A charge damping algorithm applied to a Newton solver for solving SOI devices and other ill-conditioned problems

The purpose of this paper is to present a damping algorithm for a Newton solver based on physical rather than mathematical considerations. Its performance will be compared with a more conventional technique[1´]. Special attention is paid to simulating SOI (silicon-on-insulator) with a floating substrate. Simple examples will be used to illustrate the nature of the ill-conditioning of this class of problems. Results will show that the convergence criteria must be much tighter than for conventional CMOS technologies otherwise the terminal currents could be incorrectly evaluated.