A pure realization of loss-free resistor

Realization of a loss-free resistor element (i.e., element with resistive input characteristic and yet loss-free) by means of switched mode converters operated in discontinuous current conduction mode (DCM) is presented. Practically, the input characteristic is not pure resistive due to the ripple and filtering effects. A method which enables reduction of the ripple to negligible values and the elimination of the input filter is presented, which facilitates realization of practical circuits with nearly pure input resistive characteristic. This approach is based on the operation of a group of converters operating in power sharing interleaved mode.     

Loss-free complex impedance network elements

The concept of loss-free complex impedance network elements (i.e., elements with active and reactive impedance components and yet loss-free) is introduced. Synthesis of such elements by means of switched-mode power converters with appropriate control has been demonstrated to be possible. Some possible power processing-related applications of these elements are indicated, such as improved matching between ac sources and loads and VAR compensation. It has further been demonstrated that loss-free complex impedance elements are suitable for modeling many power processing systems for the purpose of analysis as well as for design purposes.     

High-Temperature Superconducting Loss-Free Delay Network for High-Power Pulse

In this paper, a high-temperature superconducting (HTS) loss-free delay network for high-power pulses is performed. Based on the voltage and current pulse experiments carried out at 300 and 77 K, experimental results demonstrate that, under the matched resistive load condition, compared with a normal conducting lossy delay network, the HTS loss-free delay network can effectively reduce the amplitude attenuation of voltage pulses and the front-edge distortion of current pulses.     

Canonical modeling of power processing circuits based on the POPIconcept

The fundamental power-processing properties of switching converter circuits are modeled using generalized power-conservative (POPI) networks. Depending on the application, it may be most appropriate to model the first-order converter properties as those of an ideal transformer, gyrator, loss-free resistor, or other POPI network. These basic functions can be obtained either through selection of a topology that naturally possesses the desired characteristics or by addition of a suitable control network. Some well-known converter topologies are shown to behave naturally as gyrators, loss-free resistors, and constant power networks. The application of the gyrator to network two voltage sources and the use of the loss-free resistor as a unity power factor rectifier are described     

低功耗电阻型MEMS半导体气体传感器研究进展北大核心

电阻型MEMS半导体气体传感器在环境空气质量监测和有毒有害气体检测等领域得到了广泛应用，但是受限于功耗较高的原因，这类传感器难以广泛应用于便携式气体检测系统。文章综述了近年来低功耗电阻型MEMS半导体气体传感器的研究进展，分别从气敏材料、传感器结构和传感器模组的集成电路等方面探讨如何实现低功耗的电阻型MEMS半导体气体传感器的制备，并展望低功耗的电阻型MEMS半导体气体传感器未来的发展方向。     

Design of a CMOS closed-loop system with applications to bio-impedance measurements

This paper proposes a method for impedance measurements based on a closed-loop implementation of CMOS circuits. The proposed system has been conceived for alternate current excited systems, performing simultaneously driving and measuring functions, thanks to feedback. The system delivers magnitude and phase signals independently, which can be optimized separately, and can be applied to any kind of load (resistive and capacitive). Design specifications for CMOS circuit blocks and trade-offs for system accuracy and loop stability have been derived. Electrical simulation results obtained for several loads agree with the theory, enabling the proposed method to any impedance measurement problem, in special, to bio-setups including electrodes.     

Polarization-independent frequency-selective rasorber with a broadened absorption band

A polarization-independent frequency selective rasorber (FSR) with a transmission band at high frequency and a broadened absorption band at low frequency is designed and analyzed in this paper. The FSR consists of a resistive sheet and a bandpass frequency selective surface (FSS). A strip-type micro resonator (MR) is developed and applied in the resistive element. The MR is equivalent to a parallel LC circuit and resonates at the transmission band. The induced surface current distributions on the resistive element at different frequencies can be controlled as expected using the MRs, so that a high in-band transmission at high frequency and an absorption band at low frequency can be obtained, which are almost independent to each other. The absorption bandwidth can be broadened by cascading more MRs with several resistor-loaded metallic strips. Besides, due to the tiny dimensions of the MRs, polarization-independent absorptive/transmissive performances can be achieved by printing two orthogonal arrays of resistive elements on different surfaces of a dielectric substrate. The performance of the FSR is verified by both numerical simulation and experimental measurement.     

