bluuebunny/crossref_metadata_2025 huggingface dataset:
GPS low noise amplifier with high immunity to wireless jamming signals and power control option
Authors: Schulz H. , Golberg H.-J. , Gruson F. , Durler M. , Spiegel S. J.
Published: April 2010

Abstract. A SiGe GPS low noise amplifier with power control option and high immunity to wireless jamming signals is presented. These novel features applied to Atmel’s ATR0610 GPS LNA allow significant power saving at the radio interface while meeting the out-of-band linearity requirements. The results show the noise figure less than 2.1 dB, including the embedded pre-select filter, and out-of-band IIP3 above +8 dBm in the frequency range between 1.8GHz and 2 GHz with 3mA current consumption. The GPS system performance shows GPS sensitivity below -141 dBm with 5 ms integration interval.
Consideration of parasitic effects on buses during early IC design stages
Authors: Rauscher J. , Tahedl M. , Pfleiderer H.-J.
Published: April 2010

Abstract. Complex integrated systems contain more and more on-chip components which exchange data and access memories via buses. To consider parasitic effects on bus structures during the early design phase appropriate models and wiring methods must be available. A RC-Pi model is proposed to model the load of a bus driver cell that also considers capacitive coupling between the signal lines. On the basis of simple estimations it is shown under what conditions the influence of inductance on the bus is negligible. Furthermore a method to consider inductive effects is shown. An early consideration of parasitic effects on global interconnect structures and an assertion which effects have to be considered is mandatory to effectively estimate the behavior of wires. Hence it also helps to avoid wrong assumptions.
Improving the positive feedback adiabatic logic familiy
Authors: Fischer J. , Amirante E. , Bargagli-Stoffi A. , Schmitt-Landsiedel D.
Published: April 2010

Abstract. Positive Feedback Adiabatic Logic (PFAL) shows the lowest energy dissipation among adiabatic logic families based on cross-coupled transistors, due to the reduction of both adiabatic and non-adiabatic losses. The dissipation primarily depends on the resistance of the charging path, which consists of a single p-channel MOSFET during the recovery phase. In this paper, a new logic family called Improved PFAL (IPFAL) is proposed, where all n- and pchannel devices are swapped so that the charge can be recovered through an n-channel MOSFET. This allows to decrease the resistance of the charging path up to a factor of 2, and it enables a significant reduction of the energy dissipation. Simulations based on a 0.13µm CMOS process confirm the improvements in terms of power consumption over a large frequency range. However, the same simple design rule, which enables in PFAL an additional reduction of the dissipation by optimal transistor sizing, does not apply to IPFAL. Therefore, the influence of several sources of dissipation for a generic IPFAL gate is illustrated and discussed, in order to lower the power consumption and achieve better performance.
Investigations of long-term trends in the ionosphere with world-wide ionosonde observations*
Authors: Bremer J.
Published: April 2010

Abstract. Basing on model calculations by Roble and Dickinson (1989) for an increasing content of atmospheric greenhouse gases in the Earth’s atmosphere Rishbeth (1990) predicted a lowering of the ionospheric F2- and E-regions. Later Rishbeth and Roble (1992) also predicted characteristic longterm changes of the maximum electron density values of the ionospheric E-, F1-, and F2-layers. Long-term observations at more than 100 ionosonde stations have been analyzed to test these model predictions. In the E- and F1-layers the derived experimental results agree reasonably with the model trends (lowering of h'E and increase of ƒoE and ƒoF1, in the E-layer the experimental values are however markedly stronger than the model data). In the ionospheric F2-region the variability of the trends derived at the different individual stations for hmF2 as well as ƒoF2 values is too large to estimate reasonable global mean trends. The reason of the large differences between the individual trends is not quite clear. Strong dynamical effects may play an important role in the F2-region. But also inhomogeneous data series due to technical changes as well as changes in the evaluation algorithms used during the long observation periods may influence the trend analyses.
Karl Rawer’s life and scientific achievements*
Authors: Reinisch B. W.
Published: April 2010

Abstract. This laudation is given in honor of the 90th birthday of Prof. Karl Rawer. The ionosphere was discovered during Karl Rawer’s life, and he has dedicated his life to the exploration of this part of Earth’s environment. The horrible events of world wars I and II shaped his early life, but they also launched his career as one of the eminent geophysical scientists of the twentieth century.
Karl Rawer’s interest and encouragement regarding new approaches to ionospheric modeling
Authors: Tulunay Y. , Tulunay E. , Senalp E. T.
Published: April 2010

Abstract. Professor Karl Rawer encourages, stimulates researchers. He takes initiative and supports researchers in producing papers about new techniques and methods. As a typical case the authors here report their experience with Professor Rawer during the publication of their papers about a Neural Network approach to model near Earth space processes.
35 years of International Reference Ionosphere – Karl Rawer’s legacy
Authors: Bilitza D.
Published: April 2010

Abstract. This presentation is given in honor of Prof. Karl Rawer’s 90th birthday. It looks back at 35 years of research and development in the framework of the International Reference Ionosphere (IRI) project. K. Rawer initiated this international modeling effort and was the first Chairman of the IRI Working Group. IRI is a joint project of the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI) whose goal it is to establish an international standard model for the ionospheric densities, temperatures and drifts. This year we are celebrating Karl Rawer’s 90th birthday and also the 35-year anniversary of the IRI effort. My talk will review the close involvement of Karl Rawer in all stages of the development and improvement of this international standard from early on and his still very active participation in this effort.
Using scale heights derived from bottomside ionograms for modelling the IRI topside profile
Authors: Reinisch B. W. , Huang X. , Belehaki A. , Ilma R.
Published: April 2010

