Schwierz F.,TU Ilmenau
Proceedings of the IEEE | Year: 2013
Graphene is a relatively new material with unique properties that holds promise for electronic applications. Since 2004, when the first graphene samples were intentionally fabricated, the worldwide research activities on graphene have literally exploded. Apart from physicists, also device engineers became interested in the new material and soon the prospects of graphene in electronics have been considered. For the most part, the early discussions on the potential of graphene had a prevailing positive mood, mainly based on the high carrier mobilities observed in this material. This has repeatedly led to very optimistic assessments of the potential of graphene transistors and to an underestimation of their problems. In this paper, we discuss the properties of graphene relevant for electronic applications, examine its advantages and problems, and summarize the state of the art of graphene transistors. © 1963-2012 IEEE. Source
Schwierz F.,TU Ilmenau
Nature Nanotechnology | Year: 2010
Graphene has changed from being the exclusive domain of condensed-matter physicists to being explored by those in the electron-device community. In particular, graphene-based transistors have developed rapidly and are now considered an option for post-silicon electronics. However, many details about the potential performance of graphene transistors in real applications remain unclear. Here I review the properties of graphene that are relevant to electron devices, discuss the trade-offs among these properties and examine their effects on the performance of graphene transistors in both logic and radiofrequency applications. I conclude that the excellent mobility of graphene may not, as is often assumed, be its most compelling feature from a device perspective. Rather, it may be the possibility of making devices with channels that are extremely thin that will allow graphene field-effect transistors to be scaled to shorter channel lengths and higher speeds without encountering the adverse short-channel effects that restrict the performance of existing devices. Outstanding challenges for graphene transistors include opening a sizeable and well-defined bandgap in graphene, making large-area graphene transistors that operate in the current-saturation regime and fabricating graphene nanoribbons with well-defined widths and clean edges. © 2010 Macmillan Publishers Limited. All rights reserved. Source
TU Ilmenau and Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. | Date: 2013-08-22
Embodiments of the present invention provide a magnetic field sensor having a first current path, a second current path, a signal generator and an evaluator. The first current path has a first coil area, and the second current path has a second coil area, wherein the first coil area has windings in a first winding direction around a first magnetic core area, and wherein the second coil area has windings in a second winding direction around a second magnetic core area. The signal generator is implemented to provide an excitation current which divides into the first and second current paths. The evaluator is implemented to tap a voltage between the first and second coil areas and to detect an external magnetic field based on the voltage.
TU Ilmenau and Fraunhofer Gesellschaft zur Foerderung der angewandten Forschung e.V. | Date: 2013-06-13
An encoder for predictively encoding a signal having a sequence of signal values has a predictor for performing an adaptive prediction in dependence on the signal, and in dependence on one or more weighting values, to obtain predicted signal values, wherein the predictor is configured to reset the weighting values at times which are dependent on the signal, and wherein the predictor is configured to adapt the weighting values to the signal between subsequent resets.
Fraunhofer Gesellschaft zur Foerderung der angewandten Forschung e.V. and TU Ilmenau | Date: 2011-03-29
A leaky-wave antenna includes a sheet arrangement having first, second and third metalized sheets that are arranged on top of and in parallel with one another and are separated by two di-electric layers, the first metalized sheet having a first two-dimensionally periodic metalization structure, the second metalized sheet having a second two-dimensionally periodic metalization structure, and the third metalized sheet having a continuous metalization area, and an excitation structure above the first metalized sheet for exciting a leaky-wave mode in the sheet arrangement at a working frequency f