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- Traugott, F., et al.
(författare)
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Successful prototyping of a real-time hardware based terrain navigation correlator algorithm
- 2003
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Ingår i: Proceedings - Euromicro Symposium on Digital System Design, DSD 2003. - 0769520030 - 9780769520032 ; , s. 334-337
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Konferensbidrag (refereegranskat)abstract
- One of the main problems for underwater terrain navigation using the correlation method is the significant computing time due to the large amount of calculations. When the algorithm is used on a regular PC, the processing time is far too long for real time applications. The Swedish navy is interested in a none-revealing terrain navigation system that can perform in real time. The article describes an implementation of a navigation system into a hardware accelerator (in one FPGA supported by two SDRAMs). The use of a FPGA gives parallelism and will shorten the computing time considerable. The actual computing time has been decreased with over 100 times compared with similar PC applications. The implementation is programmed into a Virtex®-II Xilinx device and has been written in VHDL. A SDRAM controller IP-block was designed and implemented in the FPGA. Also a custom made prototype PCB board was developed in the project.
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- Wernersson, Lars-Erik, et al.
(författare)
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Epitaxially overgrown, stable W-GaAs Schottky contacts with sizes down to 50 nm
- 2002
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Ingår i: Journal of Vacuum Science and Technology B. - : American Vacuum Society. - 1520-8567. ; 20:2, s. 580-589
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Tidskriftsartikel (refereegranskat)abstract
- A processing scheme for the fabrication of embedded W-GaAs contacts has been established and the resulting contact characteristics have been evaluated. The main advantage of these contacts is that they are stable during high-temperature epitaxial overgrowth. The fabrication scheme is based on a liftoff process with electron beam evaporation of tungsten and subsequent epitaxial overgrowth using metalorganic vapor phase epitaxy. Various methods were used to characterize the buried contacts. First, the structural properties of GaAs surrounding embedded W features, with widths down to 50 nm, were characterized by high-resolution transmission electron microscopy. Measurements of the conductivity in individual, buried wires were performed in order to study the influence of the overgrowth process on the properties of the tungsten. We also evaluated the current-voltage characteristics for macroscopic contacts, which revealed a clear dependence on processing parameters. Optimized processing conditions could thus be established under which limited contact degradation occurred during overgrowth. Finally, we used the overgrowth technique to perform a detailed investigation of the electrical and optical properties of floating-potential embedded nano-Schottky contacts by space-charge spectroscopy.
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