bluuebunny/crossref_metadata_2025 huggingface dataset:
Implementation and modeling of parametrizable high-speed Reed Solomon decoders on FPGAs
Authors: Flocke A. , Blume H. , Noll T. G.
Published: April 2010

Abstract. One of the most important error correction codes in digital signal processing is the Reed Solomon code. A lot of VLSI implementations have been described in literature. This paper introduces a highly parametrizable RS-decoder for FPGAs. By implementing resource-sharing and by using a fully pipelined multiplier/adder-unit in GF(2m) it was possible to achieve high throughput rates up to 1.3Gbit/s on a standard FPGA, while using only an attractive small amount of logical elements (LE). The implementation, written in a hardware description language (HDL), is based on an inversionless Berlekamp Algorithm (iBA), whose structure leads to a chain of identical processing elements (PE). The critical path of one PE runs only through one adder and one multiplier. A detailed description of a resource-sharing methodology for this Berlekamp Algorithm and the achievable gain are presented in this paper. The benchmarking for the design was done for different 8bit-codes against state-of-the-art FPGA-solutions and showed a gain of up to a factor of six regarding the AT-product, compared to other implementations.
Design of a LNA in the frequency band 1.8-2.2GHz in 0.13μm CMOS Technology
Authors: Di Gioia E. , Hermann C. , Klar H.
Published: April 2010

Abstract. The subject of this work is a low noise amplifier (LNA), operating in the frequency range 1.8-2.1GHz. The CMOS 0.13μm technology is used in respect to the low cost of the final device. Among the specifications, a variable gain and an adjustable working frequency are required. In particular, four different working modes are provided: 1.8, 1.9 and 2.1GHz high gain and 2.1GHz low gain. The amplifier is designed to be used as first stage of a receiver for mobile telephony. For this reason low power consumption is taken into consideration (low supply voltage and low drain currents). A simple digital circuit, integrated on-chip, is used to select the operating mode of the LNA by means of two input pins. A Noise figure of 1dB is obtained with a supply voltage of 0.8V.
Impact of Level-Converter on Power-Saving Capability of Clustered Voltage Scaling
Authors: Henzler St. , Berthold J. , Koban M. , Reinl M. , Georgakos G. , Schmitt-Landsiedel D.
Published: April 2010

Abstract. The use of multiple supply voltages to reduce active mode power dissipation in digital ULSI circuits has been widely discussed in literature. As the reported power savings differ significantly depending on the technology and level converter circuits an abstract approach is used to investigate the impact of power consumption and delay caused by the level converters (what-if-scenarios). Actual circuits are used to map the theoretical investigations to real circuits. In contrast to clustered voltage scaling, where level conversion is only allowed in front of or within flipflops the power saving benefits of enhanced clustered voltage scaling with arbitrary converter positions vanish due to the lack of efficient asynchronous level converters.
Eine FPAA-Architektur zur rekonfigurierbaren Instantiierung von zeitkontinuierlichen Analogfiltern
Authors: Becker J. , Manoli Y.
Published: April 2010

Abstract. Im Folgenden wird eine neue Methodik von FPAAs (Field Programmable Analog Arrays) gezeigt, die speziell für die Instantiierung von zeitkontinuierlichen (continuous-time, CT) Analogfiltern in Hardware entwickelt wurde. Die Chiptopologie beinhaltet 17 digital konfigurierbare analoge Blöcke (configurable analog blocks, CABs), die durch ein hexagonales Netzwerk miteinander verbunden sind. Jeder CAB ist aus einstellbaren Gm-C Integratoren aufgebaut, welche das analoge Signal sowohl formen und seinen Weg durch die Matrix festlegen, gleichzeitig aber auch die Grundbausteine für zeitkontinuierliche Hochfrequenzfilter darstellen. Intelligente Pufferspeicher für die Ein-/Ausgänge (IO-buffer) garantieren die Rekonfigurierung der Matrix mit minimaler Störung des kontinuierlichen Analogsignals. Die Architektur wird als Hardwareplattform für beliebige Schaltungen, welche aus einer gegebenen Anzahl an Gm-C-Zellen bestehen, eingeführt und verifiziert bevor eine exemplarische Instantiierung eines Butterworth Filters 4. Ordnung in Biquad Anordnung gezeigt wird.
Challenges of VDD scaling for analog circuits: an amplifier
Authors: Bargagli-Stoffi A. , Sauerbrey J. , Wang J. , Schmitt-Landsiedel D.
Published: April 2010

Abstract. With the shrinking of the device dimensions, the power supply voltage value is continuously decreasing. Since the threshold voltage value does not decrease as much as the power supply and the drain source saturation voltage becomes an important fraction of the power supply, many amplifier architectures are no more suitable for modern processes. A transconductance amplifier based on current mirrors is analyzed highlighting the main challenges of a low-voltage analog design. Among the many proposed amplifier architectures, a topology based on current mirrors has been chosen as the most promising to operate with low voltages. Simulations with 90nm CMOS prove the feasibility of circuit operation with satisfactory performance at an operating power supply voltage as low as 0.6V.
A Contribution to Reconfigurable Analog Electronics by a Digitally Programmable Sensor Signal Amplifier
Authors: Lakshmanan S. K. , König A.
Published: April 2010