Abstract. Groundbased ionograms measure the Chapman scale height HT at the F2-layer peak that is used to construct the topside profile. After a brief review of the topside model extrapolation technique, comparisons are presented between the modeled profiles with incoherent scatter radar and satellite measurements for the mid latitude and equatorial ionosphere. The total electron content TEC, derived from measurements on satellite beacon signals, is compared with the height-integrated profiles ITEC from the ionograms. Good agreement is found with the ISR profiles and with results using the low altitude TOPEX satellite. The TEC values derived from GPS signal analysis are systematically larger than ITEC. It is suggested to use HT , routinely measured by a large number of Digisondes around the globe, for the construction of the IRI topside electron density profile.
Some remarks about flux linkage and inductance
Authors: Kurz S.
Published: April 2010

Abstract. In the area of computational electromagnetics there is an increasing demand for various coupled simulations. One example is the coupling between field and circuit simulation for the description of electromagnetic devices. In the context of such couplings, theoretical questions arise as well. How can a field device be represented as an equivalent multiport circuit element? What is meant by flux linkage if the considered conductors are not filamentary? What is meant by inductance if the magnetic media exhibit nonlinear behaviour? These questions and their answers are not new. However, according to the author’s view, these issues are not sufficiently addressed in the usual textbooks. The aim of the paper is therefore to (hopefully) answer the questions concisely and correctly. The modern language of differential forms will be employed for this purpose.
Berechnung des Hochfrequenzverhaltens komplexer Strukturen mit der Methode gekoppelter Streuparameter – CSC
Authors: Glock H.-W. , Rothemund K. , van Rienen U.
Published: April 2010

Abstract. Es wird eine Methode zur Berechnung der Hochfrequenz-Eigenschaften komplexer Strukturen vorgestellt. Das Verfahren beruht auf der Zerlegung der Gesamtstruktur in einzelne einfachere Segmente, deren breitbandige S-Matrizen mit kommerziellen Programmen berechnet werden. Das Gesamtsystem kann von beliebiger Topologie sein, und die Zahl der die Segmente verkoppelnden Hohlleiter- Moden ist nicht begrenzt. Als Ergebnis steht bei offenen Strukturen deren vollständige S-Matrix, bei abgeschlossenen deren Resonanzeigenschaften zur Verfügung. Die theoretischen Grundlagen werden beschrieben und die Anwendung mit Beispielen aus dem Gebiet der Teilchenbeschleuniger und zu Eigenschaften schwach elliptisch geformter Resonatoren illustriert. A method called Coupled S-Parameter Calculation – CSC is described which is used to calculate the rf properties of complex structures, i.e. either their scattering (devices with ports) or their resonance properties. The method is based on the segmentation of the entire system into sections being less complex, the external calculation of the section’s broadband S-matrices, and a combination scheme, which is applicable to any topology and number of modes. The method’s principle is described. Examples from the field of particle accelerator cavities and about the properties of weakly elliptical resonators are given.
Computation of the frequency response of a nonlinearly loaded antenna within a cavity
Authors: Gronwald F. , Blume E. , Nitsch J.
Published: April 2010

Abstract. We analyze a nonlinearly loaded dipole antenna which is located within a rectangular cavity and excited by an electromagnetic signal. The signal is composed from two different frequencies. In order to calculate the spectrum of the resulting electromagnetic field within the resonator we transform the antenna problem into a network problem. This requires to precisely determine the antenna impedance within the cavity. The resulting nonlinear equivalent network is solved by means of the harmonic balance technique. As a result the occurrence of low intermodulation frequencies within the spectrum is verified.
Susceptibility of personal computer systems to electromagnetic pulses with double exponential character
Authors: Camp M. , Garbe H.
Published: April 2010

Abstract. In this paper the susceptibility of personal computer systems to fast transient electromagnetic pulses with double exponential pulse shapes (EMP, UWB) is determined. The influence of the computer generation, RAM-values, different program states and the pulse shape, as well as the destruction thresholds of single PC-components (CPU, RAM, BIOS, Mainboard) have been investigated.
HPEM protection on HF transmission lines
Authors: Krzikalla R. , ter Haseborg J. L.
Published: April 2010

Abstract. Traditional protection concepts against electromagnetic interferences are combinations of nonlinear elements like spark gaps, varistors or suppressor diodes. Due to parasitic capacitances and inductivities and the general behavior of the elements, a trade off has to be made between the frequency bandwidth and the energy absorption capability of the protection circuit. For high frequency applications with signal frequencies above about 500MHz a sufficient protection can not be given without changing the transmitted signals itself. Additionally this kind of protection concept is designed and optimized against transient interferences with rise times down to some nanoseconds, for example the LEMP, the NEMP or the ESD. Current researches focus on transient interferences with rise times in the picosecond range and pulse widths of a few nanoseconds, the so called ultra wideband (UWB) pulses, combined with a significant voltage amplitude of some kilovolts. In this paper investigations on nonlinear protection elements and linear filters against line-coupled UWB pulses with high voltage amplitudes will be done with special focus on the protection of high frequency data-lines.
Experimental and numerical analysis on PCB coupling in non uniform field environment
Authors: Sonnemann F.
Published: April 2010

