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ABSTRACT: In compact wireless modules, electromagnetic (EM) interactions occurring between planar antennas and transmission lines (TML) sharing the same substrate may cause a high amount of undesired coupling and may also detune the antenna characteristics. In this paper, an approach for defining a block-out region around the planar antenna, where no components should be placed is developed, thereby ensuring that the antenna characteristics remain within tolerable limits when the antenna is integrated at board level. This region is comparable to the reactive near-field, but is determined by evaluating the reactive EM power density excited on the ground plane and deducing a threshold value. Its boundary will be termed the EM antenna boundary. Furthermore, a method for efficient estimation of EM coupling from the antenna to terminated TMLs routed outside the EM antenna boundary is developed. This method is based entirely on a postprocessing step to field simulations, i.e., the coupling is calculated based on the previously computed magnetic field distribution excited by the antenna on the ground plane. The coupling model uses the theory of field excited TMLs together with the Baum-Liu-Tesche integral equations for obtaining the terminal voltages of the TML and, hence, the coupling terms.
IEEE Transactions on Electromagnetic Compatibility 12/2011; · 1.18 Impact Factor
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ABSTRACT: In this work, a small encapsulated planar dipole antenna is designed and characterized for an UHF RFID tag. In the envisaged application, the RFID tag is applied to the front or back ends of wood logs loaded on a truck for monitoring purposes in logistics, where the tag size and form factor are crucial parameters. It is shown that the antenna needs to be designed considering the dielectric loading of the encapsulation and wood in proximity for achieving satisfactory impedance matching at 868 MHz and, hence, high read-range. The designed linear polarized antenna has the dimensions 6.5 mm × 70 mm (0.02 λ × 0.2 λ), a radiation efficiency of 55 % and a gain of 0 dBi. The antenna is screen-printed on paper (substrate) with a conductive polymer paste. The transponder integrated circuit (IC) is assembled in flip-chip technology with anisotropic conductive adhesive (ACA). The assembled tag is finally encapsulated with a material, which is preferably compatible with paper manufacturing processes.
Antennas and Propagation Conference (LAPC), 2010 Loughborough; 12/2010
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ABSTRACT: A methodology is introduced for modeling resistive losses in planar transmission lines that support the transverse electromagnetic mode. The methodology aims to accurately and systematically account for these losses by modeling the skin, proximity, edge, and surface roughness effects in a combined way. The results show a correlation with three measurements within 5%, and offer insight into the different sources of resistive losses at high frequencies. Considering a printed coplanar line as an example, approximately 8% of the resistive loss come from surface roughness, and 30% from the edge effects at 60 GHz. However, for a line with a higher conductivity metallization, this increases to 38% and 30%, respectively, from surface roughness and edge effects at only 20 GHz.
IEEE Transactions on Microwave Theory and Techniques 10/2010; · 1.85 Impact Factor
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ABSTRACT: The returning displacement currents of vias transiting multilayered stack-ups in electronic packages and boards excite parasitic transverse electromagnetic modes in power-ground plane pairs, causing them to behave as parallel-plate waveguides. These waves may cause significant coupling in the power-ground cavity, leading to electromagnetic reliability (EMR) issues such as simultaneous switching noise coupling, high insertion loss degradation of signal vias, and stray radiation from the periphery/edges of the package/board. In this contribution, we model and quantify EMR problems caused by uncontrolled return currents of signal vias in conventional multilayer stack-ups. Traditional methods used to minimize these problems, and their limitations are discussed. We propose a low-cost layer stack-up, which overcomes most of the limitations of conventional stack-ups by providing well-defined return-current paths for microstrip-to-microstrip via transitions. Test samples of the proposed configuration are designed, fabricated, and measured. Very good correlation is obtained between measurement and simulation. Finally, a circuit model for the microstrip-to-microstrip via transition, considering the return-current paths, is developed and the circuit parameters are analytically calculated. Conventional closed-form expressions used for the extraction of these parameters, particularly the via capacitance, are extended and modified.
