| 1. |
- Andersson, Mattias, 1982, et al.
(författare)
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Dielectric loss determination of fine residual waste electrical and electronic equipment for understanding of heat development during microwave pyrolysis
- 2013
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Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier BV. - 0165-2370. ; 103, s. 142-148
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Tidskriftsartikel (refereegranskat)abstract
- Waste electrical and electronic equipment (WEEE) contains rare and valuable metals which are important to recycle, but it also has high organic content. The conventional methods used today for treatment of WEEE cannot recycle 100%; they generate valuable fine residual fractions. For further processing of these residues, microwave pyrolysis has shown to be promising since it reduces the organic content and liberate enclosed metal pieces. However, to fully control the process, the dielectric properties of the materials need to be known but are difficult to determine due to the complex composition and structure of WEEE. This paper aims to describe a suitable procedure for determination of dielectric loss in six WEEE residual fine fractions and to correlate the results to heating behaviour during microwave pyrolysis. Three fractions are "dusts" (light, medium and heavy dust) and three fractions are called "particulate materials" and contain smaller particles (0-7 mm, 0-20 mm and 7-12 mm). The method chosen was Vector Network Analyzer (VNA) using waveguide WR430 equipped with polymer foam to contain the samples which consisted of 1 dl of WEEE fine fraction. The scattering parameters were measured and dielectric loss in the materials was calculated. The measurements were performed in frequency region 1.3-2.7 GHz to include the industrial frequency 2.45 GHz. Differences between dielectric losses for the materials were determined by ANOVA. It was shown that the scattering parameter measurements were rather stable for the dust materials and the losses could be determined. For the larger sized particulate materials a lot of reflection was observed during the measurements, due to fine metal wires in the material. The losses could be determined after removing these wires. The previously observed higher heating rate and shorter time for mass reduction of dusts could not be explained by differences in dielectric loss. However, since VNA measurements indicate that metal wires in the material disturb the field; presence of wires in the particulate materials might be one cause for slower heating rate and observed temperature drops during pyrolysis.
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| 2. |
- Lai, Szhau, 1985, et al.
(författare)
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Accurate Phase-Noise Prediction for a Balanced Colpitts GaN HEMT MMIC Oscillator
- 2013
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 61:11, s. 3916-3926
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an X-band balanced Colpitts oscillator in GaN HEMT technology and a method to calculate its phase noise accurately. The method employs a low-frequency (LF) noise measurement and the oscillator waveforms from a harmonic-balance simulator. These data are post-calculated by Hajimiri's phase-noise model, in which the LF noise can be activated with a cyclo-stationary effect in the calculation of phase noise. Compared to commercial phase-noise simulation using predefined stationary noise, the calculation gives significantly improved phase-noise prediction in the 30-dB/decade region near carrier. The prediction is within 3-dB accuracy at 10-kHz, 100-kHz, and 1-MHz offset frequencies. In addition to the method used for phase-noise prediction, the potential for wideband tuning of this oscillator topology is analytically investigated. The measured phase noise of the oscillator is -102 dBc/Hz at 100-kHz offset from a 8.6-GHz carrier frequency for drain voltage and current of Vd = 15 V amd Id = 40 mA.
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| 3. |
- Ringlander, Johan, et al.
(författare)
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Hepatitis B virus particles in serum contain minus strand DNA and degraded pregenomic RNA of variable and inverse lengths
- 2024
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Ingår i: LIVER INTERNATIONAL. - 1478-3223 .- 1478-3231.
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Tidskriftsartikel (refereegranskat)abstract
- This study utilized digital PCR to quantify HBV RNA and HBV DNA within three regions of the HBV genome. Analysis of 75 serum samples from patients with chronic infection showed that HBV RNA levels were higher in core than in S and X regions (median 7.20 vs. 6.80 and 6.58 log copies/mL; p < .0001), whereas HBV DNA levels showed an inverse gradient (7.71 vs. 7.73 and 7.77 log copies/mL, p < .001). On average 80% of the nucleic acid was DNA by quantification in core. The core DNA/RNA ratio was associated with viral load and genotype. In individual patients, the relations between RNA levels in core, S and X were stable over time (n = 29; p = .006). The results suggest that pregenomic RNA is completely reverse transcribed to minus DNA in approximate to 75% of the virus particles, whereas the remaining 25% contain both RNA and DNA of lengths that reflect variable progress of the polymerase.
