Fraunhofer-Institut für Zuverlässigkeit und Mikrointegration IZM

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  • Publication
    Mixed-Port Scattering and Hybrid Parameters for High-Speed Differential Lines
    ( 2019)
    Engin, A.E.
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    Ndip, I.
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    Lang, K.-D.
    ;
    Aguirre, G.
    High-speed transmission lines are commonly routed as differential lines to control sensitivity to noise on the reference planes at higher speeds. Differential lines are typically characterized in terms of mixed-mode scattering parameters, as they provide insight into the behavior of differential and common signals, as well as the mode conversion among them. These mixed-mode scattering parameters can be mathematically obtained from single-ended parameters, which can, for example, be measured with a four-port vector network analyzer. There has been recent efforts to develop extended or modified versions of mixed-mode scattering parameters, especially for tightly-coupled lines. This can be a point of confusion in interpreting the behavior of differential lines. In this paper, we introduce the mixed-port scattering and hybrid parameters, which do not suffer from any such ambiguous definitions. Mixed-port hybrid parameters are the most natural way to represent any four-port differential circuit, as they are based on intuitive differential and common-port excitations of the network. They also enable extraction of the current division factor experimentally, which is a critical parameter for electromagnetic interference analysis of differential lines. Mixed-port scattering parameters are also defined based on common and differential port excitations, allowing a simpler interpretation than their mixed-mode counterparts, without the need for defining even, odd, common, or differential-mode impedances. As such, mixed-port scattering and hybrid parameters can be used to analyze the performance of a general differential network, certainly including coupled or asymmetrical lines, without any ambiguity.
  • Publication
    Closed-form multipole debye model for time-domain modeling of lossy dielectrics
    ( 2019)
    Engin, A.E.
    ;
    Ndip, I.
    ;
    Lang, K.-D.
    ;
    Aguirre, J.
    Lossy dielectrics in printed circuit boards and integrated circuit packages can be represented by using a Debye model. This allows accurate signal and power integrity analysis, which depends on the accuracy of material properties of the board or package. Such a Debye model needs multiple poles for accurate representation of the loss tangent over a broad frequency range. Electromagnetic and circuit simulations can then include the impact of frequency-dependent dielectric constant and loss. In this letter, we present an efficient and closed-form multipole Debye model, automating the modeling of lossy dielectrics for inclusion in time-domain electromagnetic or circuit simulators.
  • Publication
    Nonoverlapping Power/Ground Planes for Suppression of Power Plane Noise
    ( 2018)
    Engin, A.E.
    ;
    Ndip, I.
    ;
    Lang, K.-D.
    ;
    Aguirre, G.
    Providing low IR-drop and inductance are two major roles of power and ground (PG) planes in chip packages and boards. However, planes can also cause switching noise coupling, especially when they resonate. This is a concern for mixed-signal boards, high-speed I/Os, and electromagnetic compatibility. Discrete decoupling capacitors are ineffective to control switching noise at gigahertz frequency regime due to their inductance. To filter such high-frequency noise, a possible approach is modifying the shape of the PG planes, such as in power islands or electromagnetic bandgap structures. In this paper, we introduce the nonoverlapping PG planes design methodology for filtering of gigahertz power plane noise. Unlike existing approaches, our approach is simple and has wide bandwidth, while avoiding narrow inductive bridges that increase IR-drop.
  • Publication
    On the Radiation Characteristics of Full-Loop, Half-Loop and Quasi Half-Loop Bond Wire Antennas
    ( 2018)
    Ndip, I.
    ;
    Lang, K.-D.
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    Reichl, H.
    ;
    Henke, H.