IEEE Transactions on Electromagnetic Compatibility 06/2010; · 1.18 Impact Factor
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ABSTRACT: In this work, a quantitative study of the shielding effectiveness of mushroom-type electromagnetic bandgap (EBG) structures placed in close proximity to patch antennas is conducted. It is shown that the E-plane coupling between two patch antennas, mainly caused by surface waves excitation on the dielectric substrate, can be reduced by 15 dB at 24 GHz in the case that the EBG is placed at a distance of only 400 ¿m (~0.03 ¿) from the radiating apertures of the patch antennas. For this purpose, the EBG cell dimensions are adapted slightly. As a result, the feasibility of placing EBG structures close to patch antennas in order to save package/board space while maintaining high coupling suppression is shown.
Antennas & Propagation Conference, 2009. LAPC 2009. Loughborough; 12/2009
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ABSTRACT: In this work, a quantitative analysis of the electromagnetic fields in the vicinity of a patch and slot antenna, excited at 24 GHz, is conducted. The spatial decay of the electric and magnetic fields as well as the power density is evaluated on top of the substrate where other package/board components can be integrated. The results reveal that the spatial decay of the fields is qualitatively similar for both antenna types. Based on this analysis, favourable component positions in the vicinity of the antennas can be deduced with the aim of ensuring electromagnetic reliability (EMR).
Antennas & Propagation Conference, 2009. LAPC 2009. Loughborough; 12/2009
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ABSTRACT: Electromagnetic bandgap (EBG) structures are currently the most effective means to suppress noise coupling in microelectronic packages and boards. Since EBGs are periodic structures, they require periodically arranged patches, vias and in some cases, surface mount capacitors and inductors, to suppress noise within a desired frequency range. However, all these components take up much of the board/package space and very little space is left for the placement and routing of the ldquoactualrdquo components needed for system functionality. EBGs therefore, reduce the integration density of electronic packages and boards. Furthermore, due to the periodicity of the patches, transmission lines referenced to the patterned layer(s) of EBGs suffer from return-path discontinuity (RPD) problems, which severely degrade their electrical performance. In this work, we quantify some of the electromagnetic reliability (EMR) problems caused by EBGs. We then propose a novel planar noise isolation structure, the interconnected patch-ring (IPR) structure, which is just as effective as EBGs in noise isolation, but overcomes some of the limitations of EBGs.
Electromagnetic Compatibility, 2009. EMC 2009. IEEE International Symposium on; 09/2009
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ABSTRACT: Predictability of transmission line parameters in both the frequency and time-domains is very important for microelectronics packaging. Proximity effects and non-rectangular cross-sections can cause a drastic deviation in transmission line parameters from the theoretically calculated values. Filament models and full-wave techniques have offered improvements over analytical models for computing the parameters of transmission lines with arbitrary cross-sections including proximity effects. This work is an analysis of some state-of-the-art skin-effect models and a quantification of their limitations.
Electromagnetic Compatibility, 2009. EMC 2009. IEEE International Symposium on; 09/2009
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ABSTRACT: In this work we modeled and simulated through silicon vias (TSV) in low, medium and high resistivity silicon (LRS, MRS and HRS) for frequencies up to 80 GHz. We then quantified the electromagnetic reliability (EMR) problems caused by conventional TSVs, in which silicon is used entirely as the medium for wave propagation. Our results revealed that using these conventional structures leads to high insertion loss, lack of impedance control, cross-talk and strong EMI. For example, for TSVs having a diameter 40 mum and depth of 200 mum, approximately 30% of the power is lost through a conventional TSV in LRS at about 5 GHz if a SiO<sub>2</sub> thickness of 1 mum is considered. We then proposed three different configurations of TSVs, based on the concept of the coaxial transmission line, namely Coax-TSV (SF), Coax-TSV (MDF) and Coax-TSV (LDF) to overcome all the limitations of conventional TSVs. This enables LRS to be used for the development of low-cost silicon-based system modules.
