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ABSTRACT: This paper presents the study and development of an electrical energy monitoring system, consisting of a digital energy meter, a supervisor and manager software, and a database to store the measurements. Algorithms of calculus are proposed for implementation in meter. Physical environment and communication protocol are also proposed. Programming languages are studied and used to develop the software and database
Industrial Electronics, 2006 IEEE International Symposium on; 08/2006
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ABSTRACT: The utilisation of progressively thinner wafers for solar cells leads to an increasing importance of rear surface passivation. In this work we investigate different solar cell processes for industrial rear side passivated solar cells using silicon nitride (SiN) on both sides and screen printed contacts. All solar cells were made by phosphorus emitter diffusion on p-type wafers. For a sufficient rear surface passivation, a parasitic rear emitter must be avoided. Therefore, we carefully compared different processes comprising rear SiN as barrier during phosphorus diffusion as well as parasitic emitter removal by etching after phosphorus diffusion. Furthermore two processes for rear side contacting through a silicon nitride layer were tested. The first process is firing of a screen printed aluminium grid through the backside SiN. The second process uses laser ablation to open a thick rear SiN followed by a full area screen printed rear contact. Additionally, a possible degradation of the SiN due to firing of aluminium contact fingers through the SiN layer was investigated using minority carrier lifetime topography before and after firing of the wafers. Efficiencies of up to 14.7 % were obtained on 200 mum thick wafers using SiN layers on both sides. However, these processes are still excelled by the conventional solar cell process using a screen printed full area aluminium rear contact, which lead to an efficiency of 15.3 % on a 200 mum thick neighbouring wafer
Photovoltaic Energy Conversion, Conference Record of the 2006 IEEE 4th World Conference on; 06/2006
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O. Kappeler,
R. Quay,
F. van Raay,
R. Kiefer,
R. Reiner,
H. Walcher, S. Muller,
M. Mikulla,
M. Schlechtweg,
G. Weimann,
D. Wiegner,
U. Seyfried,
W. Tempi
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ABSTRACT: This work describes the operation of AlGaN/GaN HEMTs on s.i. SiC substrate in a broadband AlGaN/GaN push-pull amplifier for 3G/4G infrastructure applications between between 1.8 GHz and 2.2 GHz. The device yields linear gain of 12.9 dB, a 3 dB bandwidth of 400 MHz between 1.8 GHz and 2.2 GHz, and a maximum output power of 102 W at 1.95 GHz under single carrier 16 channel W-CDMA conditions. Linearity evaluation further yields a peak output power of 45 dBm for an ACLR of -45 dBc at 5 MHz offset at 1.95 GHz
Electron Devices Meeting, 2005. IEDM Technical Digest. IEEE International; 01/2006
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F. van Raay,
R. Quay,
R. Kiefer,
W. Fehrenbach,
W. Bronner,
M. Kuri,
F. Benkhelifa,
H. Massler, S. Muller,
M. Mikulla,
M. Schlechtweg,
G. Weimann
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ABSTRACT: A two-stage high-power amplifier MMIC was realized with a chip size of 4.5 mm /spl times/ 3 mm operating between 8 GHz and 10 GHz based on a fully integrated microstrip AlGaN/GaN HEMT technology on s.i. SiC substrate. The MMIC device delivers a maximum pulsed output power of 8.9 W (39.5 dBm) at 8.5 GHz at V/sub DS/ = 31 V, 10 % duty cycle, and more than 6 dB gain compression level, and features a linear gain in excess of 20 dB.
Gallium Arsenide and Other Semiconductor Application Symposium, 2005. EGAAS 2005. European; 11/2005
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ABSTRACT: In this paper the MMIC technology, design and characterization of a high power amplifier and driver amplifier MMIC at 30 GHz in AlGaN/GaN HEMT technology are presented. The MMICs are designed using CPW technology on a 390 /spl mu/m thick SiC substrate. The measured small-signal gain of the driver is 14 dB at 28.5 GHz and the measured output power is 28.6 dBm at 28 GHz. The power amplifier shows a measured small-signal gain of 10.7 dB at 25.5 GHz and output power of 34.1 dBm at 27 GHz. Both MMICs have a very good yield and performance for a first iteration design.
