Effects of gapped groundplanes and guard traces on radiated EMI (original) (raw)
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Investigation of split groundplanes at the connector for EMI control
IEEE 1997, EMC, Austin Style. IEEE 1997 International Symposium on Electromagnetic Compatibility. Symposium Record (Cat. No.97CH36113), 1997
EM1 can often be reduced by selectively filtering various parts of a given system. One common method employed by designers is to split the groundplane near the chassis and route 1/0 lines over the split. The rationale is based on providing a large series impedance to common-mode currents on the 1/0 lines. In this manner, PCB designers hope to lower the level of noise currents contributing to radiation. This work studies the efficacy of the groundplane split as a deterrent for EM1 associated with 1/0 lines being driven against other extended reference structures. A test-board was developed to analyze the impedance of the groundplane split with various configurations.
Quantifying EMI resulting from finite-impedance reference planes
1997
Abstract Parasitic inductance in printed circuit board (PCB) geometries can detrimentally impact the electromagnetic interference (EMI) performance and signal integrity of high-speed digital designs. This paper identifies and quantifies the parameters that affect the inductance of some typical PCB geometries. Closed-form expressions are provided for estimating the inductances of simple trace and ground plane configurations
Analysis of Radiation Emission from Ground Plane Structure
High-Speed multilayer printed circuit boards have been used to the ground plane structure modified to improve electrical performance and reduce size of a micro strip circuit. The signal current through the ground plane, which causes undesired effects such as signal distortion, crosstalk and radiation. The digital circuit's printed circuit board (PCB) layout design plays a crucial role in emission mitigation technique. The Ground plane structure through a slot line are consider the propagation of transmitted and reflected waveforms will changed .The micro strip line or the strip line with a plane structures can greatly suppressed the radiation emission. In order to reduce the radiated emission from high speed board implement the various structures in HFSS and ADS Software for simulation. Analyze the simulation results by the slotted plane, solid plane, and split reference plane have compared the various Conventional structures with proposed method numerically and experimentally investigated the effects of the power/ground partitioning on the radiated emission.
IEEE Transactions on Electromagnetic Compatibility, 2000
This paper presents a method for fast and comprehensive simulation of signal propagation, power/ground noise, and radiated emissions by combining the merits of the physics-based via model, the modal decomposition technique, the contour integral method (CIM), and the equivalence principle. The physics-based via model combined with the modal decomposition technique is an efficient technique for signal integrity analysis of multilayer PCBs and packages. The CIM can be used to calculate the voltage distribution between arbitrarily shaped power planes. Far-field radiation can be obtained by applying the field equivalence principle. In this paper, we integrate the four techniques to analyze all the three effects in a fast, concurrent, and holistic manner. To the best knowledge of the authors, the four techniques are integrated here for the first time. Various structures are simulated and validated with full-wave simulations up to 20 GHz. It is shown that a reduction in simulation time of more than two orders of magnitude is achieved in comparison to a standard full-wave electromagnetic solver.
Evaluation of EMI Reduction Effect of Guard Traces Based on Imbalance Difference Model
IEICE Transactions on Communications, 2009
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.
Progress In Electromagnetics Research B, 2012
Noise reduction in PCB is a major concern in the present digital electronic systems with data rate beyond 10 Gbps. The noise, due to simultaneous switching noise, radiation from signal vias crossing the planes, etc. can propagate within parallel plane cavity at its resonant frequencies, thus allowing coupling between integrated circuits (ICs) far from each other. Electromagnetic band-gap (EBG) structures are largely employed as noise reduction technique. This paper presents a quick and efficient analytical approach for evaluating the EBG noise reduction performances in terms of band-gap limits. The study is based on the physics behavior of the planar EBG structures, focusing on its resonant properties. The resonant modes of the EBG cavity are affected by the additional inductance of the patterned plane respect to the case of the ideal solid plane cavity. The formulas provided, based on the quantification of such inductance, can be easily implemented and employed for a quick layout design of power planes in multilayer PCBs, as shown in a practical example of a partial EBG plane.
PCB ground fill design guidelines for radiated EMI
2008 IEEE International Symposium on Electromagnetic Compatibility, 2008
This paper is to alert PCB designers about potential EMI problems caused by ground fills in outer layers of PCB. Ground fills are frequently used on top and bottom layers of PCBs for manufacturing or perceived shielding reasons. However, if not well applied they may cause EMI problem, especially if they form resonators. Several types of situations need to be distinguished, by (1) the resonating structure and (2) the excitation structure. Examples of problematic structures are shown by simulation and measurement. Possible guidelines for mitigating such problems are discussed.
FDTD and experimental investigation of EMI from stacked-card PCB configurations
IEEE Transactions on Electromagnetic Compatibility, 2001
Stacked-card and modules-on-backplane printed circuit-board geometries are advantageous for conserving real-estate in many designs. Unfortunately, at high frequencies, electromagnetic 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.
Shielding Methodologies in the Presence of Power/Ground Noise
IEEE Transactions on Very Large Scale Integration (VLSI) Systems, 2000
Design guidelines for shielding in the presence of power/ground (P/G) noise are presented in this paper. The effect of P/G noise on crosstalk is analyzed for different line lengths, line widths, and interconnect driver resistances. Considering the P/G noise, a shield line can degrade rather than enhance signal integrity due to increased P/G noise coupling on the victim line.