| 1. |
- Amirmazlaghani, Mina, 1984, et al.
(författare)
-
Graphene-Si Schottky IR Detector
- 2013
-
Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 49:7, s. 589-594
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports on photodetection properties of graphene-Si schottky junction by measuring current-voltage characteristics under 1.55µm excitation laser. The measurements have been done on a junction fabricated by depositing mechanically exfoliated natural graphite on top of the pre-patterned silicon substrate. The electrical Schottky barrier height is estimated to be (0.44-0.47) eV with a minimum responsivity of 2.8mA/W corresponding to an internal quantum efficiency of 10% which is almost an order of magnitude larger than regular Schottky junctions. A possible explanation for the large quantum efficiency related to the 2-D nature of graphene is discussed. Large quantum efficiency, room temperature IR detection, ease of fabrication along with compatibility with Si devices can open a doorway for novel graphene-based photodetectors.
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| 2. |
- ANDERSSON, MICHAEL, 1988, et al.
(författare)
-
10 dB small-signal graphene FET amplifier
- 2012
-
Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 48:14, s. 861-863
-
Tidskriftsartikel (refereegranskat)abstract
- Reported is the realisation of a graphene FET microwave amplifier operating at 1 GHz, exhibiting a small-signal power gain of 10 dB and a noise figure of 6.4 dB. The amplifier utilises a matching inductor on the gate yielding a return loss of 20 dB. The design is optimised for maximum gain and the optimum noise figure is extracted by noise modelling and predicted to be close to 1 dB for the intrinsic graphene FET at this frequency. The presented results complement existing graphene FET applications and are promising for future graphene microwave circuits.
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| 3. |
- ANDERSSON, MICHAEL, 1988, et al.
(författare)
-
Noise Figure Characterization of a Subharmonic Graphene FET Mixer
- 2012
-
Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781467310871
-
Konferensbidrag (refereegranskat)abstract
- We report on the first room temperature noise figure measurement of a graphene FET subharmonic resistive mixer in the interval fRF = 2-5 GHz. Due to an 8 nm thin Al2O3 gate dielectric it can operate with a conversion loss in the range 20-22 dB at only 0 dBm of local oscillator power. The measurement yields a noise figure close to the conversion loss, thus determining the noise to be thermal in origin, which is promising for cryogenic applications. The general route to lower noise figure is an improvement of the conversion loss.
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| 4. |
- ANDERSSON, MICHAEL, 1988, et al.
(författare)
-
Resistive Graphene FET Subharmonic Mixers: Noise and Linearity Assessment
- 2012
-
Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 60:12, s. 4035-4042
-
Tidskriftsartikel (refereegranskat)abstract
- We report on the first complete RF characterization of graphene field-effect transistor subharmonic resistive mixers in the frequency interval 2–5 GHz. The analysis includes conversion loss (CL), noise figure (NF), and intermodulation distortion. Due to an 8-nm thin Al2O3 gate dielectric, the devices operate at only 0 dBm of local oscillator (LO) power with an optimum measured CL in the range of 20–22 dB. The NF closely mimics the CL, thus determining the noise to be essentially thermal in origin, which is promising for cryogenic applications. The highest input third-order intercept point is measured to be 4.9 dBm at an LO power of 2 dBm.
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| 5. |
|
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| 6. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
A novel catadioptric dielectric lens for microwave and terahertz applications
- 2008
-
Ingår i: Microwave and Optical Technology Letters. - : Wiley. - 1098-2760 .- 0895-2477. ; 50:2, s. 416-419
-
Tidskriftsartikel (refereegranskat)abstract
- A novel dielectric catadioptric lens, suitable for near-field sensing and imaging, is presented. The focusing property and the far-field pattern of the lens are investigated using a 3D full-wave electromagnetic solver. Furthermore, the proposed catadioptric lens has been designed and fabricated from Delrin. Simulations and measurements of the far-field at 5 GHz and return loss versus frequency using a Bow-tie slot feeding antenna are presented.
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| 7. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
Catadioptric Dielectric Lens for Imaging Applications
- 2008
-
Ingår i: Proceedings of 33rd International Conference on Infrared, Millimeter, and Terahertz Waves. - 9781424421190 ; , s. 1 - 2
-
Konferensbidrag (refereegranskat)abstract
- The design and characterization results of a novel catadioptric dielectric lens are presented. Although being electrically small, the lens provides a focus in the close vicinity which makes it suitable to be used in microwave and terahertz systems. Several lenses of different dielectric materials and dimensions have been fabricated. A simple backscattering measurement method has been implemented in order to determine the focusing property of the lens.
