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  • 51.
    Azad, A. K. M.
    et al.
    Northern Illinois University, United States.
    Cowan, N. J.Johns Hopkins University, United States.Tokhi, M. O.Univeristy of Sheffield, United Kingdom.Virk, Gurvinder SinghHögskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.Eastman, R. D.Loyola University, United States.
    Adaptive Mobile Robotics: Proceedings Of The 15th International Conference On Climbing And Walking Robots And The Support Technologies For Mobile Machines, Baltimore, USA, 23–26 July 20122012Konferanseproceedings (Fagfellevurdert)
    Abstract [en]

    This book provides state-of-the-art scientific and engineering research findings and developments in the area of mobile robotics and associated support technologies. The book contains peer reviewed articles presented at the CLAWAR 2012 conference. Robots are no longer confined to industrial manufacturing environments. A great deal of interest is invested in the use of robots outside the factory environment. The CLAWAR conference series, established as a high profile international event, acts as a platform for dissemination of research and development findings and supports such a trend to address the current interest in mobile robotics to meet the needs of mankind in various sectors of the society. These include personal care, public health, services in the domestic, public and industrial environments. The editors of the book have extensive research experience and publications in the area of robotics in general and in mobile robotics specifically, and their experience is reflected in editing the contents of the book.

  • 52.
    Backlund, Andreas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Konstruktion av ett automatiserat hybrid värmesystem2016Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Denna rapport presenterar hur en konstruktionsuppgift av ett automatiserat hybrid värmesystem har genomförts. Två värmekällor skulle inkluderas i systemet, primärkällan var en fastbränslepanna på 30 kW. Och som sekundärvärmekälla ett solfångarsystem med totalt tio solfångarmoduler. Värmesystemet skulle värma en bostad, en maskinverkstad samt ett maskingarage. Temperaturregleringen skulle styras med hjälp av automatik. För att inhämta data på de befintliga byggnader som var berörda av projektet gjordes fysiska mätresultat på plats, studier av ritningar, litteratur, internet källor samt samråd med den externa handledaren.Detta gav i slutändan ett system som är uppdelat i två olika delsystem. Ett system med en fastbränslepanna, och ett system med solfångarmoduler. Den uppvärmda median lagras i fyra ackumulatortankar, varje enskild ackumulatortank har olika volym och väljes med hjälp av automatik. Automatiken sköts av en så kallad PLC, som står för Programmable Logic Controller (Eng.). Denna PLC styr hela systemets elektriska utrustning, vilket innefattar pumpar, reglerventiler, avstängningsventiler och temperatur inhämtning från sensorer. Som presentations metod av resultatet valdes att använda ritningar som kan hittas som större bilagor i denna rapport. Samtliga formler som har använts för att dimensionera systemet återfinns under teori avsnittet, med kortfattade kommentarer. Vissa moment har fler än en lösning, vilket ställer krav på att även klara av att göra analyser av olika lösningar samtidigt ta i beaktande den externa handledarens önskemål.

  • 53.
    Bai, S.
    et al.
    Department of Materials and Production, Aalborg University, Aalborg, Denmark.
    Christensen, S.
    Department of Materials and Production, Aalborg University, Aalborg, Denmark.
    Islam, M.
    Department of Materials and Production, Aalborg University, Aalborg, Denmark.
    Rafique, Sajid
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Masud, Nauman
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Mattsson, Per
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    O’Sullivan, L.
    University of Limerick, Limerick, Ireland.
    Power, V.
    University of Limerick, Limerick, Ireland.
    Development and testing of full-body exoskeleton AXO-SUIT for physical assistance of the elderly2019Inngår i: Wearable Robotics: Challenges and Trends: Proceedings of the 4th International Symposium on Wearable Robotics, WeRob2018, October 16-20, 2018, Pisa, Italy / [ed] Maria Chiara Carrozza, Silvestro Micera, José L. Pons, Cham: Springer, 2019, Vol. 22, s. 180-184Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents the design and preliminary testing of a full-body assistive exoskeleton AXO-SUIT for older adults. AXO-SUIT is a system of modular exoskeletons consisting of lower-body and upper-body modules, and their combination as full body as well to provide flexible physical assistance as needed. The full-body exoskeleton comprises 27 degrees of freedom, of which 17 are passive and 10 active, which is able to assist people in walking, standing, carrying and handling tasks. In the paper, design of the AXO-SUIT is described. End-user testing results are presented to show the effectiveness of the exoskeleton in providing flexible physical assistance.

  • 54.
    Barattini, Paolo
    et al.
    kontor46, Torino, Italy.
    Virk, Gurvinder S.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Mirnig, Nicole
    University of Salzburg, Salzburg, Austria.
    Giannaccini, Maria Elena
    Bristol Robotics Laboratory, Bristol, United Kingdom.
    Tapus, Adriana
    Robotics and Computer Vision Lab ENSTA-ParisTech, Palaiseau, Paris, France.
    Bonsignorio, Fabio
    Universidad Carlos III de Madrid, Leganés, Madrid, Spain.
    Experimenting in HRI for priming real world set-ups, innovations and products2014Inngår i: HRI '14 Proceedings of the 2014 ACM/IEEE international conference on Human-robot interaction, New York: ACM Digital Library, 2014, s. 511-512Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Robotics is moving towards real world applications, beyond the well-structured environment of industrial robotics. In the world of assistant robots and medical robots, Human-Robot Interaction is essential. Also in emerging industrial scenarios there is a need of the human to be closely included in the loop. The companies are confronted with the lack of guidelines and of standards on how the higher features of HRI may be safely incorporated. Although the scientific research is burgeoning and worthy of praise, it is clear that its results are scattered and not capable of giving a clear input to be easily taken up by companies and standardization organizations like ISO and IEC. The workshop aims at the integration of empirical findings into complex real world robot systems by focusing on three typical sectors (industrial, service and medical) to develop systematic approaches to benchmark and evaluate experimental systems so that normative results can be realized rapidly. The present workshop focuses on bringing together scientists, representative of robotics companies and of standardization working groups to foster discussion in the definition of experimental scenarios and protocols in HRI, so to be able to prime real world set-ups and help realize the robotic products of the future.

