Imbalance Difference Model Research Articles

Common-Mode Radiated Emission Analysis of Cable-Connected Printed Boards with Adjacent Metal Chassis by Imbalance Difference Model

Common-Mode Radiated Emission Analysis of Cable-Connected Printed Boards with Adjacent Metal Chassis by Imbalance Difference Model

Common-Mode Emission Simulation of Communication System with Adjacent Metal Chassis Based on Imbalance Difference Model

Common-Mode Emission Simulation of Communication System with Adjacent Metal Chassis Based on Imbalance Difference Model

Imbalance difference model for prediction of unintentional radiated emission from 10-wire power cable using for power line communication

Electromagnetic fields unintentionally radiated from power-line communications used in factories interfere with wireless communications. It is important to distinguish the mechanism of this undesired and unintentional radiation from that of wired communication as it affects wireless communications. In particular, unintentional radiated emissions should be reduced in order to construct a stable wired/wireless communication network. This paper focuses on power-line communication as it is used in a factory. The power distribution network in the factory consists of multiple cables bundled together. The effects of cables other than the power cable that applies the communication signal to the radiated electromagnetic field are investigated. Some of the signal power reaching the reciever is converted into common-mode current by an imbalance mismatch. The common-mode current is one of the main causes of unwanted electromagnetic radiation. To predict this conversion, an imbalance difference model is created to account for multi-conductor transmission lines such as those in the power distribution network of the factory. The proposed model can calculate the amount of common-mode excitation associated with changes in the load condition of the power lines. To verify the proposed method, the authors measured the change in common-mode current due to the difference in pairs of power lines to which the signal is applied. The calculation using the proposed model could estimate the amount of reduction in common-mode current to within an error of 1 dB.

Validation of Prediction Method of Common-Mode Current Reduction Based on Imbalance Difference Model for Differential Transmission Line Placed Near Edge of Adjacent Ground Plane

Validation of Prediction Method of Common-Mode Current Reduction Based on Imbalance Difference Model for Differential Transmission Line Placed Near Edge of Adjacent Ground Plane

In brief

PAGE 637 Researchers from a conglomerate of countries have improved the operation of passive optical networks. They present their work on an integrated transmitter and the receiver. Their work reports on the performance evaluation of a multi-channel transmitter that employs an arrayed reflective electro absorption photonic integrated circuit. With its low power consumption and small footprint it offers advantages compared with competing solutions. PAGE 648 In their Letter, a group from China propose an improved method for nearest level modulation(NLM) for cells of a cascaded H-bridge. The nearest level modulation directly controls the phase voltage of the converter and by optimising this H-bridge the system is improved. The H-bridge converter has high modulated accuracy and can improve the dynamic response speed and steady state accuracy of the control system. These devices could offer a low cost solution for the next generation of multiplexed passive optical networks PAGE 656 A Saudi-Indian partnership proposes a charge plasma based GaN MOSFET device that is free from hetero-epitaxial defects and inverse piezo electric effects making it more reliable. Hafnium with a work function of 3.9eV is used to induce n+ charge plasmas and create source and drain regions. An improved NLM for ten or so cells of cascaded H-bridge (CHB) converter with a high modulation precision is proposed PAGE 585 In this Letter, common mode radiation from cables attached to a printed circuit board (PCB) was predicted, with an accuracy of more than 95% observed for the upper bounds of the measured radiated emissions. Presented by a team from Malaysia, they modelled the expected radiation using the imbalance difference model. Computing the expected radiation before production helps to save time and cost. The charge plasma concept has been used first time in GaN devices PAGE 573 Researchers from France have used the Total-Field / Scattered-Field formulation method to compute an electromagnetic field far from its source. Computing the electromagnetic field can be difficult because of the numerical dispersion in large scale problems. Conventional approaches do not take into account 3D topography because of the amount of space and time needed; this new, simple, method allows the easy computation of 3D scattering. This work is important for circuit designers to predict the common mode radiated emissions from two cables attached to PCB The field radiated by a source is applied on a Huygen's surface in the surroundings of the scatterers

Prediction of common‐mode radiation from cables attached to PCB using imbalance difference and asymmetrical dipole antenna models

Cables attached to a PCB can produce a significant amount of unintentional common-mode (CM) radiated emissions (REs). Therefore, it is important to predict these emissions at the design stage before the first prototype is fabricated to ensure time and cost savings. In this Letter, a novel method was proposed to estimate the CM RE from two cables attached to a PCB using the imbalance difference model and asymmetrical dipole antenna model. The proposed method consists of two steps: first, the induced CM voltages on the junctions between the cables and PCB are computed using the imbalance difference model; secondly, the CM REs are then estimated separately for each cable related to half of the ground plane using the asymmetrical dipole antenna model. The overall REs are then computed by the superposition of the RE from the two asymmetrical dipoles. The effectiveness of the proposed method has been verified by comparing the predicted results to both 3D high-frequency structure simulator simulation results and measurement results taken in a semi-anechoic chamber. A good agreement with the accuracy of more than 95% is observed for the upper bounds of the measured REs.

