| 1. |
- Andersson, Christer, 1982, et al.
(författare)
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Epitaxial and Layout Optimization of SiC Microwave Power Varactors
- 2011
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Ingår i: Asia-Pacific Microwave Conference Proceedings, APMC (APMC 2011 ;Melbourne, VIC; 5 - 8 December 2011). - 9780858259744 ; , s. 1642-1645
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Konferensbidrag (refereegranskat)abstract
- SiC Schottky diode varactors have been designed for use in tunable microwave power circuits. Epitaxial growth results show excellent material uniformity with low access layer sheet resistances. Two types of device layouts have been evaluated. Island type layouts reduce the parasitic series resistance by 50-60% compared to typical finger layouts. The Q-factors of downscaled island devices are approaching the intrinsic material performance, but are limited by an increasing parasitic parallel capacitance.
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| 2. |
- Axelsson, Olle, 1986, et al.
(författare)
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Impact of Trapping Effects on the Recovery Time of GaN Based Low Noise
- 2016
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Ingår i: IEEE Microwave and Wireless Components Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-1764 .- 1531-1309. ; 26:1, s. 31-33
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates recovery time of the gain of AlGaN/GaN HEMT based low noise amplifiers (LNA) after an input overdrive pulse. Three LNAs, fabricated in two commercial MMIC processes and a Chalmers in-house process, are evaluated. The Chalmers process has an unintentionally doped buffer instead of the intentional Fe doping of the buffer which is standard in commercial GaN HEMT technologies. It is shown that the LNAs from the two commercial processes experience a severe drop in gain after input overdrive pulses higher than 28 dBm, recovering over a duration of around 20 ms. In contrast the LNA fabricated in-house at Chalmers experienced no visible effects up to an input power of 33 dBm. These results have impact for radar and electronic warfare receivers, which need to be operational immediately after an overdrive pulse. The long time constants suggest that these effects are due to trapping in the transistors with the Fe doped buffer playing an important role.
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| 3. |
- Billström, Niklas, et al.
(författare)
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High performance GaN front-end MMICs
- 2011
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Ingår i: 14th European Microwave Week 2011: "Wave to the Future", EuMW 2011 - 6th European Microwave Integrated Circuit Conference, EuMIC 2011, Manchester, 10 October through 11 October 2011. - 9782874870231 ; , s. 348-351
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Konferensbidrag (refereegranskat)
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| 4. |
- Divinyi, Andreas, et al.
(författare)
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Transition Time of GaN HEMT Switches and its Dependence on Device Geometry
- 2023
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Ingår i: 2023 18th European Microwave Integrated Circuits Conference, EuMIC 2023. ; , s. 46-49
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Konferensbidrag (refereegranskat)abstract
- This paper presents the impact on the slow transition time of GaN HEMT switch transistor due to size and geometry. Measurements in the time domain are used to characterize the transition time of the switch from off to on. This is done for several switch transistors with variations on total gate width and number of fingers. In order to enable the comparison of transition times a figure of merit is established. This is achieved by using a commonly used model for trapping effects to quantify the amplitude of the slow transient with respect to the gate voltage. The resulting analysis indicates that transition time is sensitive to transistor size and dependent on the geometry of the device as increasing the width of the gate fingers is more advantageous compared to increasing the number of fingers.
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| 5. |
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| 6. |
- Nilsson, Joakim, et al.
(författare)
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S-band discrete and MMIC GaN power amplifiers
- 2009
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Ingår i: European Microwave Week 2009, EuMW 2009: Science, Progress and Quality at Radiofrequencies, Conference Proceedings - 39th European Microwave Conference, EuMC 2009. - 9782874870125 ; , s. 495-498
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Konferensbidrag (refereegranskat)abstract
- The use of GaN devices for microwave power amplifiers begins to be a reality in Europe. This paper describes two S-band (2.7-3.3 GHz) high power amplifier (HPA) designs; one discrete 100 W output stage and one 10 W MMIC power amplifier. The discrete power amplifier is designed using two GaN power bars with a total gate width of 19.2 mm. The GaN power bars have been developed by Selex-SI, within the european co-project Korrigan. The MMIC power amplifier was designed using a 0.25 ?m GaN HEMT process supplied and processed by Chalmers.
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| 7. |
- Sudow, Mattias, 1980, et al.
(författare)
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An AlGaN/GaN HEMT-Based Microstrip MMIC Process for Advanced Transceiver Design
- 2008
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 56:8, s. 1827-1833
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Tidskriftsartikel (refereegranskat)abstract
- A MMIC process in AlGaN/GaN technology for advanced transceiver design has been developed. The process is based on microstrip technology with a complete model library of passive elements and AlGaN/GaN HEMTs. The transistor technology in this process is suitable for both power and low noise design, demonstrated with a power density of 5 W/mm, and an ${rm NF}_{min}$ of 1.4 dB at $X$ -band. Process stability of subcircuits, complementary to power amplifiers and LNAs, in a transceiver system have been investigated. The results indicate that an all AlGaN/GaN MMIC transceiver is realizable using this technology.
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| 8. |
- Sudow, Mattias, 1980, et al.
(författare)
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An SiC MESFET-based MMIC process
- 2006
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. ; 54:12, Part 1, s. 4072-4078
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Tidskriftsartikel (refereegranskat)abstract
- A monolithic microwave integrated circuit (MMIC)process based on an in-house SiC MESFET technology has been developed. The process uses microstrip technology, and a complete set of passive components, including MIMcapacitors, spiral inductors,thin-film resistors, and via-holes, has been developed. The potential of the process is demonstrated by an 8-W power amplifierat 3 GHz, a high-linearity -band mixer showing a third-order intercept point of 38 dBm, and a high-power limiter.
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| 9. |
- Sudow, Mattias, 1980, et al.
(författare)
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The Chalmers microstrip SiC MMIC Process
- 2005
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Ingår i: Conference Proceedings Gighahertz 2005.
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Konferensbidrag (refereegranskat)abstract
- A generic microstrip MMIC process targeted for SiC and GaN technology has beendeveloped. Passive components for high power operation were developed and verified. Circuit modelsfor both passive and active components have been formulated. Using the developed MMIC process anamplifier and a limiter have been manufactured.
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| 10. |
- Thorsell, Mattias, 1982, et al.
(författare)
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An X-Band AlGaN/GaN MMIC Receiver Front-End
- 2010
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Ingår i: IEEE Microwave and Wireless Components Letters. - 1558-1764 .- 1531-1309. ; 20:1, s. 55-57
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Tidskriftsartikel (refereegranskat)abstract
- This letter presents an integrated AlGaN/GaN X-band receiver front-end. This is to the authors knowledge the first published results of an integrated AlGaN/GaN MMIC receiver front-end. The receiver uses an integrated SPDT switch to reduce size, weight and cost compared to circulator based transceiver front-ends. The integrated front-end has more than 13 dB of gain and a noise figure of 3.5 dB at 11 GHz.
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