Abstract. In particular, primary sensor electronics are prone to deviations and degradation in its performance due to environmental influences and manufacturing conditions. In order to restore its functionality, calibration or trimming techniques are usually employed. More recent, programmable or reconfigurable approaches from the field of evolutionary electronics offer great source of inspiration through their unique properties of fault-tolerance and self-repair. In our approach, we try to include efficiently, the available knowledge of recent reconfigurable devices into the otherwise attractive concept. In our approach, a flexible FPTA architecture is developed meeting the requirement of sensor signal amplifier in particular for time continuous signal processing. The developed approach is verified and implemented in 0.35μm CMOS technology.
Electro-Quasistatic Simulations in Bio-Systems Engineering and Medical Engineering
Authors: van Rienen U. , Flehr J. , Schreiber U. , Schulze S. , Gimsa U. , Baumann W. , Weiss D. G. , Gimsa J. , Benecke R. , Pau H.-W.
Published: April 2010

Abstract. Slowly varying electromagnetic fields play a key role in various applications in bio-systems and medical engineering. Examples are the electric activity of neurons on neurochips used as biosensors, the stimulating electric fields of implanted electrodes used for deep brain stimulation in patients with Morbus Parkinson and the stimulation of the auditory nerves in deaf patients, respectively. In order to simulate the neuronal activity on a chip it is necessary to couple Maxwell's and Hodgkin-Huxley's equations. First numerical results for a neuron coupling to a single electrode are presented. They show a promising qualitative agreement with the experimentally recorded signals. Further, simulations are presented on electrodes for deep brain stimulation in animal experiments where the question of electrode ageing and energy deposition in the surrounding tissue are of major interest. As a last example, electric simulations for a simple cochlea model are presented comparing the field in the skull bones for different electrode types and stimulations in different positions.
Application of Geometric Polarization to Invariance Properties in Bistatic Scattering
Authors: Bebbington D. H. O. , Carrea L. , Wanielik G.
Published: April 2010

Abstract. Bistatic polarimetric radars provide target properties which just one monostatic system can not reveal. Moreover, augmentation of monostatic systems through the provision of bistatic receive-only stations can be a cheap way to increase the amount of remote sensing data. However, bistatic scattering needs to be investigated in order to properly define target properties such as symmetries and invariance, especially regarding choices of polarization basis. In this paper we discuss how the geometric theory of polarization, in which the geometry of the Poincaré sphere is directly related to 3-D geometry of space rather than the 2-D geometry of the wavefront plane, can be used to reduce the ambiguities in the interpretation of data. We also show how in the coherent case a complex scalar invariant can be determined irrespective of the basis combinations.
Long-term Measurements of Nighttime LF Radio Wave Reflection Heights over Central Europe
Authors: Jacobi C. , Kürschner D.
Published: April 2010

Abstract. The nighttime ionospheric absolute reflection height of low-frequency (LF) radio waves at oblique incidence has been measured continuously since late 1982 using 1.8kHz sideband phase comparisons between the sky wave and the ground wave of a commercial 177kHz LF transmitter. The dataset allows the analysis of long-term trends and other regular variations of the reflection height. Beside the clear signal of the 11-year solar cycle a quasi-biennial oscillation is visible in LF reflection heights, which is correlated to the equatorial stratospheric wind field. A long-term decreasing reflection height trend is found, confirming results from other measurements and theoretical estimations. The results can be interpreted as a long-term decrease of the height levels of fixed electron density in the lower E region, reflecting a long-term cooling trend of the middle atmosphere.
An Error Correction Procedure for Multi-Port Measurements at High Frequencies
Authors: Rolfes I. , Schiek B.
Published: April 2010

Abstract. The multi-port method for the measurement of the scattering parameters of multi-ports with the help of a vector network analyzer (VNA) with only two measurement ports is presented. For the measurements only two ports of the N-port device can be connected to the two ports of the VNA at a time. The remaining N-2 ports of the device under test (DUT) are connected to external terminations. As these external terminations might be mismatched, the measured scattering parameters depend on the reflective characteristics of the terminations. An error correction becomes necessary in order to calculate the effective scattering parameters of the DUT (Tippet and Speciale, 1982; Lu and Chu, 2003). In contrast to the correction method of Tippet and Speciale (1982), the multi-port method has the advantage, that the external terminations can be chosen arbitrarily. Thus, a realization as an open or short circuit is possible as well. Furthermore, the terminations can be unknown except for one, similar to self-calibration procedures of VNAs. This helps to improve the accuracy of the measurements, because the inconsistency problem due to a slightly erroneous knowledge of the frequency characteristics of the terminations can be eliminated.
Realization of Broadband Matched Filter Structures Based on Dual Networks
Authors: Gerding M. , Schiek B.
Published: April 2010

Abstract. This paper deals with the basic electrical properties of dual networks and with their application in broadband matched filter structures. Starting with the main characteristics and different realization methods of dual networks, a filter structure is presented, which is based on a combination of dual networks and which provides a broadband matched input and two decoupled output ports. This filter synthesis focuses on the design of high pass filters, which are suitable to be used as differentiating stages in electrical pulse generators as a part of the so-called pulse shaping network. In order to achieve a proper pulse shape and for the prevention of multiple reflections between the switching circuit and the differentiating network, a broadband matched filter is a basic requirement.
Verification of Electromagnetic Field Measurements via Inter-laboratory Comparison Measurements
Authors: Mann M. , Brüggemeyer H. , Weiß P.
Published: April 2010

