A design-for-test methodology for active analog filters

A DFT (design-for-test) methodology to improve the controllability/observability of internal signals in active filters is presented. The normal filter design becomes an 'analog scan' structure in the test mode. The fundamental theory underlying the proposed methodology is presented, followed by an algorithmic description and the results of several case studies. These results are considered from the perspectives of the overhead incurred and the extension of the technique to other analog structures. The DFT algorithm includes not only the modification technique but also a test generation scheme. The algorithm is suitable for silicon compiler and CAD (computer-aided-design) implementation. Experimental results confirm the validity of the methodology.>