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  • 1.
    Ahlbom, Håkan
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Nordlander, Edvard
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Inspirerar teknikämnet i den svenska grundskolan till högre teknikstudier?2009Conference paper (Other academic)
    Abstract [sv]

    Krisen i tillströmningen till svensk teknikutbildning har uppmärksammats kraftigt av avnämarkategorierna den senaste tiden. Fackföreningen Sveriges Ingenjörer hävdar att om inget görs kommer det år 2020 att fattas 50 000 ingenjörer, vilket motsvarar en fjärdedel av arbetsstyrkan i vid bemärkelse om något mer än ett decennium. I ROSE-rapporten beskrivs ett allmänt ointresse för tekniska och naturvetenskapliga studier bland I-ländernas ungdomar i skarp kontrast till ungdomar i utvecklingsländer. Detta beror på att elevernas väljer utbildning efter värderingar och identiteter, vilket inte tycks uppfyllas av tekniska studier.

     

    I föreliggande arbete kommer faktorer för ungdomars studieval att kartläggas. Den svenska grundskolans teknikämne har ett uttalade mål - att utveckla intresse för teknik. Undersökningen vänder sig direkt till eleverna och försöker ge svar på om teknikämnet lever upp till detta mål. De lokala kursplanerna skiljer sig avsevärt och de typer som man kan hitta på skolornas webbplatser är oftast av någon av följande typer:

    1.      Lokal kursplan som i detalj beskriver vad som skall behandlas årskursvis samt de mål som eleven förväntas uppnå.

    2.      Nationella kursplanen utan lokala tolkningar eller specifikationer för ämnets genomförande.

    3.      En synnerligen kort lokal kursplan (mera traditionella ämnen är vanligtvis avsevärt mera specificerade).

    4.      Ingen kursplan för teknikämnet presenteras överhuvudtaget.

     

    Undersökningen tar även hänsyn till lärarnas kompetens inom ämnet och sätter resultatet i relation till bristfällig utbildning.

     

    Frågeställningar: Hur kan man genomföra god utbildning i teknikämnet utan kursplan eller endast med den nationella kursplanen möjligen kompletterad med synnerligen rudimentära tolkningar och specifikationer? Hur kan en lärare med bristfällig utbildning inom ämnet genomföra högkvalitativ undervisning och utveckla elevernas intresse? Finns det en korrelation mellan vagt specificerade kursplaner, lärares brister i utbildning, samhällets signaler om att förverkliga personliga mål i samklang med den egna identiteten, samt den mångfacetterade svenska gymnasieskolan, som kan ge svar på varför elever avstår från högre tekniska studier? Vilka är elevernas synpunkter på teknikämnet som inspirationskälla och vad minns man från undervisningen efter någon tid? I vilken mån utvecklade teknikämnet ett tekniskt intresse och gav det i så fall resultat i valet av gymnasieutbildning?

     

    Undersökningen är primärt baserad på en fenomenologisk kvalitativ metod med djupintervjuer. I detta arbete kommer pilotintervjuer att redovisas – ett sätt att förfina metoden och senare göra mera omfattande intervjuarbete där egna förutfattade meningar om intervjuobjekten minimeras, informationen renodlas och resultat syntetiseras.

     

    Urvalet av intervjuobjekt sker i grundskolans sista år, då eleverna bestämt sig för gymnasieinriktning (oavsett vilket) och därför sannolikt kan ge information om vilka faktorer som inverkade. Urvalet kommer att ske såväl med tanke på kön (teknikutbildning är manligt dominerad) som hemvist (uppväxt på landet eller i tätort) - faktorer som kan ha betydelse i studievalet.

     

    Elever från gymnasiets första (och möjligen andra) år kommer att delta i en enkätundersökning för att undersöka om deras teknikintresse har ändrats. Enkäten kommer senare att utnyttjas på intervjuobjekten från grundskolan, när de påbörjat gymnasiala studier, och resultaten jämförs med den tidigare informationen från intervjuerna.