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| 4. |
- ÖZEN, MUSTAFA, 1984, et al.
(författare)
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High efficiency RF pulse width modulation with tunable load network class-E PA
- 2011
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Ingår i: 2011 IEEE 12th Annual Wireless and Microwave Technology Conference, WAMICON 2011. - 9781612840819
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Konferensbidrag (refereegranskat)abstract
- In this paper, a 10 W peak power 2 GHz highly efficient RF pulse width modulation (RF-PWM) based transmitter is presented. RF-PWM signals are generated with a dedicated 65 nm CMOS modulator and subsequently amplified with a GaN Class-E power amplifier (PA). The modulator use extended drain MOS (EDMOS) high voltage transistors to provide the required voltage swing to drive the GaN used as a switch. The imaginary load impedance of the Class-E is electronically tunable and is implemented with in-house high breakdown voltage SiC varactors. The tunable imaginary load impedance enables optimization of the Class-E versus the duty cycle (pulse width). The peak efficiency is therefore preserved over a wide range of output power levels. The measured drain efficiency of the Class-E output stage is above 70% over a 6.5 dB output power dynamic range. The overall transmitter efficiency is above 60% for the same dynamic range.
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| 5. |
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| 6. |
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| 7. |
- Andersson, Kristoffer, 1976, et al.
(författare)
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Fabrication and characterization of field-plated buried-gate SiC MESFETs
- 2006
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Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 27:7, s. 573-575
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Tidskriftsartikel (refereegranskat)abstract
- Silicon carbide (SiC) MESFETs were fabricated using a standard SiC MESFET structure with the application of the "buried-channel" and field-plate (FP) techniques in the process. FPs combined with a buried-gate are shown to be favorable concerning output power density and power-added efficiency (PAE), due to higher breakdown voltage and decreased output conductance. A very high power density of 7.8 W/mm was measured on-wafer at 3 GHz for a two-finger 400-/spl mu/m gate periphery SiC MESFET. The PAE for this device was 70% at class AB bias. Two-tone measurements at 3 GHz /spl plusmn/ 100 kHz indicate an optimum FP length for high linearity operation.
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| 8. |
- Andersson, Kristoffer, 1976, et al.
(författare)
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Large-signal waveform acquisition of pulsed signals
- 2011
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Ingår i: European Microwave Week 2011: "Wave to the Future", EuMW 2011, Conference Proceedings - 41st European Microwave Conference, EuMC 2011. - 9782874870224 ; , s. 9010-913
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Konferensbidrag (refereegranskat)abstract
- Techniques for measuring large-signal waveforms of pulsed signals are fairly well described in the literature. However, most techniques are developed for very specific setups and typically require modification of the hardware. In this paper we describe an approach were no modification is necessary to the existing (Large-Signal Network Analyzer) LSNA hardware and software. Furthermore our method is very well suited for integration with other pulsed stimuli e.g. pulsed IV.
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| 9. |
- Andersson, Kristoffer, 1976
(författare)
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Microwave power device characterization
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The first part of the thesis covers work done on device characterizationmethods. A statistical method for estimating small-signal model parametersin FET-models was proposed. A maximum likelihood estimator wasderived and the new method was compared to a standard direct extractiontechnique. The comparison showed that the proposed method gaveparameter estimates that were less uncertain than the direct method.A method for extracting the thermal impedance of microwave transistorswas developed. The method was derived from a thorough theoreticalanalysis of the self-heating feedback problem. The method usessmall-signal measurements at low-frequency and a temperature controlledfixture.A technique for improving dynamic range in oscilloscope based RFmeasurements was also presented. The technique uses repeated measurementssynchronized at baseband and an extended Kalman filter for estimatingthe unknown RF-phase, which allowed for averaging and thusreduction of measurement noise. The technique was then used in anerror-corrected source-pull setup. The error-correction takes in to accountgroup-delay variations over the measurement bandwidth.The second part of the thesis contains experimental results on mixercircuits fabricated using wide bandgap semiconductor devices. Hybrid resistiveFET mixers were fabricated for S- and C-band operation. BothSiC-MESFETs and AlGaN/GaN-HEMTs were evaluated as mixing elements.The best performance was achieved with an AlGaN/GaN-HEMT,with a minimum conversion loss of 7 dB and a maximum third-order interceptpoint of 36 dBm. A monolithic integrated double balanced Schottkydiode ring mixer was also designed. The mixer was fabricated in Chalmersin-house SiC-MMIC process. The mixer had a minimum conversion lossof 12 dB and a maximum third order intercept of 38 dBm.