Abstract. HPM and UWB pulses are capable of disrupting signal processing or even destroying semiconductor structures. Hence, it is useful to estimate the induced voltage levels on printed circuit boards (PCB) in response to different excitation signals. The considered PCB is integrated within a missile-like cylindrical structure, called GENEC, and is equipped with differential sensors to measure the E- and Hfield above the PCB. Standard transmission line theory is applied to develop a SPICE model that calculates the terminal voltages at the transmission line loads.
Susceptibility and hardening of electronic systems to fast transient threats: new challenges ahead
Authors: Sabath F.
Published: April 2010

Abstract. The field of susceptibility and hardening of electronic systems to transient threats has experienced a significant growth during the past ten years. Driven by the development in the area of non-lethal electromagnetic weapons it has become necessary to extend the classical set of transient threats, consisting of LEMP, ESD and NEMP, by a fast transient threat with an extreme bandwidth. The investigation of the susceptibility to those UWB threats, characterized by a bandwidth of more than a quarter of the center frequency, rise times of less than 200 ps and pulse durations in the ns regime, is of special interest. This paper presents an overview of current challenges of the hardening against UWB threats. It discusses recent research trends in transient susceptibility measurements, protection concepts and methods of analysis.
Shielding of Electronic Systems against Transient Electromagnetic Interferences
Authors: Herlemann H. , Korte S. , Camp M. , Garbe H. , Koch M. , Sabath F.
Published: April 2010

Abstract. In order to protect electronic systems against the effects of transient electromagnetic interferences, shields made of electrically conductive material can be used. The subject of this paper is an electrically conductive textile. When applying the shield, a reliable measure is needed in order to determine the effectiveness of the shield to protect against electromagnetic pulses. For this purpose, a time domain measurement technique is presented using double exponential pulses. With these pulses, the susceptibility of an operating electronic device with and without the shield is determined. As a criterion of quality of a shield, the breakdown failure rate found in both cases is compared.
Recent Applications and Advances of Numerical Modeling and Wavefield Inversion in Nondestructive Testing
Authors: Marklein R. , Langenberg K. J. , Mayer K. , Miao J. , Shlivinski A. , Zimmer A. , Müller W. , Schmitz V. , Kohl C. , Mletzko U.
Published: April 2010

Abstract. This paper presents recent advances and future challenges of the application of different linear and nonlinear inversion algorithms in acoustics, electromagnetics, and elastodynamics. The presented material can be understood as an extension of our previous work on this topic. The inversion methods considered in this presentation vary from linear schemes, like the Synthetic Aperture Radar (SAR) applied electromagnetics and the Synthetic Aperture Focussing Technique (SAFT) as its counterpart in ultrasonics, and the linearized Diffraction Tomography (DT), to nonlinear schemes, like the Contrast Source Inversion (CSI) combined with different regularization approaches. Inversion results of the above mentioned inversion schemes are presented and compared for instance for time-domain ultrasonic data from the Fraunhofer-Institute for Nondestructive Testing (IZFP, Saarbrücken, Germany). Convenient tools for nondestructive evaluation of solids can be electromagnetic and/or elastodynamic waves; since their governing equations, including acoustics, exhibit strong structural similarities, the same inversion concepts apply. In particular, the heuristic SAFT algorithm can be and has been utilized for all kinds of waves, once a scalar approximation can be justified. Relating SAFT to inverse scattering in terms of diffraction tomography, it turns out that linearization is the most stringent inherent approximation. A comparison of the inversion results using the linear time-domain inversion scheme SAFT and well tested nonlinear frequency-domain inversion schemes demonstrates the considerable potential to extend and improve the ultrasonic imaging technique SAFT while consulting the mathematics of wavefield inversion, yet, in particular if the underlying effort is considered, the relatively simple and effective SAFT algorithm works surprisingly well. Since SAFT is a widely accepted imaging tool in ultrasonic NDE it seems worthwhile to check its formal restrictions and assumptions whether they could be overcome and whether they would outperform the standard and original SAFT algorithm.
Fast Multipole Acceleration of a MoM Code for the Solution of Composed Metallic/Dielectric Scattering Problems
Authors: Jakobus U. , van Tonder J.
Published: April 2010

Abstract. An existing method of moments (MoM) code for the solution of complex scattering bodies has been accelerated by means of a multilevel fast multipole method (MLFMM). We demonstrate the usage of this technique both for metallic structures (wires and surfaces) and for dielectric bodies (volume and surface equivalence principle). Aspects like the effect of the type of integral equation, preconditioning schemes, or iterative solution techniques are discussed. But also limitations are addressed, which are encountered when for instance attempting to model highly lossy dielectric bodies with a high permittivity. Several validation and application examples demonstrate the usefulness of this method, both with regard to the obtained accuracy, but also with respect to the potential saving in memory and run-time as compared to a standard MoM formulation.
Fast Multipole Method Applied to Volume Integral Equation Method
Authors: Hafla W. , Buchau A. , Groh F. , Rucker W. M.
Published: April 2010