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| 8. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
Design of Antenna Integrated Photomixers and Catadioptric Lenses for Emerging THz Applications
- 2008
-
Ingår i: 2008 ANSYS Regional Conference.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We will present design and modeling of antenna integrated photomixers for terahertz generation. In addition, the design and the quasioptical integration a novel catadioptric dielectric lens, suitable for imaging applications, will be presented. Although having a tremendous potential, the terahertz (0.1 – 10 THz) regime in the frequency spectrum and its applications are hindered due to the lack of viable and high power terahertz sources. This has led to the term “terahertz gap” being coined. We aim to construct compact sources utilizing the lens-coupled antenna-integrated photomixer sources based on Uni-Travelling-Carrier Photomixers (UTC-PD). These sources are one of the key components which could significantly bridge the terahertz gap.However, optimization of the epitaxial layer structure of the UTC-PD is necessary for high-power THz generation. The epilayers of the UTC-PD is designed and optimized in TCAD. Antennas are designed using HFSS while the impedance of the antenna at a specific bandwidth from HFSS is used to optimize the UTC-PD epilayers and vice versa. Thus proper impedance match and therefore high power THz generation is possible.A novel catadioptric dielectric lens is designed and characterized using HFSS. The lens provides an alternative solution to be used as a focusing element and therefore suitable for imaging or similar applications.In fine, we aim to combine the photomixer source and the lens in order to attain compact but powerful THz sources.
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| 9. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
Development and Design of a 340 GHz Photomixer Source
- 2007
-
Ingår i: 18th International Symposium on Space THz Technology – ISSTT 2007.
-
Konferensbidrag (refereegranskat)abstract
- We present the design of an InGaAlAs/InP uni-traveling-carrier photo-diode (UTC-PD) at mm-wave frequencies up to 340 GHz. The photo diode epitaxy is optimized using a quasi-3D software implementing the hydrodynamic semiconductor equations, for which an output power of 3 mW at 340 GHz was simulated. An equivalent circuit of the UTC-PD has been fitted to experimental S11 measurements up to 67 GHz. Finally, an optimized antenna coupled UTC-PD with choke filter has been designed. This MMIC circuit is intended for photomixing, with output power at 340 GHz.
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| 10. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
High Power Photonic MW/THz Generation Using UTC-PD
- 2008
-
Ingår i: GigaHertz SympoSium 2008. ; , s. 45-
-
Konferensbidrag (refereegranskat)abstract
- The ongoing research work concentrates on extending the previously accomplished UTC-PD fabrication and modelling techniques to 340 GHz and above. We have fabricated and characterized UTC-PDs intended for high power MW/THz generation. Several integrated antenna-detector circuits have been designed and characterised.
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| 11. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
Microwave S-parameter Characterization of an Antenna-Coupled Catadioptric Lens
- 2009
-
Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 8, s. 1299-1301
-
Tidskriftsartikel (refereegranskat)abstract
- The focusing property of a bow-tie antenna coupled catadioptric lens is studied experimentally using a vector measurement setup. The results show that the lens-antenna provides short-range focusing. Furthermore, the return loss of the lens-antenna was determined numerically and confirmed experimentally from 1 GHz to 10 GHz. The lens-antenna provides 60% bandwidth (VSWR ≤ 2) centered at 6 GHz. Finally, the lens-antenna was employed to detect and locate buried objects and results are presented.
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| 12. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
Millimeter Wave Characterization of a Catadioptric Lens for Imaging Applications
- 2009
-
Ingår i: IEEE Microwave and Wireless Components Letters. - 1558-1764 .- 1531-1309. ; 19:11, s. 680-682
-
Tidskriftsartikel (refereegranskat)abstract
- Characterization of a catadioptric dielectric lens-horn configuration for short-range sensing and imaging is presented. The focusing property is investigated both numerically and experimentally at 108 GHz. The lens-horn provides a focal spot of ~ 0.9λ at a distance of ~ 4.5λ. An imaging example employing the lens in a CW imaging setup is presented. A test pattern was imaged and a marked improvement in image resolution was observed. With the aid of the lens, features close to the wavelength are resolved, which are absent or indistinguishable otherwise.
