With the adoption of statistical timing across industry, there is a need to characterize all gates/cells in a digital library for delay variation (referred to as statistical characterization). ...Statistical characterization needs to be performed efficiently with acceptable accuracy as a function of several process and environmental parameter variations. In this paper, we propose an approach to consider intra-cell process mismatch variations to characterize a cell's delay and output transition time (output slew) variations. A straightforward approach to address this problem is to model these mismatch variations by characterizing for each device fluctuation separately. However, the runtime complexity for such characterization becomes of the order of number of devices in the cell and the number of simulations required can easily become infeasible. We analyze the fluctuations in switching and nonswitching devices and their impact on delay variations. Using these properties of the devices, we propose a clustering approach to characterize for cell's delay variations due to intra-cell mismatch variations. The proposed approach results in as much as 12X runtime improvement with acceptable accuracy, compared with Monte Carlo simulation. We show that this approach ensures an upper bound on the results while keeping the number of simulations for each cell independent of the number of devices.
Resonance regions similar to the Arnol'd tongues found in single oscillator frequency locking are observed in experiments using a spatially extended periodically forced Belousov-Zhabotinsky system. ...We identify six distinct 2:1 subharmonic resonant patterns and describe them in terms of the position-dependent phase and magnitude of the oscillations. Some experimentally observed features are also found in numerical studies of a forced Brusselator reaction-diffusion model.
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Four-phase patterns in forced oscillatory systems Lin, AL; Hagberg, A; Ardelea, A ...
Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics
62, Issue:
3 Pt B
Journal Article
Open access
We investigate pattern formation in self-oscillating systems forced by an external periodic perturbation. Experimental observations and numerical studies of reaction-diffusion systems and an analysis ...of an amplitude equation are presented. The oscillations in each of these systems entrain to rational multiples of the perturbation frequency for certain values of the forcing frequency and amplitude. We focus on the subharmonic resonant case where the system locks at one-fourth the driving frequency, and four-phase rotating spiral patterns are observed at low forcing amplitudes. The spiral patterns are studied using an amplitude equation for periodically forced oscillating systems. The analysis predicts a bifurcation (with increasing forcing) from rotating four-phase spirals to standing two-phase patterns. This bifurcation is also found in periodically forced reaction-diffusion equations, the FitzHugh-Nagumo and Brusselator models, even far from the onset of oscillations where the amplitude equation analysis is not strictly valid. In a Belousov-Zhabotinsky chemical system periodically forced with light we also observe four-phase rotating spiral wave patterns. However, we have not observed the transition to standing two-phase patterns, possibly because with increasing light intensity the reaction kinetics become excitable rather than oscillatory.
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SOI Transistor Model for Fast Transient Simulation Nadezhin, D.; Gavrilov, S.; Glebov, A. ...
International Conference on Computer Aided Design: Proceedings of the 2003 IEEE/ACM international conference on Computer-aided design; 09-13 Nov. 2003,
11/2003
Conference Proceeding
Progress in semiconductor process technology has made SOItransistors one of the most promising candidates for high performanceand low power designs. With smaller diffusion capacitances,SOI ...transistors switch significantly faster than theirtraditional bulk MOS counterparts and consume less power perswitching. However, design and simulation of SOI MOS circuits ismore challenging due to more complex behavior of an SOI transistorinvolving floating body effects, delay dependence on history oftransistor switching, bipolar effect and others. This paper isdevoted to developing a fast table model of SOI transistors, suitablefor use in fast transistor level simulators. We propose usingbody charge instead of body potential as an independent variableof the model to improve convergence of circuit simulation integrationalgorithm. SOI transistor has one additional terminal comparedwith the bulk MOSFET and hence requires larger tables tomodel. We propose a novel transformation to reduce number oftable dimensions and as a result to make the size of the tables reasonable.The paper also presents efficient implementation of ourSOI transistor table model using piece-wise polynomial approximation,nonuniform grid discretization, and splitting the transistormodel into the model of its equilibrium and non equilibrium states.The effectiveness of the proposed model is demonstrated byemploying it in a fast transistor level simulator to simulate highperformance industrial SOI microprocessor circuits.
A mathematical framework has been developed for numerical analysis and simulation of applications in superconducting microelectronics. The approach is similar to those used successfully in ...semiconductor modeling. Here we investigate semidiscrete simulation of the time dependent Ginzburg-Landau equations. Several interesting numerical and modeling issues regarding the structure of the solutions and their sensitivity to the data and mesh resolution are described using results from a representative problem.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
With the adoption of statistical timing across industry, there is a need to characterize all gates/cells in a digital library for delay variations (referred to as, statistical characterization). ...Statistical characterization need to be performed efficiently with acceptable accuracy as a function of several process and environment parameter variations. In this paper, we propose an approach to consider intra-cell process mismatch variations to characterize a cell's delay and output transition time (output slew) variations. A straightforward approach to address this problem is to model these mismatch variations by characterizing for each device fluctuation separately. However, the runtime complexity for such characterization becomes of the order of number of devices in the cell and the number of simulations required can easily become infeasible. We analyze the fluctuations in switching and non-switching devices and their impact on delay variations. Using these properties of the devices, we propose a clustering approach to characterize for cell's delay variations due to intra-cell mismatch variations. The proposed approach results in as much as 12X runtime improvements with acceptable accuracy, compared with Monte Carlo simulations. We show that this approach ensures an upper-bound on the results while keeping the number of simulations for each cell independent of the number of devices.
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