Heino Henke

Analytical, Numerical-, and Measurement–Based Methods for Extracting the Electrical Parameters of Through Silicon Vias (TSVs)

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.

Modeling, Quantification, and Reduction of the Impact of Uncontrolled Return Currents of Vias Transiting Multilayered Packages and Boards

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.

RF-structure design for the W-band folded waveguide TWT project of CEERI

CEERI and TU-Berlin have recently started a cooperation to design and build a W-band folded waveguide TWT. In this paper and the corresponding talk we give an insight into the design process of the slow wave structure and present detailed simulation results of the chosen folded waveguide. Due to the long calculation times of the complete structure, pic simulation were still running when writing this abstract. First results look very promising and will we presented in the talk. We are confident to present cold measurement results during the conference as well.

Analytical Models for Calculating the Inductances of Bond Wires in Dependence on their Shapes, Bonding Parameters, and Materials

Novel analytical models for accurately and efficiently calculating the inductances of bond wires in dependence on their shapes, bonding parameters, and materials are derived. For verification, the inductances of bond wires having different geometrical dimensions and material properties were analytically calculated using our proposed models, and compared to those numerically extracted using Ansys Q3D. An excellent correlation was obtained, with a maximum discrepancy of approximately 1%. These models can be applied to rapidly predict the impact of the bonding parameters and their process variations right at the beginning of the design process. For example, using the models, we could predict within seconds that the loop inductance of a ground-signal bond wire configuration can be reduced by approximately 14%, 19%, or 37%, respectively, if the loop height, pitch or the distance between the bonding positions is reduced by 50%. To quantify the impact of the reductions in inductance on realistic signal transmission characteristics of the wires, we fabricated and measured bond wire interconnects up to 40 GHz.

Compact LHM-based band-stop filter

A compact, low-insertion-loss, high selective band-stop filter is proposed. The filter is composed of four unit cells, two of which are anti-symmetrically connected left-handed metamaterial (LHM) unit cells in combination with their mirror images to obtain the symmetric return losses at both ports. The design of LHM unit cell is based on direct connection of spiral resonator and thin wire to decrease the band-stop frequency further than the conventional split ring resonator designs. The dimensions of the proposed structure are as small as 9.7 mm × 20 mm, while high frequency selectivity could be achieved due to the transmission zeros. The filter has an insertion loss of better than 2 dB even with highly lossy FR4 substrate, and a return loss of larger than 10 dB in the passbands of 2.41–2.65 GHz and 4.26–5.72 GHz. The band rejection of greater than 30 dB is numerically calculated within 3.16–3.54 GHz with high frequency selectivity of 69 dB/GHz.

Concepts for circular deflection modulated tubes and frequency multiplying millimeter wave sources

Most common microwave vacuum tubes like klystrons use a density modulated electron beam to excite electromagnetic fields in the output section of the device. In this paper we present a concept called trajectory or deflection modulation where a beam with an uniform longitudinal velocity is modulated by changing its transverse position. This allows a quite uniform deceleration of the electrons what enhances the efficiency and leads to new possibilities in the design of millimeter wave tubes. In this manuscript we will discuss the advantages of circular deflection modulated devices based on different types of modulators and it will be shown how they can be used for frequency multiplication.

Design study of planar output-cavities for deflection modulated electron vacuum tubes

Searching for new ways to generate high power microwaves with frequencies between 10 and 90 GHz, deflection modulated vacuum tubes have been under investigation in our institute in the last years. Some of the advantages we expect are reduced space charge forces, higher linearity, easier cooling and a simpler design of depressed collectors. One of the most important parts concerning the efficiency of such a device is the output cavity, which transforms the high kinetic energy of the beam to microwave power. In view of frequencies as high as 90 GHz and dimensions in the micrometer range, we have concentrated on planar structures which can be easily realized using technologies like deep x-ray lithography (LIGA). For reliable numerical results we used the 3D electromagnetic particle-in-cell code GdfidL, originally developed in our institute and improved over several years (www.gdfidl.de).

Small Signal Treatment of a 94-GHz Helical Waveguide TWT

This paper estimates with a simplified analytical model the small signal gain of a helically arranged groove-guide traveling-wave tube. It follows closely the transmission line theory approach with the modifications necessary for the very particular device. At 94 GHz and for a 15-kV, 1-A beam, a gain of ~ 1 dB per winding was derived, and realistic gains between 0.6 and 0.8 dB seem to be possible.

Streuung und Beugung von Wellen

Von Streuung spricht man, wenn eine auf einen Korper einfallende Welle reflektiert wird und die reflektierte Welle verwendet wird, um Aussagen uber Position, Bewegung, Form, u.s.w. des Korpers zu machen. Anwendungen betreffen Radar, Bestimmung atmospharischer Bedingungen, Umwelt- und Luftverschmutzung, medizinische und biologische Diagnosen, Terrainuberwachung und vieles mehr.

On the optimization of the return current paths of signal vias in high-speed interposers and PCBs using the M3-approach

In this paper, the return-current paths of signal vias transiting multilayered stack-ups are optimized using the M3-approach (methodologies, models, measures). A methodology for suppressing the excitation of parallel-plate modes in these stack-ups is first proposed. The result of this methodology is a stack-up with well-defined paths for the returning conduction currents. Secondly, a model of the stack-up is developed and experimentally verified using measurement results. The model is then applied to study the impact of the impedance of the return-current paths on the effectiveness of the proposed stack-up in suppressing the excitation of cavity resonance modes. Based on the results of this study, appropriate designs measures for optimizing the return-current paths of the signal vias are derived. To demonstrate the advantages of these measures, they are applied to fabricate a new test board with the proposed stack-up. The measurement results show excellent signal transmission and no dips in the insertion loss of the signal via for frequencies up to 20 GHz.