Abstract. An inter-laboratory comparison of field strength measurements was conducted in order to verify the comparability of high-frequency electromagnetic field measurements. For this purpose, 17 participating teams hosted by the working group "procedures of exposure determination" of the LAI (Länderausschuss für Immissionsschutz, state committee on immission control) determined the field strength at given stations around a hospital situation. At those stations very different signals were generated, such as sine wave signals at 27MHz and 433MHz, signals from a diathermy device in Continuous-Wave (CW) and Pulse-Width-Modulation (PWM) mode, from a GSM base station at 900MHz and 1800MHz, from a UMTS base station, from a babyphone device and from a DECT cordless phone. This contribution describes the evaluation of the measured values and the approach to the computation of a reference value. Considering various sources of electromagnetic fields in the areas of personal safety at work and of immission control, the most important results are presented and the conclusions drawn are discussed.
Investigation of the behavior of protection elements against field radiated line coupled UWB-pulses
Authors: Krzikalla R. , ter Haseborg J. L.
Published: April 2010

Abstract. To protect electronic systems against electromagnetic interferences in general nonlinear protection circuits are used. These protection circuits are optimized mostly against special transient interferences such as lightning electromagnetic pulses (LEMP) or electromagnetic pulses caused by nuclear explosions (NEMP). Previous investigations have shown that these protection elements could be undermined by so-called ultra wideband (UWB) pulses. Thereby a direct charge of the UWB-pulse to the elements has been assumed. This assumption was a worst case approximation because in practice UWB-pulses only get into systems by coupling effects. In this investigation the behavior of typical nonlinear protection elements has been tested with field radiated line coupled UWB-pulses. For that line coupled UWB-pulses have been defined depending on the coupling behavior of typical electronic systems and a possibility of generation of this kind of pulses is presented. After it typical nonlinear protection elements such as spark gaps, varistors and protection diodes have been tested with the previously defined test pulses. Finally the measured behavior of the elements has been compared with the behavior by direct charged UWB-pulses and the protection effect of the elements against field radiated line coupled UWB-pulses is re-evaluated.
Das Verhalten nanostrukturierter Schaltungen unter der Berücksichtigung von Quanteneffekten
Authors: Bremer J.-K. , Felgenhauer F. , Begoin M. , Mathis W.
Published: April 2010

Abstract. Aufgrund der Bedeutung der MOS-Technologie für Halbleiterindustrie und deren fortschreitende Miniaturisierung ist es wichtig sicherzustellen, dass die klassischen Schaltungskonzepte für stark skalierte Bauelemente nicht ihre Gültigkeit verlieren. Ziel unserer Arbeitsgruppe ist es ein Simulatorpaket zu entwickeln, welches von einer physikalischen Sicht heraus quantenmechanische Einflüsse in integrierten Schaltungen ermittelt und Konsequenzen für zukünftiges Schaltungsdesign prognostiziert. Zur Berechnung und Modellierung der Quanteneffekte wird ein auf dem "non equilibrium Green's functions" (NEGF) Formalismus basierender numerischer 1-dimensionaler Simulator entwickelt. Auf der Basis von numerischen Transportsimulationen werden Ersatzschaltbilder für die SPICE Simulationsumgebung erstellt, um den Einfluss der Quanteneffekte in die Schaltungssimulation einzubinden. In this paper we discuss the expected impact of quantum effects in nanostructured CMOS circuits. In order to describe transport in mesoscopic electronic systems our group develops a 1-d numerical simulation packet based on the "non equilibrium Green's functions" (NEGF) formalism. By means of the obtained simulation results we develop extended SPICE circuit models. With these SPICE models the influence of quantum effects to the functionality of classical circuit concepts can be studied. Using these results it is our intention to develop circuits with a higher robustness against these quantum effects. For the illustration of our simulation concept we discuss some results of some circuit examples.
DMT transmission in the context of industrial telecontrol applications
Authors: Edinger S. , Bauer C. , Fliege N. J.
Published: April 2010

Abstract. In this paper, we discuss the use of Discrete Multi Tone (DMT) modulation in the context of industrial telecontrol applications. We highlight the specific requirements and characteristics of the telecontrol settings and present methods to cope with the environmental challenges posed. It turns out that DMT is ideally suited for the tasks at hand. Further enhances enable our proposed system to provide superior connection stability even under the most adverse conditions.
Numerical computation of the Shock Tube Problem by means of wave digital principles
Authors: Mengel A.
Published: April 2010

Abstract. Partial differential equations can be solved numerically by means of wave digital principles. The great advantage of this method is the simultaneous achievement of high robustness, massive parallelism full localness and high accuracy. Among others this method will be applied in order to solve the Euler-equations according to one dimension in space. Especially the so called Shock Tube Problem will be examined. The analytical solution of this problem contains two discontinuities, namely a shock and a contact discontinuity. These result in oscillations which are due to numerical integration methods of higher order. Also solutions of the Wave Digital Method contain these oscillations, contrary to what had been observed of Yuhui Zhu (2000). This behaviour is also known as Gibbs Phenomena. The Navier-Stokes-equations, which are from a physical point of view more exactly, additionally take viscosity terms into account. This leads to smooth solutions near shocks. It will be shown that this approach leads to the suppression of the oscillations near the shock. Furthermore it will be shown that quite good results for the computation of velocity and pressure can be obtained.
Multicarrier systems and filter banks
Authors: Waldhauser D. S. , Nossek J. A.
Published: April 2010