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| 13. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
Optimization of the UTC-PD Epitaxy for Photomixing at 340 GHz
- 2008
-
Ingår i: International Journal of Infrared and Millimeter Waves. - : Springer Science and Business Media LLC. - 0195-9271 .- 1572-9559. ; 29:10, s. 914-923
-
Tidskriftsartikel (refereegranskat)abstract
- We present a method to optimize the epitaxial layer structure of an InGaAs/InP uni-traveling-carrier photo-diode (UTC-PD) for continuous THz-wave generation. The design approach used is general in that it can be applied for any target frequency while this study focuses on 340 GHz. The photodiode epitaxy is modeled and optimized using a TCAD software implementing the hydrodynamic semiconductor equations. This physical device model was found to be in good agreement with reported experimental results. It is shown that the UTC-PD can generate ~1 mW at 340 GHz by choosing the optimum absorption layer and collection layer thicknesses.
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| 14. |
- Banik, Biddut Kumar, 1978, et al.
(författare)
-
UTC-PD Integration for Submillimetre-wave Generation
- 2008
-
Ingår i: 19th International Symposium on Space Terahertz Technology, ISSTT 2008; Groningen; Netherlands; 28 April 2008 through 30 April 2008. ; , s. P7-1, 135
-
Konferensbidrag (refereegranskat)abstract
- Because of the inherent difficulty to generate power in the frequency range 0.l-10 THz, the term 'THzgap' has been coined. Among a number of MW/THz generation techniques, the photomixer based sources hold high potential offering wide tunability and decent amounts of output power. The photomixing technique relies on the nonlinear mixing of two closely spaced laser wavelengths generating a beat oscillation at the difference frequency. In recent years, there has been an increasing interest in the Uni-Travelling-Carrier PhotoDiode (UTCPD) [1] for photomixing, photo receivers, MW/THz-wave generation, fibre-optic communication systems, and wireless communications. UTC-PDs have become very promising by demonstrating output powers of 20 mW at 100 GHz [1] and 25 μW at 0.9 THz [2].
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| 15. |
- Barrientos, C. Z., et al.
(författare)
-
Vertically illuminated TW-UTC photodiodes for terahertz generation
- 2010
-
Ingår i: 21st International Symposium on Space Terahertz Technology 2010, ISSTT 2010; Oxford; United Kingdom; 23 March 2010 through 25 March 2010. - 9781617823626 ; , s. 405-408
-
Konferensbidrag (refereegranskat)abstract
- More efficient continuous-wave photonic nearinfrared mixers as terahertz sources are investigated with the motivation to develop a universal photonic local oscillator for astronomical submillimeter/terahertz receiver systems. For this, our group has developed new concepts for vertically illuminated traveling-wave (TW) photomixers. The new device called TWUni- Travelling Carrier photodiodes (TW-UTC PD) was simulated, modeled and shall be optical/terahertz tested at the Electrical Engineering Department of the University of Chile, whereas device fabrication is performed at the MC2 cleanroom facility at Chalmers University of technology. We are reporting on first progresses in this direction.
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| 16. |
- Barrientos Z, C. M., et al.
(författare)
-
Vertically illuminated TW-UTC photodiodes for terahertz generation
- 2012
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819491534 ; 8452
-
Konferensbidrag (refereegranskat)abstract
- More efficient and powerful continuous-wave photonic mixers as terahertz sources are motivated by the need of more versatile local oscillators for submillimeter/terahertz receiver systems. Uni-Travelling Carrier (UTC) photodiodes are very prospective candidates for reaching this objective, but so far only have been reported as lumped-elements or as edge-illuminated optical-waveguide travelling-wave (TW) devices. To overcome the associated power limitations of those implementations, we are developing a novel implementation of the UTC photodiodes which combines a traveling-wave photomixer with vertical velocity-matched illumination in a distributed structure. In this implementation called velocity-matched travelling-wave uni-travelling carrier photodiode, it is possible to obtain in-situ velocity matching of the beat-fringes of the two angled laser beams with the submm/THz-wave on the stripline. In this way, minimum frequency roll-off is achieved by tuning the angle between the two laser beams. A first design of these TW-UTC PDs from our Terahertz Photonics Laboratory at University of Chile has been micro-fabricated at the MC2 cleanroom facility at Chalmers Technical University.
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| 17. |
- Barrientos Z, C. M., et al.
(författare)
-
Vertically illuminated TW-UTC photodiodes for terahertz generation
- 2010
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819482310 ; 7741
-
Konferensbidrag (refereegranskat)abstract
- More efficient continuous-wave photonic nearinfrared mixers as terahertz sources are investigated with the motivation to develop a universal photonic local oscillator for astronomical submillimeter/terahertz receiver systems. For this, we develop new concepts for vertically illuminated traveling-wave (TW) photomixers, TW Uni-Travelling Carrier (UTC) photodiodes. Device simulation/modeling and optical/terahertz testing is being done in the new terahertz photonics laboratory at the Electrical Engineering Department of the University of Chile, whereas device fabrication is performed at the MC2 cleanroom facility at Chalmers Technical University. We report on first progress in this direction.