Abstract. The Volume Integral Equation Method (VIEM) has been used for the solution of three-dimensional non-linear magnetostatic field problems. The number of unknowns is minimal as only the magnetic material has to be discretized. For accurate solutions of problems where the magnetic field is small compared to the excitation field a difference field formulation has been developed. To reduce computational costs the fast multipole method is applied both on compression of the system matrix and during post processing. The efficiency of the formulation is demonstrated in several examples.
Uplink performance investigations of the service area based beyond 3G system JOINT
Authors: Liu Y. , Weber T. , Zirwas W.
Published: April 2010

Abstract. The joint transmission and detection integrated network (JOINT) is a novel OFDM-based vNP00 air interface solution for beyond 3G (B3G) mobile radio communications systems WMSL02. JOINT aims at eliminating the multiple access interference (MAI) and improving the system capacity by the application of MIMO techniques applied in the service area (SA) based system architecture. In a SA based structure the intra-SA multiple access interference (MAI) can be easily combated by algorithms like, e.g., joint detection (JD) Kle96,Ver98 in the uplink. The parameters like, e.g., the SA size, the system load and reuse factor show great impacts on the system performances, in terms of the average bit error rate (BER) and the BER statistics. Spectrum efficiency of JOINT is also investigated based on the simulation results.
OFDM: From the Idea to Implementation
Authors: Fechtel S. A.
Published: April 2010

Abstract. OFDM (orthogonal frequency-division multiplexing) is one of the key digital communication technologies of the current decade. The first part of this paper presents the fundamentals of OFDM and its benefits in the presence of multipath propagation in a tutorial-like fashion. The second part details on some of the most important aspects of OFDM transceiver implementation: concept of receiver channel filtering and A/D conversion, radio impairment compensation (I/Q mismatch), and OFDM demodulator (FFT) design.
Digitalsimulator für pulscodierte neuronale Netze
Authors: Hellmich H. H. , Klar H.
Published: April 2010

Abstract. Die Simulation von grossen pulscodierten neuronalen Netzen (PCNNs) für die Evaluierung einer biologisch motivierten Bildverarbeitung ist auf Einprozessor-Systemen (PCs oder Workstations) immer noch sehr zeitineffizient. Den Flaschenhals während der Simulation bildet der sequentielle Zugriff auf den Gewichtsspeicher zur Berechnung der Neuronenzustände. Es wird ein Digitalsimulator basierend auf feld-programmierbaren Gate-Arrays (FPGAs) vorgestellt, der dieses Flaschenhals-Problem durch eine verteilte Speicherarchitektur und eine erhöhte Speicherbandbreite angeht und zusätzlich eine getrennte Berechnung von Neuronenzuständen und Netzwerktopologie vorsieht. Somit ist es möglich, den des Simulationsalgorithmus zu erhöhen. Die momentane Implementierung mit einer Taktfrequenz von 50MHz verspricht einen Beschleunigungsfaktor von etwa 30 für eine spärliche Vernetzungsstruktur (Vierer- und Achternachbarschaft) im Vergleich zu einem PC mit einer 2,4GHz CPU und 1GB RAM Arbeitsspeicher.
10Gb/s Bang-Bang Clock and Data Recovery (CDR) for optical transmission systems
Authors: Dodel N. , Klar H.
Published: April 2010

Abstract. A Bang-Bang Clock-Data Recovery (CDR) for 10Gb/s optical transmission systems is presented. A direct modulated architecture is used for the design. Its loop characteristics can be derived using an analogy to Σ Δ theory. The circuit was produced and measured in a commercial 0.25μm BiCMOS technology with a transition frequency fT70=GHz.
Eine Test- und Ansteuerschaltung für eine neuartige 3D Verbindungstechnologie
Authors: Bschorr M. , Pfleiderer H.-J. , Benkart P. , Kaiser A. , Munding A. , Kohn E. , Heittmann A. , Hübner H. , Ramacher U.
Published: April 2010

Abstract. In der vorliegenden Arbeit wird eine Built-In Self-Test Schaltung (BIST) vorgestellt, welche die vertikalen Inter-Chip-Verbindungen in einer neuartigen 3D Schaltungstechnologie auf ihre Funktionalität zur Datenübertragung überprüft. Die 3D Technologie beruht auf der Stapelung mehrerer aktiver Silizium-CMOS-ICs, welche durch das Siliziumsubstrat hindurch vertikal miteinander elektrisch verbunden sind. Bei diesen Vias sind die zu erwartenden Defekte hochohmige Verbindungen und Kurzschlüsse. Die entwickelte Testschaltung ermöglicht es, beliebige Konstellationen von vertikalen Verbindungen auf Fehler zu untersuchen, und das Ergebnis entweder zur Analyse der 3D Technologie auszulesen oder innerhalb des Chipstapels zu verwenden, um defekte Vias zu umgehen. Die Schaltung wurde in einer 0,13μm Technologie entworfen und simuliert. Ein Testchip ist momentan in Produktion.
An Adiabatic Architecture for Linear Signal Processing
Authors: Vollmer M. , Götze J.
Published: April 2010

