| 1. |
- Angelov, Iltcho, 1943, et al.
(författare)
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F-band resistive mixer based on heterostructure field effect transistor technology
- 1993
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Ingår i: Proceedings of the 1993 IEEE MTT-S International Symposium on Circuits and Systems. - 0149-645X. - 0780312090 ; 2, s. 787-790
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Konferensbidrag (refereegranskat)abstract
- A fundamentally pumped millimeter wave resistive mixer based on an HFET technology working at F-band (90-140 GHz) is described for the first time. Nonlinear simulations have been performed for this mixer based on an specially designed double δ-doped pseudomorphic HFET device developed for this application. A minimum conversion loss between 12 to 13 dB was measured with the RF fixed at different frequencies between 108 to 114 GHz at an RF power of -13 dBm. Both theoretical and experimental results are presented in this paper.
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| 2. |
- Gustafsson, Lars L., et al.
(författare)
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The 'wise list'- a comprehensive concept to select, communicate and achieve adherence to recommendations of essential drugs in ambulatory care in Stockholm
- 2011
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Ingår i: Basic & Clinical Pharmacology & Toxicology. - Copenhagen : Blackwell Publishing. - 1742-7835 .- 1742-7843. ; 108:4, s. 224-233
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to present and evaluate the impact of a comprehensive strategy over 10 years to select, communicate and achieve adherence to essential drug recommendations (EDR) in ambulatory care in a metropolitan healthcare region. EDRs were issued and launched as a 'Wise List' by the regional Drug and Therapeutics Committee in Stockholm. This study presents the concept by: (i) documenting the process for selecting, communicating and monitoring the impact of the 'Wise List'; (ii) analysing the variation in the number of drug substances recommended between 2000 and 2010; (iii) assessing the attitudes to the 'Wise List' among prescribers and the public; (iv) evaluating the adherence to recommendations between 2003 and 2009. The 'Wise List' consistently contained 200 drug substances for treating common diseases. The drugs were selected based on their efficacy, safety, suitability and cost-effectiveness. The 'Wise List' was known among one-third of a surveyed sample of the public in 2002 after initial marketing campaigns. All surveyed prescribers knew about the concept and 81% found the recommendations trustworthy in 2005. Adherence to recommendations increased from 69% in 1999 to 77% in 2009. In primary care, adherence increased from 83% to 87% from 2003 to 2009. The coefficient of variation (CV%) decreased from 6.1% to 3.8% for 156 healthcare centres between these years. The acceptance of the 'Wise List' in terms of trust among physicians and among the public and increased adherence may be explained by clear criteria for drug recommendations, a comprehensive communication strategy, electronic access to recommendations, continuous medical education and involvement of professional networks and patients.
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| 3. |
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| 4. |
- Karlsson, Christer, 1967
(författare)
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Heterostructure Field-Effect Transistors for Millimeter Wave Applications
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with the development of low-noise heterostructure field-effect transistors (HFETs) on III-V materials. The emphasis is on devices for high gain and low noise applications. Fabrication processes have been developed and transistors have been fabricated and characterized. Results from pseudomorphic AlGaAs/InGaAs/GaAs, lattice matched InAlAs/InGaAs/InP, pseudomorphic InAlAs/InGaAs/InP, pseudomorphic InGaP/InGaAs/ InP, and metamorphic InAlAs/InGaAs/GaAs materials are presented. Lattice matched InAlAs/InGaAs/InP materials have been the primary material in our laboratory for some years. This material has been used for both hybrid circuits and MMICs. HFETs on this material with a gate length of 0.15 .my.m have reached an fmax of 380 GHz and an fT of 140 GHz. Metamorphic GaAs based materials with 80 % In in the channel have been evaluated by characterizing sub-micron HFETs. An fmax of 230 GHz has been achieved on these materials. After insertion of a thin InAs layer in the In0.8Ga0.2As channel, an fT of 100 GHz and a transconductance of 1100 mS/mm were achieved for a 0.3 µm gate length device. These devices exhibit low noise and extremely high gain at low voltages and are very promising for applications where high speed and low power consumption are required. An fmax of 100 GHz was achieved at Vds=0.25 V and Ids=26 mA/mm. Small-signal modeling of HFET devices is described. By measuring S-parameters of the devices for 1-50 GHz, bias dependent small signal models are extracted and used for both device and material evaluation, as well as in circuit design. We have developed an improved small signal model for millimeter wave frequencies. This model has been validated by measurements at 75-110 GHz. MMIC circuits have been designed and fabricated, including a 115 GHz single stage amplifier with 5 dB gain and a 110 GHz resistive mixer with 9 dB conversion loss at an LO power of 4 dBm. These circuits were fabricated on lattice matched InAlAs/InGaAs/InP material. Processes developed for fabricating the discrete HFETs as well as the HFET based MMICs reported in this thesis are described in detail.