Abstract. Multicarrier systems, especially orthogonal frequency division multiplex (OFDM), are already established in a lot of current communications standards. Moreover, they are very prominent candidates for future systems in mobile communications. Filter bank based multicarrier systems can be designed to provide a better spectral shaping than OFDM systems. That way, they have some advantages against OFDM, which will be shown in this work and motivate further research in the direction of channel equalizers with low complexity. This leads to optimum bandwidth efficient multicarrier systems without guard interval, i.e. cyclic prefix.
Cordic based algorithms for software defined radio (SDR) baseband processing
Authors: Heyne B. , Götze J.
Published: April 2010

Abstract. This paper presents two Cordic based algorithms which may be used for digital baseband processing in OFDM and/or CDMA based communication systems. The first one is a linear least squares based multiuser detector for CDMA incorporating descrambling and despreading. The second algorithm is a pure Cordic based FFT implementation. Both algorithms can be implemented using solely Cordic based architectures (e.g. coprocessors or ASIPs). The algorithms exactly fit the needs of a multistandard terminal as they both are freely parameterizable. This regards to the accuracy of the results as well as to the parameters of the performed function (e.g. size of the FFT).
LNA for Low-Power, Low Data Rate PAN Applications
Authors: Stücke T. , Christoffers N. , Kokozinski R. , Kolnsberg S. , Hosticka B. J.
Published: April 2010

Abstract. In this paper a common-gate LNA is presented, which is used in a low-power IEEE 802.15.4 receiver with severer requirements on the current consumption. The LNA is designed in a 0.25 μm CMOS technology and consumes only 831 μA. The LNA achieves a voltage gain of 12.89 dB, a NF of 4.86 dB, and an IIP3 of −6.0 dBm.
Yield-improving test and routing circuits for a novel 3-D interconnect technology
Authors: Bschorr M. , Pfleiderer H.-J. , Benkart P. , Kaiser A. , Munding A. , Kohn E. , Heittmann A. , Hübner H. , Ramacher U.
Published: April 2010

Abstract. This work presents a system to increase the yield of a novel 3-D chip integration technology. A built-in self-test and a routing system have been developed to identify and avoid faults on vertical connections between different stacked chips. The 3-D technology is based on stacking several active CMOS-ICs, which have through-substrate electrical contacts to communicate with each other. The expected defects of these vias are shorts and resistances that are too high. The test and routing system is designed to analyze an arbitrary number of connections. The result ist used to gain information about the reliability of the new 3-D processing and to increase its yield. The circuits have been developed in 0.13 μm technology, one chip has been fabricated and tested, another one is in production.
Spherical mode analysis of planar frequency-independent multi-arm antennas based on its surface current distribution
Authors: Armbrecht G. , Klemp O. , Eul H.
Published: April 2010

Abstract. Deployment in the design of mobile radio terminals focuses on the implementation of multiradio transmission systems, using a multiplicity of different radio standards combined with high-speed data communication over multiple-input multiple-output (MIMO) and multimode diversity techniques. Hence, planar log.-per. four-arm antennas are predistined to meet the requirements of future mobile multiradio RF-frontends and will be introduced and analysed in terms of an efficient spherical mode analysis by means of surface current distribution in order to derive an analytic access to MIMO- and polarisation-diversity performance computation. A remarkable parameter reduction and a faster numerical analysis with respect to conventional techniques may be achieved. The sources in the near-field antenna region are based on the numerical computation of surface currents involving the finite element method (FEM). Relations between the variations of the geometrical antenna parameters and the excitation of discrete spherical modes are presented and will be analysed in detail.
2.5 Gbps clock data recovery using 1/4th-rate quadricorrelator frequency detector and skew-calibrated multi-phase clock generator
Authors: Tontisirin S. , Tielert R.
Published: April 2010

Abstract. A Gb/s clock and data recovery (CDR) circuit using 1/4th-rate digital quadricorrelator frequency detector and skew-calibrated multi-phase voltage-controlled oscillator is presented. With 1/4th-rate clock architecture, the coil-free oscillator can have lower operation frequency providing sufficient low-jitter operation. Moreover, it is an inherent 1-to-4 DEMUX. The skew calibration scheme is applied to reduce phase offset in multi-phase clock generator. The CDR with frequency detector can have small loop bandwidth, wide pull-in range and can operate without the need for a local reference clock. This 1/4th-rate CDR is implemented in standard 0.18 μm CMOS technology. It has an active area of 0.7 mm2 and consumes 100 mW at 1.8 V supply. The CDR has low jitter operation in a wide frequency range from 1–2.25 Gb/s. Measurement of Bit-Error Rate is less than 10−12 for 2.25 Gb/s incoming data 27−1 PRBS, jitter peak-to-peak of 0.7 unit interval (UI) modulation at 10 MHz.
Computation of antenna pattern correlation and MIMO performance by means of surface current distribution and\\ spherical wave theory
Authors: Klemp O. , Armbrecht G. , Eul H.
Published: April 2010