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| 10. |
- Andersson, Kristoffer, 1976, et al.
(författare)
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Oscilloscope based two-port measurement system using error-corrected modulated signals
- 2012
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Ingår i: 2012 Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits, INMMIC 2012. - 9781467329491
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Konferensbidrag (refereegranskat)abstract
- A technique to accurately measure modulated wideband signals in a two-port context is presented. The technique uses a four channel high frequency digital sampling oscilloscope to perform in-situ correction of both amplitude and phase of the modulated stimulus signal. An advantage of the proposed technique is that no assumption about the group delay has to be made. The technique is demonstrated in a source-pull system. The results clearly demonstrate the necessity of using error-correction in tuner based setups due to the large variations in group-delay over the measurement bandwidth. © 2012 IEEE.
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| 11. |
- Andersson, Kristoffer, 1976, et al.
(författare)
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Resistive SiC-MESFET mixer
- 2002
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Ingår i: IEEE Microwave and Wireless Components Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1531-1309 .- 1558-1764. ; 12:4, s. 119-121
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Tidskriftsartikel (refereegranskat)abstract
- A single-ended silicon carbide resisitve MESFET mixer with minimum conversion loss (CL) of 10.2 dB and an input third order intercept point of 35.7 dB at 3.3 GHz was designed and characterized. A lumped-element, large-signal model was used for modeling the device. The drain-source resistance was measured by taking the real part of the output port impedence. Analysis suggested that the optimum gate bias for minimum CL was -6.7 V.
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| 12. |
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Angelov, Iltcho, 1943, et al.
(författare)
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Large-Signal Modelling and Comparison of AlGaN/GaN HEMTs and SiC MESFETs
- 2006
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Ingår i: IEEE Asia PAcific Microwave Conference, 2006, Yokohama, Japan. - 9784902339116 ; , s. 279-282
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Konferensbidrag (refereegranskat)abstract
- The Large Signal (LS) model for GaN and SiC FET devices was developed and evaluated with DC, S, and LS measurements. Special attention was paid to improve the management of harmonics and provide. a more physical treatment of the dispersion. The model was implemented in a commercial CAD tool and exhibit good overall accuracy.
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| 18. |
- Angelov, Iltcho, 1943, et al.
(författare)
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On the Compact Equivalent Circuit Modeling
- 2010
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Ingår i: APMC 2010 invited workshop. ; APMC 2010 invited workshop:APMC 2010 invited workshop
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Konferensbidrag (refereegranskat)
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| 19. |
- Angelov, Iltcho, 1943, et al.
(författare)
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On the Large Signal Evaluation and Modeling of GaN FET
- 2010
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Ingår i: IEICE Transactions on Electronics. - 0916-8524. ; E93C:8, s. 1225-1233
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Tidskriftsartikel (refereegranskat)abstract
- The large signal performance and model for GaN FET devices was evaluated with DC, S-parameters, and large signal measurements. The large signal model was extended with bias and temperature dependence of access resistances, modified capacitance and charge equations, as well as breakdown models. The model was implemented in a commercial CAD tool and exhibits good overall accuracy.
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| 20. |
- Angelov, Iltcho, 1943, et al.
(författare)
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On the large-signal modeling of High Power AlGaN/GaN HEMTs
- 2012
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Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781467310871
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Konferensbidrag (refereegranskat)abstract
- In this paper are given some recent results on modeling of High Power GaN HEMT devices. The GaN HEMT is very promising for high power application, but we push device to the limits, so many issues are becoming critical. For example, access resistances Rs, Rd in high power GAN HEMT are bias and temperature dependent-their extraction from cold FET measurements can lead to over optimistic prediction for output power. Thermal management, self-heating modeling are another very important issue-they influence reliability, power and PAE. Models without dynamic self-heating are not practical for GaN. The models without breakdown can easily predict world records for PAE, output power/mm etc. Some examples are given using vectorial Large Signal Measurements (LSNA/NVNA) to provide useful, global info about device behavior, influence of traps, knee voltage walkout etc.
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| 21. |
- Axelsson, Olle, 1986, et al.