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| 18. |
- Blomberg, Patrik, 1992, et al.
(författare)
-
On-wafer characterisation of resonant-tunnelling diodes up to 1.1 THz
- 2023
-
Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035.
-
Konferensbidrag (refereegranskat)abstract
- This paper presents on-wafer S-parameter characterisation of resonant-tunnelling diodes between 0.5 THz and 1.1 THz. Diodes with a peak current density of 532 kA/cm2 and a clear negative differential region have been fabricated. An on-chip Multi-Thru-Reflect-Line calibration kit was developed and utilised to achieve accurate S-parameter measurements up to 1.1 THz.
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| 19. |
- Bryllert, Tomas, et al.
(författare)
-
11% efficiency 100 GHz InP-based heterostructure barrier varactor quintupler
- 2005
-
Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 0013-5194 .- 1350-911X. ; 41:3, s. 131-132
-
Tidskriftsartikel (refereegranskat)abstract
- A record conversion efficiency of 11.4% at 100 GHz using a heterostructure barrier varactor (HBV) quintupler is demonstrated. The quintupler is based on a microstrip circuit mounted in a full-height crossed-waveguide block. The nonlinear element consists of a planar HBV diode fabricated in InGaAs=InAlAs=AlAs epitaxial layers on an InP substrate.
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| 20. |
- Bryllert, Tomas, 1974, et al.
(författare)
-
A 175 GHz HBV Frequency Quintupler With 60 mW Output Power
- 2012
-
Ingår i: IEEE Microwave and Wireless Components Letters. - 1558-1764 .- 1531-1309. ; 22:2, s. 76-78
-
Tidskriftsartikel (refereegranskat)abstract
- In this letter, we present a fixed tuned 175 GHz frequency quintupler with 60 mW output power. The peak efficiency is 6.3% and the 3 dB bandwidth is 8 GHz. The multiplier is based on a single Heterostructure Barrier Varactor (HBV) diode that is flip-chip soldered into a microtsrip matching circuit. All the matching is done “on-chip” and there is no need for dc bias. The multiplier block is very compact (25 x 9 x 8 mm^3).
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| 21. |
- Bryllert, Tomas, 1974, et al.
(författare)
-
A broadband heterostructure barrier varactor tripler source
- 2010
-
Ingår i: 2010 IEEE MTT-S International Microwave Symposium (MTT). - 0149-645X. - 9781424460571 ; , s. 344-347
-
Konferensbidrag (refereegranskat)abstract
- We present the first demonstration of a broadband Heterostructure Barrier Varactor tripler, designed to cover a major part of the WR-8 waveguide band. The source comprises a waveguide housing, a six-barrier InP-HBV diode flip-chip mounted on an AlN microstrip filter circuit. The conversion loss 3-dB bandwidth was measured to 17 % at a center frequency of 112 GHz. The maximum output power was more than 15 mW for an input power of 300 mW. There are no mechanical tuners or DC-bias, which simplifies assembly and allows for ultra-compact design.
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| 22. |
- Bryllert, Tomas, 1974, et al.
(författare)
-
A High-Power Frequency Tripler for 100 GHz
- 2006
-
Ingår i: The Joint 31st International Conference on Infrared and Millimeter Waves and 14th International Conference on Terahertz Electronics. - 1424404002 ; , s. 30-
-
Konferensbidrag (refereegranskat)abstract
- We present a Heterostructure Barrier Varactor (HBV) based tripler for power generation at ~100 GHz. The matching circuit for the HBV diode is implemented in microstrip on an AlN substrate with the diode flip-chip soldered. The microstrip circuit is mounted in a waveguide configuration. To simplify the fabrication and assembly no DC ground is used and the waveguides are full-height. 130 mW of output power at 114 GHz is achieved without the use of any tuners.
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| 23. |
- Bryllert, Tomas, 1974, et al.
(författare)
-
A monolithic 280 GHz HBV frequency tripler
- 2010
-
Ingår i: IRMMW-THz 2010 - 35th International Conference on Infrared, Millimeter, and Terahertz Waves, Conference Guide. - 9781424466573
-
Konferensbidrag (refereegranskat)abstract
- We present the design and measurements of a Heterostructure Barrier Varactor based frequency tripler for 280 GHz. The tripler is fabricated as a monolithic circuit on an InP substrate, including the input and output waveguide probes. Several circuit versions for input power levels between 100 mW and 1W have been designed. © 2010 IEEE.