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| 5. |
- Karlsson, Toni, 1984, et al.
(författare)
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Investigations into Recycling Zinc from Used Metal Oxide Varistors via pH Selective Leaching: Characterization, Leaching, and Residue Analysis
- 2015
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Ingår i: Scientific World Journal. - : Hindawi Limited. - 2356-6140 .- 1537-744X. ; 2015
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Tidskriftsartikel (refereegranskat)abstract
- Metal oxide varistors (MOVs) are a type of resistor with significantly nonlinear current-voltage characteristics commonly used in power lines to protect against overvoltages. If a proper recycling plan is developed MOVs can be an excellent source of secondary zinc because they contain over 90 weight percent zinc oxide. The oxides of antimony, bismuth, and to a lesser degree cobalt, manganese, and nickel are also present in varistors. Characterization of the MOV showed that cobalt, nickel, and manganese were not present in the varistor material at concentrations greater than one weight percent. This investigation determined whether a pH selective dissolution (leaching) process can be utilized as a starting point for hydrometallurgical recycling of the zinc in MOVs. This investigation showed it was possible to selectively leach zinc from the MOV without coleaching of bismuth and antimony by selecting a suitable pH, mainly higher than 3 for acids investigated. It was not possible to leach zinc without coleaching of manganese, cobalt, and nickel. It can be concluded from results obtained with the acids used, acetic, hydrochloric, nitric, and sulfuric, that sulfate leaching produced the most desirable results with respect to zinc leaching and it is also used extensively in industrial zinc production.
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| 6. |
- Rorsman, Niklas, 1964, et al.
(författare)
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Characterization of InAlAs/InGaAs HFETs with high indium content in the channel grown on GaAs substrate
- 1993
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Ingår i: 23rd European Solid State Device Research Conference, ESSDERC 1993. - 1930-8876. - 9782863321355 ; , s. 765-768
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Konferensbidrag (refereegranskat)abstract
- InAlAs/InGaAs HFETs having very high indium content (80 and 100%) in the channel have been fabricated on GaAs and electrically characterized. The extrinsic transconductance were 310 mS/mm (560 mS/mm at 77 K), and the saturation current were 700 mA/mm (600 mA/mm at 77 K) for an InAs channel. The value of fT and fmaxfor this device were measured to be 80 GHz and 50 GHz, respectively. The In0.8Ga 0.2As channel material had extrinsic transconductance of 320 mS/mm (470 mS/mm at 77 K), and the saturation current were 520 mA/mm (440 mA/mm at 77K). The value of fT and fmaxfor this device were measured to be 80 GHz and 50 GHz, respectively
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| 7. |
- Zirath, Herbert, 1955, et al.
(författare)
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W-band subharmonically pumped resistive mixer based on pseudomorphic heterostructure field effect transistor technology
- 1993
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Ingår i: Proceedings of the 1993 IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 0780312090 ; 1, s. 341-344
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Konferensbidrag (refereegranskat)abstract
- This paper describes the first subharmonically pumped resistive mixer (SPRM) based on HFETs, operating in the W-band (75-110 GHz). Two HFET devices, specially designed for this application, were integrated together with a coupler, 180° phase shifter, and an IF-filter. Both theoretical and experimental results are presented in this paper. A minimum conversion loss of about 22 dB was experimentally obtained at an LO-power of 10 dBm.
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