  • 2.
    Ahlbom, Håkan
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Ylva, Bjelksäter
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Eva, Hartell
    Stockholms universitet, UTEP.
    Edvard, Nordlander
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Cooperative methods for investigating the influence of Swedish compulsory technology education on pupils’ attitudes to technology2009In: PATT 22  (Pupils' Attitudes Towards Technology), 2009Conference paper (Refereed)
    Abstract [en]

    The number of Swedish students applying to technical education is decreasing, and this fact will lead to a severe shortage of engineers in a just a decade. As an example, the candidates applying to the Royal Institute of Technology (KTH) has reduced by 30 % the last couple of years. Furthermore, the ROSE report clearly describes young people’s lack of interest in science and technology in the industrialised world in sharp contrast to the situation in the developing countries.

    Why is the interest for technical education decreasing? What makes other fields of education more popular? What image of technology does the compulsory school deliver?

    Technology was introduced as a mandatory subject in Swedish compulsory school in 1980 and got its own syllabus when the current national curriculum was introduced in 1994. One of the goals of the Swedish compulsory school is to develop an interest for technology as well as capability and judgement in handling technical issues.

    In what way does the Swedish compulsory school work with this goal? Is the school successful in making pupils interested? What are the pupils’ opinions?

    Each school can decide when and how the pupils get technology education, but every pupil is expected and entitled to reach the national goals.

    To get an overall picture of the technology subject questions will be investigated as parts of tree different Ph.D. projects.

    • How do we actually know that pupils learn what they are entitled to?
    • How is the technology syllabus interpreted, in theory and practice?
    • Does the technology subject really develop an interest for technology and does it inspire to further technical studies? 

    In order to find out if pupils reach the national goals in technology, a questionnaire is launched in schools all over Sweden. The interpretation of the syllabus will be studied through observations comparing teaching practice with the local planning of the technology subject. To get answers, whether the technology subject has any impact on the interest and the choice of further studies, interviews are made among students and teachers in compulsory school as well as in upper secondary school.

    The findings of the cooperating projects will together contribute with answers about the state of the technology education in the Swedish compulsory school system, and how the subject could be developed in the future.

  • 3.
    Al-Asad, Zahir
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Implementation of NURBS Objects in a Ray TracingCode for RCS Simulation2010Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
  • 4.
    Andersen, O.
    et al.
    Ericsson AB.
    Wisell, David
    Ericsson AB.
    Keskitalo, Niclas
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Measurement of ACLR with high dynamic range2008In: IEEE MTT-S International Microwave Symposium Digest, Atlanta, GA, 2008, 273-277 p.Conference paper (Other academic)
    Abstract [en]

    In this paper a method to overcome the insufficient dynamic range of RF measurement instruments, i.e. signal generators and spectrum analyzers, for distortion measurements on feedforward and other highly linear amplifiers, is discussed. A circuit board is designed, built and verified. Its performance is found to be superior to traditional methods using filters, both from a technical performance and flexibility standpoint as well as from an economic view. ACLR measurements for WCDMA signals can be done well below -70 dBc using the produced circuit board. © 2008 IEEE.

  • 5.
    Andersen, Olav
    et al.
    Ericsson.
    Björsell, Niclas
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Keskitalo, Niclas
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    A Test-Bed Designed to Utilize Zhu’s General Sampling Theorem to Characterize Power Amplifiers2009In: Instrumentation and measurement technology conference 2009 I2MTC '09 IEEE, Singapore, 2009, 201-204 p.Conference paper (Refereed)
    Abstract [en]

    Characterizing power amplifiers require test set-ups with performance superior to the power amplifiers. A commonly used method is to use an IQ-demodulator. However, problem arises due to imperfections in the demodulator such as IQ-imbalance; an alternative method is to use a direct down converter to intermediate frequency. The drawback then is the limited bandwidth. However, the required bandwidth of the ADC does not need to be exceptional. According to Zhu’s general sampling theorem is it enough to sample the output signal at the Nyquist rate of the input. However, even though the required sampling rate is reduced the demands on the analog bandwidth remains. Unfortunately, commercially available instruments such as vector signal analyzers can not be used for this purpose since their analog bandwidth is too small. In this paper a test-bed is designed to utilize the Zhu’s general sampling theorem. The RF front-end has frequency range of 500 MHz – 2.7 GHz and a bandwidth of 1 GHz. All performance data are verified with measurements.