  • 55.
    Barbé, Kurt
    et al.
    Vrije Universiteit Brussel, ELEC.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Lauwers, L
    Vrije Universiteit Brussel.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    A Simple Nonparametric Preprocessing Technique to Correct for Nonstationary Effects in Measured Data2012Inngår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 61, nr 8, s. 2085-2094Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The general approach for modeling systems assumes that the measured signals are (weakly) stationary, i.e., the power spectrum is time invariant. However, the stationarity assumption is violated when: 1) transient effects due to experimental conditions are dominant; 2) data are missing due to, for instance, sensor failure; or 3) the amplitude of the excitation signals smoothly varies over time due to, for instance, actuator problems. Although different methods exist to deal with each of these nonstationary effects specifically, no unified approach is available. In this paper, a new and general technique is presented to handle nonstationary effects, based on processing overlapping subrecords of the measured data. The proposed method is a simple preprocessing step where the user does not need to specify which nonstationary effect is present, nor the time interval where the nonstationary effect appears. The merits of the proposed approach are demonstrated on an operational wireless system suffering from interrupted link effects.

  • 56.
    Barbé, Kurt
    et al.
    Vrije Universiteit Brussel, ELEC.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Nagels, G
    Natl Ctr Multiple Sclerosis, Melsbroek, Belgium .
    Fractional-Order Time Series Models for Extracting the Haemodynamic Response From Functional Magnetic Resonance Imaging Data2012Inngår i: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531, Vol. 59, nr 8, s. 2264-2272Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The postprocessing of functional magnetic resonance imaging (fMRI) data to study the brain functions deals mainly with two objectives: signal detection and extraction of the haemodynamic response. Signal detection consists of exploring and detecting those areas of the brain that are triggered due to an external stimulus. Extraction of the haemodynamic response deals with describing and measuring the physiological process of activated regions in the brain due to stimulus. The haemodynamic response represents the change in oxygen levels since the brain functions require more glucose and oxygen upon stimulus that implies a change in blood flow. In the literature, different approaches to estimate and model the haemodynamic response have been proposed. These approaches can be discriminated in model structures that either provide a proper representation of the obtained measurements but provide no or a limited amount of physiological information, or provide physiological insight but lacks a proper fit to the data. In this paper, a novel model structure is studied for describing the haemodynamics in fMRI measurements: fractional models. We show that these models are flexible enough to describe the gathered data with the additional merit of providing physiological information.

  • 57.
    Bashir, Babar
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Designing of High Reflectance Distributed Bragg reflectors (DBRs),mirrors using AlGaInN material system in the UV wavelength range2009Independent thesis Advanced level (degree of Master (Two Years)), 30 poäng / 45 hpOppgave
  • 58.
    Bautista Gonzalez, Oscar
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Integration of a Wireless Sensor Network and IoT in the HiG university2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The number of Internet of Things applications for Wireless Sensor Networks is increasing every year due to the emerging of new brands such as Big Data and Industry 4.0. With the rise of new technologies related to these fields, new opportunities have become possible with a reasonable cost, but the requirements of WSNs still being the same, where energy efficiency, robustness, scalability and others must be accomplished. The commercial hardware developed by companies can be configured through different programs to be compatible among them, taking into account multiple variables, protocols, mechanisms and options provided by new solutions. Therefore, the configuration of different devices and choosing the optimum configuration can become quite challenging due to the number of paths. In this thesis, the configuration of commercial devices provided is carried out to be able to apply this hardware in different Internet of Things applications for Wireless Sensor Networks. Transceivers, sensors of temperature, relative humidity and CO2, a gateway, and different development kits are provided on this work, where the selection of the software to set these devices is made. Repeaters are configured to be compatible with the sensors and perform under the TDMA protocol and the request-response pattern, which synchronize the communication on the network, and under the flooding mechanism, which allows to route packets through the nodes due to the short range of RF low power technologies. The connection between the WSN and the Internet is made through the GW, which is also connected to the WSN, under the TCP/IP protocol, which is configured to provide Message Queue Telemetry Transport and SecureSHell services to access the GW remotely through the Internet and send requests to the WSN automatically. Node-Red is the programming tool installed upon the GW to implement data processing, storage and visualization, via the JavaScript programming language, where the user can deploy the data, which is stored in a CSV file, to make an analysis and visualize the data and the status of the network through a live data dashboard. Finally, an experiment is carried out over the HiG university where sensors are placed to measure different halls of the university and integrate an Internet of Things application for a Wireless Sensor Network. Due to the followed process, we have been able to measure data of temperature, relative humidity and CO2 concentration levels, creating a WSN, where this data has been saved in a connected USB to the gateway. Having a performance of 90% of messages received by the GW, and we have also been able to connect the GW to the Internet, creating a system that can be accessed remotely via the MQTT broker and providing different services such as data visualization. 

  • 59.
    Beckman, Claes
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Center for RF-Measurement Technology2008Inngår i: Radio Science and Communication, RVK08, 2008Konferansepaper (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    In February 2006 the Centre for RF Measurement Technology was established at the University of Gävle (HIG). The long term objectives of the centre are to establish world leading research in the area of RF Measurement Technology, support education of radio engineers for local, national and international radio companies at HIG, become a natural collaboration partner for leading industry companies and universities and to support local and national small and middle sized companies in the radio business.

    Today the centre has collaboration with more than 15 national and international companies within 3 major projects in the field of RF measurement technology research spanning from power amplifiers and antennas to electromagnetic interference in industrial environments.

    The annual research budget is in the area of 10 MSEK. In addition to the research projects the centre also supports education and collaboration with local industry, high schools and community.

    The centre is located easy to find, well equipped laboratories in Gävle Technology Park, next to the University of Gävle campus.

  • 60.
    Beckman, Claes
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Eklund, Lars
    Karlsson, Bo
    Lindmark, Björn
    Ribbenfjärd, David
    Wirdemark, Per
    Verifying 3G licence requirements when every dB is worth a billion2006Inngår i: First European Conference on Antennas & Propagation: EuCAP 2006 / [ed] H. Lacoste & L. Ouwehand, 2006, s. 1-4Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the year 2000, the Swedish Telecom regulator: “Post&Telestyrelsen”, PTS, granted in a “beauty contest” four licenses for operations of 3G systems. To verify the coverage and the license requirements, PTS, has developed a test procedure where the field strength of the primary Common Pilot Channel, CPICH, is measured in a drive test. Designing such a test constitutes a number of challenges mainly due to the fact that in 3G the accuracy in the measurement needs to be extremely high since even a small systematic error of ~1dB could in Sweden have the consequence that each operator would have to build an extra +1000 sites at a staggering cost of ~1billion SEK!

    The present paper gives an overview of the considerations behind the design of the test method used for verification of the 3G licence requirements in Sweden.