Abstract. Using adiabatic CMOS logic instead of the more traditional static CMOS logic can lower the power consumption of a hardware design. However, the characteristic differences between adiabatic and static logic, such as a four-phase clock, have a far reaching influence on the design itself. These influences are investigated in this paper by adapting a systolic array of CORDIC devices to be implemented adiabatically. We present a means to describe adiabatic logic in VHDL and use it to define the systolic array with precise timing and bit-true calculations. The large pipeline bubbles that occur in a naive version of this array are identified and removed to a large degree. As an example, we demonstrate a parameterization of the CORDIC array that carries out adaptive RLS filtering.
Noise Considerations of Integrators for Current Readout Circuits
Authors: Bechen B. , Kemna A. , Gnade M. , Boom T. v. d. , Hosticka B.
Published: April 2010

Abstract. In this paper the noise analysis of a current integrator is carried out and measures to reduce the overall noise are presented. The effects of various noise sources are investigated and their dependence on the input capacitance and on the gate area of the input transistors of the OTA used for the readout is shown. Both, input capacitance and gate area, should be kept as small as possible. Moreover, the linearity of the integrator is examined. In addition to that, the available application of such sensor readout circuit, which is a CMOS photodetector readout, is introduced. It uses an automatic gain switching, so that the dynamic range is extended.
Design Space Exploration for Frequency Synchronization of BPSK/QPSK Bursts
Authors: Brack T. , Wasenmüller U. , Schmidt D. , Wehn N.
Published: April 2010

Abstract. Frequency synchronisation is a vital part of every inner receiver for wireless communication. In this paper we present different implementation alternatives for non data aided frequency estimation of BPSK/QPSK bursts with respect to implementation complexity and communications performance. Results with regard to different quantization levels, varying burstlengths, frequency offsets and modulation indices for different signal to noise ratios are presented. Implementation results are based on XILINX Virtex II Pro FPGA devices.
Analytische Betrachtung des Quantisierungsfehlers bei grundlegenden Rechenoperationen der digitalen Signalverarbeitung
Authors: Schlecker W. , Beuschel C. , Pfleiderer H.-J.
Published: April 2010

Abstract. Bei der Realisierung digitaler Schaltungen mit einem ASIC oder FPGA kann die Wortbreite der Berechnungen frei gewählt werden. Um die Fläche bzw. die benötigte Hardware zu minimieren, wird versucht, die Berechnungen mit minimaler Wortbreite zu implementieren. Dabei muss jedoch das Quantisierungsrauschen, das durch das Beschränken der Wortbreite entsteht, berücksichtigt werden. Häufig wird hierzu eine worst-case Abschätzung des Fehlers gemacht oder mit Simulationen die benötigte Wortbreite bestimmt. Der vorliegende Beitrag betrachtet die Auswirkungen der Quantisierung analytisch. Dabei wird von gleichverteilten Eingangssignalen ausgegangen. Es wird das Quantisierungsrauschen in Abhängigkeit von der Eingangs- und Ausgangswortbreite bei der Multiplikation und beim Skalarprodukt betrachtet. Die Untersuchungen wurden für Runden und für Abschneiden analytisch durchgeführt und durch Simulation bestätigt.
A new circuit technique for reduced leakage current in Deep Submicron CMOS technologies
Authors: Schmitz A. , Tielert R.
Published: April 2010

Abstract. Modern CMOS processes in the Deep Submicron regime are restricted to supply voltages below 2 volts and further to account for the transistors' field strength limitations and to reduce the power per logic gate. To maintain the high switching performance, the threshold voltage must be scaled according with the supply voltage. However, this leads to an increased subthreshold current of the transistors in standby mode (VGS=0). Another source of leakage is gate current, which becomes significant for gate oxides of 3nm and below. We propose a Self-Biasing Virtual Rails (SBVR) - CMOS technique which acts like an adaptive local supply voltage in case of standby mode. Most important sources of leakage currents are reduced by this technique. Moreover, SBVR-CMOS is capable of conserving stored information in sleep mode, which is vital for memory circuits. Memories are exposed to radiation causing soft errors. This well-known problem becomes even worse in standby mode of typical SRAMs, that have low driving performance to withstand alpha particle hits. In this paper, a 16-transistor SRAM cell is proposed, which combines the advantage of extremely low leakage currents with a very high soft error stability.
Design and Analysis of Fully Integrated Differential VCOs
Authors: Prochaska M. , Belski A. , Mathis W.
Published: April 2010

Abstract. Oscillators play a decisive role for electronic equipment in many fields - like communication, navigation or data processing. Especially oscillators are key building blocks in integrated transceivers for wired and wireless communication systems. In this context the study of fully integrated differential VCOs has received attention. In this paper we present an analytic analysis of the steady state oscillation of integrated differential VCOs which is based on a nonlinear model of the oscillator. The outcomes of this are design formulas for the amplitude as well as the stability of the oscillator which take the nonlinearity of the circuit into account.
Analysis and Simulation of Reduced FIR Filters
Authors: Radic Lj. , Mathis W.
Published: April 2010

Abstract. High order FIR filters employ model reduction techniques, in order to decrease power consumption and time delay. During reduction high order FIR filters are converted into low order IIR filters preserving stability and phase linearity as main features. Matlab simulations of an audio system with these reduced filters are presented. Furthermore, the influence of order on power consumption is discussed.
Implementierung eines verlustleistungsoptimierten Dezimators für kaskadierte Sigma-Delta Analog-Digital Umsetzer
Authors: Becker M. , Lotze N. , Becker J. , Ortmanns M. , Manoli Y.
Published: April 2010

