Strategy for soft fault diagnosis on analog circuits with tolerance

Focusing on soft fault diagnosis on analog circuit with tolerance, a novel method is presented, consisting of fault detection, element isolation and parameter estimation. Firstly, a linear-programming concept is developed to transform fault detection of circuit with limited accessible terminals for measurement to check existence of a feasible solution under tolerance constraints. Secondly, node-voltage-increment-ratio under different current excitation is deduced to locate the faulty component and fault eigenvalues of circuit with tolerance are manifested to be the same as that with nominal parameters. Lastly, fault detection of the circuit with revised deviation restriction for suspected faulty components is proceeded to locate faulty element and estimate its parameter. The diagnosis accuracy and parameter identification precision of the method are verified by simulation results.