  • 61.
    Beckman, Claes
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Lindmark, Björn
    Base station antennas for mobile communications2007Inngår i: 2007 IEEE International Symposium on Antennas and Propagation: Short Courses & Workshops, 2007Konferansepaper (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    This course gives the participants a general overview of the application, implementation and design of current and future base station antennas for mobile communications. It is aimed at microwave, RF- and antenna engineers in the wireless area, but also useful for researchers looking for relevant research topics and system engineers needing a deeper understanding of the antenna component of their system. The course explains underlying theoretical and practical implementation aspects of base station antennas in mobile communication networks of today and the future.

    The course is divided into three main parts:

    (i) System Aspects,

    (ii) BTS Antenna Design,

    (iii) Diversity and MIMO

    In the first part the fundamental parameters of a base station antenna are discussed in the context of radio network design. In particular we discuss parameters such as gain, radiation patterns, frequency bands and power handling and put them in the context of cell planning, propagation and capacity.

    In the second part a general overview of base station antenna design is given. In particular the design aspects of radiators, feed networks and reflectors are discussed. Furthermore, a general discussion of array synthesis for base station antennas is given.

    In the final part of the course we give an overview of the underlying theory of diversity and MIMO systems. In particular we discuss the requirements that these systems put on the base station antennas in order to be able to deliver the data rates expected from WiMAX and the long term evolution of 3G systems.

  • 62.
    Beckman, Claes
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Lindmark, Björn
    The evolution of base station antennas for mobile communications2007Inngår i: International Conference on Electromagnetics in Advanced Applications: ICEAA 07, 2007Konferansepaper (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    During the last two decades, mobile telephony has virtually exploded around the world. Whereas fixed telephony has merely around 800 milion phone lines globally, cellular mobile telephony has today close to 4 bilion subscribers less than 20 years after the introduction of digital mobile telephony!

    In the centre of a mobile cell is the base station antenna whose vertical and horizontal beam pattern creates the borders. The first base station antennas deployed for cellular communications were omni-directional in the horizontal plane. These antennas are typically based on stacked circular dipole elements fed by a series feed network. However, as the need for capacity increased more radio channels were being used and the radio networks soon reconfigured to 3 sector systems. The base station antennas in these type of systems typically has half power beam widths in the horizontal plane of around 65 degrees and the elements are fed by corporate feed networks.

    Through the choice of antenna length and the selection of vertical element positions and excitations a broad range of antenna gains and vertical beam patterns can be achieved. We show that for a linear array the gain is mainly determined by the vertical and horizontal beam widths but reduced by losses in the feed network. The electrical down tilt is needed to provide good coverage within the desired cell and is preferred to mechanical down tilt as it is independent of horizontal angle. Remotely adjustable electrical down tilt is also available today and an important cost saver during the expansion part of a network. As we will see, system requirements on reduced channel interferencemlead to a simple expression for the necessary phase shift in such an array.

    Due to the rapid increase in subscribers it was soon realized by the regulators around the world that one frequency band for digital mobile communications was not enough to provide the capacity needed. Therefore, in the mid 90-ties second frequency bands were introduced in both North America and Europe. Since operators are not keen to put up bigger towers and more antennas, ´this development called for dual-band antennas. The introduction of the UMTS band in the beginning of this millennium of course then called for triple band functionality!

    Traditionally the diversity is achieved by using two receive antenna branches separated in space. In mobile phone networks, all base stations for macro cellular communications incorporate diversity on the up-link. Otherwise it would be virtually impossible to communicate with a low power mobile over the rapidly fading channel. Since space diversity uses two horizontally separate antennas positioned about 20 wavelengths apart it become soon of interest for the operators to incorporate polarization diversity. With polarization diversity only one dual polarized antenna is used for each sector at the base. In order to ensure good polarization diversity it is necessary and sufficient to have symmetrical patterns with equal power in horizontal and vertical polarization.

    In 3G it is of great interest to strengthen the up- and down-links in order to be able to increase the data rates from today’s 16kbit/s (voice) to a wireless broadband of around 10Mbits/s. However, in the Long Term Evolution of 3G, LTE, data rates of up to and around 100MBits/s are expected. In order accomplish this diversity at the base station will not be enough but complemented by multiple branch reception and transmission at both the base station and the mobile terminal (Multiple-Input-Multiple-Output, MIMO systems). For such arrays it is of interest to reduce the mutual coupling between elements. Although the mutual coupling could be compensated for by perfect channel estimation it is still of interest to reduce the coupling in practice in order to be able to handle the mismatch loss. In order to do so the use of e.g. corrugations, hard and soft surfaces as well as Electronic Band Gap, EBG materials for the inclusion into the antenna structure has been studied.

    In conclusion we find that the base station antenna has developed dramatically during the last two decades and base station antenna technology may become a key enabler for the Long Term Evolution of 3G.

  • 63.
    Beckman, Claes
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Smith, Gregory
    Shared Networks: More than making wireless communication affordable2005Inngår i: Vehicular Technology Conference, 2005: VTC 2005-Spring., 2005, s. 2984-2988Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the wake of the substantial financial commitments incurred by European and other UMTS network operators in the form of license fees, licensees have turned to network sharing as a means of reducing the capital requirements needed to bring 3G services to market. The reception from European regulators has been mixed, due to concerns that this inhibits competition, slow build-out, or otherwise result in reduced consumer benefits. The authors believe that the generic product life-cycle model provides insights that indicate that network sharing, within an appropriately constructed regulatory framework, is not a threat to vigorous competition in the 3G industry, and in fact, is one of the keys to stimulating the development of advanced, ubiquitous, affordable services.

  • 64.
    Beckman, Claes
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Smith, Gregory
    The Benefits of network Sharing2005Inngår i: Radiovetenskap och Kommunikation: RVK 2005, 2005, s. 147-151Konferansepaper (Annet vitenskapelig)
  • 65.
    Bengtsson, Olof
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Design and Characterization of RF-Power LDMOS Transistors2008Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In mobile communication new applications like wireless internet and mobile video have increased the demand of data-rates. Therefore, new more wideband systems are being implemented. Power amplifiers in the base-stations that simultaneously handle these wideband signals for many terminals (handhelds) need to be highly linear with a considerable band-width.

    In the past decade LDMOS has been the dominating technology for use in these RF-power amplifiers. In this work LDMOS transistors possible to fabricate in a normal CMOS process have been optimized and analyzed for RF-power applications. Their non-linear behavior has been explored using load-pull measurements. The mechanisms of the non-linear input capacitance have been analyzed using 2D TCAD simulations. The investigation shows that the input capacitance is a large contributor to phase distortion in the transistor.

