| 1. |
|
|
| 2. |
|
|
| 3. |
- Sudow, Mattias, 1980, et al.
(author)
-
A Single-Ended Resistive $X$-Band AlGaN/GaN HEMT MMIC Mixer
- 2008
-
In: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 56:10, s. 2201-2206
-
Journal article (peer-reviewed)abstract
- A broadband highly linear X-band mixer in AlGaN/GaN monolithic microwave integrated circuit technology has been designed, processed, and characterized. The design is based on a 4 times 100 mum AlGaN/GaN HEMT in a single-ended circuit topology. The mixer has an IF bandwidth of 2 GHz with a conversion loss (CL) of
|
|
| 4. |
- Sudow, Mattias, 1980, et al.
(author)
-
An AlGaN/GaN HEMT-Based Microstrip MMIC Process for Advanced Transceiver Design
- 2008
-
In: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 56:8, s. 1827-1833
-
Journal article (peer-reviewed)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.
|
|
| 5. |
- Suijker, Erwin M., et al.
(author)
-
GaN MMIC power amplifiers for S-band and X- band
- 2008
-
In: 38th European Microwave Conference, EuMC 2008; Amsterdam; Netherlands; 27 October 2008 through 31 October 2008. - 9782874870064 ; , s. 297-300
-
Conference paper (peer-reviewed)abstract
- The development of two GaN MMIC power amplifiers is reported. The amplifiers are processed in the AlGaN/GaN technology of Chalmers University of Technology using 0.25 ?m HEMTs. The S-band amplifier operates at frequencies from 3 to 4 GHz and has a maximum output power of 5.6 W with an associated efficiency of 28 %. The X-band amplifier has a maximum output power of 4.8 W.
|
|
| 6. |
- Thorsell, Mattias, 1982, et al.
(author)
-
Characterization of the temperature dependent access resistances in AlGaN/GaN HEMTs
- 2008
-
In: Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits, 2008. INMMIC 2008.. - 9781424426454 ; , s. 17-20
-
Conference paper (peer-reviewed)abstract
- The temperature dependence of the access resistances for AlGaN/GaN HEMTs is investigated. The self-heating is measured using infrared microscopy and the access resistances are extracted at different ambient temperatures. Their influence on the intrinsic small signal parameters is studied versus bias and ambient temperature.
|
|
| 7. |
- Thorsell, Mattias, 1982, et al.
(author)
-
Thermal characterization of the intrinsic noise parameters for AlGaN/GaN HEMTs
- 2008
-
In: International Microwave Symposium Digest, 2008, Atlanta. - 0149-645X. - 9781424417810 ; , s. 463-466
-
Conference paper (peer-reviewed)abstract
- The noise parameters of AlGaN/GaN-HEMTs are measured between 298 K and 423 K. The temperature dependent access resistances are de-embedded and the intrinsic noise parameters are studied as a function of temperature. It is shown that the parasitic access resistances are limiting the highfrequency noise performance of the AlGaN/GaN-HEMT.The intrinsic noise sources are extracted and a noise model is derived and verified for a MMIC amplifier.
|
|
| 8. |
- Thorsell, Mattias, 1982, et al.
(author)
-
Thermal Study of the High-Frequency Noise in GaN HEMTs
- 2009
-
In: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 57:1, s. 19-26
-
Journal article (peer-reviewed)abstract
- The high-frequency noise performance of the GaN HEMT is studied for temperatures between 297–398 K. The access resistances ${ R}_{ S}$ and ${ R}_{ D}$ have a limiting effect on the noise performance, and in this paper, their temperature dependence is studied in detail for a ${hbox{2}}times {hbox{100}} mu{hbox{m}}$ GaN HEMT. ${ R}_{ S}$ and ${ R}_{ D}$ show an increase of 0.71 and 0.86 %/K, respectively. The self-heating effect due to dissipated power is also studied to allow accurate intrinsic small-signal and noise parameter extraction. The thermal resistance is measured by infrared microscopy. Based on these results, a temperature dependent noise model including self-heating and temperature-dependent access resistances is derived and verified with measurements.
|
|
| 9. |
- Dammann, M., et al.
(author)
-
Reliability and degradation mechanism of AlGaN/GaN HEMTs for next generation mobile communication systems
- 2009
-
In: Microelectronics and Reliability. - : Elsevier BV. - 0026-2714. ; 49:5, s. 474-477
-
Journal article (peer-reviewed)abstract
- Excellent reliability performance of AlGaN/GaN HEMTs on SiC substrates for next generation mobile communication systems has been demonstrated using DC and RF stress tests on 8 x 60 mu m wide and 0.5 mu m long AlGaN/GaN HEMTs at a drain voltage of V-d = 50 V. Drain current recovery measurements after stress indicate that the degradation is partly caused by slow traps generated in the SiN passivation or in the HEMT epitaxial layers. The traps in the SiN passivation layer were characterized using high and low frequency capacitance-voltage (CV) measurements of MIS test structures on thick lightly doped GaN layers. (C) 2009 Elsevier Ltd. All rights reserved.
|
|
| 10. |
- Fagerlind, Martin, 1980, et al.
(author)
-
A room temperature HEMT process for AlGaN/GaN heterostructure characterization
- 2009
-
In: Semiconductor Science and Technology. - : IOP Publishing. - 1361-6641 .- 0268-1242. ; 24:4, s. 045014-
-
Journal article (peer-reviewed)abstract
- A simple, room temperature, AlGaN/GaN high electron mobility transistor (HEMT) process is presented. The process consists of only two steps which can be performed by hand. The first step is to deposit gallium (Ga) metal for ohmic contacts, which without thermal processing have a specific contact resistivity ρ_c=0.10 Ohm cm2. Silver (Ag)-based conductive paint is then deposited to form a Schottky contact. The simplicity of the process facilitates fast fabrication and characterization of HEMTs, without unwanted effects on the material. The process is useful for initial material characterization and screening. The process is also found to be a useful tool for process monitoring of the conventional HEMT micro-fabrication process by detecting material/process quality problems. In this work the process is used for initial material characterization and screening, where a leaky buffer can easily be detected. The process is also used to identify the ohmic contact annealing as a potentially damaging step in a conventional micro-fabrication process. A decrease in the electron sheet carrier concentration and an increase of leakage currents are measured after annealing.
|
|
