Assessment of digital integrated circuit electromagnetic emissionbased on radiated power evaluation

This paper deals with the assessment of digital integrated circuit (IC) electromagnetic emission (EME), and concentrates on the specific aspect of EME of long external wiring, driven by IC input-output pins. In particular, the contribution of single IC pins is investigated by analyzing the structure composed of an IC output driver connected via a microstrip line to a receiver. A transmission-line model is used, and an approach based on the concept of radiated power is applied to the characterization of single-pin IC EME in terms of external-wiring radiation effects. By the analysis of typical driver-wiring configurations, it is shown that the spectrum of the driver output current is the quantity of interest, and that the use of wiring with smaller characteristic impedance leads to larger radiated power. The use of a specific test setup (IEC 61967-4-150-Ω direct coupling method) for the experimental assessment of single pin IC emissions is also considered. Frequency-dependent setup effects are experimentally ascertained via a scattering parameter characterization, and definition of suitable circuit functions. An estimate of the degree of correlation between voltage measurements foreseen by the test procedure and the total power radiated by the loading network of an IC driver is derived     

The re-emission spectrum of digital hardware subjected to EMI

The emission spectrum of digital hardware under the influence of external electromagnetic interference is shown to contain information about the interaction of the incident energy with the digital circuits in the system. The generation mechanism of the re-emission spectrum is reviewed, describing how nonlinear effects may be a precursor to the failure of the equipment under test. Measurements on a simple circuit are used to demonstrate how the characteristics of the re-emission spectrum may be correlated with changes to the digital waveform within the circuit. The technique is also applied to a piece of complex digital hardware where similar, though more subtle, effects can be measured. It is shown that the re-emission spectrum can be used to detect the interaction of the interference with the digital devices at a level well below that which is able to cause static failures in the circuits. The utility of the technique as a diagnostic tool for immunity testing of digital hardware, by identifying which subsystems are being affected by external interference, is also demonstrated.     

Investigation of radiated susceptibility during EFT tests

The aim of this paper is to focus on a problem: during an electrical fast transient (EFT) conducted susceptibility test, a very strong radiated field is produced and a radiated coupling with the internal circuitry of the equipment under test (EUT) occurs. Therefore in case of EUT malfunctions, it is difficult to understand whether the resulting failures are due to the injected conducted current (requiring a filtering action) or to the impinging radiated EM field (requiring a shielding action). A model to describe the EM radiation, coming from the current flowing along the EUT power cord, is presented as well as its experimental validation     

Robust design of low EMI susceptibility CMOS OpAmp

This paper addresses a new approach to design a CMOS operational amplifier which provides a good tradeoff between high gain and strong immunity to electromagnetic interferences. The proposed amplifier is based on two main blocks: the first is a fully differential folded cascode with modified input pair and the second is a source cross coupled AB class buffer. Thanks to the folded cascode stage and to the symmetrical output buffer, the amplifier exhibits both intrinsic robustness to interferences and good amplifier performances. The circuit was fabricated in a 0.8-/spl mu/m n-well CMOS technology (AMS CYE process). Experimental results, in terms of electromagnetic interference (EMI) immunity, are presented and successfully compared with commercial amplifiers. Measurements carried out on the chip and the amplifier overall performances are provided along with the corresponding simulation results.     

Behavioral EMI models of complex digital VLSI circuits

Increasing EMI potential of high-performance digital circuits like 32bit microcontrollers demand for switching current models and feasible ways to run netlist-based EMI simulations. A promising modeling approach for digital VLSI circuits is presented and a silicon test vehicle for correlation between models and measurements is described.     

数字信号光耦合器应用电路设计

较强的输入信号可直接驱动光耦的发光二极管,较弱的则需放大后才能驱动光耦。在光耦光敏三极管的集电极或发射极直接接负载电阻即可满足较小的负载要求;在光耦光敏三极管的发射极加三极管放大驱动,通过两只光电耦合器构成的推挽式电路以及通过增加光敏三极管基极正反馈,既达到较强的负载能力,提高了功率接口的抗干扰能力,克服了光耦的输出功率不足的缺点,又提高光耦的开关速度,克服了由于光耦自身存在的分布电容,对传输速度造成影响。最后给出了光耦合器在数字电路中应用示例。     

An improved method to estimate the impact on digital radio receiverperformance of radiated electromagnetic disturbances

