Extension of the method of analog circuit parameter identification for the specified design performances, originally presented by the same author in 1982, is described. These parameters are designated by means of PSpice simulation of the adjoint circuit to the original one. In this adjoint circuit, elements of the original circuit, described by the sized parameters, are replaced by controlled ... [Show full abstract] sources. Each such source is controlled by the differential voltage or current, difference between the calculated voltage or current and the specified one, with infinitely large gain. The method is applicable to both linear and nonlinear DC circuits and AC circuits and can be used in many fields of analog circuit design, such as: finding of acceptability region, analog fault diagnosis, postproduction identification and tuning. In the later cases, design performances are replaced by measurements of Circuit Under Test (CUT). Simplicity, extremely low computational complexity and high accuracy are the main benefits of the proposed, basic Circuit Theory based, approach – the solution is found after a single PSpice simulation. For better understanding of the presented methodology, five practical examples are discussed.