    Computational load-pull TCAD methods have been developed for analysis of RF-power devices in high-efficiency operation. Methods have been developed for class-F with harmonic loading and for bias-modulation. Load-pull measurements with drain-bias modulation in a novel measurement setup have also been conducted. The investigation shows that the combination of computational load-pull of physical transistor structures and direct measurement evaluation with modified load-pull is a viable alternative for future design of RF-power devices. Simulations and measurements on the designed LDMOS shows a 10 to 15 % increase in drain efficiency in mid-power range both in simulations and measurements. The computational load-pull method has also been used to investigate the power capability of LDMOS transistors on SOI. This study indicates that either a low-resistivity or high-resistivity substrate should be used in manufacturing of RF-power LDMOS transistors on SOI to achieve optimum efficiency. Based on a proper substrate selection these devices exhibit a 10 % higher drain-efficiency mainly due to lower dissipated power in the devices.

  • 66.
    Bengtsson, Olof
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Integration and Analysis of RF-Power LDMOS Transistors2006Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 67.
    Bengtsson, Olof
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Johansson, Ted
    Nordlander, Edvard
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Rydberg, Anders
    Optimization of High-Voltage RF Power SiGe Transistors for Cellular Applications1999Inngår i: High Power Microwave Electronics: Measurements, Identification, Applications, 1999. MIA-ME '99. Proceedings of the IEEE-Russia Conference, 1999Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The base profile design for high-voltage RF power silicon transistors with epitaxial SiGe base was studied using 2-D process and device simulations. The addition of Ge in the base makes thin base widths with very high base doping possible. This gives rise to a higher maximum oscillation frequency thus improving the critical power gain for these devices

  • 68.
    Bengtsson, Olof
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Litwin, Andrej
    Olsson, Jörgen
    Small Signal and Power Evaluation of Novel BiCMOS Compatible, Short Channel LDMOS Technology2003Inngår i: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 51, nr 3, s. 1052-1056Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We describe a very short-channel 0.15-mum LDMOS transistor with a breakdown voltage of up to 60 V, manufactured in a standard 0.35-mum BiCMOS process. At 1900 MHz and a 12-V supply voltage, the 0.4-mm-gatewidth device with shortest drain drift region gives 100-mW output power P-1 dB at a drain efficiency of 43%. It has a transducer power gain of over 20 dB. The maximum current gain cutoff frequency f(T) is 15 GHz, and the maximum available gain cutoff frequency f(MAX) is 38 GHz. We show the dependence of f(T), an f(MAX) of gate and drain bias for transistors with different-drain drift region length. The LDMOS process module does not affect the performance or the models of other devices. We present for the first time a simple way to create high-voltage high-performance LDMOS transistors for an RF power amplifier use even in a very downscaled silicon technology.

  • 69.
    Bengtsson, Olof
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Vestling, Lars
    A Method for Device Intermodulation Analysis from 2D, TCAD Simulations using a Time-domain Waveform Approach2006Inngår i: Proceedings of the 36th European Microwave Conference, 2006, s. 169-171Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper describes a fast method useful for IMD analysis at TCAD design level. The method is based on the static load-line transfer function extracted from 2D device simulations. The transfer function is exposed to a time domain signal through a look-up table and the output response is analyzed using the Fast Fourier Transform. The response is compared to measurements of a fabricated device. The method is shown to accurately predict the IMD behavior of a two-tone signal for the 3’rd, 5’th and 7’th order IMD products with regards to sweet spot tracking and relative IMD magnitude. We present a fast and simple way to predict IMD performance from TCAD simulations at an early stage in the design process. The method enables prediction of output response from any signal due to the time domain approach.

  • 70.
    Bengtsson, Olof
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Vestling, Lars
    FTE Uppsala Universitet.
    Olsson, Jörgen
    FTE Uppsala Universitet.
    A Computational Load-Pull Investigation of Harmonic Loading effects on AM-PM conversion2008Inngår i: GigaHertz Symposium 2008: Abstract Book, 2008, s. 83-83Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    In this work computational harmonic load-pull have been used to study the effect of harmonic loading on AM-PM conversion for an RF-Power LDMOS transistor. It is found that especially the load impedance seen at the 2nd harmonic has a large impact (up to 2° or 15% difference) on the phase distortion at P1dB in this investigation conducted at chip level.

  • 71.
    Bengtsson, Olof
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Vestling, Lars
    FTE Uppsala.
    Olsson, Jörgen
    FTE Uppsala.
    A Computational Load-Pull Method for TCAD Optimization of RF-Power Transistors in Bias-Modulation Applications2008Inngår i: 2008 European Microwave Integrated Circuits Conference (EuMIC), 2008, s. 222-225Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Abstract— In this paper a method for TCAD evaluation of RF-Power transistors for high-efficiency operation using drain bias-modulation is presented. The method is based on large signal time-domain transient computational load-pull. With the method, intrinsic device parasitics and mechanisms affecting device efficiency under drain bias modulation can be investigated and optimized for the application making it very useful for RFIC design. A case study has been done on a CMOS compatible LDMOS. For verification under dynamic operation two-tone signals with varying envelope has been simulated. The results show a possible 15% increase in the efficiency of a modulated signal for the studied device at the expense of increased phase distortion observable also in the time-domain waveforms generated. Since the method is based on TCAD it is also useful in the investigation of e.g. dynamic breakdown during high envelope under bias-modulation operation.

  • 72.
    Bengtsson, Olof
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Vestling, Lars
    The Ångström Laboratory, Solid State Electronics, Uppsala University, Uppsala, Sweden.
    Olsson, Jörgen
    The Ångström Laboratory, Solid State Electronics, Uppsala University, Uppsala, Sweden.
    A Computational Load-Pull Method with Harmonic Loading for High-Efficiency Investigations2009Inngår i: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 53, nr 1, s. 86-94Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper a method for TCAD evaluation of RF-power transistors in highefficiency operation using harmonic loading is presented. The method is based on large signal timedomain

    computational load-pull. Active loads are used in the harmonic load-pull for simulation time reduction. With the method device performance under different harmonic load impedance can

    be investigated at an early stage in the design process. Alternative designs can be compared and the mechanisms affecting device efficiency in class-F can be studied at chip level. For method validation a case study is made on an LDMOS transistor. The transistor is load-pulled in class-AB and then optimized for efficiency at 2f0 and 3f0 using a novel approach with passive fundamental load and active harmonic loads. A swept simulation is conducted using passive fundamental and

    harmonic loads. Waveforms in compression are analyzed and the mechanisms creating the increased efficiency for in class-F are indentified by a comparative study of class-AB. Class-F harmonic termination is shown to give a 17 % overall reduction of dissipated power and a 9 % increase in output power. The expected efficiency increase is about 3-10 % in the compression

    region depending on level of compression.

