Patent Document ID: 6072947
Application ID: 08933733
Patent Flag: 1

Claim One:
1. A method of analyzing a circuit, comprising the steps of: a) writing the equations characterizing the circuit, in terms of the time-domain circuit variables x(t), a vector of large-signal excitations b(t), the resistive elements of the circuit f(x(t)), the dynamic elements of the circuit q(x(t)), and the small perturbations of the system Au(t); b) solving the equations from step (a) for a nonlinear steady state; c) performing a time-varying linearization of the circuit equations from step (a), giving the linearized small signal differential equation, in terms of the derivative matrices of resistive and dynamic elements of the circuit, giving the equation EQU C(t)x+G(t)x+Au(t)=0, where x(t) represents the small-signal deviations of the perturbed solution of the equations of step (a), C(t) is the derivative matrix of f(.cndot.), and G(t) is the derivative matrix of q(.cndot.); d) obtain C.sub.i and G.sub.i using the equations ##EQU28## e) selecting a frequency .omega. for which noise is to be evaluated; f) evaluate the equation EQU S.sup.t.sub.xx(.cndot.,0).sbsb.(.cndot.,p) (.omega.)=H(.omega.)S.sup.T.sub.uu (.omega.)H.sup.t (.omega.)E.sub.0 e.sub.p applying block matrix functions H.sup.T, S.sup.T.sub.uu and H analyzing the propagation of noise through the circuit using the linearized small signal differential equations; g) if a noise characteristic of the circuit is not within predetermined limits, modifying the circuit in accordance with the evaluation.