Abstract. Dieser Beitrag stellt die Implementierung eines neuartigen Ansatzes einer effizienten Dezimator-Architektur für kaskadierte Sigma-Delta Modulatoren vor. Die Rekombinationslogik kaskadierter Modulatoren und die Korrektur des Verstärkungsfehlers zeitkontinuierlicher (CT) Modulatoren werden in die erste Stufe des Dezimators integriert. Eine entsprechende Filtertopologie wird hergeleitet und auf einem Hardware-Emulator der Firma Mentor Graphics implementiert. Der Vergleich der vorgeschlagenen Struktur mit einer herkömmlichen Implementierung zeigt eine nennenswerte Verbesserung der Effizienz.
Principal Component Analysis In Radar Polarimetry
Authors: Danklmayer A. , Chandra M. , Lüneburg E.
Published: April 2010

Abstract. Second order moments of multivariate (often Gaussian) joint probability density functions can be described by the covariance or normalised correlation matrices or by the Kennaugh matrix (Kronecker matrix). In Radar Polarimetry the application of the covariance matrix is known as target decomposition theory, which is a special application of the extremely versatile Principle Component Analysis (PCA). The basic idea of PCA is to convert a data set, consisting of correlated random variables into a new set of uncorrelated variables and order the new variables according to the value of their variances. It is important to stress that uncorrelatedness does not necessarily mean independent which is used in the much stronger concept of Independent Component Analysis (ICA). Both concepts agree for multivariate Gaussian distribution functions, representing the most random and least structured distribution. In this contribution, we propose a new approach in applying the concept of PCA to Radar Polarimetry. Therefore, new uncorrelated random variables will be introduced by means of linear transformations with well determined loading coefficients. This in turn, will allow the decomposition of the original random backscattering target variables into three point targets with new random uncorrelated variables whose variances agree with the eigenvalues of the covariance matrix. This allows a new interpretation of existing decomposition theorems.
Comparison of linear and logarithmic receiver signals from polarimetric weather radar echoes and their temporal decorrelation properties
Authors:   Tracksdorf,   Ghorbani,   Chandra,   Hagen,   Bebbington
Published: April 2010

Abstract. Usually common polarimetric weather radar DSP-products (e.g.: reflectivity, differential reflectivity, linear depolarisation ratio - for both - co-polar and cross-polar signal components) are based on the logarithmic receiver output, because of the large dynamic range provided by the logarithmic receiver. In this paper for the first time we also use the linear receiver output to calculate common weather radar DSP-Products. Using the raw time series radar data recorded with the coherent polarimetric C-band weather radar of the DLR (''Poldirad'', Wessling, Germany) it is possible to do a comparison between processed weather radar echoes from the linear receiver and the logarithmic receiver. After the comparison showed very good results, we continued the work with the linear receiver data, especially on the topic named temporal decorrelation properties of the linear receiver data. This paper includes the first results obtained from two observables that belong to our working topic. The first observable is the ''Time Decorrelation Factor-TDF'' and the second one is the ''Decorrelation Time DTτ''The results have been summarised in the form of empirical relationships, plots and the least mean square (LMS) method of curve fitting was used to give the mathematical relationship for the observables TDF and DTτ. Generally, the paper will also reflect on the statistical properties of radar echoes measured with linear receivers. The usage of the linear receiver data opens a wide field of new applications and products for the work with polarimetric weather radar data, because the linear receiver data also provides phase information which a logarithmic receiver does not.
Application of the Cloude-Pottier decomposition to weather radar signatures
Authors: Galletti M. , Chandra M. , Pottier E. , Ghorbani A.
Published: April 2010

Abstract. In this paper we apply the Cloude-Pottier decomposition to Weather Radar Signatures. First, we present the results of a simulation carried out at the Chemnitz University of Technology and give the expected H-α values for different rain intensities. A comparison with standard radarmeteorological variables is also given. Then, first ever images of Entropy and Anisotropy are presented for clouds and precipitation. Experimental Data are from the POLDIRAD Weather Facility in Oberpfaffenhofen, Germany.
A hybrid method combining the TD-MoM with the TD-UTD to calculate the transient radiation of thin dipoles in presence of a perfectly conducting screen
Authors: Becker A. , Hansen V.
Published: April 2010

Abstract. A time domain Method of Moments algorithm (TD-MoM) is combined with the time domain version of the Uniform Theory of Diffraction (TD-UTD). By use of the TD-MoM the fields radiated from thin wire structures positioned in free space are determined. The TD-UTD is applied to calculate the fields scattered by a perfectly conducting screen. Both techniques are hybridized by adding possible reflected and diffracted fields in the TD-MoM algorithm and by using the TD-MoM solution to calculate the fields which impinge on to the screen. To show the accuracy of the developed hybrid method, numerical results are compared to results obtained by established frequency domain numerical codes.
Influence of nonideal LRL or TRL calibration elements on VNA S-parameter measurements
Authors: Stumper U.
Published: April 2010

Abstract. For the 7-term LRL and TRL calibration of a four-sampler vector network analyser (VNA), expressions for the deviations of the measured S-parameters of two-port test objects from their actual values are presented as functions of the deviations of the S-parameters of the LRL/TRL calibration elements from their ideal values. The obtained sensitivity coefficients are suitable for establishing the Type-B uncertainty budget for S-parameter measurements. They show how the measurements are affected by imperfect calibration elements and nonideal connections.
Reciprocity and mutual impedance formulas within lossy cavities
Authors: Gronwald F. , Blume E.
Published: April 2010

