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In this article, a common-mode noise filter with a wideband suppressing and dual-band high absorbing common mode filter, which is called absorptive common-mode filter, is proposed. The filter is constructed by a reflective-type common-mode filter, a phase matching, and an absorber. It is composed of three layers with 14.98 mm × 9.585 mm. The broadband common-mode noise suppression can be achieved by positioning multiple transmission zeros. By using dual-band phase matching and an absorber, the dual-band absorption can be realized. The frequencies are in the range of 2.4 to 2.5 GHz and 5.17 to 5.33 GHz, respectively. The positioning of transmission zeros and absorption points at those frequencies leads to a high absorption efficiency. The simulation result shows that the common-mode suppression, which is below −10 dB, is from 2 to 11 GHz. The fractional bandwidth is 138%. The differential-mode signal keeps integrity in the range from DC to 12 GHz. The absorption efficiencies in the two frequency sections are 97% and 96%, respectively. The experiment results show only slight differences from the simulation results.

In this article, a novel circuit is proposed to synthesize absorption common-mode filters (A-CMFs) in only one stage, which can be implemented with different kinds of transmission lines. This proposed one-stage absorption circuit has been derived with analytical equations, and design formulas are found to determine circuit parameters. To validate the proposed circuit and derived formulas, an intuitional structure composed of a meander slotline (MSL), a straight differential pair, and one resistor is proposed. Moreover, a technique named meander asymmetrical coplanar strip (MACPS) has also been developed to reduce the size of MSL-type A-CMF by up to 26%. Finally, the proposed test sample of MACPS-type A-CMF is fabricated in a two-layer printed circuit board (PCB) and measured. The common-mode (CM) noise absorption efficiency of above 80% can be obtained from 2.33 to 2.67 GHz to eliminate CM noises in the Wi-Fi 2.4 GHz band. Besides, the MACPS-type A-CMF provides an excellent differential-mode (DM) signal integrity. The −3 dB bandwidth of DM insertion loss can reach 7.5 GHz, and the measured eye diagram of the proposed work is identical to that of the reference board even the transmitted data rate is up to 16 Gb/s. To our best knowledge, the smallest A-CMF implemented in a two-layer PCB is achieved in this article with the electrical dimension being only 0.0358 λg2.

An efficient multiconductor transmission line (MTL) model of a shielded twisted wire pair (TWP) with apertures on its sheath is developed for predicting common mode (CM) and differential mode (DM) currents induced in the shielded TWP cable. Its transfer impedance and admittance with one-line apertures on its sheath are derived in a closed form. Therefore, the MTL equations are formulated and solved to obtain the CM and DM currents induced in the shielded TWP. Moreover, the proposed MTL model is generalized to be applicable for the braided–shielded TWP, in which the transfer impedance and admittance are formulated analytically. Results showed that the induced DM current inside the braided–shielded TWP is suppressed dramatically due to the uniform structure of the cable. The models are validated by comparing their results with those obtained by the commercial software FEKO; good agreements are obtained.

In this article, a novel method to suppress differential-to-common mode conversion noise in differential serpentine delay microstrip lines (DSDMLs) is proposed. To suppress the remnant mode conversion noise, embedded coupled lines are adopted in the parallel traces section of DSDMLs. Embedded coupled lines can minimize the timing delay between even- and odd-modes in the parallel traces section. In specific dimensions, embedded coupled lines propagate even- and odd-mode signals with the same velocity without changing the differential-mode impedance, so DSDMLs with embedded coupled lines can suppress differential-to-common mode conversion noise without degrading differential-mode signal quality. In simulations, the proposed DSDMLs exhibit about 93.0% suppression of the peak common-mode conversion voltage compared with conventional DSDMLs, regardless of the length of the parallel traces section of DSDMLs. The performance of our proposed DSDMLs is verified by conducting measurements with millimeter-scale test boards in the frequency and time domains. The test board exhibited 78.7% suppression of common-mode conversion noise without degrading the differential insertion loss compared with conventional DSDMLs. Simulations and measurement results exhibited good agreement.