Abstract. In order to satisfy the stringent demand for an accurate prediction of MIMO channel capacity and diversity performance in wireless communications, more effective and suitable models that account for real antenna radiation behavior have to be taken into account. One of the main challenges is the accurate modeling of antenna correlation that is directly related to the amount of channel capacity or diversity gain which might be achieved in multi element antenna configurations. Therefore spherical wave theory in electromagnetics is a well known technique to express antenna far fields by means of a compact field expansion with a reduced number of unknowns that was recently applied to derive an analytical approach in the computation of antenna pattern correlation. In this paper we present a novel and efficient computational technique to determine antenna pattern correlation based on the evaluation of the surface current distribution by means of a spherical mode expansion.
Wieviel Feldstärke ist notwendig für akzeptable portabel-indoor-Versorgung mit digitalem Rundfunk?
Authors: Philipp J.
Published: April 2010

Abstract. Durch eine Fragebogenaktion wurde ermittelt, welche Anforderungen potentielle Teilnehmer an die Güte des indoor-portabel-Empfangs von Radio und Fernsehen stellen. Mittels eines einfachen statistischen Feldstärkemodells wurde daraus abgeleitet, welche mittlere Mindestfeldstärke in 10 m Höhe über Grund bereit zu stellen ist, damit mindestens 95% der im Erdgeschoss wohnenden Teilnehmer akzeptabel versorgt sind. Es ergibt sich für DAB im Band~III ein um 6 bis 8 dB höherer Wert als der, welcher für mobile Versorgung mit 99% Ortswahrscheinlichkeit anzusetzen ist (und welcher den bisher geplanten Sendernetzen zu Grunde liegt). Für DVB-T im Band~III sind mindestens 3 dB mehr anzusetzen als eine Rechnung nach "Chester"-Parametern bei 95% Ortswahrscheinlichkeit verlangt, während bei DVB-T im Band V die Werte der 95%-Chester-Rechnung nur geringfügig nach oben korrigiert werden müssen. Die Ergebnisse für DVB-T gelten unter der Voraussetzung, dass ein C/N von 17 dB für einen zufrieden stellenden Empfang ausreicht. Höhere Anforderungen an C/N sind zusätzlich in Ansatz zu bringen.
Breakdown behavior of electronics at variable pulse repetition rates
Authors: Korte S. , Garbe H.
Published: April 2010

Abstract. The breakdown behavior of electronics exposed to single transient electromagnetic pulses is subject of investigations for several years. State-of-the-art pulse generators additionally provide the possibility to generate pulse sequences with variable pulse repetition rate. In this article the influence of this repetition rate variation on the breakdown behavior of electronic systems is described. For this purpose microcontroller systems are examined during line-led exposure to pulses with repetition rates between 1 KHz and 100 KHz. Special attention is given to breakdown thresholds and breakdown probabilities of the electronic devices.
Different biological effectiveness of ionising and non-ionising radiations in mammalian cells
Authors: Schmid E. , Schrader T.
Published: April 2010

Abstract. It has been discussed ever since among the scientific communities, whether non-ionising radiation can alter or harm biological systems. While the mechanisms of underlying effects of ionising radiation are well understood and described here, there is less understanding in the effects caused by non-ionising radiation except for heating effects. Recent results have been interpreted, that numerical chromosome aberrations may be induced by exposure to RF radiation. Our own experiments employing the µTEM cell yield results similar to findings observed for aneugenic-inducing chemical agents which can cause spindle disturbances. For comparison purpose to the effects caused by those agents we used the well established human-hamster hybrid (AL) cell line to evaluate the biological effects after exposure to RF radiation (835 MHz).
A hybrid method combining the Time-Domain Method of Moments, the Time-Domain Uniform Theory of Diffraction and the FDTD
Authors: Becker A. , Hansen V.
Published: April 2010

Abstract. In this paper a hybrid method combining the Time-Domain Method of Moments (TD-MoM), the Time-Domain Uniform Theory of Diffraction (TD-UTD) and the Finite-Difference Time-Domain Method (FDTD) is presented. When applying this new hybrid method, thin-wire antennas are modeled with the TD-MoM, inhomogeneous bodies are modelled with the FDTD and large perfectly conducting plates are modelled with the TD-UTD. All inhomogeneous bodies are enclosed in a so-called FDTD-volume and the thin-wire antennas can be embedded into this volume or can lie outside. The latter avoids the simulation of white space between antennas and inhomogeneous bodies. If the antennas are positioned into the FDTD-volume, their discretization does not need to agree with the grid of the FDTD. By using the TD-UTD large perfectly conducting plates can be considered efficiently in the solution-procedure. Thus this hybrid method allows time-domain simulations of problems including very different classes of objects, applying the respective most appropriate numerical techniques to every object.
Extended post processing for simulation results of FEM synthesized UHF-RFID transponder antennas
Authors: Herschmann R. , Camp M. , Eul H.
Published: April 2010

Abstract. The computer aided design process of sophisticated UHF-RFID transponder antennas requires the application of reliable simulation software. This paper describes a Matlab implemented extension of the post processor capabilities of the commercially available three dimensional field simulation programme Ansoft HFSS to compute an accurate solution of the antenna's surface current distribution. The accuracy of the simulated surface currents, which are physically related to the impedance at the feeding point of the antenna, depends on the convergence of the electromagnetic fields inside the simulation volume. The introduced method estimates the overall quality of the simulation results by combining the surface currents with the electromagnetic fields extracted from the field solution of Ansoft HFSS.
Position finding using simple Doppler sensors
Authors: Schelkshorn S. , Detlefsen J.
Published: April 2010