Present emission standards are developed with respect to analog communication services. Therefore, knowledge of how relating present standards to the impact on digital radio receivers must be available for system design purposes. For a digital radio receiver, the bit error probability (BEP) is often used to show the impact of the receiver performance from a disturbing signal. A simple, previously proposed method relates present emission standards to the BEP for broad-band (BE) disturbance. This method has to be modified for use on narrow-band (NB) disturbance such as the NB spectral components from periodic signals. A method based on a modification of the earlier method is presented for this NB disturbance. This represents typical disturbance from information technology equipment working with periodic signals. The conclusion is that the method presented delivers a useful value of the BEP, which can be used when radiated emission requirements are to be chosen on electronic equipment co-located to digital radio systems     

Full-wave analysis of radiated emission from arbitrarily shapedprinted circuit traces

A mixed (scalar and vector) potential surface integral equation formulation, developed for microstrip antennas, is employed in conjunction with the method of moments to predict the radiated emission from arbitrarily shaped printed circuit traces. Computed currents and radiated fields for a typical trace configuration in the form of a rectangular loop loaded by low- or high-impedance lumped loads indicate good agreement with transmission line theory and/or elementary loop antenna analysis, when the trace size is electrically small. Computed results are presented to highlight the radiation and coupling due to common-mode currents     

数字钟电路的设计

数字钟是采用数字电路实现的计时装置,主要介绍了555定时器构成的多谐振荡电路作为时钟源的数字钟的基本组成和工作原理。电路元件大多为中小规模集成电路,是现下较为流行的数字钟的制作方案。     

Effect of logic family on radiated emissions from digital circuits

Radiated emissions were measured for simple digital circuits designed to operate with various logic families. Emissions in the near and far field were found to depend both on the circuit layout and the choice of logic family. However, the difference in peak emissions between any two logic families was found to be independent of the circuit layout. The greatest difference in peak emissions was between high-speed 74ACT logic and low-speed 4000 CMOS logic devices, with a mean value of approximately 20 dB. Emissions from a more complex circuit were compared with the measurements on simple loop circuits. Test circuits were used to measure the propagation delay, the rise and fall times, the maximum operating frequency and the transient switching currents between two successive logic gates for each logic family. Empirical formulas have been derived that relate relative peak emissions to these switching parameters. It is hoped that these will assist designers to assess the effect of choice of logic family on electromagnetic compatibility     

On the use of a conical cornucopia antenna to reduce EMI

The wide-angle radiation form a prime-fed parabolic reflector antenna and the associated EMI (electromagnetic interference) it produces can be greatly reduced by constructing the antenna in the form of an absorber-lined conical cornucopia (CC). Measured RPEs (radiation pattern envelopes) are inspected for the case where all antennas have about a 10-ft diameter and 43-dBi gain at 6 GHz and typify the type of WAR (wide-angle radiation)-RPE improvement achievable if scaled to other bands/sizes. It is shown that the CC's RPEs for angles from about 10 full half-power beamwidths (here 10°) and beyond, and most especially from about 30 full half-power beamwidths (here 30°) and beyond, are vastly superior to those of either the standard or improved (UHX/UMX) parabolic dishes. Indeed, it is seen that the CC's RPE levels are about 95 dB down from on axis for angles greater than about 90°. In other words, the CC's wide-angle RPE is about 40 dB lower than that of a standard parabolic-dish antenna of the same gain. These very low WAR levels then greatly mitigate the EMI to adjacent microwave routes in terrestrial radio relay applications     

Twisted differential line structure on high-speed printed circuit boards to reduce crosstalk and radiated emission

Differential signaling has become a popular choice for high-speed digital interconnection schemes on printed circuit boards (PCBs), offering superior immunity to crosstalk and external noise. However, conventional differential lines on PCBs still have unsolved problems, such as crosstalk and radiated emission. When more than two differential pairs run in parallel, a line is coupled to the line adjacent to it because all the lines are parallel in a fixed order. Accordingly, the two lines that constitute a differential pair are subject to the differential-mode crosstalk that cannot be canceled out by virtue of the differential signaling. To overcome this, we propose a twisted differential line (TDL) structure on a high-speed multilayer PCB by using a concept similar to a twisted pair in a cable interconnection. It has been successfully demonstrated by measurement and simulation that the TDL is subject to much lower crosstalk and achieves a 13-dB suppression of radiated emission, even when supporting a 3-Gb/s data rate.     

