Transient response testing of nonlinear analogue circuits using optimised fault sets

Transient response testing has been shown to be a very powerful and economical functional test technique for linear analogue cells in mixed-signal systems. Unfortunately not all analogue circuits are linear in nature, and this has to date been the major disadvantage of this technique, since the concepts that are exploited in the linear domain do not transfer to the nonlinear domain. It is proposed that transient response testing could be considered to be a structural test for nonlinear analogue circuits. The authors have taken typical nonlinear circuits, derived suitable fault sets and looked at the fault coverage that can be obtained using transient response testing. The preliminary results presented look very promising, offering 100% fault coverage for accessible and buried circuits, and indicate that by taking this approach it may be possible to employ transient response testing for both linear and nonlinear analogue circuits. The simple nature of the required test has also indicated that BIST is a possibility.