In this article, design and characteristics of 20-GHz electromagnetic bandgap (EBG) common-mode (CM) filters for microstrip (MS) and stripline (SL) differential pairs are considered. CM filter notch (resonance) frequency, depth, and width at the −15 dB level are calculated from the mixed-mode S-parameters. The agreement between the measured and modeled S-parameters of the baseline structures validates the models and allows for further numerical experiments. The systematic analysis of the trends for both MS and SL filter characteristics as functions of various geometrical and material design parameters is presented. Sensitivity to various technological features (conductor surface roughness, trapezoid shape of the traces, and line length imbalance) is also analyzed. It is shown that the MS EBG structure is more sensitive and less monotonic to most of the design parameters than those for the SL. This is attributed to the less electromagnetic field containment and more complex mode structure in the MS structures as compared to the SL. Systematic sensitivity analysis allows for an optimal design of the EBG CM notch filters for any printed circuit board layer where a differential pair runs. Though the analysis is presented for 20-GHz EBG filters, most of the trends would be applicable to the filters for the other frequencies.

This article presents a novel circuit topology for ultra-wideband common-mode filter (CMF). The common-mode (CM) noise suppression stopband is enhanced by the capacitance coupling between two dual-mode LC tanks. Moreover, the RLC equalizers are integrated with the proposed CMF circuit topology to improve the signal integrity of the differential mode. Finally, the CMF chips are fabricated by the GaAs process for low-cost massive industry applications. For the CMF chip with equalizers, the measured differential-mode insertion losses are kept nearly constant at around −5 dB from dc to 8.1 GHz. The measured −10 dB CM stopband is from 2.2 to 9.4 GHz with a fractional bandwidth of 124%, which is the widest CM noise suppression stopband, compared with the other CMF chips based on the semiconductor process.

In wired signal transmission, conversion between the differential and common modes deteriorates the quality of the transmitted signal and also causes electromagnetic compatibility problems in the environment. Therefore, the transmission-line components are requested to be tested on their conversion loss characteristics, such as the longitudinal conversion loss (LCL), transverse conversion loss (TCL), and mixed-mode S -parameters. Theoretical investigations are carried out to analyze the mode conversion of a differential one-port device in order to express the conversion loss parameters in terms of the modal impedances of the device. Consequently, the mutual relationships among the parameters are derived using the modal impedances. In addition, a new LCL measurement method is proposed that can accurately determine LCL values of a device under test by using a vector network analyzer instead of a traditional balun-transformer measuring instrument. Furthermore, it is found that the ratio of the TCL to LCL is not constant but varies with device characteristics. Therefore, a new definition of the TCL is proposed in place of the conventional one. The validity of these theoretical results is confirmed through SPICE simulation and measurements.

Very high frequency (VHF)-line impedance stabilization network (VHF-LISN), which is defined as the termination device for mains cable of equipment under test to specify the input impedance of each line at the mains power supply outlet, can improve correlation between test sites that perform radiated emission measurement. Balanced and unbalanced types of VHF-LISN are currently under proposal with International Special Committee on Radio Interference (CISPR) as a device for prescribing the terminating condition of the power supply cable. Simulation analysis with common mode (CM)/differential mode (DM) signal sources was performed to investigate the emission characteristics with the two types of termination devices under several measurement arrangements that used two-wire and three-wire mains cables. Furthermore, to confirm the validity of the simulation analysis, measurement of a versatile comb-generator-operated by ac mains was performed under the same test arrangement and two types of termination devices. Quasi CM/DM signal from an ac-operated comb generator was injected back into the mains cable of the same comb generator. This article explains how we ascertained the radiated emission characteristics with each termination device, and provides guidance for their appropriate usage.

In this article, impedance mismatch effects on the characteristics of common-mode (CM) electromagnetic bandgap (EBG) filters are studied using three-dimensional (3-D) full-wave numerical simulations. The CM EBG filters considered herein are designed using standard printed circuit board technology and contain either microstrip (MS) differential pairs running above the EBG plane, or stripline (SL) differential pairs running on one of the layers next to the EBG plane. First, the terminations are fixed at 50 Ω, and the effects of the differential line impedance variations on the EBG filter parameters are studied. Overall, the considered variations in the widths of the traces and edge-to-edge separation distances in both the MS and SL structures do not drastically deteriorate the performance of the EBG CM filters. Then impedances of the ports are set different from 50 Ω, and the effects of this mismatch on the baseline SL and MS EBG structures are studied. It is shown that lower port impedances may have significant effect on the characteristics of filters. In addition, baseline EBG filters are cascaded with unmatched four-port load, and this may also deteriorate performance of filters.

