A Study on the Transfer Function Based Analog Fault Model for Linear and Time-Invariant Continuous-Time Analog Circuits

Abstract

How to efficiently test analog circuits is an open issue because of the lack of widely-accepted analog fault model. This paper studies the impacts of the parametric faults on the transfer function's coefficients of continuous-time and linear-and-time-invariant (LTI) analog circuits from the design's point of view. It is found the parametric faults change the coefficients but not the template of the transfer function (TF) of the circuit under test (CUT). Based on this observation, a test procedure that does not need time-consuming fault simulations is proposed. We show the practical TF coefficients of the CUT can be accurately measured by conducting a simple multi-tone test. In addition, conventional coefficient based tests make pass/fail decisions by checking if any coefficient is outside its pre-computed tolerance box. From the design's point of view, we propose comparing the frequency responses of the measured TF with the design specification to make the final pass/fail decision, the same as what conventional functional tests do.