Gallium Arsenide and Other Semiconductor Application Symposium, 2005. EGAAS 2005. European; 11/2005
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ABSTRACT: Broadband microstrip and coplanar MMIC amplifiers featuring beyond 10 W for X-band radar applications are realized in a AlGaN/GaN HEMT technology on 2" s.i. SiC substrate. Single-stage and dual-stage demonstrators with flat gain from 1 GHz to 2.7 GHz and up to 40 W peak power in hybrid microstrip technology for basestation applications are presented. The performance illustrates the potential of this technology with very high bandwidth and superior power density in comparison to GaAs.
Gallium Arsenide and Other Semiconductor Application Symposium, 2005. EGAAS 2005. European; 11/2005
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F. van Raay,
R. Quay,
R. Kiefer,
F. Benkhelifa,
B. Raynor,
W. Pletschen,
M. Kuri,
H. Massler, S. Muller,
M. Dammann,
M. Mikulla,
M. Schlechtweg,
G. Weimann
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ABSTRACT: This work presents a two-stage high-power amplifier monolithic microwave integrated circuit (MMIC) operating between 9 GHz and 11 GHz based on a fully integrated AlGaN/GaN high electron mobility transistor (HEMT) technology on s.i. SiC substrate and is suitable for radar applications. The MMIC device with a chip size of 4.5×3 mm<sup>2</sup> yields a linear gain of 20 dB and a maximum pulsed saturated output power of 13.4 W at 10 GHz equivalent to 3.3 W/mm at V<sub>DS</sub>=35V, 10% duty cycle, and a gain compression level of 5 dB. Further, dc reliability data are given for the MMIC HEMT technology.
IEEE Microwave and Wireless Components Letters 08/2005; · 1.72 Impact Factor
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ABSTRACT: A tunable broadband inverted microstrip line phase shifter filled with Liquid Crystals (LCs) is investigated between 1.125 GHz and 35 GHz at room temperature. The effective dielectric anisotropy is tuned by a DC-voltage of up to 30 V. In addition to standard LCs like K15 (5CB), a novel highly anisotropic LC mixture is characterized by a resonator method at 8.5 GHz, showing a very high dielectric anisotropy Δn of 0.32 for the novel mixture compared to 0.13 for K15. These LCs are filled into two inverted microstrip line phase shifter devices with different polyimide films and heights. With a physical length of 50 mm, the insertion losses are about 4 dB for the novel mixture compared to 6 dB for K15 at 24 GHz. A differential phase shift of 360° can be achieved at 30 GHz with the novel mixture. The figure-of-merit of the phase shifter exceeds 110°/dB for the novel mixture compared to 21°/dB for K15 at 24 GHz. To our knowledge, this is the best value above 20 GHz at room temperature demonstrated for a tunable phase shifter based on nonlinear dielectrics up to now. This substantial progress opens up totally new low-cost LC applications beyond optics.
Microwave Symposium Digest, 2004 IEEE MTT-S International; 07/2004
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R. Quay,
A. Tessmann,
R. Kiefer,
R. Weber,
F. van Raay,
M. Kuri,
M. Riessle,
H. Massler, S. Muller,
M. Schlechtweg,
G. Weimann
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ABSTRACT: The operation of AlGaN/GaN HEMTs on SiC substrate at V-band frequencies (50-75 GHz) is discussed. Both common source and dual-gate AlGaN/GaN HEMTs on SiC substrate are optimized and investigated by active and passive load-pull measurements. At 60 GHz, a power density of ≥0.5 W/mm can be measured for a small common source AlGaN/GaN HEMT limited so far by the available input power of the newly developed load-pull system. A common source HEMT with W<sub>g</sub>=0.18 mm yields a power density of 1.9 W/mm at 40 GHz and a linear power gain of ≥5 dB at 60 GHz, while several dual-gate AlGaN/GaN HEMTs of W<sub>g</sub>=0.18 mm and 0.36 mm yield MSG/MAG values ≥12 dB at 60 GHz.