The effect of the scattered field on the terminal risers in twisted-wire pairs (TWPs) is investigated in the presence of an electromagnetic plane wave incidence. An equivalent circuit of the common mode (CM), represented by a wire above the ground, is used to obtain the CM current along such TWP connected to a floating terminal together with the approximation of their near field. It is shown that the scattered field radiated by a TWP can be coupled with any floating terminals, and in turn, it has significant effects on the differential mode response at the resonant frequencies of such transmission line system.

For the radiated electromagnetic interference pre-compliance diagnosis in power electronics systems, the measurement of common mode (CM) currents, impedances, and voltages are essentially important. In this article, two measurement issues are first identified in CM current and impedance measurement. The first is the coupling between the cables attached to a power converter and the coaxial cable connected to the measurement equipment. It degrades the measurement accuracy. The second is the coupling between the converter's attached cables and the ac grid. It degrades the repeatability of measurements. To improve the measurement accuracy and repeatability, this article proposes an improved measurement technique to address these two issues. Furthermore, for the measurement of the voltage difference between primary and secondary grounds, this article also identifies two issues. The first is the poor measurement resolution for the low noise voltage in the high-frequency range due to the high magnitude of line-frequency voltages. The second is that the loading effects of the voltage probe can reduce the measurement accuracy. This article proposed a technique to address these two issues. Finally, the proposed measurement techniques were validated on a flyback converter.

High-speed digital systems require differential lines for chip-to-chip links. A common concern in differential lines is the presence of common-mode noise, which is a major contributor to signal integrity problems in high-speed digital systems. Common-mode noise is typically excited by skew. It can occur due to timing mismatches at the driver, length mismatches due to routing constraints, or phase velocity mismatches due to inhomogeneous dielectrics with fiber-weave effect. Common-mode noise results in increased crosstalk and electromagnetic interference on packages and boards. This paper presents a methodology based on varying the common-mode impedance of a differential line, while keeping the differential-mode constant. The variation in impedance results in a filter response solely for the common-mode signals, improving the noise immunity of the differential pair. This design is applied on stripline-type differential lines and the performance is enhanced by adjusting the ground via pitch to create resonant planes with a high-impedance current return path for common-mode signals.

This work analyzes the effect of conducting bands placed close to a common mode choke on the attenuation provided by an electromagnetic interference filter where the common mode choke is mounted. The main aim was to determine whether the response of the common mode choke can be modified and to clearly identify and quantify the physical mechanism responsible for the changes found in the attenuation of the common mode choke and the electromagnetic interference filter. The impact of grounded and ungrounded conducting surfaces was studied for the two more typical configurations of common mode chokes: vertically and horizontally mounted. This study has allowed us to devise an optimum shield for a common mode choke that can significantly improve the attenuation to both common mode and differential mode noise of an electromagnetic interference filter at high frequencies, where parasitic effects usually undermine the performance of the filter. Key features of the technique described here are that it can be applied easily and that it does not result in an increase of the weight, volume, or cost of the filter.

This paper presents a design methodology on the broadband common-mode filter (CMF) with four transmission zeros for solving electromagnetic interference in high-speed differential digital systems. An equivalent circuit model is established based on the mushroom structure to characterize the common-mode bandstop response, and the simplified transmission zeros condition is derived to predict the transmission zeros. Furthermore, the design criteria as well as design flow through the simplified transmission zeros condition can be employed to synthesize the four zeros CMF systematically. Finally, in order to verify the proposed design methodology, a broadband CMF with four transmission zeros is fabricated on a four-layer printed circuit board. The experimental results show that the proposed CMF can reduce the common-mode noise over 10 dB from 1.23 to 5.15 GHz with a fractional bandwidth of 123%. Compared with other literature on mushroom-like CMFs, the proposed CMF has the widest common-mode suppression bandwidth. The electrical size is only ${\text{0.0427}}\lambda _{g}^{2}$ , where λ $_{g}$ is the guided wavelength of the central frequency of its common-mode stopband. The insertion loss of differential mode is below 3 dB from dc to 8.5 GHz. In addition, the measured eye diagram of the proposed CMF indicates that it maintains good signal integrity for high-speed differential signals.

In this work, an enhanced model of injection probes for bulk current injection (BCI) is proposed, allowing for circuit simulation of BCI test setups involving complex wiring harnesses. Accuracy of the proposed model is assessed by means of electromagnetic (EM) full-wave simulation of different wiring structures comprising a large number of conductors. To this end, a virtual calibration setup, including an EM model of the injection device mounted on the calibration jig provided by the probe manufacturer, is preliminary developed and validated versus measurement data. The model is then used to investigate the main factors influencing RF noise injection in practical BCI setups. Particularly, it is used to predict the significantly different levels of noise measured at the terminations of each wire in the bundle during the BCI test, as well as to provide such differences with an explanation in terms of characteristics of the wiring harness, positioning of each conductor in the bundle with respect to the others, equivalent common mode impedance of the terminal networks.

