Applications of the Superposition Theorem to Nonlinear Resistive Circuits

The superposition theorem (ST) and the substitution theorem are two important theorems in circuit theory. By principle, ST can only be used in linear circuits, while nonlinear circuits are regarded as a forbidden zone. However, the substitution theorem can be used in both linear and nonlinear circuits. For those nonlinear circuits that have a unique solution, we can use the substitution theorem in the equivalent transformation. Based on the mathematical fundamentals of ST and the substitution theorem, we propose the original approach for applying ST to nonlinear resistive circuits. As an intermediate step, the superposition method is useful in evaluating nonlinear resistive circuits