  • 6.
    Andersen, Olav
    et al.
    Ericsson Telecom AB, Gävle, Sweden.
    Wisell, David
    Ericsson Telecom AB, Stockholm, Sweden.
    Staenvard, Patrik
    Ericsson Telecom AB, Gävle, Sweden.
    Keskitalo, Niclas
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Extending the Bandwidth and Dynamic Range of Old RF Instruments to Meet State-of-the-Art Performance, Using a Synthetic Instrument Approach2009In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 58, no 2, 248-254 p.Article in journal (Refereed)
    Abstract [en]

    A decrease in life cycle cost is a key issue for testing mobile communication systems. The rapid development and edge technology requires high-performance instruments and state-of-the-art measurement technology. New investments are expensive, but even older generation instruments are capable of extending their bandwidth and dynamic range to meet even the latest Third-Generation Partnership Project (3GPP) cellular measurement requirements by the addition of external hardware using a synthetic instrument approach. The novelty of this paper is the high performance on the most crucial parameters, i.e., the dynamic range and bandwidth achieved by only replacing some parts of the legacy instrument. Moreover, the demonstrated direct IF synthesis has a high degree of novelty at wide modulation bandwidths. It is desired to use virtual/synthetic instruments and make the signal processing in the software independent of the hardware, i.e., software-defined measurements (SDMs). In this paper, a state-of-the-art experimental setup for signal generation and signal analysis is demonstrated. A direct IF synthesis is used to generate a wideband code-division multiple-access (WCDMA) carrier with more than 72-dB adjacent carrier leakage ratio (ACLR) up to 12 parallel carriers with more than 68-dBc ACLR over a total bandwidth of 100 MHz. The signal analysis capabilities (e.g., ACLR performance) for a WCDMA carrier is better than -70 dBc and for a continuous wave better than -85 dBc over a bandwidth of 42.5 MHz. The critical RF downconverter in the setup is carefully designed not to degrade the dynamic range performance.

  • 7.
    Andersson, Tommy
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Department of Technology and Built Environment.
    Algilany, Gazwan
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Department of Technology and Built Environment.
    Konstruktion Signalgenerator2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    SAAB Aerotech division FGR in Arboga builds and develops equipment and components used in both military and civilian applications. To build a test system for a specific project that SAAB is responsible for requires a simple signal generator that can provide a pulse modulated signal. The need to buy a new advanced signal generator for example from Agilent is not as profitable as the instrument is expensive and contains features that SAAB does not require in their applications and test systems. That was the reason why SAAB offers two students a thesis where the goal is to construct a signal generator in accordance with what SAAB requests.

    This thesis contains several different phases. The first step was a meeting with our supervisor Mats Bergman and by reading the data sheets for components to be used in the project, with these information and specifications that we have received from SAAB we started to construct the signal generator.

    What we did during the construction work was to simulate and draw a schematic to be able to design the circuit board. Simulation was done both in software and on laboration board. The card is then ordered from a circuit board manufacturer in Bulgaria. On the finished card the components will be fitted. Then the card will plugged in into a rack and then presented finished as a signal generator that can be used in a test system.

    The final results of all phases are satisfactory in the part of design and laboratory work. The finished mother board was tested and test results corresponded well with the theory. The final results will be presented with a spoken presentation at the University of Gävle and at SAAB Aerotech in Arboga division FGR

  • 8.
    Bashir, Babar
    University of Gävle, Department of Technology and Built Environment, 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 credits / 45 HE creditsStudent thesis
  • 9.
    Beckman, Claes
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Center for RF-Measurement Technology2008In: Radio Science and Communication, RVK08, 2008Conference paper (Other (popular science, discussion, etc.))
    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.

