Fault macromodeling and a testing strategy for opamps

Abstract

In this paper, we propose a simple testing technique based on DC measurements for operational amplifiers. We first develop a comprehensive macromodel for the transistor-level opamp to alleviate the efforts of fault simulation. By incorporating appropriate I/O characteristics into the macromodel, the output deviation due to the modeling error can be significantly reduced. We use the transistor short/bridging faults to illustrate the efficiency of our proposed technique. Experimental results show that a high fault coverage can be achieved for the stand-alone opamp by measuring two DC parameters V _o-max ^* and V _o-min ^*. For the embedded opamps, many short/bridging faults cannot be detected by traditional functional testing. However, by using similar DC measurements along with a design for testability (DFT) scheme, we can improve the fault coverage dramatically.