Comparison of high impedance input topologies with low EMI susceptibility

Different Input Topologies with resistance to electromagnetic interferences (EMI) are analyzed and compared in terms of EMI reduction. The emphasis in this study is put on circuit robustness and applicability to industrial applications, which requires sufficient EMI rejection over all process corners. Furthermore, a new topology based on a replica amplifier is introduced, that is more robust to process variation compared to previous works (Jean-Michel Redouté and Michiel Steyaert, ESSCIRC, Sept. 2008; Fiori, IEEE Transac Electromag Compat 49(4):834–839, 2007) that rely on accurate matching of absolute values in order to achieve efficient EMI cancellation.     

Design of a low EMI susceptibility CMOS transimpedance operational amplifier

In this work we analyze the effects of electromagnetic-induced interferences conveyed at the input of a transimpedance CMOS operational amplifier. In particular, it will be highlighted that transimpedance amplifiers natural exhibit a lower EMI susceptibility compared to common voltage-feedback opamps. Moreover, it will be shown through simulations that a careful circuit design can lead to opamps with a practically vanishing EMI susceptibility.     

《数字电路基础》教学改革研究

为培养学生掌握数字电路的理论知识和基本分析方法,并培养应用型创新人才的需要,进行了数字电路的教学改革。主要从教学内容、实验教学、课程设计这三大环节的改革进行探讨,经过2年教改的经验证明,改革后的教学方法更能培养学生的自主设计、创新能力,符合应用型人才培养的需要。     

Hybrid TFET-MOSFET circuit: A solution to design soft-error resilient ultra-low power digital circuit

In this work, to increase the reliability of low power digital circuits in the presence of soft errors, the use of both III-V TFET- and III-V MOSFET-based gates is proposed. The hybridization exploits the facts that the transient currents generated by particle hits in TFET devices are smaller compared to those of the MOSFET-based devices while MOSFET-based gates are superior in terms of electrical masking of soft errors. In this approach, the circuit is basically implemented using InAs TFET devices to reduce the power and energy consumption while gates that can propagate generated soft errors are implemented using InAs MOSFET devices. The decision about replacing a subset of TFET-based gates by their corresponding MOSFET-based gates is made through a heuristic algorithm. Furthermore, by exploiting advantages of TFETs and MOSFETs, a hybrid TFET-MOSFET soft-error resilient and low power master-slave flip-flop is introduced. To assess the efficacy of the proposed approach, the proposed hybridization algorithm is applied to some sequential circuits of ISCAS’89 benchmark package. Simulation results show that the soft error rate of the TFET-MOSFET-based circuits due to particle hits are up to 90% smaller than that of the purely TFET-based circuits. Furthermore, energy and leakage power consumptions of the proposed hybrid circuits are up to 79% and 70%, respectively, smaller than those of the MOSFET-only designs.     

一种数字控制的三相移相触发电路

设计了一款用于可控硅控制的三相移相触发电路.针对点电网及现场出现的噪声干扰问题,提出了一种去抖动电路设计方案,阐述了移相电路的基本设计思路.通过仿真和实际测试,该触发器的移相范围达到0°～178°,移相精度为0.35°/mV.     

Remarks on models for prediction of radiated fields in electricaldischarge events

Ambiguities have appeared in the literature on the role of the arc in the electromagnetic radiation associated with electrostatic discharges. The authors discuss the contribution of the arc channel to the total emission and present experimental evidence that this contribution is negligible compared to that of the rest of the circuit     

多层印制电路板边缘辐射的一种精确计算方法

研究了精确评估多层印制电路板电源分布网络辐射发射的计算方法.采用高效的两维边界元法计算出信号返回电流经过电源/地平面的阻抗,将过孔转换结构的等效物理电路模型与外部电路连接成整体电路,采用电路仿真的方法获得精确的辐射发射激励电流.由边界元法计算出激励电流在电源/地平面边缘产生的场分布,进而由边缘场的等效磁流求出远区的辐射场.计算了不同频率时的辐射发射激励电流及最大辐射值.研究结果表明：在反谐振频率处辐射场达到极大值.计算结果与全波有限元电磁场仿真的结果基本吻合.