  • 10.
    Beckman, Claes
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Belkow, Elena
    Eklund, Lars
    Landmark, Urban
    Wirdemark, Per
    Verifying 3G License Requirements: some Preliminary Swedish Results2008In: The 68th IEEE Vehicular Technology Conference: VTC2008-Fall, 2008, 1-4 p.Conference paper (Other academic)
    Abstract [en]

    In the year 2000, the Swedish Telecom regulator “Post&Telestyrelsen” (PTS) granted in a “beauty contest” four licenses for operation of 3G mobile networks. Through this process, the licensees committed themselves to cover 8.860.000 inhabitants of the Swedish population. In order to verify the coverage and confirm compliance with the license requirements, PTS, developed a test procedure in close collaboration with the licensees.

    The present paper gives an overview of the considerations behind the design of the test method and presents some preliminary results. Today all Swedish 3G operators comply with the licence requirement and it is concluded that a method for verifying the requirement accepted by the licensees is an important tool for successful licensing of spectrum and fulfilment of licensing obligations.

  • 11.
    Beckman, Claes
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Eklund, Lars
    Karlsson, Bo
    Lindmark, Björn
    Ribbenfjärd, David
    Wirdemark, Per
    Verifying 3G licence requirements when every dB is worth a billion2006In: First European Conference on Antennas & Propagation: EuCAP 2006 / [ed] H. Lacoste & L. Ouwehand, 2006, 1-4 p.Conference paper (Refereed)
    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.

  • 12.
    Beckman, Claes
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Klahr, Stefan
    Ett ödesval för regionen2009In: Gefle Dagblad, Vol. 6 februariArticle in journal (Other (popular science, discussion, etc.))
  • 13.
    Beckman, Claes
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Lindmark, Björn
    Base station antennas for mobile communications2007In: 2007 IEEE International Symposium on Antennas and Propagation: Short Courses & Workshops, 2007Conference paper (Other (popular science, discussion, etc.))
    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.

  • 14.
    Beckman, Claes
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Lindmark, Björn
    The evolution of base station antennas for mobile communications2007In: International Conference on Electromagnetics in Advanced Applications: ICEAA 07, 2007Conference paper (Other (popular science, discussion, etc.))
    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.

  • 15.
    Beckman, Claes
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Smith, Gregory
    Shared Networks: Making Wireless Communications Affordable2005In: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, Vol. 12, no 2, 78-85 p.Article in journal (Refereed)
    Abstract [en]

    In the wake of the substantial financial commitments incurred by European and other UMTS network operators in the form of licence 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 buildout, 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.

  • 16.
    Beckman, Claes
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Smith, Gregory
    Shared Networks: More than making wireless communication affordable2005In: Vehicular Technology Conference, 2005: VTC 2005-Spring., 2005, 2984-2988 p.Conference paper (Refereed)
    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.

  • 17.
    Beckman, Claes
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Smith, Gregory
    The Benefits of network Sharing2005In: Radiovetenskap och Kommunikation: RVK 2005, 2005, 147-151 p.Conference paper (Other academic)
  • 18.
    Bengtsson, Olof
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Design and Characterization of RF-Power LDMOS Transistors2008Doctoral thesis, comprehensive summary (Other academic)
    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.

  • 19.
    Bengtsson, Olof
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Integration and Analysis of RF-Power LDMOS Transistors2006Licentiate thesis, comprehensive summary (Other academic)
  • 20.
    Bengtsson, Olof
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Johansson, Ted
    Nordlander, Edvard
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Rydberg, Anders
    Optimization of High-Voltage RF Power SiGe Transistors for Cellular Applications1999In: High Power Microwave Electronics: Measurements, Identification, Applications, 1999. MIA-ME '99. Proceedings of the IEEE-Russia Conference, 1999Conference paper (Refereed)
    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

  • 21.
    Bengtsson, Olof
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Litwin, Andrej
    Olsson, Jörgen
    Small Signal and Power Evaluation of Novel BiCMOS Compatible, Short Channel LDMOS Technology2003In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 51, no 3, 1052-1056 p.Article in journal (Refereed)
    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.

