| 1. |
- Lin, Yen-Ku, et al.
(författare)
-
A versatile low-resistance ohmic contact process with ohmic recess and low-temperature annealing for GaN HEMTs
- 2018
-
Ingår i: Semiconductor Science and Technology. - : IOP Publishing. - 1361-6641 .- 0268-1242. ; 33:9
-
Tidskriftsartikel (refereegranskat)abstract
- Deeply recessed ohmic contacts for GaN-based high electron mobility transistors (HEMTs) are demonstrated. It is shown that low-resistance ohmic contacts can be achieved with recessing beyond the AlGaN Schottky barrier where the ohmic contacts are formed on the sidewall of the recess. This makes the process versatile and relatively insensitive to the exact recess depth. The ohmic contact is based on a gold-free metallization scheme consisting of a Ta/Al/Ta metal stack requiring a low-temperature annealing. Important parameters for this type of ohmic contact process include the metal coverage, slope of the etched sidewall, bottom Ta-layer thickness, as well as annealing temperature and duration. The optimized contact resistance is as low as 0.24 Omega mm after annealing at 575 degrees C. Moreover, this sidewall contact approach was successfully implemented on different epitaxial heterostructures with different AlGaN barrier thickness as well as with and without AlN exclusion layer. All the samples exhibited excellent contact resistances in a wide range of recess depths. The Ta-based, sidewall ohmic contact process is a promising method for forming an ohmic contact on a wide range of GaN HEMT epitaxial designs.
|
|
| 2. |
- Campion, James, 1989-, et al.
(författare)
-
Toward Industrial Exploitation of THz Frequencies : Integration of SiGe MMICs in Silicon-Micromachined Waveguide Systems
- 2019
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 2156-342X .- 2156-3446. ; 9:6, s. 624-636
-
Tidskriftsartikel (refereegranskat)abstract
- A new integration concept for terahertz (THz) systems is presented in this article, wherein patterned silicon-on-insulator wafers form all DC, IF, and RF networks in a homogeneous medium, in contrast to existing solutions. Using this concept, silicon-micromachined waveguides are combined with silicon germanium (SiGe) monolithic microwave integrated circuits (MMICs) for the first time. All features of the integration platform lie in the waveguide’s H-plane. Heterogeneous integration of SiGe chips is achieved using a novel in-line H-plane transition. As an initial step toward complete systems, we outline the design, fabrication, and assembly of back-to-back transition structures, for use at D-band frequencies (110ï¿œ170 GHz). Special focus is given to the industrial compatibility of all components, fabrication, and assembly processes, with an eye on the future commercialization of THz systems. Prototype devices are assembled via two distinct processes, one of which utilizes semiautomated die-bonding tools. Positional and orientation tolerances for each process are quantified. An accuracy of $\pm \text3.5\; μ \textm$, $\pm \text1.5 °$ is achieved. Measured $S$-parameters for each device are presented. The insertion loss of a single-ended transition, largely due to MMIC substrate losses, is 4.2ï¿œ5.5 dB, with a bandwidth of 25 GHz (135ï¿œ160 GHz). Return loss is in excess of 5 dB. Measurements confirm the excellent repeatability of the fabrication and assembly processes and, thus, their suitability for use in high-volume applications. The proposed integration concept is highly scalable, permitting its usage far into the THz frequency spectrum. This article represents the first stage in the shift to highly compact, low-cost, volume-manufacturable THz waveguide systems.
|
|
| 3. |
- de Graauw, Th., et al.