    The theory, modeling, measurement and analysis of the radiation characteristics of bond wire antennas (BWAs) is presented in this work. We commence with rigorous formulations, and derivations of analytical models for calculating the vector potential, radiated electromagnetic fields and directivity of full-loop BWAs (FL-BWAs), considering non-constant current distribution along the BWAs. Based on the image theory, we derive an analytical model for calculating the directivity of half-loop BWAs (HL-BWAs) from that of FL-BWAs. Very good correlation is obtained between the directivities calculated analytically using the derived models, and numerically using commercial full-wave solvers, thus validating our analytical approach. We apply the verified models to thoroughly analyze the radiation characteristics of FL-BWAs and HL-BWAs. The radiation characteristics of a HL-BWA is based on the assumption that its reference plane is infinitely large and perfectly conducting. However , for the development of wireless systems, reference planes of finite sizes are required. Therefore, we investigate the impact of realistic dimensions of reference planes. Our results reveal that the radiation characteristics of BWAs referred to as ""HL-BWAs"" in published literature differ significantly from those of true HL-BWAs. Hence, we introduce the term ""quasi half-loop BWA (QHL-BWA)"" to describe BWAs with small reference planes. Finally, we analyze the radiation characteristics of QHL-BWAs, and compare their radiation patterns to that of HL-BWAs. For experimental verification, QHL-BWAs were fabricated and measured in the 60 GHz band. Very good correlation was obtained between measurement and simulation results.
  • Publication
    Development and Validation of a Chip Integration Concept for Multi-Die GaAs Front Ends for Phased Arrays up to 60 GHz
    ( 2018)
    Curran, B.
    ;
    Reyes, J.
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    Tschoban, C.
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    Höfer, J.
    ;
    Grams, A.
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    Wüst, F.
    ;
    Hutter, M.
    ;
    Leiß, J.
    ;
    Martínez-Vázquez, M.
    ;
    Baggen, R.
    ;
    Ndip, I.
    ;
    Lang, K.-D.
    High-gain steerable antenna arrays in the K-, Ka-, and V-frequency bands have the potential to facilitate high-bandwidth satellite communication for a variety of applications. Copper-core printed circuit boards (PCBs) can offer a cost-effective integration platform for such systems by simultaneously addressing both the high frequency and thermal challenges. Integrating GaAs dies into test vehicles has shown that copper-core PCBs can be automatically assembled and provide high-frequency systems that show adequate reliability during thermal cycling. A single 60-GHz transmitter front end, designed to drive a single element of a phased array, with a 2-GHz bandwidth signal, composed of four GaAs dies, including a phase shifter, integrated onto a copper-core PCB produces an output power of -4 dBm and maintains an on-chip temperature under 51 °C.
  • Publication
    Power plane filter using higher order virtual ground fence
    ( 2017)
    Engin, A.E.
    ;
    Ndip, I.
    ;
    Lang, K.-D.
    ;
    Aguirre, G.
    The virtual ground fence (VGF) has been recently proposed to filter power plane noise in gigahertz frequency range. The VGF has distinct advantages over existing approaches, such as power islands and electromagnetic bandgap structures: The IR drop is not increased; transmission-line return-path discontinuities can be avoided; and the design procedure is simple. The basic VGF is created by using quarter-wave resonators referenced to the power or the ground plane. At the design frequency, the resonator creates an ac short circuit between the power and ground planes. An array of such resonators can be placed in electrically short intervals to create a VGF. Power plane noise will then ideally be shorted to ground at the location of the VGF. The operation principle is similar to the series resonance of a decoupling capacitor, which is usually ineffective in the gigahertz frequency range. This paper proposes a new design procedure for determining the number of quarter-wave resonators needed, their characteristic impedances, and their placement on the board. The design approach is based on the well-known insertion loss method in microwave filter theory, which allows for higher order VGF designs consisting of multiple rows of resonators.
  • Publication
    On the Modeling, Characterization, and Analysis of the Current Distribution in PCB Transmission Lines With Surface Finishes
    ( 2016)
    Curran, B.
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    Fotheringham, G.
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    Tschoban, C.
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    Ndip, I.
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    Lang, K.-D.