Abstract. An increasing number of modern applications and services is based on the knowledge of the users actual position. Depending on the application a rough position estimate is sufficient, e. g. services in cellular networks that use the information about the users actual cell. Other applications, e. g. navigation systems use the GPS-System for accurate position finding. Beyond these outdoor applications a growing number of indoor applications requires position information. The previously mentioned methods for position finding (mobile cell, GPS) are not usable for these indoor applications. Within this paper we will present a system that relies on the simultaneous measurement of doppler signals at four different positions to obtain position and velocity of an unknown object. It is therefore suiteable for indoor usage, extendig already existing wireless infrastructure.
Kindliche Leukämien und EMF-Expositionen in der Umgebung hochfrequenter Sendestationen (KiSS) – Fragestellung und Studienbeschreibung
Authors: Brüggemeyer H. , Philipp J. , Merzenich H. , Schmiedel S. , Blettner M. , Schüz J.
Published: April 2010

Abstract. Im Rahmen einer Fall-Kontroll-Studie wird untersucht, ob es einen Zusammenhang zwischen dem Leukämierisiko bei Kindern und der Exposition gegenüber elektromagnetischen Feldern in der Umgebung leistungsstarker Sendestationen von Rundfunk und Fernsehen gibt. Bislang wurden fünf Studien im Umkreis von Rundfunksendeanlagen durchgeführt. Deren Aussagekraft ist jedoch durch eine grobe Expositionsabschätzung und ihren ökologischen Studienansatz ohne individuelle Expositionsbestimmung limitiert. Wesentliches Element der hier vorgestellten Studie ist dagegen eine individuelle Expositionsabschätzung, die zum einen auf der Geocodierung von Wohnadressen und Expositionspunktquellen und zum andern auf den tatsächlichen Strahlungsleistungen und Betriebsdaten der Senderbetreiber beruht. Das Studiengebiet besteht aus den Umgebungen von 17 leistungsstarken AM-Mittelwellensendern und 8 UKW-FM- bzw. analogen TV-Sendern in Westdeutschland. Zur Studienpopulation gehören alle im Diagnosezeitraum von 1984 bis 2003 aufgetretenen Fälle, die im Studiengebiet leben bzw. gelebt haben. Als Fälle werden alle Kinder definiert, die zum Zeitpunkt der Diagnose zwischen 0–14 Jahren alt waren, bei denen eine primäre Leukämie diagnostiziert wurde und die dem Deutschen Kinderkrebsregister bekannt sind. Jedem Fallkind werden 3 gleich alte Kontrollkinder gleichen Geschlechts aus der gleichen Senderumgebung gegenübergestellt. Möglich wurde diese Untersuchung durch die Förderung durch Mittel des Deutschen Mobilfunkforschungsprogramms sowie durch die Mitarbeit aller relevanten Senderbetreiber und des Deutschen Kinderkrebsregisters an der Universität Mainz. Sie soll bis August 2007 abgeschlossen sein.
Radiation characteristics of a coaxial waveguide with eccentric inner conductor for application in hyperthermia and microwave reflex therapy
Authors: Herschmann R. , Büchel O.
Published: April 2010

Abstract. This paper examines the radiation characteristics of a contact emitter conceived for application in hyperthermia and microwave reflex therapy. It is important to analyse the distribution of power density in the near field area, as the radiator's therapeutic sphere of activity is localized here. The contact emitter is a coaxial radiator with an eccentric course of the inner conductor. According to Huygens principle, a theoretical view of the near field radiation characteristics is made by determining the equivalent current densities in the emitter aperture. It is shown that by an eccentric shift of the inner conductor, an almost isotropic near field radiation pattern and power density can be achieved. For this, the electromagnetic field in the emitter aperture is determined by using a Bipolar coordinate system. This calculation considers only the fundamental TEM mode of the contact emitter. Besides the theoretical results near and far fields are simulated using the programme system Ansoft HFSS.
Adaptive decoding of convolutional codes
Authors: Hueske K. , Geldmacher J. , Götze J.
Published: April 2010

Abstract. Convolutional codes, which are frequently used as error correction codes in digital transmission systems, are generally decoded using the Viterbi Decoder. On the one hand the Viterbi Decoder is an optimum maximum likelihood decoder, i.e. the most probable transmitted code sequence is obtained. On the other hand the mathematical complexity of the algorithm only depends on the used code, not on the number of transmission errors. To reduce the complexity of the decoding process for good transmission conditions, an alternative syndrome based decoder is presented. The reduction of complexity is realized by two different approaches, the syndrome zero sequence deactivation and the path metric equalization. The two approaches enable an easy adaptation of the decoding complexity for different transmission conditions, which results in a trade-off between decoding complexity and error correction performance.
Optimierungsverfahren für schaltungstechnische Realisierungen zellularer Rechner
Authors: Geis G. , Gollas F. , Tetzlaff R.
Published: April 2010

