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Wolfgang Fichtner

Bio: Wolfgang Fichtner is an academic researcher from ETH Zurich. The author has contributed to research in topics: Very-large-scale integration & Power semiconductor device. The author has an hindex of 48, co-authored 401 publications receiving 10251 citations. Previous affiliations of Wolfgang Fichtner include Bell Labs & École Polytechnique Fédérale de Lausanne.


Papers
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Journal ArticleDOI
TL;DR: This paper shows that complementary CMOS is the logic style of choice for the implementation of arbitrary combinational circuits if low voltage, low power, and small power-delay products are of concern.
Abstract: Recently reported logic style comparisons based on full-adder circuits claimed complementary pass-transistor logic (CPL) to be much more power-efficient than complementary CMOS. However, new comparisons performed on more efficient CMOS circuit realizations and a wider range of different logic cells, as well as the use of realistic circuit arrangements demonstrate CMOS to be superior to CPL in most cases with respect to speed, area, power dissipation, and power-delay products. An implemented 32-b adder using complementary CMOS has a power-delay product of less than half that of the CPL version. Robustness with respect to voltage scaling and transistor sizing, as well as generality and ease-of-use, are additional advantages of CMOS logic gates, especially when cell-based design and logic synthesis are targeted. This paper shows that complementary CMOS is the logic style of choice for the implementation of arbitrary combinational circuits if low voltage, low power, and small power-delay products are of concern.

911 citations

Journal ArticleDOI
27 Jun 2005
TL;DR: Two ASIC implementations of MIMO sphere decoders with efficient implementation of the enumeration approach recently proposed in .
Abstract: Multiple-input multiple-output (MIMO) techniques are a key enabling technology for high-rate wireless communications. This paper discusses two ASIC implementations of MIMO sphere decoders. The first ASIC attains maximum-likelihood performance with an average throughput of 73 Mb/s at a signal-to-noise ratio (SNR) of 20 dB; the second ASIC shows only a negligible bit-error-rate degradation and achieves a throughput of 170 Mb/s at the same SNR. The three key contributing factors to high throughput and low complexity are: depth-first tree traversal with radius reduction, implemented in a one-node-per-cycle architecture, the use of the /spl lscr//sup /spl infin//-instead of /spl lscr//sup 2/-norm, and, finally, the efficient implementation of the enumeration approach recently proposed in . The resulting ASICs currently rank among the fastest reported MIMO detector implementations.

666 citations

Journal ArticleDOI
TL;DR: In this article, the transmission coefficients and the density of states of biased and unbiased Si and GaAs nanowires are simulated using the $s{p}^{3d}^{5}{s}^{*}$ empirical tight-binding method.
Abstract: As the active dimensions of metal-oxide field-effect transistors are approaching the atomic scale, the electronic properties of these ``nanowire'' devices must be treated on a quantum mechanical level. In this paper, the transmission coefficients and the density of states of biased and unbiased Si and GaAs nanowires are simulated using the $s{p}^{3}{d}^{5}{s}^{*}$ empirical tight-binding method. Each atom, as well as the connections to its nearest neighbors, is represented explicitly. The material parameters are optimized to reproduce bulk band-structure characteristics in various crystal directions and various strain conditions. A scattering boundary method to calculate the open boundary conditions in nanowire transistors is developed to reduce the computational burden. Existing methods such as iterative or generalized eigenvalue problem approaches are significantly more expensive than the transport simulation through the device. The algorithm can be coupled to nonequilibrium Green's function and wave function transport calculations. The speed improvement is even larger if the wire transport direction is different from [100]. Finally, it is demonstrated that strain effects can be easily included in the present nanowire simulations.

418 citations

Proceedings ArticleDOI
02 Apr 2000
TL;DR: This paper describes a complete design methodology for a globally asynchronous on-chip communication network connecting both locally-synchronous and asynchronous modules and confirmed the validity of the concept by applying it to an ASIC design implementing the Safer crypto-algorithm.
Abstract: In this paper we describe a complete design methodology for a globally asynchronous on-chip communication network connecting both locally-synchronous and asynchronous modules. Synchronous modules are equipped with asynchronous wrappers which adapt their interfaces to the self-timed environment and prevent metastability. These wrappers are assembled from a concise library of predesigned technology-independent elements and provide high-speed data transfer. We confirmed the validity of our concept by applying it to an ASIC design implementing the Safer crypto-algorithm.

