Mixed-signal test band guarding using digitally coded indirect measurements

Testing analog and mixed-signal circuits is a costly task due to the required test time targets and high end technical resources. Indirect testing methods partially address these issues providing an efficient solution using easy to measure CUT information. In this work, the pass/fail test regions are encoded using octrees in the measure space. These octrees, generated in the training phase, will serve to cluster the forthcoming circuits in the production testing phase solely relying on indirect measurements. Also, a band guarding criterion is used to achieve the specified test targets in terms of test escapes and test yield loss metrics. The combined use of octree based encoding and specification band guarding makes the testing procedure fast and efficient. The proposed method has been applied to test a band-pass Biquad filter affected by parametric variations. Different scenarios have been studied and evaluated in the presence of noisy measurements. Promising simulation results are reported showing remarkable improvements when the band guarding criterion is used.