Abstract. We discuss the validity of reciprocity and mutual impedance formulas within lossy cavities. Mutual impedance formulas are well-known from antenna theory and useful to describe the electromagnetic coupling between electromagnetic interference sources and victims. As an example the mutual impedance between two dipole antennas within a lossy rectangular cavity is calculated from a system of coupled Hallén's equations that efficiently is solved by the method of moments.
On the applicability of conventional transmission line theory within cavities
Authors: Gronwald F.
Published: April 2010

Abstract. We investigate whether or not conventional transmission line theory needs to be modified if transmission lines are considered that are located in a cavity rather than in free space. Our analysis is based on coupled Pocklington's equations that can be reduced to integral equations for the antenna mode and the transmission line mode. Under the usual assumptions of conventional transmission line theory these modes do approximately decouple within a cavity. As a result, cavity properties will primarily influence the antenna mode but not the transmission line mode.
WCDMA outphasing power amplifier with a software defined transmitter/receiver architecture for determination of the predistortion function
Authors: Gerhard W. , Knöchel R.
Published: April 2010

Abstract. A flexible and easily configurable software defined transmitter/receiver (TX/RX) architecture is described, which allows the determination of the distorted complex transfer characteristics of a 3 port nonlinear outphasing power amplifier (PA) for application in a WCDMA base station. The TX/RX architecture is capable of generating high precision single sideband signals (SSB) using a DSP algorithm, which is almost insensitive to measurement errors and to the frequency response of the output measurement channel. Based on this an inverse predistortion function for a necessary linearization is calculated and implemented into a FPGA (field programmable gate array) through look-up-tables (LUT). The common base band and the differential phase angles are predistorted, resulting in a linearization of the PA.
Photonic crystals as host material for a new generation of microwave components
Authors: Daschner F. , Knöchel R. , Foca E. , Carstensen J. , Sergentu V. V. , Föll H. , Tiginyanu I. M.
Published: April 2010

Abstract. In order to verify simulations of a concave lens based upon a photonic crystal, it was scaled and built for the application in the microwave range. Its field distribution was measured between 5.5 and 12 GHz. Due to the effective refractive index smaller than 1, focusing points were found in spite of the concave shape. The survey of the field distributions at the investigated frequencies leads to other possible applications of photonic crystals in the microwave and millimetre wave region, like beam-splitter and prism.
Analysis and simulations of a frequency synthesizer with internal and external noise sources
Authors: Sangha G. S. , Hoffmann M. H. W.
Published: April 2010

Abstract. In this paper, a novel technique to analyse the noise behaviour of a second-order-PLL based synthesizer is demonstrated. Its non-linear behaviour is analyzed with independent noise-sources introduced at different points of the circuit. Phase plane trajectories will be used to demonstrate that noise sources at different locations in the loop produce qualitatively different contributions to the output signal of the synthesizer.
Hardware implementation of smart antenna systems
Authors: Wang H. , Glesner M.
Published: April 2010

Abstract. Smart antenna systems attract a lot attentions now and believably more in the future, as it can increase the capacity of mobile communication systems dramatically. Design of smart antenna systems combines the technologies of antenna design, signal processing, and hardware implementation. In this paper, a propose of smart antenna structure, as well as some function blocks that have been already implemented in hardware will be presented.
A varactor tuned low-cost 24 GHz harmonic VCO
Authors: Olbrich M. O. , Huang L. , Biebl E. M.
Published: April 2010

Abstract. We present a low-cost 24 GHz VCO that is based on a microstrip design combined with discrete packaged devices. The output frequency is generated by a harmonic oscillator. The tunabilty was reached using a varactor diode. Two versions of the VCO were built, one has a wide tuning range of 1.1 GHz and the other one has a high output power of 3.7 dBm.
Auswirkungen der Quantisierung bei nichtlinearen Funktionen
Authors: Schlecker W. , Pfleiderer H.-J.
Published: April 2010

Abstract. Um bei der Implementierung von digitalen Signalverarbeitungsalgorithmen den Hardwareaufwand zu mini\\-mieren, kann die Wortbreite der einzelnen Berechnungen optimiert werden. Dabei müssen die entstehenden Quantisierungsfehler berücksichtigt werden. In linear zeitinvarianten Systemen (LTI) können die Quantisierungfehler in Abhängigkeit der statistischen Werte der Eingangssignale ermittelt werden. In vielen Algorithmen der digitalen Signalverarbeitung werden zusätzlich zu linearen Funktionen nichtlineare Funktionen verwendet. Dieser Beitrag befasst sich mit den Besonderheiten der Quantisierung bei Verwendung von nichtlinearen Funktionen. Dabei wird erläutert, welche Eigenschaften der Quantisierungsfehler am Eingang einer nichtlinearen Funktion haben sollte, um durch die Funktion die Verschlechterung des Signal-zu-Rauschleistungsverhältnis (SNR) zu minimieren. Weiter wird der Fehler, der durch die Quantisierung nach einer nichtlinearen Funktion entsteht, am Beispiel der Multiplikation untersucht.
Towards a generic operational amplifier with dynamic reconfiguration capability
Authors: Lakshmanan S. K. , Koenig A.
Published: April 2010

