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SUMMARYA preconditioning methodology for an iterative solution of discrete stress analysis problems based on a space decomposition and subspace correction framework is analysed in this paper. The principle idea of our approach is a decomposition of a global discrete system into the series of subproblems each of which correspond to the di erent Cartesian co-ordinates of the solution (displacement) vector. This enables us to treat the matrix subproblems in a segregated way. A host of well-established scalar solvers can be employed for the solution of subproblems. In this paper we constrain ourselves to an approximate solution using the scalar algebraic multigrid (AMG) solver, while the subspace correction is performed either in block diagonal (Jacobi) or block lower triangular (Gauss-Seidel) fashion. The preconditioning methodology is justiÿed theoretically for the case of the block-diagonal preconditioner using Korn's inequality for estimating the ratio between the extremal eigenvalues of a preconditioned matrix. The e ectiveness of the AMG-based preconditioner is tested on stress analysis 3D model problems that arise in microfabrication technology. The numerical results, which are in accordance with theoretical predictions, clearly demonstrate the superiority of a component decomposition AMG preconditioner over the standard ILU preconditioner, even for the problems with a relatively small number of degrees of freedom.

Abstract-A measurement system comprised of an ultra-low-distortion function generator, lock-in amplifier, and semiconductor parameter analyzer is used for sensitive extraction of the smallsignal thermal impedance network of bipolar devices and circuits. The extraction procedure is demonstrated through measurements on several silicon-on-glass NPN test structures. Behavioral modeling of the mutual thermal coupling obtained by fitting a multipole rational complex function to measured data is presented.

In this paper, we report a systematic approach to extract parameters from organic thin film transistors (OTFTs) that are used for compact Spice models. The universal organic thin-film transistor (UOTFT) model and Silvaco's Smartspice platform are utilized for simulations whereas experimental data are collected from Plastic Logic's (PL) thin-film transistors that are processed on flexible plastic substrates. The parameter extraction procedure is outlined where both current-voltage and capacitance-voltage measurements are employed. This is then followed by simulations of inverters and ring oscillators to assess the results against simple logic circuits.

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