Microelectronics and Packaging Conference, 2009. EMPC 2009. European; 07/2009
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ABSTRACT: Through Silicon Vias (TSVs) are expected to play an increasingly important role in next-generation microelectronics packaging. Even when the challenge of attenuation is overcome, crosstalk remains a major concern in TSV design. In this paper, it is shown that, at frequencies above 20 GHz, near-end crosstalk can easily exceed -20 dB. Traditional analytical models for crosstalk are compared to full-wave simulations to determine their limitations and a lumped element equivalent circuit model is presented. An examination of the impact of TSV dimensions is presented. Then, three TSV structures are compared and the impact of their dimensions on crosstalk is investigated.
Electronic Components and Technology Conference, 2009. ECTC 2009. 59th; 06/2009
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ABSTRACT: In this work, elevated microstrip patch antennas are designed and characterized at quasi millimeter-wave frequencies. Radiation efficiencies of up to 83% are reported at 24 GHz. The designed circular and rectangular patch antennas are fed through impedance controlled microstrip lines by means of proximity coupling. The elevated patches are supported by conventional vias. The proposed layer build-up comprises a low cost board substrate, a low loss 100 mum-thick prepreg layer and an elevated copper layer. The fabrication of the antennas is particularly favourable because the structures are manufactured with typical PCB manufacturing processes like copper plating, etching, resist lamination and laser drilling. This allows the manufacturing of many structures on large area panels.
Electronic Components and Technology Conference, 2009. ECTC 2009. 59th; 06/2009
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ABSTRACT: Electronic systems are exposed to a variety of environmental impacts causing multiple degradations of important characteristics such as signal propagation. Interconnect failures due to environmental stress are most often cracks. The ability to measure growing fatigue cracks on strip line conductive paths or solder joints is a desirable feature for reliability estimation of electronic assemblies. In this paper, we discuss the electrical, non-destructive measurement of micrometer scale crack propagation in functional signal paths. For this approach, electrical high frequency scattering parameters of coplanar lines are investigated. Correlation calculations suppress parasitic noise and coupling effects and reduce the amount of data. The electrical measurement of degradations in micrometer dimensions is the first step to a novel generation of reliability monitoring systems.
Electronic Components and Technology Conference, 2009. ECTC 2009. 59th; 06/2009
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ABSTRACT: The read-range of passive inductively-coupled high frequency RFID tags is strongly dependent on the inductance of the antenna-coils. Inductance calculations, whether numerical or analytical, are significantly complicated when the antenna-coil is not planar, but used in a bent state. This latter form of application has been made possible by the development of flexible substrates. A parameterization of the inductance in terms of its geometrical parameters including the bend radius would be advantageous. Therefore, in this work, we demonstrate the possibility of using the Response Surface Method (RSM) based on a suitable Design of Experiment (DOE) to derive a closed-form expression for calculating the inductance of a bent antenna-coil for a given design space. For the regression, we apply a combined approach which could be termed ldquoPhysics plus Taylorrdquo. In deriving the formula we exploit physical insight to reduce the number of unknown fitting coefficients. For the DOE we implement a so-called space-filling design based on a three-level full factorial design to derive the unknown coefficients. We reach an approximation equation for the inductance with a squared correlation coefficient r<sup>2</sup> of about 99.97% and an accuracy which is consistently better than 3%.
Electronic Components and Technology Conference, 2009. ECTC 2009. 59th; 06/2009
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ABSTRACT: Predictability of transmission line parameters is very important for microelectronics packaging. Surface roughness can cause a drastic deviation in transmission line parameters from the ideal theoretically calculated values. State-of-the-art analytical and full-wave surface roughness models have been helpful in closing this gap but they have considerable limitations, especially when applied to certain types of thin-film structures. This work analyzes some state-of-the-art surface roughness models and quantifies their limitations. A new approach to surface roughness characterization is then presented.
