations were made through direct current (DC), alternating current (AC), and transient analysis with Cadence Analog Design Environment. The stability was also verified on the basis of phase margin simulations from extracted circuit net‐lists. Copyright © 2013 John Wiley & Sons, Ltd.     

Cantilevers and tips for atomic force microscopy

The key component of the atomic force microscope (AFM) is a cantilever with a tip. The tip must be sharp enough to record with high lateral resolution the topography. The cantilever must also have the appropriate compliance and resonant frequency for the type of operation selected, which can be either a contact or a noncontact mode of operation. The requirement for a low spring constant (less than 1 N/m) and a high resonant frequency (greater than 10 kHz) led to silicon micromachining techniques early on in the development of the AFM. Silicon micromachining is a technology by which a silicon wafer is processed through a series of deposition, photolithography, and etching steps to produce a mechanical structure with dimensional tolerances in the order of 1 μm. The use of silicon micromachining techniques has benefited the AFM in several aspects: (1) sharper tips can be manufactured with micromachining techniques than with alternative electrochemical etching techniques, as used for scanning tunneling microscopy tips; (2) batch fabrication simultaneously of thousands of cantilevers guarantees a high degree of reproducibility in the mechanical properties of the cantilevers; and (3) micromachined cantilevers are inexpensive     

Near-field direct antenna modulation

Modern silicon-based technology processes have opened a plethora of opportunities for designing highly integrated millimeterwave systems by providing transistors with cutoff frequency, fT, of more than 200 GHz [1]-[5]. At millimeter-wave frequencies, the wavelengths are comparable to the die size, and this inspires the integration of the radiating elements and active circuit components on a single silicon die. Although integration of millimeter-wave systems on a silicon substrate lowers the cost and improves reliability, there are several challenges that must be addressed appropriately [1], [2]. Because of constraints imposed by the fabrication of active components, the substrate resistivity of the silicon substrate has to be very small (∼1?10 Ω cm). This low resistivity causes energy loss into the substrate and lowers the quality factor Q of unshielded on-chip passive components such as inductors, transmission lines, and antennas and hence results in the degradation of power efficiency and noise performance. The finite conductivity of metal structures causes further energy loss in integrated systems. Since the skin depth becomes very small at millimeter-wave frequencies (e.g., the skin depth of copper at 60 GHz is approximately 300 nm), the ohmic loss in metal structures significantly increases, degrading the performance of passive devices.     

基于序网等值电路的双馈风电机组接入系统短路电流计算方法

为了方便和准确地计算双馈风电机组(DFIG)接入系统的短路电流分布,提出了投撬棒后DFIG的工频和转频序网等值电路,并给出了利用该等值电路计算系统短路电流的方法。通过求解投撬棒后DFIG磁链的状态微分方程,得到其工频分量和转频分量的解析表达式。在此基础上,将DFIG的电压空间矢量方程按转频和工频分量进行分解,并根据空间矢量与相量间的关系,分别形成了转频和工频序网等值电路。其中,转频正序、负序等值电路分别为带内阻抗的电势和无源阻抗,而工频正序、负序等值电路均为无源阻抗。利用该等值电路只需已知DFIG的电机参数和故障初值条件而无需仿真即可求得DFIG接入系统各处的短路电流。以某DFIG接入系统为例,通过PSCAD仿真验证了该等值电路和短路计算方法在不同故障条件下的有效性。     

Broadband and compact impedance transformers for microwave circuits

Most microwave circuits and antennas use impedance transformers. In a conventional power amplifier, large number of inductors and capacitor or transmission line sections are use to realize an impedance transformer. This article presents an asymmetric broadside-coupled microstrip TLT (transmission line transformer) on the GaAs substrate. This matching network can be easily implemented using any monolithic microwave integrated circuit (MMIC) process supporting multilevel metallization.