  • 22.
    Bengtsson, Olof
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Rydberg, Anders
    Chen, Quian
    Johansson, Ted
    Ahl, Bengt
    Purroy-Martin, Fransisco
    Large-Signal Characterization and Modeling of LDMOS-Transistors for RF-Power Applications1997In: GHz97, 1997Conference paper (Other (popular science, discussion, etc.))
  • 23.
    Bengtsson, Olof
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Vestling, Lars
    A Method for Device Intermodulation Analysis from 2D, TCAD Simulations using a Time-domain Waveform Approach2006In: Proceedings of the 36th European Microwave Conference, 2006, 169-171 p.Conference paper (Refereed)
    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.

  • 24.
    Bengtsson, Olof
    et al.
    University of Gävle, Department of Technology and Built Environment, 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 conversion2008In: GigaHertz Symposium 2008: Abstract Book, 2008, 83-83 p.Conference paper (Other academic)
    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.

  • 25.
    Bengtsson, Olof
    et al.
    University of Gävle, Department of Technology and Built Environment, 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 Applications2008In: 2008 European Microwave Integrated Circuits Conference (EuMIC), 2008, 222-225 p.Conference paper (Refereed)
    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.

  • 26.
    Bengtsson, Olof
    et al.
    University of Gävle, Department of Technology and Built Environment, 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 Investigations2009In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 53, no 1, 86-94 p.Article in journal (Refereed)
    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.

  • 27.
    Bengtsson, Olof
    et al.
    University of Gävle, Department of Technology and Built Environment, 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 Pull2009In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 56, no 3, 505-511 p.Article in journal (Refereed)
    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.

  • 28.
    Bengtsson, Olof
    et al.
    University of Gävle, Department of Technology and Built Environment, 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 Distortion2008In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 52, no 7, 1024-1031 p.Article in journal (Refereed)
    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.

  • 29.
    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
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Automatic design of pulse coupled neurons for image segmentation2008In: Neurocomputing, ISSN 0925-2312, E-ISSN 1872-8286, Vol. 71, no 10-12, 1980-1993 p.Article in journal (Refereed)
    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.

  • 30.
    Björsell, Niclas
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Modeling analog to digital converters at radio frequency2007Doctoral thesis, comprehensive summary (Other academic)
    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.

  • 31.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Andersen, Olav
    Händel, Peter
    High Dynamic Range Test-Bed for Characterization of Analog-To-Digital Converters Up To 500 MSPS2005In: 10th Workshop on ADC modelling and testing, 2005, 601-604 p.Conference paper (Refereed)
    Abstract [en]

    A measurement set-up of for the characterization of analog-to-digital converters (ADCs) is described. The measurement set-up characterizes ADCs up to 16 bits at 350 MHz (option for>500 MHz). Testing dynamic performance of high-speed ADCs is regarded as difficult and expensive. By using existing state-of-the-art instruments in combination with specially designed amplifiers and filters, a high performance, cost efficient test-bed has been built-up. Practical performance corresponds to ADC datasheet and exceeds the performance obtained if using commercial instruments only. Consequently, the measurement results represent the true performance of the ADC without impact from the test-bed. 1.

  • 32.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    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 management2009In: XIX IMEKO World Congress, 2009, 568-573 p.Conference paper (Refereed)
    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.

  • 33.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Händel, Peter
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    A Statistical Evaluation of ADC Histogram Tests with Arbitrary Stimuli Signal2005In: ADDA 2005, 2005, 259-264 p.Conference paper (Refereed)
    Abstract [en]

    Histogram tests are a commonly used method for characterizing analogue to digital converters. However, different stimuli signals can be used in the histogram test. An overview of common input stimuli for the test is presented. Previous works have analysed the statistical properties of the resulting histograms for different stimuli signals, separately. In this paper, generally applicable results for asymptotically unbiased minimum variance estimator and Cramer-Rao lower bound are derived, irrespective of used input stimuli. Where available, the general expression is compared and found in accordance with signal-specific expressions.

  • 34.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, 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 Nonlinearity2008In: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, 497187Article in journal (Refereed)
    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).

