Diagnosis of a soft short and local variations of parameters occurring simultaneously in analog CMOS circuits

This paper is devoted to fault diagnosis of nonlinear analog CMOS circuits designed in nanometer technology. A method that allows diagnosing a single soft short and local parameter variations, occurring simultaneously, is developed. The method exploits DC measurements at limited number of points in the test phase. The diagnostic test leads to a system of nonlinear algebraic equations, not given in explicit analytical form, that may have multiple solutions. The solutions determine the sets comprising one soft short value and several values of the preliminary selected parameters. To find them an extended simplicial algorithm is developed. It allows tracing different space curves, leading to different solutions. Moreover, a procedure for selecting the actual solution from among the obtained ones is proposed. For illustration a representative numerical example is discussed in detail.