(författare)
-
The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI)
- 2010
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518, s. L6-
-
Tidskriftsartikel (refereegranskat)abstract
- Aims: This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI) that was launched onboard ESA's Herschel Space Observatory in May 2009. Methods: The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480-1250 GHz with SIS mixers and the 1410-1910 GHz range with hot electron bolometer (HEB) mixers. The local oscillator (LO) subsystem comprises a Ka-band synthesizer followed by 14 chains of frequency multipliers and 2 chains for each frequency band. A pair of auto-correlators and a pair of acousto-optical spectrometers process the two IF signals from the dual-polarization, single-pixel front-ends to provide instantaneous frequency coverage of 2 × 4 GHz, with a set of resolutions (125 kHz to 1 MHz) that are better than 0.1 km s-1. Results: After a successful qualification and a pre-launch TB/TV test program, the flight instrument is now in-orbit and completed successfully the commissioning and performance verification phase. The in-orbit performance of the receivers matches the pre-launch sensitivities. We also report on the in-orbit performance of the receivers and some first results of HIFI's operations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
|
|
| 4. |
- Hassona, Ahmed Adel, 1988, et al.
(författare)
-
A non-galvanic D-band MMIC-to-waveguide transition using eWLB packaging technology
- 2017
-
Ingår i: 2017 IEEE MTT-S International Microwave Symposium (IMS). - : Institute of Electrical and Electronics Engineers (IEEE). - 0149-645X. - 9781509063604 ; , s. 510-512
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a novel D-band interconnect implemented in a low-cost embedded Wafer Level Ball Grid Array (eWLB) commercial process. The non-galvanic transition is realized through a slot antenna directly radiating to a standard air filled waveguide. The interconnect achieves low insertion loss and relatively wide bandwidth. The measured average insertion loss is 3 dB across a bandwidth of 22% covering the frequency range 110138 GHz. The measured average return loss is -10 dB across the same frequency range. Adopting the low-cost eWLB process and standard waveguides makes the transition an attractive solution for interconnects beyond 100 GHz. This solution enables mm-wave system on chip (SoC) to be manufactured and assembled in high volumes cost effectively. To the authors' knowledge, this is first attempt to fabricate a packaging solution beyond 100 GHz using eWLB technology.
|
|
| 5. |
- He, Zhongxia Simon, 1984, et al.
(författare)
-
A Hardware Efficient Implementation of a Digital Baseband Receiver for High-Capacity Millimeter-Wave Radios
- 2015
-
Ingår i: IEEE transactions on microwave theory and techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 63:5, s. 1683-1692
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents an implementation solution for a digital baseband receiver, which consists mainly of an analog symbol timing recovery (STR) block and a digital carrier recovery block. The STR is realized based on "one-sample-per-symbol" sampling, resulting in relaxed requirement on the A/D converters sampling speed. In this sense, the proposed implementation solution is hardware efficient. To functionally verify the solution, a proof-of-concept E-band link system is implemented and tested in the laboratory, which supports 5-Gbit/s data traffic using 16 quadrature amplitude modulation. The test results demonstrate that the proposed solution works for high-capacity millimeter-wave radios for point-to-point links, one of the targeted applications.
|
|
| 6. |
- Li, Y., et al.
(författare)
-
D-band SiGe transceiver modules based on silicon-micromachined integration
- 2019
-
Ingår i: Asia-Pacific Microwave Conference Proceedings, APMC. - : Institute of Electrical and Electronics Engineers (IEEE). ; 2019-December, s. 883-885
-
Konferensbidrag (refereegranskat)abstract
- This paper reports on 130 GHz transceiver modules consisting of integrated multi-functional chipsets in a commercial 130nm SiGe BiCMOS process. The interconnect between the chipset and the package is non-galvanic and is realized in silicon micromachining technique. After successful fabrication and assembly, the individual Tx and Rx modules as well as the combined Tx-Rx link were tested using CW signals. Then realtime data transport over the link were carried out using different modulation formats and bandwidths. With 16QAM over a 750 MHz channel a 2.66 Gbit/s data rate was demonstrated with BER<10-11. These tests show that the D-band modules, obtained in a single implementation trial, work well functionally. The interconnect method is applicable to the full D-band and expected to also support frequencies in the sub-millimeter-wave range where traditional methods become challenging to apply.
|
|
| 7. |
- Fhager, Andreas, 1976, et al.