Electromagnetic interference (EMI) couplings between a motor drive and an adjacent communication network induce a considerable common-mode (CM) current in a communication cable, which has a serious impact on the performance of the communication network. In order to estimate the CM current, it is necessary to study the coupling mechanism between the motor drive and the communication network. In this paper, a commercial motor drive system with an RS485 communication circuit is used for analysis. The conducted and near-field coupling paths are analyzed and modeled. By integrating the models of coupling paths with the EMI models of the motor drive and the dc/dc converter, an estimation model of the CM current coupled to the communication cable is built. Furthermore, online measurement methods and numerical simulation are presented to extract the impedance parameters of the conducted and near-field coupling paths. The estimation model is validated by comparing the simulated currents with the measured currents in the two configurations. This model is applicable for estimating the CM current coupled to the communication cable in various configurations.

An equivalent two terminal model based on the Thevenin equivalents describes the common mode (CM) currents on the input and output side of two widely used types of dc-to-dc power converters—buck and boost. Thus, it describes a nonlinear circuit by a linear equivalent circuit. The maximized spectrum of the CM currents is extracted for converters with stochastic signals using a novel characterization procedure. The extracted Thevenin model is used in co-simulation combined with a full-wave electromagnetic solver to predict the radiated emissions from the system consisting of the shielded dc–dc converters with attached cables and a DC brushless motor as load. The results using the terminal model agree well with the measurements providing that the actual CM loads are within the range of CM loads used while obtaining the Thevenin equivalent circuit.

Different methods to determine the common-mode impedance of coupling/decoupling networks (CDNs) are investigated. They are based on vector network analyzer (VNA) measurements by using a test adapter between the coaxial 50 $\Omega$ VNA test port and the equipment under test port of the CDN. It is shown that the influence of the test adapter should be taken into account above 50 MHz, which is far below the upper test frequency bound as defined in the IEC 61000-4-6 standard. Measurement results for the presented approaches are given for a CDN-M3 and a CDN-M5 type up to 500 MHz along with associated measurement uncertainties.

This paper provides a generalized technique for predicting bulk current injection (BCI) test results. The injected RF disturbance that reaches an integrated circuit (IC) is calculated using electromagnetic (EM) analysis. A three-dimensional (3-D) model of the equipment under test (EUT) can provide the terminal voltages of an IC whose references are the ground terminal of the IC, not the BCI test setup reference ground plane. Auxiliary equipment (AE) comprising an electric load and artificial networks are also modeled in 3-D, making it possible to take into account the mode conversion from common mode (CM) to differential mode. The most important technique for the modeling is the interfaces between each 3-D model. Quasi-transverse-EM port calculated by 2-D EM analysis at the cross section of the wires is adopted as the interface. In defining the failure threshold, we adopted the IC immunity macromodel for conducted immunity, which is based on the measurement of the direct RF power injection method. The proposed method was applied to several BCI tests with AEs that have different mode conversion characteristics and EUTs that have different CM impedances. The simulated results showed good correlation with the experimental results.

A codesign of an electrostatic discharge (ESD) protection device and a common-mode suppression circuit on printed circuit board (PCB) for high-speed input/output interfaces is introduced in this paper. The characteristic and the circuit model of the ESD protection device are investigated and applied into the design of the common-mode suppression circuit. The proposed one-stage design of two-layered PCB structure performs –10-dB common-mode noise suppression from 2.22 to 2.76 GHz; the proposed two-stage design with additional common-mode suppression unit performs wideband suppression from 2.25 GHz to over 8 GHz, covering IEEE 802.11ac WiFi band with –20-dB suppression level. The mode conversion for both designs is lower than –30 dB. The signal integrity and the ESD protection function of proposed design are investigated by eye diagram measurement and system-level ESD simulation. The proposed PCB design provides a low-cost solution for the integration on the high-speed input/output interface of next generation.