Abstract. Bei intelligenten Sensoren soll die Aufnahme von Signalen und deren, zumindest teilweise durchgeführte, Verarbeitung mit einer einzigen Anordnung erfolgen. Dazu steht häufig eine elektronische Schaltung zur Verfügung, die allerdings zur Einhaltung von Echtzeitbedingungen nur für eine relativ einfache Signalverarbeitung verwendet werden kann. Einen möglichen Ausweg bildet die Verwendung parallel arbeitender Rechnersysteme. In dieser Hinsicht sind programmierbare Schaltungen mit z.B. optischen Sensor-Anordnungen besonders interessant, die auf Zellularen Nichtlinearen Netzwerken basieren. Derartige miniaturisierte Systeme eröffnen aufgrund ihrer zellularen Architektur neue Möglichkeiten zur Signalverarbeitung mit einem Leistungsvermögen, das im Bereich von Tera-Operationen pro Sekunde liegt. Für viele aktuelle Problemstellungen wäre es von Vorteil, wenn diese zellularen Systeme eigenständig Parameteradaptionen durchführen könnten. Eingangssignale, die beispielsweise über die vorhandenen optischen Sensoren aufgenommen werden, führten dann zu einer Neuberechnung bzw. Anpassung der Netzwerksparameter. Aufgrund der beachtlichen Leistungsfähigkeit solcher Schaltungen wäre damit die Möglichkeit gegeben, eine adaptive Signalverarbeitung bei zeitlich veränderlichen Problemen vorzunehmen. In diesem Beitrag wird die Implementierung und Analyse von Lernverfahren auf dem EyeRISTM System, das einen zellularen Prozessor ACE16kv2TM mit 128×128 Zellen enthält, zur adaptiven Parameterbestimmung betrachtet. Anhand verschiedener Problemstellungen aus dem Bereich der Bildverarbeitung werden unterschiedliche Lernverfahren verglichen und deren Leistungsfähigkeit untersucht.
Considering even-order terms in stochastic nonlinear system modeling with respect to broadband data communication
Authors: Schmitz O. , Hampel S.K. , Eul H. , Schwingshackl D.
Published: April 2010

Abstract. As a tradeoff between efficiency and costs \\mbox{modern} communication systems contain a variety of components that can at least be considered weakly nonlinear. A critical element in evaluating the degree of nonlinearity of any underlying nonlinear system is the amount of undesired signal strength or signal power this system is introducing outside the transmission bandwidth. This phenomenon called spectral regrowth or spectral broadening is subject to stringent restrictions mainly imposed by the given specifications of the particular communication standard. Consequently, achieving the highest possible efficiency without exceeding the linearity requirements is one of the main tasks in system design. Starting from this challenging engineering problem there grows a certain need for specialized tools that are capable of predicting linearity and efficiency of the underlying design. Besides a multitude of methods aiming at the prediction of spectral regrowth a statistical approach in modeling and analyzing nonlinear systems offers the advantage of short processing times due to closed form mathematical expressions in terms of input and output power spectra and is therefore further examined throughout this article.
Phase noise and jitter modeling for fractional-N PLLs
Authors: Osmany S. A. , Herzel F. , Schmalz K. , Winkler W.
Published: April 2010

Abstract. We present an analytical phase noise model for fractional-N phase-locked loops (PLL) with emphasis on integrated RF synthesizers in the GHz range. The noise of the crystal reference, the voltage-controlled oscillator (VCO), the loop filter, the charge pump, and the sigma-delta modulator (SDM) is filtered by the PLL operation. We express the rms phase error (jitter) in terms of phase noise of the reference, the VCO phase noise and the third-order loop filter parameters. In addition, we consider OFDM systems, where the PLL phase noise is reduced by digital signal processing after down-conversion of the RF signal to baseband. The rms phase error is discussed as a function of the loop parameters. Our model drastically simplifies the noise optimization of the PLL loop dynamics.
Impact of process variations and long term degradation on 6T-SRAM cells
Authors: Fischer Th. , Olbrich A. , Georgakos G. , Lemaitre B. , Schmitt-Landsiedel D.
Published: April 2010

Abstract. In modern deep-submicron CMOS technologies voltage scaling can not keep up with the scaling of the dimensions of transistors. Therefore the electrical fields inside the transistors are not constant anymore, while scaling down the device area. The rising electrical fields bring up reliability problems, such as hot carrier injection. Also other long term degradation mechanisms like Negative Bias Temperature Instability (NBTI) come into the focus of circuit design. Along with process device parameter variations (threshold voltage, mobility), variations due to the degradation of devices form a big challenge for designers to build circuits that both yield high under the influence of process variations and remain functional with respect to long term device drift. In this work we present the influence of long term degradation and process variations on the performance of SRAM core-cells and parametric yield of SRAM arrays. For different use cases we show the performance degradation depending on temperature and supply voltage.
Simulation eines rekonfigurierbaren Gm-C filter arrays
Authors: Henrici F. , Becker J. , Manoli Y.
Published: April 2010

Abstract. Es wird ein Gm-C Filter für den Einsatz in rekonfigurierbaren Analogfiltern (FPAAs) präsentiert. Das Filter ist auf den Einsatz in FPAAs mit hexagonalem Grid und auf den Verzicht auf Transmissiongates optimiert. Trotzdem können nicht nur die Parameter der instanziierten Filter geändert werden, sondern auch ihre Struktur. Beim Design des digital programmierbaren Transkonduktors musste auf die hohe Anzahl parallel geschalteter, gleichartiger Transkonduktoren und ihre parasitären Kapazitäten Rücksicht genommen werden. Ein FPAA mit 49 Gm-Zellen erreicht in Simulationen in einem 130 nm 1.2 V CMOS Prozess eine maximale Bandbreite von 164 MHz. Die Verzerrung beträgt weniger als –70 dB bei einem 50m V @1 MHz Signal.
A new shielding effectiveness measurement method based on a skin-effect transmission line coupler
Authors: Kleine-Ostmann T. , Münter K. , Schrader T.
Published: April 2010

