使用发射信道模型降低液晶显示屏电磁干扰

本文介绍一种发射通道模型来仿真液晶显示屏所产生的电磁干扰噪声。通道模型包含基于IEC61967-2标准(横电磁波传输室的辐射发射)的封装、印刷电路板以及辐射柔性印刷电路板等模型来仿真电磁发射能量。最后,本文所用的仿真平台已经验证带有不同时序控制驱动器的真实37"液晶显示屏,而实验结果显示降低电磁干扰的效果极佳。配合所提出的发射通道模型,我们能够很容易的设计低发射驱动器,避免因电磁干扰问题所导致的成本增加。     

Electromagnetic Design Techniques for Liquid Crystal Display Driver ICs

A simple method of verifying electromagnetic interference (EMI) reduction effects for liquid crystal display (LCD) driver integrated circuits (ICs) is proposed. In this paper, we discuss correlations between radiated emissions and high-frequency currents of power system at three different levels: print circuit board (PCB) level, chip level, and functional circuit level. The EMI design points for LCD driver ICs are presented too. Simulated and measured results prove that our EMI design effectively reduces LCD EMI noise.     

基于互感模型的混合封装电力电子集成模块内 电磁干扰的研究

研究了大电流混合封装电力电子集成模块(IPEM)内功率电路对控制驱动电路的电磁干扰问题研究表明,功率电路的内部环流通过互感耦合的方式会对IPEM内部的控制和驱动电路产生重要影响,特别是环流的高频分量为了对环流的EMI进行评估,建立了IPEM的内部环流实验模型另外,一种简化的基于局部元等效电路(PEEC)原理的建模和计算方法被用于计算环流回路与控制和驱动回路之间的互感,实验证明结果是比较准确的.     

Multiple Slope Switching Waveform Approximation to Improve Conducted EMI Spectral Analysis of Power Converters

An improved and simplified electromagnetic interference (EMI) modeling method based on multiple slope approximation of device-switching transitions for EMI analysis of power converters is presented. The traditional noise source modeling method, which uses single slope for rise and fall transition, is studied, and the criteria for reasonable modeling in the frequency range is analyzed. The turn-on and turn-off dynamics are investigated by dividing the nonlinear transitions into several stages based on an insulated gate bipolar transistor (IGBT) behavior circuit model. Real device-switching voltage and current waveforms are approximated by piece-wise linear lines and modeled by multiple dv/dt and di/dt slopes. The predicted EMI spectra suggest that high-frequency EMI noise is modeled with an acceptable accuracy. The proposed method was verified experimentally for a dc-dc buck converter     

一种基于DC/DC变换器的LED驱动电路的设计

提出一种基于电流模式DC/DC变换器的驱动控制电路。该电路可以与恒流电路结合在一起,用作LED驱动。电路由误差放大器、斜坡信号产生电路、电流采样与叠加电路以及PWM比较器四部分构成。采用华虹BCD350工艺进行仿真验证,结果显示,电路成功实现了电流采样信号与斜坡补偿信号的叠加,在Vea信号的控制下,输出了控制功率管关断的PWM脉冲信号。     

An Externally Trimmed Integrated DC Current Regulator Insensitive to Conducted EMI

This paper introduces a new integrated dc current regulator using external resistive trimming, which presents a high degree of immunity against conducted electromagnetic interference (EMI). While classic topologies generate erratic bias currents that are totally different from the expected value once EMI is injected into the circuit, this new topology succeeds in producing the same fixed dc current, whether EMI is present or not. Extra filtering requiring small on-chip capacitors ensures that the ripple on the output current due to the interference remains at a very low value.     

基于LIN总线的汽车后视镜控制模块设计

以MC9S12DG128为主控单元、MM908E622为后视镜单元,采用单主多从的总线控制方式,设计了一种基于LIN总线的汽车后视镜控制模块。主控单元以单片机MC9S12DG128为核心,通过LIN收发器MC33661实现对总线数据的收发,同时将液晶触摸信号转换为LIN指令以达到对后视镜单元的整体控制。后视镜单元以MM908E622作为从单元控制器,内置LIN收发器和电机驱动电路,具有优异的调控能力,适用于控制汽车高端后视镜。设计中体现了汽车车身电子的智能化和网络化,在汽车工业中有较高的应用价值。     

Modeling of Parasitic Inductive Couplings in a Pi-Shaped Common Mode EMI Filter

This paper analyzes the effects of parasitic inductive couplings among the filter components and printed circuit board traces in a pi-shaped common mode (CM) electromagnetic interference (EMI) filter. The result shows that some parasitic inductive couplings related with CM choke do not affect the CM EMI filter performance. And then, it proposes a high-frequency circuit model for filtration performance evaluation and prediction for pi-shaped CM EMI filter, in which the parasitic inductive coupling between input and output loops of the investigated filter is considered to be the crucial coupling parameter while other parasitic couplings are ignored. The model is simple because only one coupling parameter is involved. A procedure is introduced to extract the inductive coupling between input and output loops in pi-shaped CM EMI filter using Z parameters through virtual prototyping. Simulation and experiment finally validate the model.     