One of the recent frontiers of the multiple objectives optimization strategies is the introduction of an artificial neural network in place of a more time-consuming numerical tool or approach to compute the cost functions. This paper describes the development of a multiple objectives optimization strategy for an electromagnetic bandgap common mode filter by using an artificial neural network. The network training, that is to say the evaluation of the internal weights and biases, is optimized by a genetic algorithm. The results are discussed and also compared with those stemming from an already developed multiple objective sequential optimization strategy applied to the same common mode filter. In both strategies, the cost functions are the same and the optimization algorithm is a differential evolutionary one.

The selection of electromagnetic interference (EMI) output filters in a power drive system can be a challenge that involves a “cut and try” process with several retro-designed EMI filters, which are often not optimized in term of size, weight, or cost. Key components of an EMI filter are common mode chokes. They are needed to reduce common mode currents which are the main source of radiated emission in power drive systems. Using a “static modification factor,” this paper analyses effects of its designable parameters on its final performance as if it was already in situ . All in situ impedances of the common mode current loop have been taken into account. Two test setups are used to validate effects related to changes of core material, size, number of turns, and wiring system.

The multiple objective sequential optimization (MOSO) is one of the recent fronteers of the multiple objectives optimization strategies. Such an optimization is applied, for the first time in the open literature, to the optimization of the performances of a common mode filter based on a planar electromagnetic (EM) bandgap structure. The relevant design variables of this component are evaluated to increase the ${\rm{S}}_{{\rm{cc21}}}$ bandwidth around the design frequency and to decrease the unwanted total EM radiated power. The MOSO implements, for the optimization, a differential evolutionary (DE) algorithm. The results are validated either by measurement or by the computations obtained by substituting the DE with a standard genetic algorithm.

Electromagnetic interference (EMI) is correlated with mode conversion, from differential-mode signals to common-mode currents and further to antenna-mode currents on the outside of cables or enclosures. This paper presents methods to quantify the mode conversion caused by discontinuities in the digital visual interface (DVI) signal link. These discontinuities are mostly present in the DVI connector, the DVI cable, and the connector–cable interface. A systematic approach was developed in this study to isolate and identify the different coupling paths in a high-speed interface (in this case, DVI is shown) and also to identify which discontinuity is most critical to mitigate EMI. The method developed in this study can be used for any high-speed interface in modern communication systems.

Electromagnetic interference (EMI) from the low-voltage power-line network has been a major concern for the power-line communications (PLC) technology. The conventional EMI measurement is based on the mixed mode, including common mode, and differential mode (DM). However, the dominant transmission mode of PLC is DM. Therefore, for electromagnetic compatibility designing purposes, knowledge of the DM noise of the household appliances in the frequency range of 150 kHz to 30 MHz is essential to provide insight of conducted disturbance on the low-voltage power-line network. In this paper, a simple and useful method of DM conducted emission (DMCE) measurement using a PLC coupler is proposed and it offers a suitable interface and a convenient way for the household appliance to obtain the DMCE with the existing equipment. The obtained results compare the levels of DMCE and mixed-mode conducted emission (MMCE) from different kind of household appliance. It shows that even when MMCE meets the current limits in standard CISPR 14, DMCE may still exceed these limits. In order to suppress EMI on the PLC network, the limits and measurement methods of DMCE for the household appliance should be taken into account in the future.

This paper concerns a new approach for the characterization of power-line electromagnetic interference/radio-frequency interference (EMI/RFI) filters in a general impedance environment and continues to broaden the scope of one of previously published works. Specifically, the paper focuses on analyzing the lowest possible insertion loss of three-wire, single-phase EMI/RFI power-line filters in their stop-band at high megahertz or gigahertz frequencies. In contrast to the published work, the presented approach takes into account the reflections of converted modes at the filter input and output ports. A commercial single-phase EMI/RFI filter is analyzed in the frequency range of 1 to 10 GHz, in terms of common mode, differential mode and their conversions, by using the measured S-parameters of the filter and subsequently processing the obtained data. The results show that due to the reflections of conversion modes back into the structure of the filter, insertion loss values can be more than 20 dB lower than the results achieved by the previous known methods.

In this paper, the effects of undesired asymmetry and nonuniformity on differential line (DL) circuits are modeled as deviations from the ideal, nominal geometrical characteristics of a perfectly symmetrical and uniform DL, whose performance is taken as reference. To this end, the involved multiconductor transmission line equations are solved in the modal domain by a decoupled approach based on the perturbation of the p.u.l. parameters of the ideal DL on one hand, and on the assumption of weak coupling between the corresponding differential and common mode equivalent circuits on the other. Three illustrative DL structures are considered and analytically solved, with the objective to put in evidence the effects of the aforesaid geometrical nonidealities on the degradation of the differential mode signal propagating along the DL as well as on the generation of undesired common mode currents/voltages. A circuit interpretation of the involved phenomena is provided, and the relevant geometrical parameters are identified.