Abstract. We propose a new convenient material shielding effectiveness measurement method based on a skin-effect transmission line coupler. The method is somewhat similar to the arrangement with two coupled TEM cells known from literature. The transmission line coupler consists of a pair of identical transmission line 2-port devices. Each device contains a coaxial waveguide, with a circular inner conductor and an outer conductor having a square cross section. One side of the outer conductor is left completely open as a slot. The slot is surrounded by a large metal housing to contact the two halves. As a measure for the shielding effectiveness the coupling between the two devices is measured in terms of scattering parameters after the test material is brought between the two halves. The devices can be used in a range from low frequencies to a few GHz.
Characteristics, calibration and measurement uncertainty of RF field strength meters in the frequency range up to 18 GHz
Authors: Pape R. , Münter K. , Schrader T.
Published: April 2010

Abstract. Due to their construction, the devices used for the measurement of electromagnetic fields (radiation monitors) must be calibrated individually. The measurement data obtained are documented in a calibration certificate and the user must take them into account in the uncertainty budget he has to draw up. In addition to the uncertainty contributions of the field representation and of the transfer, other contributions occur which depend on the special constructive features of these devices. When the uncertainty budget is drawn up, it depends on the application and the information about the field structure which contributions will have an effect and which will not. The procedure will be explained by an example.
Protective properties of a missile enclosure against electromagnetic influences
Authors: Fisahn S. , Garbe H.
Published: April 2010

Abstract. In order to predict the immunity of a generic missile (GENEC), not only the electronic system but also the enclosure has to be taken into consideration. While a completely closed metallic missile enclosure shows a high electric shielding effectiveness, it is decreased substantially by apertures which could not be avoided by different reasons. The shielding effectiveness of the generic missile could be investigated by means of a hollow cylinder equipped with different apertures. Numerical simulations and measurements of this hollow cylinder will be carried out and analyzed.
Measurement of the transient shielding effectiveness of enclosures using UWB pulses inside an open TEM waveguide
Authors: Herlemann H. , Koch M.
Published: April 2010

Abstract. Recently, new definitions of shielding effectiveness (SE) for high-frequency and transient electromagnetic fields were introduced by Klinkenbusch (2005). Numerical results were shown for closed as well as for non closed cylindrical shields. In the present work, a measurement procedure is introduced using ultra wideband (UWB) electromagnetic field pulses. The procedure provides a quick way to determine the transient shielding effectiveness of an enclosure without performing time consuming frequency domain measurements. For demonstration, a cylindrical enclosure made of conductive textile is examined. The field pulses are generated inside an open TEM-waveguide. From the measurement of the transient electric and magnetic fields with and without the shield in place, the electric and magnetic shielding effectiveness of the shielding material as well as the transient shielding effectiveness of the enclosure are derived.
Correlation properties of dual polarized antennas with finite pattern orthogonality in mobile fading channels
Authors: Armbrecht G. , Klemp O. , Rolfes I.
Published: April 2010

Abstract. Starting from planar broadband log.-per. antenna design, offering the possibility of dual-polarized reception properties, in this article a generalized mathematical approach for rapidly estimating the resulting signal correlation coefficient in a stochastically modeled propagation environment solely based on measured or simulated radiation characteristics of one single antenna element is presented. The obtained results are marking an upper limit and are describing the worst-case scenario according to the signal correlation at the antenna feeding points in terms of line-of-sight (LOS) reception in main beam direction. The knowledge of the derived relationship may be helpful especially for antenna designers to combine antenna performance values with the significant communication system performance parameters, as e.g. in case of Multiple-Input Multiple-Output (MIMO) and diversity configurations.
Comparison of reconfigurable structures for flexible word-length multiplication
Authors: Pfänder O. A. , Nopper R. , Pfleiderer H.-J. , Zhou S. , Bermak A.
Published: April 2010

Abstract. Binary multiplication continues to be one of the essential arithmetic operations in digital circuits. Even though field-programmable gate arrays (FPGAs) are becoming more and more powerful these days, the vendors cannot avoid implementing multiplications with high word-lengths using embedded blocks instead of configurable logic. But on the other hand, the circuit's efficiency decreases if the provided word-length of the hard-wired multipliers exceeds the precision requirements of the algorithm mapped into the FPGA. Thus it is beneficial to use multiplier blocks with configurable word-length, optimized for area, speed and power dissipation, e.g. regarding digital signal processing (DSP) applications. In this contribution, we present different approaches and structures for the realization of a multiplication with variable precision and perform an objective comparison. This includes one approach based on a modified Baugh and Wooley algorithm and three structures using Booth's arithmetic operand recoding with different array structures. All modules have the option to compute signed two's complement fix-point numbers either as an individual computing unit or interconnected to a superior array. Therefore, a high throughput at low precision through parallelism, or a high precision through concatenation can be achieved.