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| 24. |
|
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| 25. |
- Bryllert, Tomas, 1974, et al.
(författare)
-
High Power HBV Multipliers
- 2007
-
Ingår i: 18th International Symposium on Space THz Technology.
-
Konferensbidrag (refereegranskat)abstract
- We present a high-power frequency tripler for 100 GHz. The tripler - that is based on a single HBV diode - produces >200 mW of output power with a 3-dB bandwidth of 6%. This is the highest output power ever recorded for an HBV based multiplier irrespective of output frequency. The module features an ultra-compact waveguide block design and a microstrip matching circuit on high-thermal-conductivity AlN to improve the power handling capability.
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| 26. |
- Dahlbäck, Robin, 1985, et al.
(författare)
-
A compact 128-element Schottky diode grid frequency doubler generating 0.25 W of output power at 183 GHz
- 2017
-
Ingår i: IEEE Microwave and Wireless Components Letters. - 1558-1764 .- 1531-1309. ; 27:2, s. 162-164
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a compact varactor grid frequency doubler encapsulated in a waveguide environment, thus providing single mode (H₁₀) waveguide connection at both input and output. Schottky diodes are used as varactors in this 128-element grid frequency doubler. By packaging the grid and its embedding network together with a stepped waveguide taper on the output, a module measuring 9 mm x 19 mm by 19 mm is created. A peak output power of 0.25 W is produced at 183 GHz with 1.32 W of input power and a corresponding conversion efficiency of 19%. The peak conversion efficiency is 23% at 183 GHz with 666 mW of input power.
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| 27. |
- Dahlbäck, Robin, 1985, et al.
(författare)
-
A Tunable 240–290 GHz Waveguide Enclosed 2-D Grid HBV Frequency Tripler
- 2016
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 6:3, s. 503-509
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a high-power 240–290 GHz waveguide enclosed two-dimensional (2-D) grid heterostructure barrier varactor (HBV) frequency multiplier. A 35 mW of output power is produced at 247 GHz with an input power of 900 mW. The operational bandwidth is tunable within a 50 GHz span by the use of an input tuner able to adjust the input matching of the 2-D grid HBV frequency multiplier. Tuning is achieved by moving a suspended dielectric slab in the input waveguide.
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| 28. |
- Dahlbäck, Robin, 1985, et al.
(författare)
-
A Waveguide Embedded 250 GHz Frequency-Tripler 2D Array
- 2014
-
Ingår i: Micro-and Millimetre Wave Technology and Techniques Workshop 2014, 25-27 November 2014.
-
Konferensbidrag (refereegranskat)abstract
- This work reports on a 248 GHz HBV (Heterostructure Barrier Varactors)-varactor quasi-optical multiplier array with a maximum output power of 18 mW and a corresponding conversion efficiency of 2 %. The module utilizes a mechanically compact and simple shim system, combining the large array power handling capability with the convenience of waveguide interfaced circuits. At the same time this approach offers excellent power and frequency scalability. The multiplier is based on a 12 by 6 element, 72 in total, planar 2D HBV varactor array. The diodes are fabricated on a three barrier InGaAs/InAlAs material system on InP as carrier substrate. Easch diode consist of two 20um^2 serially connected mesas, yielding a total of six barrier per diode. The HBV diodes are coupled to a uniform dipole array through which the power is coupled in and out. One HBV diode and the corresponding dipole make up a square unit cell with a side of 211 um. The chip measures 2,54 x 1,27 mm^2, fitting inside a standard WR10 waveguide. The complete module consists of three parts, the 2D HBV array, a combined output filter and output matching slab and an input matching slab. A rhombic aperture frequency selective surface is used as the uutput bandpass filter and the quartz filter substrate also serves as a matching slab for the output tone. On the input a piece of InP substrate is used to match the incoming pump signal to the diodes. The components are mounted inside two WR-10 waveguide shims, providing an easy assembly and a modular system. The current version of the multiplier module produces 18 mW at 248 GHz but a significant increase in output power and efficiency is expected with a new output matching network and more pump power. Recent measurement results will be presented together with a detailed discussion regarding the design, pointing out advantages and challenges compared to more traditional approaches to frequency multiplier design in the frequency range. Future improvements and challenges will also be covered.