This work studies the possible reduction of the direct near-field radiation from electromagnetic bandgap-based comm-on-mode filters on printed circuit boards by using lossy dielectric and magnetic materials. Different combinations of materials are considered and numerically simulated. The comparisons of their performances are reported and discussed.

A hybrid analytical/numerical conducted an electromagnetic interference (EMI) modeling approach, which adopts both numerical method and analytical method, is proposed in this paper. In this model, the noise source is calculated directly with the original data from oscilloscopes. The noise path at different operating status is extracted from the original converter topology and its analytical expression is then derived. Also, according to the EMI receiver detector mode, the algorithm of the EMI receiver is proposed in this paper. Peak (PK), average (AV), and quasipeak (QP) values of the EMI can then be calculated to analyze the impact of each relevant component. The analytical method is provided to carry out PK, AV, and QP simulations accurately and fast. The simulation and experimental results for common mode leakage currents validate this EMI model. Furthermore, two analysis examples are given to illustrate how this model is applied for engineers.

We present a new scheme using a periodically corrugated reference plane (PCRP) for wideband suppression of a common mode (CM) noise in high-speed differential signals. In the PCRP, the CM return current path is designed to have a stepped impedance profile; thus, inducing the stopband for the CM noise. To analyze the CM noise suppression of the PCRP, an analytic dispersion equation is derived and verified by the full-wave simulation results and measurements. The PCRP experimentally demonstrates the CM noise suppression over the wideband frequency range from 5.3 to 10.4 GHz. In addition, good signal integrity characteristics for odd-mode propagation are verified by the measurements of the differential insertion loss and the eye diagram.

This letter presents an on-chip common-mode cancelation circuit (CMCC), which increases the immunity to electromagnetic interference (EMI) of the input stage in a classic CMOS operational amplifier. Two test chips, containing a classic Miller amplifier and a Miller amplifier with CMCC, respectively, have been fabricated in the UMC 180 nm CMOS process. Measurements illustrate how the latter amplifier exhibits an increased immunity to EMI compared with the former.

Common-mode (CM) noise on differential microstrip lines can be suppressed by PCB-embedded filters. These filters use resonating or broadband structures such that only the field from the CM signal couples to them. Based on a quarter-wavelength resonator, a new PCB filter is designed having an electrical size of only 0.15 λ × 0.065 λ, where λ is the effective wavelength in the CM filter. Its interdigital structure is also capable of suppressing higher order harmonics of the CM signal and can be used for USB 3.0 to mitigate electromagnetic interference. Further, a novel broadband suppression structure is described that uses magnetically lossy material to suppress the CM signal from 4.6 to 20 GHz without strongly affecting the intended differential signal.

This paper deals with the filters based on EBG cavities employed for reducing common-mode currents along differential stripline traces. The crosstalk among differential interconnects routed in close proximity to EBG-based filters, and next to filtered pairs, is accurately quantified. The comparison between the experimental and simulation frequency-domain results validate the proposed filter's effectiveness and make the simulation model reliable for investigating the complex multichannel crosstalk problem. This paper focuses on the stripline environment, where crosstalk occurs among traces routed on adjacent layers, with the EBG cavity acting as a coupling path. Multichannel time-domain simulations complete the characterization of the filter, showing the limited effects of the filter on the intentional differential signal, and the beneficial impact on reducing the potentially radiating common-mode harmonics. The quantification of the common-mode spectrum shows that the filtered harmonics are reduced by 10–15 dB; thus, minimizing the corresponding electromagnetic interference. Design guidelines are defined for the filter layout according to the relative position of unfiltered differential traces, when constraints force them to be placed in close proximity to EBG cavities and filtered pairs. In particular, the best layout for unfiltered traces on adjacent layers is orthogonal with respect to the filtered pair, whereas the parallel routing should be carefully used taking into account the signal bandwidth on the victim pairs.