304 citations

Journal ArticleDOI
TL;DR: This paper describes the numerical techniques used to solve the coupled system of nonlinear partial differential equations which model semiconductor devices, and the efficient solution of the resulting nonlinear and linear algebraic equations.
Abstract: This paper describes the numerical techniques used to solve the coupled system of nonlinear partial differential equations which model semiconductor devices. These methods have been encoded into our device simulation package which has successfully simulated complex devices in two and three space dimensions. We focus our discussion on nonlinear operator iteration, discretization and scaling procedures, and the efficient solution of the resulting nonlinear and linear algebraic equations. Our companion paper [13] discusses physical aspects of the model equations and presents results from several actual device simulations.

278 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: In this paper, a water-cooled integral heat sink for silicon integrated circuits has been designed and tested at a power density of 790 W/cm2, with a maximum substrate temperature rise of 71°C above the input water temperature.
Abstract: The problem of achieving compact, high-performance forced liquid cooling of planar integrated circuits has been investigated. The convective heat-transfer coefficient h between the substrate and the coolant was found to be the primary impediment to achieving low thermal resistance. For laminar flow in confined channels, h scales inversely with channel width, making microscopic channels desirable. The coolant viscosity determines the minimum practical channel width. The use of high-aspect ratio channels to increase surface area will, to an extent, further reduce thermal resistance. Based on these considerations, a new, very compact, water-cooled integral heat sink for silicon integrated circuits has been designed and tested. At a power density of 790 W/cm2, a maximum substrate temperature rise of 71°C above the input water temperature was measured, in good agreement with theory. By allowing such high power densities, the heat sink may greatly enhance the feasibility of ultrahigh-speed VLSI circuits.

4,214 citations

Journal ArticleDOI
TL;DR: Black phosphorus (BP), the most stable allotrope of phosphorus with strong intrinsic in-plane anisotropy, is reintroduced to the layered-material family and shows great potential for thin-film electronics, infrared optoelectronics and novel devices in which anisotropic properties are desirable.
Abstract: The applications of graphene and transition metal dichalcogenides in electronics are limited by their zero-bandgap and low mobility, respectively. Here, the authors demonstrate the potential of an emerging layered material—black phosphorous—for thin film electronics and infrared optoelectronics.

2,983 citations

Proceedings ArticleDOI
01 May 2000
TL;DR: Wattch is presented, a framework for analyzing and optimizing microprocessor power dissipation at the architecture-level and opens up the field of power-efficient computing to a wider range of researchers by providing a power evaluation methodology within the portable and familiar SimpleScalar framework.
Abstract: Power dissipation and thermal issues are increasingly significant in modern processors. As a result, it is crucial that power/performance tradeoffs be made more visible to chip architects and even compiler writers, in addition to circuit designers. Most existing power analysis tools achieve high accuracy by calculating power estimates for designs only after layout or floorplanning are complete. In addition to being available only late in the design process, such tools are often quite slow, which compounds the difficulty of running them for a large space of design possibilities.This paper presents Wattch, a framework for analyzing and optimizing microprocessor power dissipation at the architecture-level. Wattch is 1000X or more faster than existing layout-level power tools, and yet maintains accuracy within 10% of their estimates as verified using industry tools on leading-edge designs. This paper presents several validations of Wattch's accuracy. In addition, we present three examples that demonstrate how architects or compiler writers might use Wattch to evaluate power consumption in their design process.We see Wattch as a complement to existing lower-level tools; it allows architects to explore and cull the design space early on, using faster, higher-level tools. It also opens up the field of power-efficient computing to a wider range of researchers by providing a power evaluation methodology within the portable and familiar SimpleScalar framework.

2,848 citations