Determining when a DC operating point is unstable: a new algorithm for SPICE

The authors show that SPICE can sometimes converge to an unstable operating point, and that this can be misleading to a circuit designer. They show that the linearized DC hybrid equations of a given circuit´s operating point can yield information about operating point stability, and that this information can easily be obtained from the results of the usual SPICE DC operating point analysis. This information can then be passed on to the user as a warning when an unstable operating point is found. The authors show that this algorithm can be implemented in SPICE with a minor modification, incurring a negligible increase in CPU time