(författare)
-
Microwave Technology in Medical Diagnostics and Treatment
- 2015
-
Ingår i: 2015 Ieee Mtt-S International Microwave Workshop Series on Rf and Wireless Technologies for Biomedical and Healthcare Applications. - New York : Ieee. - 9781479985432 ; , s. 133-134
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- There is a great need for novel diagnostics and treatment tools in today's healthcare. In this paper we describe our development and progress in novel microwave based diagnostics and treatment applications. The target applications are stroke diagnostics, breast cancer detection and microwave hyperthermia.
|
|
| 8. |
- Persson, Mikael, 1959, et al.
(författare)
-
Microwave based diagnostics and treatment in practice
- 2013
-
Ingår i: 2013 IEEE MTT-S International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications, IMWS-BIO 2013 - Proceedings.
-
Konferensbidrag (refereegranskat)abstract
- Globally, around 15 million people each year suffer a stroke. Only a small fraction of stroke patients who could benefit from thrombolytic treatment reach diagnosis and treatment in time. To increase this low figure we have developed microwave technology aiming to differentiate hemorrhagic from ischemic stroke patients. The standard method for breast cancer diagnosis today is X-ray mammography. Despite its recognized ability to detect tumors it suffers from some limitations. Neither the false positive nor the false negative detection rates are negligible. An interesting alternative being researched extensively today is microwave tomography. In our current strive to develop a clinical prototype we have found that the most suitable design consists of an antenna array placed in a full 3D pattern. During the last decade clinical studies have demonstrated the ability of microwave hyperthermia to dramatically enhance cancer patient survival. The fundamental challenge is to adequately heat deep-seated tumors while preventing surrounding healthy tissue from undesired heating and damage. We are specifically addressing the challenge to deliver power levels with spatial control, patient treatment planning, and noninvasive temperature measurements. © 2013 IEEE.
|
|
| 9. |
- Chen, Jingjing, 1982, et al.
(författare)
-
10 Gbps 16QAM transmission over a 70/80 GHz (E-band) radio test-bed
- 2012
-
Ingår i: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 7th European Microwave Integrated Circuits Conference, EuMIC 2012. - : IEEE. - 9782874870286 - 9781467323024 - 9782874870262 ; , s. 556-559
-
Konferensbidrag (refereegranskat)abstract
- A millimeter-wave radio test-bed is implemented which demonstrates 16QAM transmission over 70/80 GHz band for data rate up to 10 Gbps. Performance of the 16QAM transmitter and receiver is evaluated in a loop-back lab set-up. With the proposed 10 Gbps on single carrier system architecture, it is possible to achieve 40 Gbps over a 5 GHz bandwidth when combined with polarization and spatial multiplexing.
|
|
| 10. |
- Ejebjörk, Niclas, 1984, et al.
(författare)
-
Optimization of SiC MESFET for high power and high frequency applications
- 2011
-
Ingår i: Materials Science Forum. - : Trans Tech Publications Inc.. - 1662-9752 .- 0255-5476. ; 679-680, s. 629-632, s. 629-632
-
Konferensbidrag (refereegranskat)abstract
- SiC MESFETs were scaled both laterally and vertically to optimize high frequency and high power performance. Two types of epi-stacks of SiC MESFETs were fabricated and measured. The first type has a doping of 3×10^17 cm-3 in the channel and the second type has higher doping (5×10^17 cm-3) in the channel. The higher doping allows the channel to be thinner for the same current density and therefore a reduction of the aspect ratio is possible. This could impede short channel effects. For the material with higher channel doping the maximum transconductance is 58 mS/mm. The maximum current gain frequency, fT, and maximum frequency of oscillation, fmax, is 9.8 GHz and 23.9 GHz, and 12.4 GHz and 28.2 GHz for the MESFET with lower doped channel and higher doping, respectively.
|
|
