The evolution of the node voltages during DC operating point calculation is
shown in Fig. 6.9. Best results were obtained with
= 4. With ABC 34 iterations were needed and
*K*^{A} = 34/30 = 1.13 whereas with DBC 38 iterations were needed and
*K*^{D} = 38/31 = 1.226.

For the DC transfer characteristic the required number of iterations is shown in Fig. 6.10. In addition is shown to represent the internal state of the circuit. In this case DBC is superior compared to ABC.

To demonstrate the importance of *G*_{S}^{k} the evolution of the node
voltages for a constant
*G*_{S}^{k} = 1/*G*_{min} is shown in
Fig. 6.11. To obtain convergence at all, the global
damping parameter
had to be increased by a factor of 100 and 170
iterations were necessary.

Although ABC required less iterations than DBC this type of boundary condition seems to have a negative impact on the condition of the system matrix as each contact voltage depends on the node voltages of all other contacts. Since an iterative solver is used which is very sensitive to the condition of the matrix the total simulation time is unfortunately larger than for DBC.

1999-05-31