Field-Line-Circuit Coupling Based Method for Predicting Radiated Electromagnetic Emission of IGBT-PMSM Drive System

Electric drive system with Insulated gate bipolar transistor (IGBT) power device is widely used in Electric vehicle (EV), which consists of inverter, cables and Permanent magnet synchronous motor (PMSM). Due to the fast switching in di/dt and dv/dt of IGBT device, the system produces serious radiated Electromagnetic interference (EMI) through the interconnection cables. Thus, modeling of EMI source, propagation path and load PMSM is the key to accurately evaluate the system's radiation level. In addition, the system's radiated EMI involves the integrated calculation of circuit, cable and electromagnetic field, which cannot be solved by using a single circuit or electromagnetic calculation method. Therefore, this paper develops an effective field-linecircuit coupling based method to investigate the radiated EMI problems for IGBT-PMSM drive system, which is validated by experimental measurement. Besides, the impact of power cable parameters on radiated EMI is discussed. The proposed approach has guiding significance for electromagnetic compatibility design of EV.     

Cost-Effective Zero-Voltage and Zero-Current Switching Current-Fed Energy-Recovery Display Driver for ac Plasma Display Panel

A new cost-effective zero-voltage and zero-current switching (ZVZCS) current-fed energy-recovery display driver for a plasma display panel (PDP) is proposed. It features a simpler structure, less mass, and lower cost of production. Furthermore, since all power switches are turned on or off under zero-voltage or zero-current switching, it has several favorable advantages such as an improved electromagnetic interference (EMI), low switching losses, and reduced burden on the cooling system. Particularly, since the current source built in the inductor can compensate the large gas-discharge current, main inverter switches have the reduced current stress and turn-on timing margin. Therefore, the undesirable voltage notch problem caused by the improperly controlled gate signal can be solved, which enables the panel to light at lower voltage such as 143 V compared with about 165 V of the prior circuit. To confirm the operation, validity, and features of the proposed circuit, experimental results from a prototype built with 6-in test PDP are presented.     

SXGA TFT-LCD驱动电路的设计

文中详细分析了一种分辨率为ＳＸＧＡ的液晶显示器驱动电路的设计概要,介绍了其所使用的驱动方法－－三级电压驱动方法、数据驱动器和扫描驱顺的结构及其功能,对在驱顺的灰度级产生方法进行了分析,并阐述了电路中电磁干扰（ＥＭＩ）的解决方法,对接口中所应用的ＬＶＤＳ技术进行了说明。     

FDTD and experimental investigation of EMI from stacked-card PCBconfigurations

Stacked-card and modules-on-backplane printed circuit-board geometries are advantageous for conserving real-estate in many designs. Unfortunately, at high frequencies, electromagnetic magnetic interference (EMI) resulting from the nonnegligible impedance of the signal return at the connector may occur. This effective EMI coupling path results in the daughtercard being driven against the motherboard and attached cables, resulting in common-mode radiation. The connector geometry can be modified to minimize the EMI coupling path when high frequencies are routed between the motherboard and daughtercard. Current speeds and printed circuit board (PCB) sizes result in geometries that are of significant dimensions in terms of a wavelength at the upper frequency end of the signal spectrum. The PCB geometries are then of sufficient electrical extent to be effective EMI antennas. The resonant lengths of the EMI antennas may, however, be quite removed from the typical half-wavelength dipole resonances. The finite difference time-domain method can be used to numerically analyze the printed circuit board geometries, determine antenna resonances, and investigate EMI coupling paths. EMI resulting from the stacked-card configuration has been investigated experimentally and numerically to ascertain the EMI coupling path at the bus connector, and EMI antennas     

A systematic coupled approach for electromagnetic susceptibility analysis of a shielded device with multilayer circuitry

This paper presents a systematic coupled approach for electromagnetic susceptibility (EMS) analysis of a shielded electronic device in the presence of an ambient electromagnetic interference (EMI). A full-wave electromagnetic modeling technique coupled with a circuit-based method is developed for the overall EMS performance analysis. The mixed-potential electric field integral equation (MPIE) is formulated via the method of moments to model the electromagnetic properties of an arbitrary structure consisting of wires and surfaces with any applied excitation. With numerical analysis, the effect of an ambient electromagnetic noise is characterized, and an equivalent circuit model is extracted for further analysis of EMI to internal high-speed sensitive circuits. Numerous examinations exhibit that this systematic coupled approach is a computationally efficient method to address the EMS problems at system level, in which the external EMI effects are fully considered and the circuit-based simulator is also exploited.     