Abstract. Analog and analog-digital mixed signal electronics needed for sensor systems are indispensable components which tend to drifts from the normal phase of operation due to the impact of manufacturing conditions and environmental influences like etching, aging etc. Precise design methodology, trimming / calibration are essential to restore functionality of the system. Recent block level granular approaches using Field Programmable Analog Array and the more recent approaches from evolutionary electronics providing transistor level granularity using Field Programmable Transistor Arrays offers considerable extensions. In our work, we started on a new medium granular level approach called Field Programmable medium-granular Mixed-signal Array (FPMA) providing basic building blocks of heterogeneous array of active and passive devices to configure established circuit structures which are adaptive, biologically inspired and dynamically re-configurable. Our design objective is to create components of clear compatibility to that of the industrial standards having predictable behavior along with the incorporation of existing design knowledge. The cells can be used in as a single instance or multiple instances. Further, we will focus on a generic dynamic reconfigurable amplifier cell with flexible topology and dimension called Generic Operational Amplifier (GOPA). The incentive of our work comes from recent development in the field of measurement and instrumentation. The digital programming of analog devices is carried out using range of algorithms from simple to evolutionary. Physical realization of the basic cells is carried out in 0.35 μm CMOS technology.
Rekonfigurationstechniken und Anwendungsgebiete für ein programmierbares Gm-C Analog-Filter
Authors: Becker J. , Henrici F. , Manoli Y.
Published: April 2010

Abstract. FPAAs (Field Programmable Analog Arrays) erlauben es, analoge Signalübertragungsfunktionen auf Hardware abzubilden, die von veränderbaren digitalen Konfigurationsdaten abhängen. Sowohl für das Design von Filterstrukturen auf Systemebene als auch für die genaue Simulation ihrer analogen Übertragungsfunktion auf Transistorebene ist es dabei notwendig, die entsprechenden Konfigurationsdaten einzugeben bevor die Phasen/Betragsanalyse durchgeführt werden kann. Die vorliegende Arbeit stellt ein graphisches Entwurfsprogramm zur Instantiierung von analogen Filtern für ein FPAA mit 17 gm-C Blöcken vor. Es wird über erste Simulationsergebnisse berichtet, die die Machbarkeit mit Eckfrequenzen bis zu hundert Mhz bestätigen. Simulierte Übertragungsfunktionen von grundlegenden Bausteinen werden mit der Theorie verglichen und zu einer exemplarischen Instantiierung eines Butterworth-Filters der vierten Ordnung weitergeführt.
Power-Clock-Gating in adiabatischen Logikschaltungen
Authors: Teichmann Ph. , Fischer J. , Amirante E. , Schmitt-Landsiedel D.
Published: April 2010

Abstract. In statischen CMOS-Schaltungen wird Clock-Gating verwendet, um inaktive Schaltungsgruppen abzuschalten und damit dynamische Verluste zu reduzieren. Leckströme gewinnen in den neuen Technologien zunehmend an Bedeutung, und statische Verluste treten auf, die durch Power-Gating reduziert werden. Da adiabatische Logik eine getaktete Versorgungsspannung benutzt, kann hier mittels eines einzigen Switches sowohl ein Clock- als auch ein Power-Gating implementiert werden. Da der Switch auch die Verluste im eingeschalteten Zustand erhöht, muss ein besonderes Augenmerk auf die Auswahl und die Dimensionierung des Switches gelegt werden. Dieser Artikel zeigt die Grundlagen des Power-Clock-Gatings (PCG) in adiabatischer Logik, Betrachtungen zur Auswahl der geeigneten Switchtopologie und Vorschriften für die Dimensionierung des Switches. Des weiteren wird auf die Auswirkungen des PCG auf den Oszillator eingegangen.
From algorithm to implementation: a case study on blind carrier synchronization
Authors: Schmidt D. , Brack T. , Wasenmüller U. , Wehn N.
Published: April 2010

Abstract. Increasing chip complexities demand a higher design productivity. IP cores, which implement commonly needed operations, can help to dramatically shorten development and verification times for new designs. They often allow for a efficient mapping of algorithmic tasks to a hardware architecture. In this paper we present a novel configurable building block for blind carrier synchronization that features combined frequency and phase offset estimation and an alternative modulation removal that improves communication performance compared to state-of-the-art designs. The used design flow exploits the benefits of IP cores for rapid development times while still offering the designer the full range of optimization possibilities for a specific design. It allowed us to do an almost complete design space exploration, assuring a near-optimal solution to the given problem. The implementation platform is a XILINX Virtex II Pro FPGA.
Assessing polarization effects for the Airborne imaging spectrometer APEX
Authors: Böttger U. , Nieke J. , Schläpfer D.
Published: April 2010

Abstract. In the scope of hyperspectral airborne imaging spectrometer (APEX) design activities, the acceptable sensitivity of linear polarization of the spectrometer is analyzed by assessing the amount of polarization of reflected light in the atmosphere-surface system. A large number of calculations is performed for a wide variaty of viewing geometries to study the influences of aerosol models, natural surfaces and flight altitudes over the spectral range from the near-UV to the short-wave infrared (SWIR). Thereinafter the design of the imaging spectrometer is outlined accounting for these requirements and a method of partially correcting the instrument polarization sensitivity is briefly introduced. APEX design and post-processing capabilities will enable to reduce the influence of polarization sensitivity of at-sensor radiance and its higher-level products generated for most of the observation conditions.