Towards 100% testable FIR digital filters

Testability problems that arise in the design of fixed-coefficient finite impulse response (FIR) filters are examined. A class of redundant faults that naturally derive from the structure and behavior of these filters are examined, and design-for-test (DFT) techniques based on scaling theory are used to eliminate the redundancies. Eliminating these redundancies makes it possible for built-in self-test (BIST) approaches to reach 100% coverage, and automatic test-pattern generation (ATPG) based approaches can benefit by more than an order of magnitude reduction in test generation time. A case study provides a demonstration of the approach.