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| 29. |
- Dahlbäck, Robin, 1985, et al.
(författare)
-
A waveguide embedded 250 GHz quasi-optical frequency-tripler array
- 2014
-
Ingår i: 44th European Microwave Conference, EuMC 2014 - Held as Part of the 17th European Microwave Week, EuMW 2014; Fiera di RomaRome; Italy; 6 October 2014 through 9 October 2014. - 9782874870354 ; , s. 802-805
-
Konferensbidrag (refereegranskat)abstract
- A waveguide embedded 250 GHz HBV-varactor quasi-optical multiplier array is presented. The module utilizes a mechanically compact and simple shim system, combining the large array power handling capability with the convenience of waveguide interfaced circuits. At the same time this approach offers excellent power and frequency scalability. The current tripler prototype produces a non saturated output power of 8 mW at 248 GHz during initial measurements at medium pump power.
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| 30. |
- Dahlbäck, Robin, 1985, et al.
(författare)
-
Development of a waveguide integrated sub-millimetre wave spatially power combined HBV multiplier
- 2011
-
Ingår i: 6th ESA Workshop on Millimetre-Wave Technology and Applications and 4th Global Symposium on Millimeter Waves.
-
Konferensbidrag (refereegranskat)abstract
- The development of a sub-millimetre wave, spatially power combined, quasi optical HBV multiplier is presented. Emphasis is placed on key concepts of spatial power combining of frequency multipliers, as well as design challenges. The current state of the design as well as the final goal is further discussed.
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| 31. |
- Drakinskiy, Vladimir, 1977, et al.
(författare)
-
Reliability study of THz Schottky mixers and HBV frequency multipliers for space applications
- 2020
-
Ingår i: Proceedings of the 31st Symposium on Space Terahertz Technology, ISSTT 2020. ; , s. 118-
-
Konferensbidrag (refereegranskat)abstract
- We report status and current results of the preliminary reliability study on 300 GHz InP heterostructure barrier varactor diode multipliers and 1200 GHz GaAs Schottky diode mixers. Both types of diodes are monolithically integrated with circuits and were processed on 3" InP and GaAs wafers respectively using established III-V processing. We will present results on thermal step-stress tests up to 300oC, indicating the operational temperature limitations of the devices. Also, the analysis of the accelerated lifetime testing (1000h) will be discussed.
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| 32. |
- Emadi, Arezoo, 1977, et al.
(författare)
-
Design, Fabrication and characterisation of High Power HBV Diodes
- 2005
-
Ingår i: 16th International Symposium on Space Terahertz Technology; Chalmers Conference Centre, May 2-4, 2005, Gothenburg, Sweden, (Eds. Jan Stake, Harald Merkel.). ; , s. Session: P05-04
-
Konferensbidrag (refereegranskat)abstract
- We present design and analysis of material structures and device geometries for heterostructure barrier varactor diodes (HBVs) for high-power frequency multipliers. The methods aim at finding optimum epitaxial layer structures with respect to diode power handling capability and efficiency. A distributed device geometry for further increasing the output power levels whilst maintaining acceptable device temperatures is also presented. Finally, an electro-thermal HBV model with the ability of incorporating temperature-dependent device parameters is used to simulate the introduced devices, followed by a design example of a 3×4-barrier high-power HBV diode.
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| 33. |
- Emadi, Arezoo, 1977, et al.
(författare)
-
High power HBV multipliers for F- and G- band applications
- 2004
-
Ingår i: IRMMW 2004/THz 2004 / M. Thumm, W. Wiesbeck. - 0780384903 ; , s. 319-320
-
Konferensbidrag (refereegranskat)abstract
- Progress and realisation of applications in the 100-240 GHz region is inhibited by the lack of high-power sources. Therefore, in an effort to reach watts of output power, we have tailored devices, circuits, materials, and design and fabrication methods for improved thermal management and high overall conversion efficiencies.
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| 34. |
- Emadi, Arezoo, 1977, et al.
(författare)
-
Optimum Barrier Thickness Study for the Heterostructure Barrier Varactror Diode
- 2006
-
Ingår i: WOCSDICE 2006. - 1652-0769. ; , s. 55-57
-
Konferensbidrag (refereegranskat)abstract
- This experimental study aims at finding the optimum barrier thickness in heterostructure barrier varactor (HBV) diodes, to improve the diode efficiency especially for high-power frequency multiplier applications. The influence of barrier thickness on the conduction current is investigated for different biases and device temperatures. We found that for an InP-based HBV, there is an optimum barrier thickness range between 10 to 14 nm which causes the lowest possible leakage current.