Electron Devices Meeting, 2003. IEDM '03 Technical Digest. IEEE International; 01/2004
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ABSTRACT: The present paper presents the preliminary results of a research aiming at evaluating the potential of knowledge-based approaches for the interpretation of low-resolution satellite images. This work applies a knowledge-based image interpretation system, so-called GEOAIDA, developed at the University of Hannover, Germany, which hires semantic networks and external operators to model the knowledge basis as well as takes advantage of additional data from geographic information systems, GIS. GEOAIDA is used to perform automatically the post-editing, one of the steps of visual interpretation, aiming at mimicking the reasoning of a trained photo-interpreter when he refines the result of a pixel classification procedure. The results obtained hitherto show that the use of knowledge-based approaches for this purpose is promising and, in the future, can be used to automate the post-editing.
Geoscience and Remote Sensing Symposium, 2003. IGARSS '03. Proceedings. 2003 IEEE International; 08/2003
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ABSTRACT: The operation of AlGaN/GaN HEMTs on SiC in the Ka-band is analyzed with respect to the achievable output power between 35 GHz and 40 GHz. 150 nm gate length AlGaN/GaN HEMTs are investigated by active load-pull measurements. Further, small-signal and noise analysis are performed with regard to the use at Ka-band and robust receiver applications.
Electron Devices Meeting, 2002. IEDM '02. International; 01/2003
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R. Kiefer,
R. Quay, S. Muller,
K. Kohler,
F. van Raay,
B. Raynor,
W. Pletschen,
H. Massler,
S. Ramberger,
M. Mikulla,
G. Weimann
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ABSTRACT: A 0.15 μm T-gate AlGaN/GaN-HEMT 2-inch technology has been developed. Transistors with 120 μm gatewidth show a peak transconductance of 300 mS/mm and cut-off frequencies f<sub>t</sub> and f<sub>max</sub> of 65 GHz and 149 GHz, respectively. Large periphery 720 μm gatewidth devices are capable of CW operation up to 40 GHz yielding an output power of 0.91 W and a linear gain of 6 dB at 35 GHz. To the authors' knowledge these results represent the highest absolute power level so far achieved with a GaN-HEMT in the Ka-band.
High Performance Devices, 2002. Proceedings. IEEE Lester Eastman Conference on; 09/2002
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ABSTRACT: Tapered power laser amplifiers have a wide range of applications such as in free space communication. In an optical intersatellite communication system based on the coherent transmission scheme, a narrow linewidth 1064 nm Nd:YAG laser in combination with a phase modulator acts as the coherent optical source. A tapered power InGaAs-AlGaAs MQW laser amplifier chip for the wavelength of 1064 nm was developed to boost the optical output power to the watt level. We show the amplifier device fabrication and characterisation and the first steps to space qualification
Lasers and Electro-Optics Society Annual Meeting, 1998. LEOS '98. IEEE; 01/1999
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ABSTRACT: The realization of high-power tapered amplifiers at 1064 nm on a low-modal gain structure is presented. More than 1.5-W continuous-wave optical output power at 3-A injection current is achieved with only 13-mW input optical power and a near-diffraction-limited output beam quality. The use of a low-modal gain structure in conjunction with a very low AR-coating value avoids the addition of cavity spoilers. The implementation of such amplifiers in an optical intersatellite communication system is studied. The devices showed excellent resistance to 160-krad proton irradiation. Preliminary aging tests on broad-area laser diodes demonstrate extrapolated lifetimes as long as 20000 h at 50/spl deg/C.
IEEE Photonics Technology Letters 12/1998; · 2.19 Impact Factor
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ABSTRACT: The simulation of power semiconductor devices is faced with
several problems that are not usually found in VLSI device modeling: the
huge and often complicated structures, the interaction with external
circuit environment, the effects of surface phenomena, etc. The large
variety of device structures and the lack of compact circuit models
makes TCAD very important for the design and optimization of these
devices
Electron Devices Meeting, 1993. IEDM '93. Technical Digest., International; 01/1994