(författare)
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Highly linear gallium nitride MMIC LNAs
- 2012
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Ingår i: 2012 IEEE Compound Semiconductor Integrated Circuit Symposium, CSICS 2012, La Jolla, CA, 14 - 17 October 2012. - 1550-8781. - 9781467309295
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Konferensbidrag (refereegranskat)abstract
- In this paper, two Low Noise Amplifiers designed in Gallium Nitride HEMT MMIC technology are presented. The focus of the designs is to achieve good linearity at low power consumption and acceptable noise figure. The first design achieves an OIP3/PDC of 12 using traditional LNA design techniques. In a second design, the OIP3 is improved by 2 dB, raising OIP3/PDC to 19, among the highest figures reported for GaN LNAs. This is achieved by using both inductive source feedback and drain-gate RC feedback.
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| 22. |
- Axelsson, Olle, 1986, et al.
(författare)
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Noise temperature of an electronic tuner for noise parameter measurement systems
- 2012
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Ingår i: 79th ARFTG Microwave Measurement Conference: Non-Linear Measurement Systems, ARFTG 2012. ; , s. Article number 6291197-
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Konferensbidrag (refereegranskat)abstract
- In this paper, the noise temperature of an electronic tuner is determined and its significance for the suitability of such tuners in noise parameter measurement systems discussed. The noise temperature of the tuner was found to be higher than the ambient room temperature in the laboratory and vary significantly between tuner states. For impedance states with small input reflections coefficients, the excess noise temperature is around 25 K. For some of the states with higher reflection coefficients, this figure increases, reaching around 45 K at |Γ| = 0.75. Unless accounted for, this leads to errors in noise parameter extraction when using an electronic tuner in noise parameter measurements.
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| 23. |
- Bremer, Johan, 1991, et al.
(författare)
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Electric-Based Thermal Characterization of GaN Technologies Affected by Trapping Effects
- 2020
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Ingår i: IEEE Transactions on Electron Devices. - 1557-9646 .- 0018-9383. ; 67:5, s. 1952-1958
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Tidskriftsartikel (refereegranskat)abstract
- This article presents an electric-based methodology for thermal characterization of semiconductor technologies. It is shown that for technologies such as gallium nitride (GaN) high electron mobility transistors, which exhibit several field induced electron trapping effects, the thermal characterization has to be performed under specific conditions. The electric field is limited to low levels to avoid activation of trap states. At the same time, the dissipated power needs to be high enough to change the operating temperature of the device. The method is demonstrated on a test structure implemented as a GaN resistor with large contact separation. It is used to evaluate the thermal properties of samples with different silicon carbide suppliers and buffer thickness.
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| 24. |
- Chehrenegar, Pirooz, 1964, et al.
(författare)
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Design and characterization of a highly linear 3 GHz GaN HEMT amplifier
- 2011
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Ingår i: 2011 Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits, INMMiC 2011. Vienna, 18-19 April 2011. - 9781457706493
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Konferensbidrag (refereegranskat)abstract
- In this paper a highly linear amplifier using an in-house gallium nitride (GaN) high electron mobility transistor (HEMT) technology is presented. A 3 dB bandwidth of 2.7-3.6 GHz with a maximum gain of 18 dB was measured. The output third-order intercept point (OIP3) was measured to 39 dBm with a maximum power consumption of 2.1 W. With a reduction of power consumption to 1 W the noise figure was improved by 0.6 dB while the OIP3 was degraded 3 dB.
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| 25. |
- Chehrenegar, Pirooz, 1964, et al.
(författare)
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Highly linear 1-3 GHz GaN HEMT low-noise amplifier
- 2012
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Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781467310871
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Konferensbidrag (refereegranskat)abstract
- A highly linear low-noise amplifier (LNA) based on a commercial Gallium Nitride (GaN) high electron mobility transistor (HEMT) technology is presented. The amplifier can be operated at three frequency bands of 1, 2 and 3 GHz. The maximum measured gain is 31 dB at 1GHz and the output referred third-order intercept point (OIP3) is constant for all three frequency bands and equal to 41±1 dBm at a power consumption of L.2 W. A minimum noise figure (NF) of 0.5 dB is measured for the amplifier at the same bias point demonstrating the simultaneous linearity and low noise performance. The presented performance together with the reasonably low power consumption is outstanding in comparison with recently published amplifiers in GaN technology and available commercial GaAs LNAs.
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