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| 35. |
- Emadi, Arezoo, 1977, et al.
(författare)
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Optimum barrier thickness study for the InGaAs/InAlAs/AlAs heterostructure barrier varactor diodes
- 2007
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 90:1, s. 012108-3
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Tidskriftsartikel (refereegranskat)abstract
- This experimental study aims at finding the optimum barrier thickness in heterostructure barrier varactor (HBV) diodes to improve the diode efficiency especially for high-power frequency multiplier applications. The influence of barrier thickness on the destructive current leaking over and through the barrier is investigated for different biases and operating temperatures. The authors found that for an InP-based HBV, there is an optimum barrier thickness range between 10 to 14 nm which causes the lowest possible leakage current.
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| 36. |
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| 37. |
- Gustavsson, Johan, 1974, et al.
(författare)
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Mode and polarization control in VCSELs using shallow surface structures
- 2007
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Ingår i: IET Optoelectronics. ; 1:5, s. 197-205
-
Tidskriftsartikel (refereegranskat)abstract
- Monolithic techniques for mode and polarisation control in vertical-cavity surface emitting lasers (VCSELs) using shallow surface structures are summarized and put in the context with other techniques in terms of performance and manufacturability. The method of using circular-symmetric surface structures for mode control and their combination with a sub-wavelength surface grating for simultaneous mode and polarisation control is described in detail, and adherent experimental results for both 850-nm and 1.3-µm oxide-confined VCSELs are presented.
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| 38. |
- Habibpour, Omid, 1979, et al.
(författare)
-
A 30-GHz Integrated Subharmonic Mixer based on a Multichannel Graphene FET
- 2013
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 61:2, s. 841-847
-
Tidskriftsartikel (refereegranskat)abstract
- A 30 GHz integrated subharmonic mixer based on a single graphene field effect transistor (G-FET) has been designed, fabricated and characterized. The mixer is realized in microstrip technology on a 250 um high resistivity silicon substrate. In order to enhance the current on-off ratio, the G-FET utilizes a channel consisting of an array of bow-tie structured graphene, yielding a current on-off ratio of 7. A conversion loss (CL) of 19 ± 1 dB over the frequency range of 24 to 31 GHz is obtained with an LO to RF isolation better than 20 dB at an LO power of 10 dBm. The overall minimum CL is 18 dB at 27 GHz. The mixer has a 3 GHz ±1-dB IF bandwidth, which is achieved with a fixed LO signal of 15 GHz. The mixer linearity is characterized and the highest third order intercept point is measured to be 12.8 dBm.
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| 39. |
- Habibpour, Omid, 1979, et al.
(författare)
-
A Large Signal Graphene FET Model
- 2012
-
Ingår i: IEEE Transactions on Electron Devices. - 1557-9646 .- 0018-9383. ; 59:4, s. 968-975
-
Tidskriftsartikel (refereegranskat)abstract
- We propose a semiempirical graphene field effect transistor (G-FET) model for analysis and design of G-FET based circuits. The model describes the current-voltage characteristic for a G-FET over a wide range of operating conditions. The gate bias dependence of the output power spectrum is studied and compared with simulated values. A good agreement between the simulated and the experimental power spectrum up to the 3rd harmonic is demonstrated which confirms the model validity. Moreover, S-parameter measurements essentially coincide with the results obtained from the simulation. The model contains a small set of fitting parameters which can straightforwardly be extracted from S-parameters and DC measurements. The developed extraction method gives a more accurate estimation of the drain and source contact resistances compared to other approaches. As a design example, we use a harmonic-balance load-pull approach to extract optimum embedding impedances for a subharmonic G-FET mixer.
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| 40. |
- Habibpour, Omid, 1979, et al.
(författare)
-
A subharmonic graphene FET mixer
- 2012
-
Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 33:1, s. 71-73
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a subharmonic resistive graphene FET (G-FET) mixer utilizing the symmetrical channel resistance vs. gate voltage characteristic. A down-conversion loss of 24 dB is obtained with fRF=2 GHz, fLO=1.01 GHz and fIF=20 MHz in a 50 Ω impedance system. Unlike the conventional subharmonic resistive FET mixers, this type of mixer operates with only one transistor and does not need any balun at the LO port which makes it more compact.
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| 41. |
- Habibpour, Omid, 1979, et al.
(författare)
-
Characterisation of Exfoliated Graphene
- 2009
-
Ingår i: WOCSDICE 2009.