Localized bonding processes for assembly and packaging of polymeric MEMS

Localized bonding schemes for the assembly and packaging of polymer-based microelectromechanical systems (MEMS) devices have been successfully demonstrated. These include three bonding systems of plastics-to-silicon, plastics-to-glass, and plastics-to-plastics combinations based on two bonding processes of localized resistive heating: 1) built-in resistive heaters and 2) reusable resistive heaters. In the prototype demonstrations, aluminum thin films are deposited and patterned as resistive heaters and plastic materials are locally melted and solidified for bonding. A typical contact pressure of 0.4 MPa is applied to assure intimate contact of the two bonding substrates and the localized bonding process is completed within less than 0.25 s of heating. It is estimated that the local temperature at the bonding interface can reach above 150/spl deg/C while the substrate temperature away from the heaters can be controlled to be under 40/spl deg/C during the bonding process. The approach of localized heating for bonding of plastic materials while maintaining low temperature globally enables direct sealing of polymer-based MEMS without dispensing additional adhesives or damaging preexisting, temperature-sensitive substances. Furthermore, water encapsulation by plastics-to-plastics bonding is successfully performed to demonstrate the capability of low temperature processing. As such, this technique can be applied broadly in plastic assembly, packaging, and liquid encapsulation for microsystems, including microfluidic devices.     

基于云平台的同步电机远程数据采集与监视控制系统设计

数据采集与坚实控制系统在智能制造领域中是一项重要的组成。电动机是一种动力输出设备,并且应用十分广泛,同时还拥有许多的种类。基于工作电源的差异,电动机可以将其分为交流电动机、直流电动机两个大体类型。而同步电机则是一种交流感应电机,与异步电机十分类似。本文将监视控制系统应用于生产中的同步电机,设计数据采集与监视控制系统,该系统可以有效的增强生产的安全性,并获得良好的效果。     

ROF技术在蜂窝无线系统中的应用

目前，ROF（Radio-Over-Fiber）技术已经成为了通信领域的一个研究热点。本文探讨了两种ROF系统。一种是已经得到广泛应用（在日本）的相对来说比较传统的ROF系统；另一种ROF系统采用了新型技术，这种新技术可以让它在没有电力供应（without electric power supply）的情况下工作，具有很好的应用前景。后者的关键技术包括：射频（RF）电路和光电转换（E/O）设备之间的阻抗匹配，超低功率损耗的射频信号（RF）放大器，以及光功率的传送技术。     

Improvement of Resistive Switching Characteristics in $hbox{SrZrO}_{3}$ Thin Films With Embedded Cr Layer

The stabilization of the resistive switching properties is necessary to realize the memory application of the SrZrO₃(SZO)-based resistive switching devices. During continuous resistive switching cycle, broad variations of the resistive switching parameters of the SZO-based memory devices can be improved by a thin embedded Cr layer. The Cr metal layer is proposed to diffuse into and dope the SZO thin film to produce the space charge region, further reducing the effective resistive switching region. Hence, the good stabilization of the resistive switching properties can be obtained in the SZO films with embedded Cr layer.     

A monolithic quad line driver for industrial applications

The device described in this paper is a new quad line driver to be used in the hostile and noisy industrial environment and developed in mixed technology (BCD: Bipolar, CMOS, DMOS). It consists of four independent line drivers, each of which has a rail-to-rail push-pull output stage realized with power DMOS transistors connected in half bridge configuration. Even though the device is designed to be used primarily in the output cards of programmable controllers, it is a general purpose device, since it can drive any kind of load (resistive, capacitive, or inductive) with an output current of 100 mA. The novel structure of the top driver allows full protection of the output stage against any kind of short circuits and/or overloads, providing a linear current limitation. Furthermore, when a channel is tristated, for every applied voltage ranging from ground to the supply voltage, virtually zero current is absorbed from the output. An innovative high efficiency central charge pump circuit has also been designed and implemented, making both a very wide supply voltage operation (6-50 V) and high switching frequency (up to 500 KHz) possible, The device can also be used as a receiver since the input voltage can swing from -10-50 V     

Refined model of low-impedance film resistors with a comb-like structure

Using the methods of finite element and conformal mapping, analytical models with low and ultralow resistance of the film resistors of the main types of comb-like (interdigital) structures with an arbitrary ratio between the surface resistivities of resistive and conductive films have been worked out. In the resultant resistance, the resistances of comb-like and connecting electrodes are taken into account, as well as the additional resistance caused by the passage of the current from the conductive to the resistive film and vice versa. The conditions under which an interface between the films can be treated as an equipotential surface are revealed. An equivalent circuit of low-impedance comb resistors, which are used as the sensors of the current in the circuits of stabilization and control, as well as thermal and current protection.     