Signal Propagation on Interconnects, 2009. SPI '09. IEEE Workshop on; 06/2009
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ABSTRACT: Three patch antenna configurations commonly used for automotive radar applications, namely the conventional, suspended and partially-suspended patch, are modeled, analyzed and compared. This comparison takes into account not only size and performance issues but also considers the robustness of the antennas to process tolerances. Our results reveal that if a low-loss substrate is used, then the partially-suspended patch has a better efficiency, larger bandwidth and gain than the suspended and conventional patch configurations. The conventional patch is much smaller and may be more cost-effective because special technological processes are needed for the fabrication of the partially-suspended and suspended patch configurations. All these three patch antennas respond similarly to changes in geometrical fluctuations which occur because of process tolerances. We realized that fluctuations in patch length of about 10% detune all three antennas because the resonance frequency is shifted completely out of the operating range of the automotive radar.
Antennas and Propagation, 2009. EuCAP 2009. 3rd European Conference on; 04/2009
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ABSTRACT: In this contribution, a study of the interactions between a 2.4 GHz microstrip patch antenna and a microstrip transmission line integrated in close proximity on the same board, is presented. Our results reveal that the electromagnetic (EM) coupling between these components becomes very strong at or near the resonance frequencies of the TM-modes of the patch, especially when the distance of separation between the patch antenna and the transmission line is smaller than the difference between the physical length and the effective electrical length of the antenna, due to stray fields. Under these conditions, the antenna causes degradation of the insertion loss of the line. On the other hand, the presence of the transmission line leads to a shift in the resonance frequency of the antenna as well as a change in its impedance matching, due to fluctuations in the input impedance. To experimentally validate the simulation results, a test board was designed, fabricated and measured. A very good correlation was obtained between the measurement and simulation results.
Antennas and Propagation, 2009. EuCAP 2009. 3rd European Conference on; 04/2009
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ABSTRACT: In this work, a single-layered CPW-fed slot antenna element for low cost 60 GHz radio applications is designed, modeled and analyzed. The results show a -10 dB impedance bandwidth of over 7 GHz with a radiation efficiency of over 95% making it suitable for short-range WPAN/WLAN applications. It is shown that two of the slot antennas can be configured orthogonally to achieve polarization diversity when fed separately. An isolation of at least 18 dB is obtained with an element spacing of ¿/2. This can be advantageous for applications where the orientation of the terminal is not known.
Advanced Packaging and Systems Symposium, 2008. EDAPS 2008. Electrical Design of; 01/2009
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ABSTRACT: The viability of multimode high-speed transmission structures in 3D silicon system-in-package modules is examined with full-wave simulations. Multimode transmission is achieved by integrating a stripline into a dielectric filled waveguide built over a silicon substrate shielded with walls instead of the via fence used in the traditional substrate integrated waveguide (SIW) structure. Isolation and transmission properties are evaluated using the full-wave solver Ansoft HFSS. The improvement of shielding walls eliminates potential bandgaps, offers a more predictable response, and reduces attenuation at high frequencies by 10% on the TEM mode.
Advanced Packaging and Systems Symposium, 2008. EDAPS 2008. Electrical Design of; 01/2009
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ABSTRACT: In this paper, electromagnetic interference (EMI) in power-ground cavities is quantified for conventional layer stack-ups used in low-cost electronic packaging. Traditional methods to minimize EMI and their limitations are discussed. Our novel approach to minimize EMI by minimizing/preventing the excitation of parallel-plate-modes in power ground cavities is then presented. Finally, the advantages of our approach in ensuring Electromagnetic Reliability (EMR) of microsystems are discussed.
Advanced Packaging and Systems Symposium, 2008. EDAPS 2008. Electrical Design of; 01/2009
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ABSTRACT: The high bulk conductivity of silicon, leading to high attenuation, will become a significant challenge for designers of silicon-based system-in-package modules. In this paper, losses in TSV interconnect schemes are quantified with full-wave simulations. Several techniques for optimizing transmission using different return current paths are investigated, including ground shielding vias and two coaxial via structures. Then, a comparison of the losses in structures with different return current paths is made.
Electronics Packaging Technology Conference, 2008. EPTC 2008. 10th; 01/2009
