Black-Box Models for Linear Integrated Circuits

The paper presents a general approach to the modeling of linear integrated circuits for computer-aided analysis in the frequency domain. The modeling is done through black boxes whose internal details are ignored and which are characterized only at their external terminals. Lumped and distributed, ideal and experimentally characterized multiterminal devices can be handled. The mathematical characterization is the indefinite admittance matrix. The implementation of the methods discussed is very simple, since no topological matrices are required. The method lends itself to analyzing large circuits by tearing them and then reconnecting the pieces. The method has been implemented in a program entitled BELNAP. A transient counterpart BELTIP and a design program IMPROVE have been in use by designers at Bell Laboratories for some time. An example circuit is solved in detail in the paper using BELNAP.