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Computational load pull simulations of SiC microwave power transistors
FOI, Linköping.
Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
FOI, Linköping.
Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Electronic Devices.
2003 (English)In: Solid-State Electronics, ISSN 0038-1101, Vol. 47, no 11, 1921-1926 p.Article in journal (Refereed) Published
Abstract [en]

The design of power transistors for microwave applications requires a good understanding of their large signal behaviour in a real circuit context. The computational load-pull simulation technique is a powerful new way to evaluate the full time-domain voltages and currents of microwave power transistors during realistic operation. With this method it is possible to relate details in the time domain voltages and currents to corresponding variations in carrier densities, electrical field, etc. in the device. We have utilised the standard device simulator Medici, directly driven by sine voltage sources on both input and output. The resulting data from the simulations was then analysed using Matlab. Several 4H-SiC MESFET structures were evaluated by this technique and we found the p-type buffer layer doping and thickness to be crucial to obtain an optimum RF power. A 4H-SiC MESFET structure was found to have an output power of 6.2 W/mm at 1 GHz. ⌐ 2003 Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
2003. Vol. 47, no 11, 1921-1926 p.
Keyword [en]
Physical large signal modelling; Time-domain; Simulation; SiC; MESFET; Microwave; Load-pull
National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-34759DOI: 10.1016/S0038-1101(03)00251-XLocal ID: 23131OAI: diva2:255607
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2010-02-25
In thesis
1. Silicon Carbide Microwave Transistors and Amplifiers
Open this publication in new window or tab >>Silicon Carbide Microwave Transistors and Amplifiers
2005 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Ibis work deals with silicon carbide (SiC) metal semieonduetor field effect transistors (MESFETs) and microwave amplifiers using them. The wide bandgap (WBG) semiconductors silicon carbide and gallium nitride have a large potential for microwave power generation. The high power density combined with the comparably high impedance attainable by devices in these materials also offers new possibilities for wideband high power microwave systems. To realise these possibilities we need transistors that are well understood and optimised and amplifier designs that take advantage of the broadband possibilities offered by the transistors.

We have developed and used physical drift-diffusion simulation models for SiC MESFETs. The simulation results showed a large influence of the doping and thickness of the channel and buffer layers, and the properties of the semi-insulating substrate on the DC and small signal device performance. A comparison between the physical simulations and measured device characteristics has also been carried out. A novel and efficient way to extend the physical simulations to the large signal high frequency domain has been developed. The method was used to investigate experimentally detected problems in the dynamies of the transistors during large signal operation and to further optimise the device structure.

In this work a number of broadband SiC MESFET amplifiers were designed, fabricated and characterized. The packaging and charaeterisation of transistors is described and the design and characterisation of the amplifiers are presented.

A 100-500 MHz amplifier showed a measured output power above 20 W and gain >15 dB across the band and a peak power of 26 W at 400 MHz, corresponding to a power density of 5.2 W/mm, with an associated power added efficiency (PAE) of 46 %. A 0.8-2 GHz feedback amplifier showed a measured output power above 5 W, gain >7 dB and PAE above 15 % across the band. A two stage 2.8-3.3 GHz amplifier had a maximum measured output power of 12.6 W with 22 dB gain and 9% PAE measured at 2.8 GHz. These results clearly show that SiC devices have a large potential for microwave power amplifiers in general and broadband amplifiers in particular.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2005. 44 p.
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1186
SiC, MESFET, Physical simulations, Microwave power amplifier
National Category
Natural Sciences
urn:nbn:se:liu:diva-31212 (URN)LiU-TEK-LIC-2005:41 (Local ID)91-85457-03-5 (ISBN)LiU-TEK-LIC-2005:41 (Archive number)LiU-TEK-LIC-2005:41 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2010-02-25Bibliographically approved

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