-
Konferensbidrag (refereegranskat)abstract
- High-frequency devices based on graphene is a promising field of research. In this paper we investigate two important parameters which based on theory are essential in order to have nonlinear responses in graphene. The first parameter is scattering time which should be as high as 1ps. Also the electrical field of the incident radiation should be higher a certain threshold in order to have nonlinear response. This threshold is generally quite high and increases with frequency and carrier density, so it is essential that graphene flake tolerate high electrical field. The first condition cannot be reached by graphene on SiO2/Si substrate according to ourinvestigation.
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| 42. |
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| 43. |
- Habibpour, Omid, 1979, et al.
(författare)
-
Mobility Improvement and Microwave Characterization of a Graphene Field Effect Transistor With Silicon Nitride Gate Dielectrics
- 2011
-
Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 32:7, s. 871-873
-
Tidskriftsartikel (refereegranskat)abstract
- We report on the influence of a silicon nitride gate dielectric in graphene-based field-effect transistors (FETs). The silicon nitride is formed by a plasma enhanced chemical vapor deposition method. The process is based on a low density plasma at a high pressure (1 torr), which results in a low degradation of the graphene lattice during the top-gate formation process. Microwave measurements of the graphene FET show a cutoff frequency of 8.8 GHz for a gate length of 1.3 μm. A carrier mobility of 3800 cm2/V · s at room temperature was extracted from the dc characteristic.
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| 44. |
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| 45. |
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| 46. |
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| 47. |
- Hanning, Johanna, 1981, et al.
(författare)
-
HBV MMIC frequency tripler and quintupler for high power THz applications
- 2011
-
Ingår i: Millimetre Wave Days Proceedings,The 6th ESA Workshop on Millimetre-Wave Technology and Applications AND The 4th Global Symposium on Millimeter Waves GSMM2011, May 23rd – May 25th, 2011, MilliLab, Espoo, Finland.
-
Konferensbidrag (refereegranskat)abstract
- We present the development status of two different HBV frequency multipliers, with x3 and x5 multiplication for a 282 GHz and 470 GHz output respectively. The multipliers are designed for high power operation and fabricated in an InP monolithic process. Preliminary measurements of the x3 multiplier demonstrate 10 % conversion efficiency at 296 GHz.
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| 48. |
- Ingvarson, Mattias, 1974, et al.
(författare)
-
An electro-thermal HBV model
- 2005
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Ingår i: IMS 2005. ; , s. 1151-1153
-
Konferensbidrag (refereegranskat)
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| 49. |
- Ingvarson, Mattias, 1974, et al.
(författare)
-
Thermal constraints for heterostructure barrier varactors
- 2004
-
Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 25:11, s. 713-715
-
Tidskriftsartikel (refereegranskat)abstract
- Current research on heterostructure barrier varactors (HBVs) devotes much effort to the generation of very high power levels in the millimeter wave region. One way of increasing the power handling capacity of HBVs is to stack several barriers epitaxially. However, the small device dimensions lead to very high temperatures in the active layers, deteriorating the performance. We have derived analytical expressions and combined those with finite element simulations, and used the results to predict the maximum effective number of barriers for HBVs. The thermal model is also used to compare the peak temperature and power handling capacity of GaAs and InP-based HBVs. It is argued that InP-based devices may be inappropriate for high-power applications due to the poor thermal conductivity of the InGaAs modulation layers.
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| 50. |
- Katona, Gergely, 1975, et al.
(författare)
-
Bayesian analysis of non-thermal structural changes induced by terahertz radiation in protein crystals
- 2016
-
Ingår i: 2016 41ST INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES (IRMMW-THZ). - New York : IEEE conference proceedings. - 2162-2027 .- 2162-2035. - 9781467384858
-
Konferensbidrag (refereegranskat)abstract
- We have periodically (25ms on - 25ms off) illuminated lysozyme crystals with 0.4 THz radiation and simultaneously monitored their X-ray diffraction intensity in order to study non-thermal structural changes in the protein. In this work we analyze the X-ray scaled and unmerged diffraction intensity observations using a multivariate Bayesian model in order to improve the accuracy of the intensity estimates. The diffraction intensity pairs of the illuminated and non-illuminated state show a predominantly positive correlation. The correlation decreases with increasing resolution suggesting that finer slicing and faster sampling of the rocking curve may further improve the accuracy and effect size of structure factor amplitude differences, making the interpretation of structural changes more straightforward. The improved analysis retains the most important structural features described previously (in helix 3) and provide addition details about the B-factor changes close to the substrate binding site.
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