Analog VLSI for robot path planning

Analog VLSI provides a convenient and high-performance engine for robot path planning. Laplace's equation is a useful formulation of the path-planning problem; however, digital solutions are very expensive. Since high precision is not required, an analog approach is attractive. A resistive network can be used to model the robot's domain with various boundary conditions for the source, target, and obstacles. A gradient descent can then be traced through the network by comparing node voltages. We built two analog CMOS VLSI chips to investigate the feasibility of this technique. Design issues included the choice of resistive element, tessellation of the domain, programming of the network, and readout of the settled network. Both chips can be connected to a standard VME bus interface to permit their use as coprocessors in otherwise digital systems. A preliminary short version of this paper was presented at the 1992 ASILOMAR Conf. on Computers, Signals and Systems.     

Analog VLSI for robot path planning

Analog VLSI provides a convenient and high-performance engine for robot path planning. Laplace's equation is a useful formulation of the path-planning problem; however, digital solutions are very expensive. Since high precision is not required, an analog approach is attractive. A resistive network can be used to model the robot's domain with various boundary conditions for the source, target, and obstacles. A gradient descent can then be traced through the network by comparing node voltages. We built two analog CMOS VLSI chips to investigate the feasibility of this technique. Design issues included the choice of resistive element, tessellation of the domain, programming of the network, and readout of the settled network. Both chips can be connected to a standard VME bus interface to permit their use as coprocessors in otherwise digital systems.A preliminary short version of this paper was presented at the 1992 ASILOMAR Conf. on Computers, Signals and Systems.     

Simplified Analysis of Resistive Mixers

This letter gives a simple method for calculation by hand of the conversion efficiency of resistive mixers. The method assumes the same embedding impedances at all mixing frequencies and the mixing element is modeled as a time varying reflection coefficient. This gives simple expressions for the conversion efficiency. It, therefore, allows analytical parameter studies of the impact of the embedding impedance and parameters of the mixing element on the conversion efficiency. The theory is developed in two stages. First at optimum local oscillator power and second for arbitrary power. The theory agrees well with verifying measurements made on a field-effect transistor (FET)-based resistive mixer.     

Differential and common mode stability analysis of differential mm-wave CMOS amplifiers with capacitive neutralization

In this paper differential mode and common mode stability analysis of differential transformer-coupled CMOS mm-wave amplifiers with capacitive neutralization is investigated. Simulation of a differential amplifier implemented with a complete PSP transistor model shows that capacitive neutralization can improve the differential stability. In common mode however, the differential pair becomes potentially unstable over a wider frequency range. A robust common mode resistive stabilization technique, which ensures complete stability of the amplifier, is also discussed and analyzed. The analysis and stabilization techniques were successfully applied to stabilize a common mode unstable integrated F-band 45 nm CMOS amplifier. Measurements confirm the stabilization of the amplifier and a differential gain of 16 dB at 110 GHz is achieved.     

基于声光调制的中波红外激光功率稳定系统

针对中波红外激光器输出功率波动较大, 采用声光反馈调节的方法, 研发出一套声光反馈调节中波红外激光器腔体外功率的稳定控制系统, 系统主要由声光调制器、探测器、微电流放大器、反馈控制电路等组成。经实验验证, 该系统有效地抑制了激光器输出功率的波动, 波动可控制在0.08%范围之内, 达到了低温绝对辐射计对输入激光稳定性的要求。同时该系统具有软件调节输出功率的功能, 能够便捷、低成本地实现激光器多种不同功率的连续可调性输出, 通过增量式PID算法使得系统在2s内便可完成不同功率之间的调节, 亦解决了以往一台激光器只有唯一的输出功率的局限问题, 满足用户的多种使用需求, 具有实用性、创新性。     

Approach for Evaluating Effects of Wall Losses on Quarter-Wave Short-Circuit Impedance Standards

The conservation of energy principle and first-order perturbation theory have been applied to obtain formulas for the physical lengths and reflection coefficient magnitudes of quarter-wave coaxial and rectangular waveguide short-circuit impedance standards. The expressions for the physical lengths ensure zero phase angle at the mating interface when wall losses are present. The method can be extended to include small dielectric and magnetic losses, and requires only knowledge of the loss-free solutions. It can also be applied to other waveguiding structures which support uncoupled modes.     

Resistive interpolation biasing: a technique for compensatinglinear variation in an array of MOS current sources

A new technique called resistive interpolation biasing for accurately biasing a large number of analog cells on a VLSI chip is presented. Variations in oxide thickness, mobility, doping concentration, etc., cause inaccuracies in current ratios of two identically biased transistors if they are placed sufficiently far apart on a chip. The proposed technique compensates for these inaccuracies without using any sampling or switching. The technique has been verified using a 2 μm n-well CMOS process. Measurements show a factor of 3 improvement in terms of current ratio accuracy when the resistive interpolation technique is used. The circuit can be implemented with a small chip area and low power dissipation. This technique finds applications where extensive current duplication over a large area is required (e.g., analog memories, D/A converters, continuous-time filters, imaging arrays, neural networks, and fuzzy logic systems)