  • 73.
    Bengtsson, Olof
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Vestling, Lars
    Solid State Electronics, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Olsson, Jörgen
    Solid State Electronics, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Investigation of SOI-LDMOS for RF-Power Applications Using Computational Load Pull2009Inngår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 56, nr 3, s. 505-511Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Small-signal and computational load-pull simulations are used to investigate the effect of substrate resistivity on efficiency in high-power operation of high-frequency silicon-on insulator-LDMOS transistors. Identical transistors are studied on substrates with different resistivities. Using computational load pull, their high-power performance is evaluated. The results are compared to previous investigations, relating the OFF-state out put resistance to high-efficiency operation. From the large-signal simulation, an output circuit model based on a load-line match is extracted with parameters traceable from small-signal simu lations. It is shown that, albeit high OFF-state output resistance is a good indication, it is not sufficient for high efficiency in a high-power operation. The bias and frequency dependence of the coupling through the substrate makes a more detailed ON-state analysis necessary. It is shown that very low resistivity and high resistivity SOI substrates both result in a high efficiency at the studied frequency and bias point. It is also shown that a normally doped medium-resistivity substrate results in a significantly lower efficiency.

  • 74.
    Bengtsson, Olof
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Vestling, Lars
    The Ångström Laboratory, Solid State Electronics, Uppsala University, Uppsala, Sweden.
    Olsson, Jörgen
    The Ångström Laboratory, Solid State Electronics, Uppsala University, Uppsala, Sweden.
    Investigation of the Nonlinear Input Capacitance in LDMOS Transistors and its Contribution to IMD and Phase Distortion2008Inngår i: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 52, nr 7, s. 1024-1031Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper the mechanisms causing the capacitive, reactive non-linearities in a lateral double diffused MOS, LDMOS, transistor are investigated. The non-linear input capacitance under load-line power match is extracted and analyzed. Computational TCAD load-pull is used to analyze the effect of non-linear capacitance on two-tone intermodulation distortion and AM–PM conversion in class-A operation. High-frequency measurements have been made to verify the use of 2D numerical device simulations for the analysis. It is found that the input capacitance, Cgg, of the LDMOS transistor working under power match conditions is a strongly non-linear function of gate voltage Vg but with an almost linear initial increase in Cgg. The voltage dependence of Cgg is found to mainly affect higher order IMD products in class-A operation. Transient simulations however show that Cgg seriously contributes to the onset of AM–PM conversion well below the 1 dB compression point.

  • 75.
    Berg, Henrik
    et al.
    Faculty of Computer Sciences, Østfold University College, Halden, Norway.
    Olsson, Roland
    Faculty of Computer Sciences, Østfold University College, Halden, Norway.
    Lindblad, Thomas
    Royal Institute of Technology, Department of Physics, Stockholm, Sweden.
    Chilo, José
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Automatic design of pulse coupled neurons for image segmentation2008Inngår i: Neurocomputing, ISSN 0925-2312, E-ISSN 1872-8286, Vol. 71, nr 10-12, s. 1980-1993Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Automatic Design of Algorithms through Evolution (ADATE) is a program synthesis system that creates recursive programs in a functional language with automatic invention of recursive help functions and self-adaptive optimization of numerical values. We implement a neuron in a pulse coupled neural network (PCNN) as a recursive function in the ADATE language and then use ADATE to automatically evolve better PCNN neurons for image segmentation. Our technique is generally applicable for automatic improvement of most image processing algorithms and neural computing methods. It may be used either to generally improve a given implementation or to tailor that implementation to a specific problem, which with respect to image segmentation for example can be road following for autonomous vehicles or infrared image segmentation for heat seeking missiles that are to distinguish the heat source of the target from flares.

  • 76.
    Bergroth, Simon
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Implementering av MPPT-enhet med återkoppling: avsedd för solceller2019Independent thesis Basic level (university diploma), 180 hpOppgave
  • 77.
    Bergstrand, Marcus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Datainsamlingssystem för underhåll och kontroll av elkvalitet2017Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    SSAB i Borlänge ska byta ut deras befintliga loggsystem som övervakar elkvalitet på verkets fem huvudtransformatorer. Loggsystemen ska ersättas med modulära DAQsystem från Iba, vilket är system som redan används i flera av verkets processer. Syftet med arbetet är att visa hur de nya DAQ-systemen kan implementeras och målet är att skapa förutsättningar för felsökning vid elkvalitetstörningar och analys av eltillförseln. Rapporten beskriver hur två utdömda loggsystem ersätts mot ett modulärt DAQ-system under skarp drift, som sedan konfigureras enligt önskad funktion. Tillvägagångssättet innefattar tre större delar vilka är datainsamling, hårdvarukonstruktion och mjukvarukonfiguration. Datainsamlingen har till stor del varit att studera befintliga kretsscheman och manualer till systemets hård- och mjukvara. Informationen som samlades in gav förutsättningarna för konstruktionsarbetet och mjukvarukonfigurationer. Utgången blev ett driftsatt system som konfigurerades så att felsökning och analys av elkvalitet är möjlig. Det nya loggsystemet gör det även möjligt för fler användare att komma åt mätningar kring elkvalitetsstörningar. Användare kan sedan ställa dessa i korrelation till de mätningar som utförs med iba-system vid processerna.

  • 78.
    bi, xiaofei
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap.
    Compressed Sampling for High Frequency Receivers Applications2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In digital signal processing field, for recovering the signal without distortion, Shannon sampling theory must be fulfilled in the traditional signal sampling. However, in some practical applications, it is becoming an obstacle because of the dramatic increase of the costs due to increased volume of the storage and transmission as a function of frequency for sampling. Therefore, how to reduce the number of the sampling in analog to digital conversion (ADC) for wideband and how to compress the large data effectively has been becoming major subject for study. Recently, a novel technique, so-called “compressed sampling”, abbreviated as CS, has been proposed to solve the problem. This method will capture and represent compressible signals at a sampling rate significantly lower than the Nyquist rate.

     

    This paper not only surveys the theory of compressed sampling, but also simulates the CS with the software Matlab. The error between the recovered signal and original signal for simulation is around -200dB. The attempts were made to apply CS. The error between the recovered signal and original one for experiment is around -40 dB which means the CS is realized in a certain extent. Furthermore, some related applications and the suggestions of the further work are discussed.

  • 79.
    Björklund, Johan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap.
    PLC Back-up system2014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    The purpose of this bachelor thesis was to investigate the PLC systems used in ABBs breaker factory in Ludvika and to create a system specification suitable to be used in the procurement of a back-up solution for this workshop.

    This work involved information gathering from different sources, such as archives, physical installations and interviews of maintenance personnel and operators.