  • 35.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Händel, Peter
    Analog-to-Digital Converters for High-Speed Applications2005In: GigaHz 2005, 2005, 151-154 p.Conference paper (Refereed)
    Abstract [en]

    There is a rapid development of the performance of state-of-the-art analog to digital converters (ADC). Resolution and sampling rate are increasing continuously. Sampling rates in the high intermediate frequency (IF) range with sufficient dynamic range for communication applications were introduced about the turn of the millennium. Post-correction methods enable fast ADCs with modest linearity, and thereby weak dynamic performance, for high-speed applications.

    A post-correction procedure involves a characterization of the ADC non-linearity and then utilizing this information by processing the ADC output samples to remove the distortion. ADC characterization is usually performed by estimating ADC characteristics from measurements. Consequently, successful characterizations require both developed test methods and high performance test-beds.

    Characterization and testing ADCs are interesting in many different aspects. Not only that a proper characterization can be used for error compensation, testing is a major factor of cost for manufacturers, and shortening of the test cycle implies large savings. Testing ADCs is complicated, time consuming and demands high-performance instrumentation.

  • 36.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Händel, Peter
    Benefits with Truncated Gaussian Noise in ADC Histogram Tests2004In: IMEKO 04, 2004, 787-792 p.Conference paper (Refereed)
  • 37.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Händel, Peter
    Royal Institute of Technology, Stockholm.
    Dynamic behavior models of analog to digital converters aimed for post-correction in wideband applications2006In: IMEKO Workshop on ADC and DAC Modelling and Testing, September 17-22, 2006, Rio de Janeiro, 2006, 5- p.Conference paper (Refereed)
    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.

  • 38.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Händel, Peter
    Signal Processing Laboratory, Royal Institute of Technology, Stockholm, Sweden.
    Histogram Tests for Wideband Applications2008In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 57, no 1, 70-75 p.Article in journal (Refereed)
    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.

  • 39.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Händel, Peter
    On Gaussian and Sine Wave Histogram Tests for Wideband Applications2005In: IMTC 2005, Ottawa, 2005, 677-682 p.Conference paper (Refereed)
  • 40.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Händel, Peter
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Post-Correction of Under-Sampled Analog to Digital Converters2007In: IEEE Instrumentation and Measurement Technology Conference, 2007Conference paper (Refereed)
    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.

  • 41.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Händel, Peter
    Royal Institute of Technology, Signal Processing Laboratory, Stockholm, Sweden.
    Truncated Gaussian noise in ADC histogram tests2007In: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 40, no 1, 36-42 p.Article in journal (Refereed)
    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.

  • 42.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Isaksson, Magnus
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Händel, Peter
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Rönnow, Daniel
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Kautz-Volterra modelling of an analogue-to-digital converter using a stepped three-tone excitation2007In: 12th IMEKO TC-4 International Workshop on ADC MODELLING AND TESTING, Iasi, Romania, September 2007, 2007, 107-112 p.Conference paper (Refereed)
  • 43.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Rönnow, Daniel
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Händel, Peter
    Measuring Volterra kernels of analog to digital converters using a stepped three-tone scan2006In: Proceedings of the IEEE Instrumentation and Measurement Technology Conference, 2006. IMTC 2006, 2006, 1047-1050 p.Conference paper (Refereed)
    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.

  • 44.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, 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
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. WesternGeco, Asker, Sweden.
    Measuring Volterra kernels of analog to digital converters using a stepped three-tone scan2008In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 57, no 4, 666-671 p.Article in journal (Refereed)
    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.

  • 45.
    Borg, Daniel
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Mantling, Ulf
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Syntetiska Instrument2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    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.

  • 46.
    Carlsson, Carl
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Stenumgaard, Peter
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Wiklund, Kia
    Intersystem Interference between Middle-tons Class A Noise and Bluetooth2008In: Radio Science and Communication, RVK08, 2008Conference paper (Other academic)
  • 47. Castillo, Patricia
    et al.
    San-Roman, Ebert
    Bengtsson, Olof
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    On the design of a planar, harmonic, triplex-filter for 3G, load-pull measurement applications2007In: RFMTC-07, 2007Conference paper (Other (popular science, discussion, etc.))
    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.