Prediction of radiated emissions from high‐speed printed circuit board traces using dipole antenna and imbalance difference model

The ever-increasing clock speeds on printed circuit board (PCB) have enhanced PCB traces to become efficient radiators of electromagnetic energy. Conventionally, the radiated emissions (REs) of electrically short PCB traces are estimated using expressions developed based on electric/magnetic dipole antenna. In this study, a novel method was proposed to estimate RE from electrically long PCB traces. In this method, the differential-mode (DM) RE was estimated using the transmission-line theory and dipole antenna model, whereas the common-mode (CM) RE was computed by a combination of imbalance difference model and a dipole antenna. Conceptually, the electrically long trace was chunked into multiple electrically short segments and the fields of each segment were superimposed to obtain the net radiated fields. Additionally, closed-form expressions were derived to estimate the DM REs from electrically long PCB traces based on dipole antenna model. On the other hand, CM RE was predicted by line integration of CM current distribution which was approximated using imbalance difference model and asymmetrical dipole antenna model. The effectiveness of the proposed method was verified using compact single-sided PCB by comparing the computed results with the measured results taken in a semi-anechoic chamber, and a good agreement with accuracy more than 90% was observed for upper bounds of the REs.

Prediction of Common-Mode Radiated Emission of PCB with an Attached Cable Using Imbalance Difference Model

Prediction of Common-Mode Radiated Emission of PCB with an Attached Cable Using Imbalance Difference Model

Calculating Radiated Emissions Due to I/O Line Coupling on Printed Circuit Boards Using the Imbalance Difference Method

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.

Imbalance Difference Model for Common-Mode Radiation From Printed Circuit Boards

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.

Calculation of Common-Mode Radiation from Single-Channel Differential Signaling System Using Imbalance Difference Model

In a differential transmission line, a large common-mode radiation is excited due to its asymmetry. In this paper, the imbalance difference model, which was proposed by the authors for estimation of common-mode radiation, is extended to apply to the differential signaling systems. The authors focus on a differential transmission line with asymmetric property, which consists of an adjacent return plane and two signal lines which are placed close to an edge of the return plane. Three orthogonal transmission modes, a normal mode, a primary common mode and a secondary common mode, are defined. Among these transmission modes, the secondary common mode is dominant in radiation, and a mechanism of the secondary common-mode generation is explained. The radiated emission which was calculated using the imbalance difference model was in good agreement with that obtained by full wave calculation.

Evaluation of EMI Reduction Effect of Guard Traces Based on Imbalance Difference Model

Placing a guard trace next to a signal line is the conventional technique for reducing the common-mode radiation from a printed circuit board. In this paper, the suppression of common-mode radiation from printed circuit boards having guard traces is estimated and evaluated using the imbalance difference model, which was proposed by the authors. To reduce common-mode radiation further, a procedure for designing a transmission line with guard traces is proposed. Guard traces connected to a return plane through vias are placed near a signal line and they decrease a current division factor (CDF). The CDF represents the degree of imbalance of a transmission line, and a common-mode electromotive force depends on the CDF. Thus, by calculating the CDF, we can estimate the reduction in common-mode radiation. It is reduced not only by placing guard traces, but also by narrowing the signal line to compensate for the variation in characteristic impedance due to the guard traces. Experimental results showed that the maximum reduction in common-mode radiation was about '14 dB achieved by placing guard traces on both sides of the signal line, and the calculated reduction agreed with the measured one within 1 dB. According to the CDF and characteristic impedance calculations, common-mode radiation can be reduced by about 25 dB while keeping the characteristic impedance constant by changing the gap between the signal line and the guard trace and by narrowing the width of the signal line.

Increase of Common-Mode Radiation due to Guard Trace Voltage and Determination of Effective Via-Location

SUMMARY A guard trace placed near a signal line reduces commonmode radiation from a printed circuit board. The reduction effect is evaluated by the imbalance difference model, which was proposed by the authors, when the guard trace has exactly the same potential as the return plane. However, depending on interval of ground connection of the guard trace, the radiation can increase when the guard trace resonates. In this paper, the authors show that the increase of radiation is caused by the common mode, and extend the imbalance difference model to explain a mechanism of increase of common-mode radiation. Additionally, the effective via location of the guard trace is proposed to reduce the number of vias. The guard trace voltage due to the resonance excites the common mode at the interface where the cross-sectional structure of the transmission line changes since the common-mode excitation is expressed by the product of the voltage and the difference of current division factors. To suppress the common-mode excitation, the guard trace should be grounded at the point