    The results included the requested system specification (in Swedish) including suggestions for pilot test installations and evaluations. The work also resulted in an extensive listing of all PLC systems with placement, typedesignations, expansion modules and other pertinent information. This information ismade available as a macro enabled multipage Microsoft Excel document.

    A summary and suggestions for follow up work is also included.

  • 80.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    AD and DA conversion2015Inngår i: Modern Measurements: Fundamentals and Applications / [ed] Ferrero, A., Petri, D., Carbone, P. and Catelani, M., Hoboken: John Wiley & Sons, 2015, s. 125-148Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    This chapter describes the conversion process and its limitations and discusses methods to reduce the impact of these limitations in various applications. The process of converting analog signals into digital signals can be divided into two parts. First, the signal will be measured at discrete time instants and then quantized into fixed amplitude levels. The key parameters to consider when selecting an analog-to-digital converter (ADC) or digital-to-analog converter (DAC) are the resolution of the quantizer in number of bits and the sampling rate of the sampler. The chapter discusses these two functions with a basic example. It introduces some commonly used sampling techniques for improving the performance of an existing ADC, such as oversampling, sigma-delta conversion, dithering, time-interleaved sampling, undersampling, harmonic sampling, time-equivalent sampling and post-correction methods. The theory behind signal reconstruction is discussed with respect to the sampling theorem.

  • 81.
    Björsell, Niclas
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Modeling analog to digital converters at radio frequency2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This work considers behavior modeling of analog to digital converters with applications in the radio frequency range, including the field of telecommunication as well as test and measurement instrumentation, where the conversion from analog to digital signals often is a bottleneck in performance. The models are intended to post-process output data from the converter and thereby improve the performance of the digital signal. By building a model of practical converters and the way in which they deviate from ideal, imperfections can be corrected using post-correction methods.

    Behavior modeling implies generation of a suitable stimulus, capturing the output data, and characterizing a model. The demands on the test setup are high for converters in the radio frequency range. The test-bed used in this thesis is composed of commercial state-of-the-art instruments and components designed for signal conditioning and signal capture. Further, in this thesis, different stimuli are evaluated, theoretically as well as experimentally.

    There are a large number of available model structures for dynamic nonlinear systems. In order to achieve a parameter efficient model structure, a Volterra model was used as a starting-point, which can describe any weak nonlinear system with fading memory, such as analog to digital converters. However, it requires a large number of coefficients; for this reason the Volterra model was reduced to a model structure with fewer parameters, by comparing the symmetry properties of the Volterra kernels with the symmetries from other models. An alternative method is the Kautz-Volterra model, which has the same general properties as the Volterra model, but with fewer parameters. This thesis gives experimental results of the Kautz-Volterra model, which will be interesting to apply in a post-correction algorithm in the future.

    To cover behavior not explained by the dynamic nonlinear model, a complementary piecewise linear model component is added. In this thesis, a closed form solution to the estimation problem for both these model components is given. By gradually correcting for each component the performance will improve step by step. In this thesis, the relation between a given component and the performance of the converter is given, as well as potential for improvement of an optimal post-correction.

  • 82.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle.
    Daponte, Pasquale
    Department of Engineering, University of Sannio, Italy.
    De Vito, Luca
    Department of Engineering, University of Sannio, Italy.
    Rapuano, Sergio
    Department of Engineering, University of Sannio, Italy.
    Automatic signal recognition for a flexible spectrum management2009Inngår i: XIX IMEKO World Congress, 2009, s. 568-573Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper presents the prototype of an automatic digital modulation classifier, to be used for signal recognition in frequency bands managed in a flexible way. The prototype is based on a Data Acquisition System, consisting of an Analog-to-Digital converter embedded in an evaluation board, a frame grabber and a Personal Computer. The modulation classifier is able to recognize the most used digital modulations. An experimental validation of the realized prototype in a radio environment is also provided.

  • 83.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    De Vito, Luca
    University Sannio.
    Rapuano, Sergio
    University Sannio.
    A GNU radio-based signal detector for cognitive radio systems2011Inngår i: 2011 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), New York: IEEE conference proceedings, 2011, s. 1045-1049Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper deals with the hardware and software architecture of a signal detector prototype. It is able to observe a wide band and to find, in such band, the empty or occupied channels. It is intended to be used either in telecommunication devices or in spectrum monitoring instruments working in the new scenarios of telecommunications, where a flexible and dynamic spectrum management will be introduced. The signal detector has been validated on simulated and emulated signals showing high detection percentages even with low signal to noise ratios.

  • 84.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Händel, Peter
    Signal Processing Lab., ACCESS Linnaeus Center, School of Electrical Engineering, Royal Institute of Technology, Stockholm, Sweden.
    Achievable ADC Performance by Postcorrection Utilizing Dynamic Modeling of the Integral Nonlinearity2008Inngår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, artikkel-id 497187Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is a need for a universal dynamic model of analog to digital converters (ADC) aimed for post-correction. However, it is complicated to fully describe the properties of an ADC by a single model. An alternative is to split up the ADC model in different components, where each component has unique properties. In this paper, a model based on three components is used, and a performance analysis for each component is presented. Each component can be post-corrected individually and by the method that best suits the application. The purpose with post-correction of an ADC is to improve the performance. Hence, for each component, expressions for the potential improvement have been developed. The measures of performance are total harmonic distortion (THD) and signal to noise and distortion (SINAD) and to some extent spurious free dynamic range (SFDR).

  • 85.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Händel, Peter
    Royal Institute of Technology, Stockholm.
    Dynamic behavior models of analog to digital converters aimed for post-correction in wideband applications2006Inngår i: IMEKO Workshop on ADC and DAC Modelling and Testing, September 17-22, 2006, Rio de Janeiro, 2006, s. 5-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper a dynamic behavior model of analog to digital converters is proposed. The model is aimed for post correction in wideband applications. The suggested post correction method is a combination of look up tables and model based correction. The model consists of three components. The first is a component represented by a Hammerstein model; that is a static nonlinearity followed by a time invariant linear filter. The second component is a nonparametric model caused by significant deviation from the characterized integral nonlinearity and the output from the Hammerstein model. The third component contains of the remaining deviation and is considered as a random model error. Results from simulations verify that the examined ADC can be described by an ordinary Hammerstein model and a static look-up table.

  • 86.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Händel, Peter
    Signal Processing Laboratory, Royal Institute of Technology, Stockholm, Sweden.
    Histogram Tests for Wideband Applications2008Inngår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 57, nr 1, s. 70-75Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Characterization and testing of analog-to-digital converters (ADCs) are important in many different aspects. Histogram test is a common method to characterize the linearity features of an ADC. Two commonly used stimuli signals are sine waves and Gaussian noise. This paper presents a metrological comparison between Gaussian and sine wave histogram tests for wideband applications; that is we evaluate the performance in characterization of the ADC and the usability of post-correction. A post-correction procedure involves characterization of the ADC non-linearity and then use of this information by processing the ADC output samples to remove the distortion.