  • 48.
    Chilo, José
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Feature Extraction for Low-Frequency Signal Classification2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The development of the International Monitoring System (IMS) for the verification of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has led to a rapid revival of interest in infrasound. Furthermore, the installation of low-frequency sensors at seismic sites has increased in recent years, providing researchers with large and heterogeneous data-sets in near real-time. New techniques are needed to better process all of this data and to extract meaningful information quickly for various applications. In particular, there is a need to find distinct features in the infrasonic signals that allow one to distinguish low level nuclear tests from seismic events.

    In this thesis three methods for feature extraction from infrasound and other types of low frequency signal data are discussed: (1) discrete wavelets transforms (DWTs); (2) time scale spectra (TSSs) using continuous wavelet transforms (CWTs); and (3) empirical mode decomposition (EMD). The dimensionality of the feature space can range from a few to thousands. For processing high-dimensional data we use multi-modal data space to find low-dimensional structures. The advantage of this space is that multiple metrics of similarity are converted into one single Euclidean space.

    The overall goal of our research is a system for automatic identification and classification of low-frequency signals in real-time that is easy to implement in hardware. In this thesis we present our design and implementation of the discrete wavelet transform (DWT) on FPGAs for processing a continuous flow of data to obtain optimal extraction of feature information. FPGA simulation and implementation has been realized by using the polyphase structure, the filter reuse method and techniques such as pipelining and basic operations on the QUARTUS II platform. VHDL has been used to describe the functionality of the discrete wavelet transform and ModelSim has been used for the functional verification.

    Advancements in electronics provide a vital new option for implementation of low-frequency smart sensors that can perform signal processing close to the sensors and transmit the data wirelessly. These smart sensors can improve the efficiency of an automatic classification system and reduce the cost of actual infrasound microphones. The design of a digital wireless data acquisition system using a QF4512 programmable signal converter from Quickfilter Technologies, a MSP430 microcontroller from Texas Instruments and a F2M03GLA Bluetooth module from Free2move for infrasonic records is also presented in this thesis. The digital wireless data acquisition system has passed extensive laboratory and field tests (e.g. with man-made explosions).

    A study of using a miniature 3-axis fluxgate magnetometer to get fingerprints from ferrous objects is also presented in this thesis. In this experiment, distinguishing features of iron samples of four different shapes were determined using wavelet methods. Systematic differences were observed between the signatures of the four shaped iron samples.

  • 49.
    Chilo, José
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Filtering extracting features from infrasound data2006Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

     

    The goal of the research presented in this thesis is to extract features, to filter and get fingerprints from signals detected by infrasound, seismic and magnetic sensors. If this can be achieved in a real time system, then signals from various events can be detected and identified in an otherwise torrent data.

    Several approaches have been analyzed. Wavelet transform methods are used together with ampligram and time scale spectrum to analyze infrasound, seismic and magnetic data. The energy distribution in the frequency domain may be seen in wavelet scalograms. A scalogram displays the wavelet coefficients as a function of the time scale and of the elapsed time. The ampligram is a useful method of presentation of the physical properties of the time series. The ampligram demonstrate the amplitude and phase of components of the signal corresponding to different spectral densities. The ampligram may be considered as an analogy to signal decomposition into Fourier components. In that case different components correspond to different frequencies. In the present case different components correspond to different wavelet coefficient magnitudes, being equivalent to spectral densities. The time scale spectrum is a forward wavelet transform of each row (wavelet coefficient magnitude) in the ampligram. The time scale spectrum reveals individual signal components and indicates the statistical properties of each component: deterministic or stochastic.

    Next step is to distinguish between different sources of infrasound on-line. This will require signal classification after detection is made. The implementation of wavelet – neural network in hardware may be a first choice. In this work the Independent Component Analysis is presented to improve the quality of the infrasonic signals by removing background noise before the hardware classification. The implementation of the discrete wavelet transform in a Field Programmable Gate Array (FPGA) is also included in this thesis using Xilinx System Generator and Simulink software.

    A study of using infrasound recordings together with a miniature 3-axis fluxgate magnetometer to find meteorites as soon as possible after hitting the earth is also presented in this work.

  • 50.
    Chilo, José
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Low-Frequency Signal Classification: Filtering and extracting features from infrasound data2008Book (Other academic)
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