In this paper, a novel compact and wideband common-mode suppression structure is proposed, which is composed of a meander line and several quarter wavelength resonators. A simple and accurate transmission line model is employed to describe the stopband behavior of the proposed structure. The resonance frequencies and harmonics of quarter wavelength resonators are employed to form stopbands of the common mode. Those stopbands together with the stopband of the meander line are connected in series, which are useful to expand the common-mode suppression bandwidth. Meanwhile, compensation strips are proposed to reduce the insertion loss of the differential mode. A reduction of 15 dB of common-mode propagation above 0.8 GHz is obtained by using the proposed hybrid structure. The measurement results of printed circuit boards, which are designed and fabricated on the simulation model, show good correlation with the simulation results.

The aim of this study is to analyze from a modeling and experimental point of view the filter effectiveness and the crosstalk among signal traces crossing the same common-mode filter based on electromagnetic bandgap structures in a modern server design configurations. Both microstrips and striplines are considered in the study, detailing the differences among them in the design step as well as in filter geometry and response. Simulation models and experimental setups are carefully described, and the numerical and measurement results are compared and discussed.

In this paper, mode conversion occurring in differential lines with cross section affected by geometric imbalance is investigated by recognizing a strict analogy with crosstalk, and by rephrasing in the modal domain the assumption of weak coupling (usually exploited for crosstalk analysis) in terms of weak imbalance. The derivation focuses on the conversion of the differential mode signal into common mode (CM) noise responsible for undesired radiated emissions, and leads to an approximate circuit model for CM-current prediction, in which the effects due to mode conversion are included by distributed voltage and current sources. Model accuracy is assessed by experimental and numerical validations involving unbalanced microstrip lines.

In this paper, immunity of differential dc power lines, recently considered as the physical layer for power line communications (PLC) onboard spacecraft, is assessed from the theoretical viewpoint. The analysis focuses on conducted immunity of the PLC channel to noise generated by the terminal units of the power line (PL). Particularly, multiconductor transmission line theory and modal decomposition are used to characterize the susceptibility of the PLC link to common mode and differential mode (DM) components of the conducted noise. Closed-form expressions for signal and noise contributions at the receiving modem are derived and used to develop design rules for the involved coupling/decoupling networks. By combining the spectral properties of the PL noise with the propagation properties of the link, it is shown that DM signaling, besides assuring a nearly flat channel frequency response, results to be more immune to the PL noise. Finally, the role that possible unbalance of the power units may play on the system conducted immunity and radiation properties is discussed by deriving analytical expressions of the longitudinal and transversal conversion loss associated with the PL terminal networks.

Modern power electronic semiconductors are switching very fast to reduce heat dissipation. Due to parasitic capacitances in the system, for instance, in a motor driven by an adjustable speed electrical power drive system, common mode currents are developed creating electromagnetic interference. The high common-mode current can saturate the core of conventional common mode inductors. Nanocrystalline material shows excellent properties, with high saturation, and high permeability in a broad frequency range. This combination makes them more suitable for common mode inductors than laminated or powder iron, and ferrites. Nanocrystalline material properties are discussed and compared with conventional materials. Common mode inductors for power drives systems have been designed and electromagnetic interference tests have been carried out.

A planar electromagnetic bandgap configuration of a compact common mode filter that is laid out on printed circuit board is studied. This filter is used to mitigate the common mode noise traveling on high-speed differential signal traces. These differential signal lines may be connected to I/O connectors and cables and small amounts of common mode noise can result in significant electromagnetic emissions. The filter is obtained by a very simple planar geometry based on the electromagnetic bandgap structures. A cavity made by a rectangular/square patch (together with a solid plane underneath) has a well known and predictable resonant behavior; the coupling between the differential pair routed on top of the patterned plane and the patch cavity, occurring when the traces cross the gap between adjacent patches, is used to reduce the energy associated with the propagation of the common mode noise. The properties of this filter are studied taking into account the layout of a real differential microstrip and the number of gap crossings. A compact configuration is proposed. Time domain simulations validate the suggested layout approach.

High frequency signals on printed circuit board (PCB) traces can couple to I/O nets that carry the coupled energy away from the board resulting in significant radiated emissions. Automated tools to detect unacceptable levels of coupling during the board layout rely on fast methods for estimating the amount of coupling and the resulting radiated emissions. A modeling technique is proposed to speed up the analysis of PCBs with coupled traces that induce common-mode currents on attached cables. Based on the concept of imbalance difference, differential-mode sources are converted to equivalent common-mode sources that drive the attached cable and the PCB reference plane. A closed-form expression based on the imbalance difference model is developed to estimate the maximum radiated emissions due to I/O line coupling in PCBs.

