next up previous contents
Next: 6.2.2 Pseudo-Transient Method Up: 6.2 Circuit Equation Damping Previous: 6.2 Circuit Equation Damping

6.2.1 Source Stepping

In essence the method of source stepping is equivalent to determining the DC operating point with a DC transfer curve. All independent sources are not directly applied to the circuit but damped with a value $ \alpha$ which is between zero and unity. After convergence for a distinct $ \alpha$ is obtained, $ \alpha$ is increased by a factor depending on the iteration count of the last solution until convergence is obtained. In case no convergence is obtained within a distinct number of iterations, $ \alpha$ is decreased until convergence is obtained again. As pointed out in [43] this method needs an excessively large number of iterations for conventional circuit simulation. For good reasons, the same behavior can be expected for mixed-mode simulation. The method can be improved by making use of a predictor which calculates an initial-guess out of previous solutions [43].

Tibor Grasser