    Due to manufacturing requirements, surface finishes have become a necessity in printed circuit board design. These finishes have significant effects on the RF performance of the transmission lines. In this paper, a filament modeling approach is used to model skin, proximity, and surface roughness effects in transmission lines with surface finishes up to 70 GHz. The approach shows a high accuracy compared with measurements. The model also gives an insight into how the current distributes itself by showing the frequency dependent proportion of the current that flows in each surface finish layer. In the case of NiP-Au or Ni-Au surface finishes, current migrates increasingly into gold at high frequencies and reaches a maximum in the Ni or NiP at around 3.5 GHz, and then declines. The distribution of the current in different materials can also be explained as the decay of an electromagnetic wave at the surface of the conductor.
  • Publication
    Efficient total crosstalk analysis of large via arrays in silicon interposers
    ( 2016)
    Dahl, D.
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    Reuschel, T.
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    Preibisch, J.B.
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    Duan, X.
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    Ndip, I.
    ;
    Lang, K.-D.
    ;
    Schuster, C.
    In this paper, we present for the first time a rigorous crosstalk analysis of through silicon via (TSV) arrays consisting of several hundreds of TSVs in interposers with metallized surfaces, using the physics-based via (PBV) modeling approach for applications up to 500 GHz. The PBV modeling approach is valid for complete and almost complete metallizations of the substrate where radial wave propagation in the parallel-plate structure dominates the electromagnetic properties and is utilized with models of good accuracy for localized and propagating fields in the inhomogeneous dielectrics. The approach shows very good to good agreement of crosstalk results for frequencies up to 500 GHz in comparison to full-wave simulations and attains a speedup of at least two orders of magnitude in comparison to general-purpose simulators. The definition of a weighted power sum for total uncorrelated crosstalk is applied for all channels in the TSV array. These power sum results give more meaningful insights into the global effects of the parameter variations than single crosstalk contributions. Based on variations of several technology and design parameters of TSVs, we derive quantitative estimations of the impact of these parameters on the total crosstalk.
  • Publication
    Efficient computation of localized fields for through silicon via modeling up to 500 GHz
    ( 2015)
    Dahl, D.
    ;
    Duan, X.
    ;
    Ndip, I.
    ;
    Lang, K.-D.
    ;
    Schuster, C.
    This paper presents methods for the modeling of the localized (near) fields of vertical interconnects in silicon interposers and the applications of these methods for the efficient computation of the electromagnetic properties of through silicon via structures. The localized fields are due to the mode conversions of the coaxial-to-radial waveguide junctions present in these structures. Because exact analytical techniques exist only for the homogeneously filled junction, an efficient numerical technique is proposed in this paper for the modeling of the inhomogeneous cases. This technique provides accurate results in the form of network parameters with three ports, which can be applied, e.g., in the framework of the physics-based via models. The finite-difference frequency domain method for the case of rotational symmetry is adapted to variable grid distances along the axial and radial coordinates, and interface conditions for the inhomogeneous filling of silicon and electrically isolating silicon dioxide are implemented. The method is validated with full-wave results from finite-element simulations and with the results from the published analytical methods that are adapted to the layered structures. The main focus is in the modeling for signal integrity analysis from the frequencies where the skin effect is well developed at about 100 MHz up to 100 GHz. Nevertheless, good agreement with the results from finite-element simulations up to 500 GHz is obtained for several relevant example structures, and a speedup of at least two orders compared with the finite-element simulations is achieved.
  • Publication
    Analytical, numerical-, and measurement-based methods for extracting the electrical parameters of through silicon vias (TSVs)
    ( 2014)
    Ndip, I.
    ;
    Zoschke, K.
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    Löbbicke, K.
    ;
    Wolf, M.J.
    ;
    Guttowski, S.
    ;
    Reichl, H.
    ;
    Lang, K.-D.
    ;
    Henke, H.
    In this paper, analytical, numerical-, and measurement-based methods for extracting the resistance, inductance, capacitance, and conductance of through silicon vias (TSVs) are classified, quantified, and compared from 100 MHz to 100 GHz. An in-depth analysis of the assumptions behind these methods is made, from which their limits of accuracy/validity are defined. Based on this, the most reliable methods within the studied frequency range are proposed. The TSVs are designed, fabricated, and measured. Very good correlation is obtained between electrical parameters of the TSVs extracted from the measurements and electromagnetic field simulations.