An MRI Receiver Coil Produced by Inkjet Printing Directly on to a Flexible Substrate

Inkjet printing has been used to produce resonant radio frequency coils that are comparable to those produced by conventional printed circuit board (PCB) methods. The coils, which consist of a conductive loop and in-series capacitors, form part of a receiver circuit that is used for magnetic resonance imaging (MRI). The resonant circuit is selective at the predetermined frequency of 400 MHz. The required electrical components (resistor, capacitor, and inductor) were produced by inkjet printing, with scaling experiments for resistor and capacitor performed before the complete loops with integrated capacitors were printed. Numerical simulation was used to determine the required values for the components. The inkjet printed circuit was combined with a small tuning and matching board before being connected to a network analyzer and the MRI hardware. With a matching of ${-}$ 38 dB at 400 MHz the achieved results were comparable to those from standard PCB techniques. The performance of the inkjet printed component as a receiver device for nuclear magnetic resonance and MRI was verified by imaging reference phantoms and a whole kiwifruit; it compares favorably to standard MRI devices. Inkjet printing can, therefore, be considered a feasible technique for producing MRI receiver circuits on flexible substrates.      

聚合物基复合材料的PTC效应机理初探

本文就复合材料的ＰＴＣ效应及影响因素进行了系统试验，并着重对聚合物基复合材料ＰＴＣ效应的渗滤－隧道机制及导电粒子链的作用进行了讨论，为优化复合ＰＴＣ材料物理性能和材料设计提供了依据。     

ESD应力下n阱扩散电阻的潜在损伤

电阻在静电放电(Electrostatic Discharge,ESD)保护电路中,起隔离和分压的作用。利用传输线脉冲(Transmission Line Pulsing,TLP)测试系统,在宽度为100ns的脉冲作用下,研究了n阱扩散电阻在ESD应力下的工作特性。结果表明,n阱扩散电阻在发生初次瞬态击穿(瞬态击穿电压79.0V,瞬态击穿电流1.97A)后,由于阳极n+-n结构被破坏,内部结构已经出现潜在损伤,不再具备隔离和分压的作用。     

Miniature humidity micro-sensor based on organic conductive polymer - poly(3,4-ethylenedioxythiophene)

A resistive micro-sensor for humidity sensing based on a conductive polymer material that is deposited electrochemically is presented. The resistor is formed by filling a narrow air gap (12 mum) between two conductor pads with conductive poly(3,4-ethylenedioxythiophene) (PEDOT) polymer, and the resistance of the polymer micro-resistor thus formed is measured to be 41 Omega at a temperature of 20degC. The conductor pads are prepared with a thick layer (20 mum) of nickel using a multi-user microelectromechanical systems (MEMS) process. The area of the entire sensor is around 100 times 200 mum, making it very compact. The humidity sensor has been characterised within a sealed chamber where the relative humidity is controlled by different saturated salt solutions at a constant temperature of 20degC. The resistance of the sensor varies from 37 to 62 Omega from 22 to 99.9% of relative humidity at room temperature.     

基于频谱分析的积分电路设计

积分电路主要用于波形变换、放大电路失调电压的消除及反馈控制中的积分补偿等场合,是模拟电路教学中的重要内容。本文在频域范围内经过推导,证明在基本积分电路的基础上引入反馈电阻R_F可以限制电路的低频增益,减少失调电压带来的积分漂移。并基于multisim仿真平台上验证这一结论,最后给出了反馈电阻、反馈电容的参数设计方法,可供模拟电子电路设计人员参考。     

Universal Control on Pyroresistive Behavior of Flexible Self‐Regulating Heating Devices

