Analog testing by characteristic observation inference

This paper presents a new approach to the test design of analog circuits, c alled characteristic observation inference (COI), The COI method considers parametric as well as catastrophic faults. A strict distinction between the operational environment, defined hy the specifications of the circuit, and the test environment, defined by the test configuration and the test equip ment, is introduced. A parametric fault model is developed that combines ci rcuit specifications, statistical parameters reflecting parametric faults, and measurements of the circuit under test, These measurements are called c haracteristic observations. For each specification, a test inference criter ion is computed using feature extraction and logistic discrimination analys is. From a set of such criteria the satisfaction or violation of the specif ications can be inferred from characteristic observations. Based on these r esults, additional test criteria for catastrophic faults are determined usi ng test set compaction. Moreover, measurement noise and parasitic effects, which crucially influence the test design, are systematically considered, a nd a physically interpretable sampling strategy is presented. The COI metho d applied to two different test designs yields very good results with respe ct to parametric faults as well as to catastrophic faults.