    The results show that the Gaussian histogram test gives reasonable accuracy to measure non-linearities. However, it does not result in a suitable model for post-correction in wideband applications. A single-tone sine wave histogram will be a better basis for post-correction. Best result can be obtained if the look-up table is trained with several single-tone sine waves in the frequency band.

  • 87.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Händel, Peter
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Post-Correction of Under-Sampled Analog to Digital Converters2007Inngår i: IEEE Instrumentation and Measurement Technology Conference, 2007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Applications with wide bandwidth and high center frequencies force the analog to digital converter (ADC) to be active in a working range with less dynamic performance in relation to lower frequency bands. However using under-sampling techniques in combination with post-correction methods enable a combination of high sampling rate, wide bandwidth and low distortion. In this paper the employed dynamic post-correction is a combination of look-up tables and model based correction. The results are mainly based on measurements on a 12 bit 210 MSPS ADC. The improvement in total harmonic distortion and spurious free dynamic range are acceptable over a wide frequency range and it is robust to variations in amplitude.

  • 88.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Händel, Peter
    Royal Institute of Technology, Signal Processing Laboratory, Stockholm, Sweden.
    Truncated Gaussian noise in ADC histogram tests2007Inngår i: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 40, nr 1, s. 36-42Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One method to characterize analogue to digital converters (ADCs) is to use a histogram, where Gaussian noise may be used as stimulus signal. However, a Gaussian noise signal that excites all transition levels also generates input values outside working range of the ADC. Modern signal generators can generate arbitrary signals. Hence, excluding undesired values outside the ADC full scale can minimize test sequences. Truncating the signal to the working range gives further advantages, which are explored in this paper. The Cramér-Rao lower bound and a minimum variance estimator for histogram tests with an arbitrary stimulus are derived. These are applied for truncated Gaussian noise and the result is theoretically evaluated and compared to untruncated noise. It is shown that accuracy increases for a fixed sample length and that variation over transition levels decrease.

  • 89.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Händel, Peter
    Royal Institute of Technology, Signal Processing Lab, ACCESS Linnaeus Center.
    Jansson, Magnus
    Royal Institute of Technology,Signal Processing Lab, ACCESS Linnaeus Center.
    Medawar, Samer
    Royal Institute of Technology, Signal Processing Lab, ACCESS Linnaeus Center.
    Improved Estimate of Parametric Models for Analogue to Digital Converters by Using Weighted Integral Nonlinearity Data2010Inngår i: 17th Symposium IMEKO TC4 - Measurement of Electrical Quantities, 15th International Workshop on ADC Modelling and Testing, and 3rd Symposium IMEKO TC19: Environmental Measurements / [ed] Linus Michaeli, Jan Saliga, 2010, s. 597-600Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Error modelling has played a major role in generating post-corrections of analogue to digital converters (ADC). Benefits by using parametric models for post-correction are that they requires less memory and that they are easier to identify for arbitrary signals. However, the parameters are estimated in two steps; firstly, the integral nonlinearity (INL) is estimated and secondly, the model parameters. In this paper we propose a method to improve the performance in the second step, by utilizing information about the statistical properties of the first step.

  • 90.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Isaksson, Magnus
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Händel, Peter
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Rönnow, Daniel
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Kautz-Volterra modelling of an analogue-to-digital converter using a stepped three-tone excitation2007Inngår i: 12th IMEKO TC-4 International Workshop on ADC MODELLING AND TESTING, Iasi, Romania, September 2007, 2007, s. 107-112Konferansepaper (Fagfellevurdert)
  • 91.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Royal Inst Technol, ACCESS Linnaeus Ctr, Stockholm, Sweden.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Royal Inst Technol, ACCESS Linnaeus Ctr, Stockholm, Sweden.
    Händel, Peter
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Royal Inst Technol, ACCESS Linnaeus Ctr, Stockholm, Sweden.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Kautz-Volterra modelling of analogue-to-digital converters2010Inngår i: Computer Standards & Interfaces, ISSN 0920-5489, E-ISSN 1872-7018, Vol. 32, nr 3, s. 126-129Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In many test and measurement applications, the analogue-to-digital converter (ADC) is the limiting component. Using post-correction methods can improve the performance of the component as well as the over all measurement system. In this paper an ADC is characterised by a Kautz-Volterra (KV) model, which utilises a model-based post-correction of the ADC with general properties and a reasonable number of parameters. It is also shown that the inverse model has the same dynamic properties as the direct KV model. Results that are based on measurements on a high-speed 12-bit ADC, shows good results for a third order model.

  • 92.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Nader, Charles
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Signal Processing Lab, Royal Institute of Technology, Stockholm, Sweden.
    Händel, Peter
    Signal Processing Lab, Royal Institute of Technology, Stockholm, Sweden.
    Multi-tone design for out-of-band characterization of nonlinear RF modules using harmonic sampling2010Inngår i: 2010 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2010: Proceedings, Piscataway, NJ: IEEE Service Center , 2010, s. 620-623, artikkel-id 5488231Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we evaluate the generation of a multi-tone set for characterizing the behavior of nonlinear radio frequency (RF) modules in its out-of-band when harmonic sampling is used as digitizer. The purpose is to provide the reader with a tool to select proper frequencies and record length for a given application and test-bed. The method is based on simulations and the use of Sidon sequences. The proposed method is applicable to sparse discrete frequency multi-tones.

  • 93.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Rönnow, Daniel
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Händel, Peter
    Measuring Volterra kernels of analog to digital converters using a stepped three-tone scan2006Inngår i: Proceedings of the IEEE Instrumentation and Measurement Technology Conference, 2006. IMTC 2006, 2006, s. 1047-1050Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Volterra theory can be used to mathematically model nonlinear dynamic components such as analog-to-digital converter (ADC). This paper describes how frequency domain Volterra kernels of an ADC are determined from measurements. The elements of Volterra theory are given and practical issues are considered, such as methods for signal conditioning, finding the appropriate test signals scenario and suitable sampling frequency. The results show that for the used pipeline ADC, the frequency dependence is significantly stronger for second order difference products than for sum products and the linear frequency dependence was not as pronounced as that of the second order Volterra kernel.