Smart heating devices with reliable self‐regulating performances and high efficiency, combined with additional properties like mechanical flexibility, are of particular interest in healthcare, soft robotics, and smart buildings. Unfortunately, the development of smart heaters necessitates managing normally conflicting requirements such as good self‐regulating capabilities and efficient Joule heating performances. Here, a simple and universal materials design strategy based on a series connection of different conductive polymer composites (CPC) is shown to provide unique control over the pyroresistive properties. Hooke's and Kirchhoff's laws of electrical circuits can simply predict the overall pyroresistive behavior of devices connected in series and/or parallel configurations, hence providing design guidelines. An efficient and mechanically flexible Joule heating device is hence designed and created. The heater is characterized by a zero temperature coefficient of resistance below the self‐regulating temperature, immediately followed by a large and sharp positive temperature coefficient (PTC) behavior with a PTC intensity of around 10⁶. Flexibility and toughness is provided by the selected elastomeric thermoplastic polyurethane (TPU) matrix as well as the device design. The universality of the approach is demonstrated by using different polymer matrices and conductive fillers for which repeatable results are consistently obtained.     

A temperature sensor with single resistor set-point programming

An integrated circuit set point temperature controller has an open collector output which switches low at a temperature determined by an external resistor. The programming resistor may be determined from a universal formula relating resistance to desired trip temperature. The circuit is laser trimmed at a single temperature in manufacture to conform with the formula to better than 1°C over a range between -40°C and 150°C. The circuit is low cost and includes temperature hysteresis, for well defined switching, and an optional output pull-up resistor     

基于电阻网络的网线故障检测装置研究

文章阐述了一种基于电阻网络的网线故障检测装置,基于电学原理在网线周围构造电阻网络,并结合电阻一次性测量方法,使其在没有短路或断路状态时测得的阻值与网线内部有短路或断路的坏网线情况下所测得的阻值不相同。通过实验确定出网线良好时的电阻阻值,并将该阻值作为基础与以后的检测值作为比较。此方法克服了传统检测方式中的繁琐过程,提出了新型的网线状态判断方法,实现了低成本。     

基于SOP生产工艺的系统级封装

提出了一种基于SOP24基板及生产工艺,利用空余的管脚焊盘放置被动元件实现内部互连,制作SiP封装集成电路的封装工艺。选择红外发射电路,使用HT6221红外编码器芯片、电阻、三极管等无源元件,制造出集成了驱动电路的红外发射芯片。建立开发平台对内部器件的布置进行优化,最终制作出工艺简单、性能可靠的SiP封装器件。用一个标准的SOP24封装组件实现了完整的系统功能,面积比系统级封装前减少50％,可靠性大幅度提高,用户使用该芯片开发产品的难度大大降低。     

试析炭黑填充物基PTC导电复合材料的研究进展及展望

本文基于炭黑填充物基PTC导电复合材料的研究进展进行分析,分析了影响复合材料PTC效应的相关影响因素,具体阐述了消除NTC效应的主要方法,并对炭黑填充物基PTC导电复合材料的未来发展进行了展望,希望能以此推动PTC导电复合材料在各个领域中的进一步应用.     

一种新型脉冲氙灯预燃电路

介绍一种为高压脉冲氙灯（型号为４×６５Ｆ）而设计的预燃电路，电路采取开关电源方式供电，磁饱和方式降压、稳流。因此去掉了传统触发和预燃电路中的升压变压器、限流电阻、触发高压包等。整个电路的体积、重量明显减小，效率提高．实际运行表明，该电路工作可靠，运行稳定．     

Experimental Analysis of Mechanical and Electrical Characteristics of Metal-Coated Conductive Spheres for Anisotropic Conductive Adhesives (ACAs) Interconnection

An accurate characterization for the deformation behavior of conductive particles is important: 1) to understand the anisotropic conductive adhesive (ACA) interconnection and 2) to optimize the ACA bonding parameter. This paper introduces an experimental technique, which has been developed to allow continuous monitoring of deformation characteristics of a single conductive particle. The load-deformation curve of a single conductive particle is measured, which provides the quantitative estimation of the mechanical and electrical characteristics of metal-coated polymer spheres used in ACAs. Based on the load-deformation result of a single conductive particle and the number of trapped particles on a bump, equivalent spring models are used to predict the deformation degree of conductive particles after flip chip assembly. For two kinds of conductive particles with different polymer cores, the mechanical and electrical characteristics of ACA interconnection were studied. Such results are used to further achieve a more sophisticated approach of the ACA bonding process and contact reliability.     

