An efficient prediction framework for multi-parametric yield analysis under parameter variations
FRONTIERS OF INFORMATION TECHNOLOGY & ELECTRONIC ENGINEERING
Authors: Li, Xin; Sun, Jin; Xiao, Fu
Abstract
Due to continuous process scaling, process, voltage, and temperature (PVT) parameter variations have become one of the most problematic issues in circuit design. The resulting correlations among performance metrics lead to a significant parametric yield loss. Previous algorithms on parametric yield prediction are limited to predicting a single-parametric yield or performing balanced optimization for several single-parametric yields. Consequently, these methods fail to predict the multi-parametric yield that optimizes multiple performance metrics simultaneously, which may result in significant accuracy loss. In this paper we suggest an efficient multi-parametric yield prediction framework, in which multiple performance metrics are considered as simultaneous constraint conditions for parametric yield prediction, to maintain the correlations among metrics. First, the framework models the performance metrics in terms of PVT parameter variations by using the adaptive elastic net (AEN) method. Then the parametric yield for a single performance metric can be predicted through the computation of the cumulative distribution function (CDF) based on the multiplication theorem and the Markov chain Monte Carlo (MCMC) method. Finally, a copula-based parametric yield prediction procedure has been developed to solve the multi-parametric yield prediction problem, and to generate an accurate yield estimate. Experimental results demonstrate that the proposed multi-parametric yield prediction framework is able to provide the designer with either an accurate value for parametric yield under specific performance limits, or a multi-parametric yield surface under all ranges of performance limits.
VORTEX STRUCTURE OF NEUTRON STARS WITH TRIPLET NEUTRON SUPERFLUIDITY
ASTROPHYSICS
Authors: Shahabasyan, K. M.; Shahabasyan, M. K.
Abstract
The vortex structure of the "npe" phase of neutron stars with a (3)P(2) superfluid neutron condensate of Cooper pairs is discussed. It is shown that, as the star rotates, superfluid neutron vortex filaments described by a unitary ordering parameter develop in the "npe" phase. The entrainment of superconducting protons by the rotating superfluid neutrons is examined. The entrainment effect leads to the appearance of clusters of proton vortices around each neutron vortex and generates a magnetic field on the order of 10(12) G. (3)P(2) neutron vortex filaments combine with quark semi-superfluid vortex filaments at the boundary of the "npe" and "CFL" phases. At the boundary of the "Aen" and "npe" phases, they combine with (1)S(0) neutron vortex filaments. In this way, a unified vortex structure is formed. The existence of this structure and its collective elastic oscillations explain the observed oscillations in the angular rotation velocity of pulsars.