An asymmetrical grounded resonators technique to suppress the common-mode radiation (or electromagnetic interference) and mode conversion caused by the slot-crossing differential signals is proposed. The grounded resonators can be implemented on printed circuit board or package substrate without additional cost by just designing open stubs with shorting via connecting to the reference plane. The design theory based on the transmission line model is developed to estimate the physical length and effective bandwidth of the grounded resonators. In a fabricated example, the measured common-mode passband is from 2.21 to 3.35 GHz with a fractional bandwidth of 41%. Meanwhile, with the integrated grounded resonators, the differential-mode signal can still maintain good signal integrity. The reductions of the mode conversion and the common-mode radiation are also investigated. It shows that the frequency range of more than 5-dB improvement is consistent to the designed common-mode passband. The effectiveness of this novel noise mitigation approach is well validated by both simulation and experiment.

The differential-mode signals in printed circuit board (PCB) traces are unlikely to produce significant amounts of radiated emissions directly; however these signals may induce common-mode currents on attached cables, enclosures, or heat sinks that result in radiated electromagnetic (EM) interference. Full-wave EM modeling can be performed in order to determine the level of radiated emissions produced by a PCB, but this modeling is computationally demanding and does not provide the physical insight necessary to explain how differential signals induce common-mode currents on distant objects. This paper describes a model for determining the common-mode currents on cables attached to a PCB that is based on the concept of imbalance difference . The imbalance difference model is derived from research that shows that changes in geometrical imbalance cause differential- to common-mode conversion. This paper applies an imbalance difference model to PCB structures and compares the resulting equivalent source configurations to those obtained with traditional voltage- and current-driven models, as well as full-structure simulations.

Presents corrections to the paper, “Study of the propagation of common mode IEMI signals through concrete walls,” (Mora, N., et al), IEEE Trans. Electromagn. Compat., vol. 60, no. 2, pp. 385–393, Apr. 2018.

In this paper, a new methodology to characterize common-mode chokes is presented. It is based on a model where common-mode and differential-mode interference is separated into different ports. This methodology is used to explain modal conversion inside common-mode chokes, predict the common-mode and differential-mode conducted emissions when common-mode chokes are connected to electric devices, and improve the filtering performance of common-mode chokes by finding the optimal common-mode choke parameters.

This paper analyzes the transformation between differential-mode and common-mode noises due to the unbalance of noise sources and electromagnetic interference filters in power electronics circuits. Both insertion gain and electromagnetic interference measurements prove the analysis.

The electromagnetic emissions (EME) of integrated circuits (ICs) are of increasing importance in the selection of automotive components. Although the IC is treated as the main cause for these emissions, the electrical environment, i.e., the application of an IC including the minimal circuitry on the application board and its layout, as well as the global connection terminals (i.e., supply pins and bus signals) representing the load of an IC are crucial in determining the emission behavior of the entire system. This paper provides application engineers information about different aspects related to the EME of a controller area network (CAN) bus system and how emissions are generated and transformed within the application environment. It presents a methodology to investigate and predict the effects by using Very High-Speed IC Hardware Description Language-Analog Mixed Signal (VHDL-AMS). The description focuses on the interaction between the CAN transceivers and the twisted pair transmission line connecting them. Both common mode and differential mode as well as mode conversion aspects are considered. It highlights the fact that EMEs from a CAN bus system highly depend on the application environment.

In this paper, a model for permanent magnet synchronous motors to deal with high-frequency emissions from an inverter system is proposed and analyzed. The model permits study of the common-mode (CM) effects on the motor line currents. The experimental measurements show that the CM stray capacitors are not affected by rotor magnet positions. The simulated and experimental results show that the CM currents increase with decreasing sampling time.

The two current probes measurement method was employed by other researchers to measure the radio-frequency impedance of ac power mains. In this paper, with a modified measurement setup, the method is extended to measure the common-mode (CM) impedance of a CM choke under in-circuit condition.With a premeasurement characterization process, the effect of the measurement setup can be determined and eliminated. The proposed measurement provides a more realistic assessment of the CM impedance characteristic of any CM choke under actual operating condition. Published version

Three algorithms developed for expert system electromagnetic compatibility tools are used to evaluate a printed circuit board design. The maximum radiated emissions estimated by the algorithms are compared to the measured data for various board configurations. The algorithms identify the most important electromagnetic interference source mechanisms, drawing attention to the design parameters that have the most significant effect on the radiated emissions