基才DC／DC开关稳压器的大功率LED恒流驱动设计

针对当前市面上DC／DCLED（发光二极管）专用恒流控制芯片价格高、不易购买的情况,阐述了基于市面常用DC／DC稳压器的高效率恒流稳压电源的通用设计方法,并给出了基于LM2596-ADJ开关稳压器的设计实例。与传统的恒压电源相比．电路增加了阻值很小的采样电阻以及由通用运算放大器组成的电压反馈回路和电流采样、放大反馈回路．同时增加了电压、电流反馈回路自动切换电路,使电路能根据负载大小在恒压和恒流模式之间自动切换。实验数据表明．基于该方法设计的LED恒流稳压电源恒流精度高,误差小于1％,效率超过87％,且电路工作稳定,元件取材广泛．价格低廉。     

接触电阻对聚合物PTC元件性能的影响

经过粗化或形变的电极能有效改善和导电聚合物的附着力，降低接触电阻，使ＰＴＣ元件的电性能更加稳定．在电极上用化学沉积镍层，减少了和复合材料的相互作用，增强和复合材料的黏结力，提高了ＰＴＣ元件的电重复性。     

Electronically tunable floating resistor

A new design for an electronically tunable floating resistor is proposed. The proposed circuit can be realized as a positive or negative resistor without changing the circuit topology, and can be tuned electronically. Simulation results are obtained to show adequate agreement with theory.     

A true integrable noninverting integrator with adaptive gain constant

A circuit with a true noninverting integrator with an adaptive gain constant is described. The circuit uses a junction field effect transistor (JFET) as a voltage controlled resistor. This resistor is controlled to change the RC product of the circuit to achieve adaptivity. The adaptivity was observed over a frequency range of 1:3. The circuit is suitable for IC implementation because the performance characteristics are determined by a feedback loop, thereby making them independent of the usual tolerance in passive parameter values.     

Flip chip attachment on flexible LCP substrate using an ACF

In this study the reliability of a flip chip bonding process using anisotropic conductive adhesives (ACA) was evaluated. The flexible substrates used were made of liquid crystal polymer (LCP), which is an interesting new material having excellent properties for flexible printed circuit boards. The test samples were prepared using two different anisotropic conductive films (ACF) having the same fast-cure resin matrix, but different conductive particles. The reliability of the test samples was studied by accelerated environmental tests. In the constant humidity test the temperature was 85 °C and the relative humidity was 85%. The temperature cycling test was carried out between temperatures of −40 °C and 85 °C. To determine the exact time of a failure the resistance of each test sample was measured using continuous real-time measurement. A clear difference between the behaviour of the conductive particles was seen in the test. While the adhesive having polymer particles had only one failure during testing, the adhesive having nickel particles had a considerable number of failures in both tests. Cross sections of the samples were made to analyze the failure mechanisms.     

A new continuously tunable sinusoidal oscillator without external capacitors

A new sinusoidal oscillator circuit using only operational amplifiers (OA's) and resistors, which is attractive for monolithic IC fabrication, is presented. The circuit can be made to oscillate by adjusting a resistor ratio, while its frequency can be controlled over a wide range by a grounded resistor, independent of condition of oscillation. Experimental results are given which agree with the theoretical analysis.     

Body ballast resistor enhances ESD robustness of deep sub-micron CMOS circuit

In this paper, the body ballast resistor design is introduced in electrostatic discharges (ESD) protection circuit for deep submicron CMOS integration circuit applications. With having the resistor, the ESD strength, turn-on resistance and trigge-on speed are greatly modulated. Those good characteristics enhance the efficiency of ESD protection circuit and keep the gate-oxide away from ESD damages. The consequence is caused from the fact that body ballast resistor builds up a positive substrate potential during the ESD stressing; consequently, reduces source to substrate barrier height. It should be further addressed that only a few design complexity is added, which is especially useful in deep sub-micron ULSI manufacturing.