  • 94.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Sucháneck, Petr
    Department of Measurement, Czech Technical University, Prague, Czech Republic.
    Händel, Peter
    Signal Processing Laboratory, Royal Institute of Technology, Stockholm, Sweden.
    Rönnow, Daniel
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. WesternGeco, Asker, Sweden.
    Measuring Volterra kernels of analog to digital converters using a stepped three-tone scan2008Inngår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 57, nr 4, s. 666-671Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Volterra theory can be used to mathematically model nonlinear dynamic components such as analog-to-digital converter (ADC). This paper describes how frequency domain Volterra kernels of an ADC are determined from measurements. The elements of Volterra theory are given and practical issues are considered, such as methods for signal conditioning, finding the appropriate test signals scenario and suitable sampling frequency. The results show that for the used pipeline ADC, the frequency dependence is significantly stronger for second order difference products than for sum products and the linear frequency dependence was not as pronounced as that of the second order Volterra kernel. It is suggested that the Volterra kernels have the symmetry properties of a specific box model, namely a parallel Hammerstein systems.

  • 95.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Adding errors to reduce the PAPR and BER of OFDM-based transmissions2013Inngår i: 2013 IEEE International Instrumentation and Measurement Technology Conference (I2MTC 2013), New York: IEEE , 2013, s. 743-746Konferansepaper (Fagfellevurdert)
    Abstract [en]

    When transmitting signals, one of the most important issues is to keep the transmission errors as low as possible. Or in other words, to obtain a reliable transmission link, the bit-error-rate (BER) should be kept within certain limits. However, the probability of transmission errors strongly depends on the signal-to-noise ratio (SNR) of the transmitted signals. Hence, the power amplifier plays a key role in the sender part: the more power, the higher the SNR, the lower the probability of transmission errors. Unfortunately, this is a too simple vision.

    One should take care to keep the peak-to-average power ratio (PAPR) of the transmitted signal low in order not to push the power amplifier into its nonlinear operation region. Classical techniques use clipping or backing-off the input signal to reduce the PAPR of the transmitted signal. However, these techniques have a negative influence on the SNR and hence on the BER.

    In this paper, we present a technique to reduce the PAPR of the transmitted signals and hence to reduce the BER, by introducing errors into Orthogonal Frequency Division Multiplexing (OFDM) signals in a controlled way. Channel coding will be used to compensate for the introduced errors.

  • 96.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Measuring and Characterizing Nonlinear RF Systems: Faculty Course Development Award 20132017Inngår i: IEEE Instrumentation & Measurement Magazine, ISSN 1094-6969, E-ISSN 1941-0123, Vol. 20, nr 4, s. 45-48Artikkel i tidsskrift (Fagfellevurdert)
  • 97.
    Borg, Daniel
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Mantling, Ulf
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Syntetiska Instrument2009Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    This thesis aims to investigate SAAB AB´s possibilities to use synthetic instruments in their test systems. The reason for this is reducing costs and the risk of obsolescence which is common when test systems operate for several decades.

    The market around synthetic instruments has been explored in the search for suitable hardware and software. Software has been developed in LabVIEW and synthetic instruments have been created with the help of IVI-drivers. The hardware consisted of PXI-instruments (Waveform generator and Digitizer), connected to a computer using a fiber optic link and PXI-chassi. The created instruments was then compared to common instruments used today, and the comparison turned out well. Advantages, disadvantages and the theory surrounding synthetic instruments is also covered. This thesis is only an introduction and further work will be necessary to implement synthetic instruments at SAAB.

    The thesis also purposes suitable hardware and further development based on the test systems used today, and how it is possible to solve the layer structure.

  • 98.
    Brossa Dachs, Núria
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap.
    Machine learning in classification of latex gloves2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The project consists in develop a tool that make a classification of latex

    gloves taking into account the different features that make the difference

    between them using a Matlab code in machine learning.

    This project has the purpose to have a tool that classify those gloves in

    order to know in which market of the world they could be sold and at

    what price. So as to achieve this purpose, it is necessary to collect the data

    and prepare them to introduce in the code.

    The project can be divided in three different parts; the first one is to make

    a research of all the theory about latex gloves, achieve the basic

    fundamentals with the program Matlab and the theory about image

    processing and machine learning. After that, I will collect the 125 data

    and the features to take into account are if the gloves have black spots and

    if they are yellow or white colour. With all the material, it will possible

    to generate a code in Matlab to prepare all the data and finally, train a

    model with machine learning.

    After training this model, the classifier performed well, achieving 82%

    accuracy. However, it is not perfect because the main mistake has been in

    the images taken, some of the gloves had wrinkles, so the code detects

    them as black spots. That is why, as a future work, the quality of the

    images should be improved in order to not have wrinkles and hence

    improve the precision for the classifiers.

    Moreover, it has been proven that this tool can be implemented in the

    company that has provided the gloves. With that, his plan to sell gloves in

    Europe could be feasible if the bath of gloves accomplishes the required

    Acceptance Quality Limit but it has not been possible to prove because the

    gloves have not been randomly selected to carry out this project. Even so

    knowing that the code works, it could be applied to corroborate this fact.

  • 99.
    Cappello, Barbara
    et al.
    Politecnico di Torino, Torino, Italy.
    Shestopalov, Yury
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Matematik.
    Matekovits, Ladislau
    Politecnico di Torino, Torino, Italy.
    Analysis of the surface impedance of a sinusoidally modulated metasurface2019Inngår i: 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), IEEE, 2019, s. 0075-0077Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Metasurfaces have been extensively exploited in recent years for mantle cloaking applications. In this type of problems it is of fundamental importance to determine the connection between the metasurface geometrical parameters and the realised value of surface impedance, in order to properly design the metasurface. In this paper the surface impedance of a non homogeneous metasurface, based on a sinusoidally modulated metallic pattern is analysed.

  • 100. Castillo, Patricia
    et al.
    San-Roman, Ebert
    Bengtsson, Olof
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    On the design of a planar, harmonic, triplex-filter for 3G, load-pull measurement applications2007Inngår i: RFMTC-07, 2007Konferansepaper (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    This paper describes the design of a planar harmonic triplex-filter for 3G load-pull measurement applications. The designs are based on planar 2D field simulations on individual and combined filters of different structures like stepped impedance, coupled lines and ring resonators. Triplex-filters of different combinations on Teflon substrate and mixed substrates for loss reduction were simulated, fabricated and evaluated in this work. It is found that using lithographic process on Teflon with SMA endlaunchers a filter with 0.44 dB f0 insertion loss, IL, and 50 dB isolation can be achieved. On the low loss substrate the mechanical design process limits the results to about 1.0 dB IL. Low loss launchers and substrate interconnects are suggested and 3D simulations performed for the mixed design.

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