一种用于千兆以太网的高增益、宽带限幅放大器

设计了一种高增益、宽带限幅放大器,最大速率为1.25Gb/s。限幅放大器包括多级放大级、输出驱动级、失调消除和信号检测电路,提供固定的正参考发射机耦合逻辑(PECL)输出电平,且可通过编程设定信号丢失(LOS)指示。当输入信号降低到设定门限时关闭输出以达到静噪之目的。放大器采用3.3V单一电源,采用TSMC0.35μmBiCMOS工艺设计版图,放大器版图面积为1.3mm×1.1mm。测试结果显示,在3.3V电源下具有超过52dB的动态范围,功耗仅60mW。     

Analogue control of the slew-rate in LIN bus digital transitions using translinear circuits

A novel technique to control the LIN (Local Interconnect Network) bus slew-rate transitions in automotive environment, where large fluctuations of the battery voltage are present, is reported. A bipolar translinear circuit generates a non-linear current that is used to modulate a MOS relaxation oscillator, producing a clock frequency that delivers a constant number of pulses during the LIN bus digital signal transition. This frequency modulated clock when applied to a digitally controlled analogue wave-shape driver results in a LIN bus digital transition with a slew-rate that is constant and independent of the car battery voltage. Experimental results measured in an IC implemented in a BiCMOS process showed that constant slew-rate transition of 1?±?2% V/??s is obtained for battery voltages varying from 6 to 40 V, over the temperature range of ?40 to 150°C.     

Electromagnetic interference from discharge phenomena of electriccontacts

The electromagnetic interference (EMI) from steady arc and showering arc electrical discharges was investigated. The experiment was carried out on Ag, Pd, and Ag-Pd alloy contacts under several circuit current conditions. Radiated noise levels were measured at frequencies up to 200 MHz. Experimental results show that the EMI levels from a steady arc, which is generally the phenomenon of the break of a noninductive circuit, are dependent on the composition of contact materials. The EMI levels from a showering arc, which is generally the phenomenon of the break of an inductive circuit, are independent of the composition of contact materials. The EMI from a steady arc is roughly inversely proportional to the frequency in the 0.1-10.0-MHz range, whereas in the 25-200-MHz range, the maximum level of EMI appears at about 70 MHz. The frequency characteristics of EMI from a showering arc are similar to those from a steady arc. The EMIs from these arcs exceed, in part, statutory limits     

A 70 mΩ intelligent high side switch with full diagnostics

A new, smart power switch for industrial, automotive, and computer applications developed in BCD (Bipolar, CMOS, DMOS) technology is described. It consists of an on-chip 70 mΩ power DMOS transistor connected in high side configuration and its driver makes the device virtually indestructible and suitable to drive any kind of load with an output current of 2.5 A. If the load is inductive, an internal voltage clamp allows fast demagnetization down to 55 V below the supply voltage. The device includes novel structures for the driver, the fully integrated charge pump circuit, and its oscillator. These circuits have specifically been designed to reduce electromagnetic interference (EMI) thanks to an accurate control of the output voltage slope and the reduction of the output voltage ripple caused by the charge pump itself. An innovative open load circuit allows the detection of the open load condition with high precision (3 mA ±10% within the temperature range from -25 to 150°C and including process spreads). Furthermore, the device protects the load from ground disconnection and is compatible with the new IEC standards concerning burst and surge tests. The quiescent current has also been reduced to 600 μA. Diagnostics for CPU feedback is externally available from the chip by two dedicated pins when the following fault conditions occur: open load, overload and short circuit to ground or to the supply voltage, overtemperature, and undervoltage supply     

液晶显示模块电磁干扰的防护

液晶显示模块是由ITO玻璃、液晶驱动芯片、背光模块与软性印刷电路板所组成,基于这种设计架构,当处理器通过输入/输出传输接口传送大量显示数据至液晶驱动芯片的过程中,会产生相当程度的电磁波,并通过模块上的软性印刷电路板（FPC）发散出来,进而影响电子产品内部的组件效能,因此文中将针对电磁干扰的问题说明一些防护的方法。     

高速PCB板的电磁兼容设计

以某一嵌入式系统核心PCB板设计为例，介绍了电磁兼容的基本概念及一些高速PCB板设计的基本知识，着重分析了无高频器件时高速PCB板设计中存在的电源系统干扰、地线噪声干扰和信号线阀的串扰等电磁干扰，并分析了这些电磁干扰产生的主要原因，从PCB总体设计和元器件布局、布线等方面考虑，对可能存在的这些干扰，提出了防止和抑制方法以及一些提高PCB板电磁兼容性的具体措施；在工程实践中证明这些方法和措施有效可靠。     

Study on design and electro magnetic compatibility of high-power pulse driver

A kind of high-power pulse driver is designed to drive semiconductor laser. The circuit consists of three parts: generator of pulse signal, power amplifier of pulse signal and storage circuit controlled by metal-Oxide-semiconductor field-effect transistor (MOSFET). According to the experimental results, this kind of high-power pulse driver well restrained the pulse spike and overshoot by proper design, better choice of components and improvement of electro magnetic compatibility (EMC). The circuit can output pulse signal with better quality, which provides qualified driving signal to laser diode. The pulse width is under 50 ns and the output ranges from 10 A to 50 A.