FAULT-BASED ATPG FOR LINEAR ANALOG CIRCUITS WITH MINIMAL SIZE MULTIFREQUENCY TEST SETS

An automatic test pattern generation (ATPG) procedure for linear analo g circuits is presented in this work. A fault-based multifrequency tes t approach is considered. The procedure selects a minimal set of test measures and generates the minimal set of frequency tests which guaran tee maximum fault coverage and, if required, maximal fault diagnosis, of circuit AC hard/soft faults. The procedure is most suitable for lin ear time-invariant circuits which present significant frequency-depend ent fault effects. For test generation, the approach is applicable onc e parametric tests have determined DC behaviour. The advantage of this procedure with respect to previous works is that it guarantees a mini mal size test set. For fault diagnosis, a fault dictionary containing a signature of the effects of each fault in the frequency domain is us ed. Fault location and fault identification can be achieved without th e need of analog test points, and just in-circuit checkers with an obs ervable go/no-go digital output are required for diagnosis. The proced ure is exemplified for the case of an analog biquadratic filter. Three different self-test approaches for this circuit are considered. For e ach self-test strategy, a set of several test measures is possible. Th e procedure selects, in each case, the minimal set of test measures an d the minimal set of frequency tests which guarantee maximum fault cov erage and maximal diagnosis. With this, the self-test approaches are c ompared in terms of the fault coverage and the fault diagnosability ac hieved.