An active Thevenin equivalent circuit approach to problems with non-linear circuit loads

The analysis of electromagnetic coupling in nonlinear circuits requires a bidirectional, fully consistent approach. Nonlinear responses of semiconductor devices in electronic circuit components can change the impedances seen at circuit nodes, changing the boundary conditions encountered by impressed electromagnetic fields, and thus changing the characteristics of the energy coupled from these external fields into that circuit. It is important to include the coupling in the circuit simulation self-consistently because this allows us to accurately predict the responses to various EMI/EMC problems of interest. It is also important to predict circuit responses efficiently because that opens the door to statistical applications for the technique being used. In this paper, we review a technique that we have developed called ATHENA (A THevenin Equivalent Network Approach). This approach is shown to be quite robust in that it is computationally efficient, it can be implemented in a variety of commonly available circuit solving codes, it already includes a few additional techniques required to enhance its implementation in those codes, and it is quite accurate.