Improved fault coverage for adaptive fault tolerant filters

Adaptive fault tolerance (AFT) has been developed recently for achieving reliable performance of FIR adaptive filters in the presence of certain types of hardware failures. Previous studies limited the use of AFT to one-dimensional FIR filter structures with simple `stuck-at' fault models that account for errors introduced into the adaptive process by faulty coefficients that cease to adjust properly. This paper considers a broader class of hardware errors which, in addition to `stuck-at' errors in the multiplier inputs, can be modeled by errors in the outputs of both multipliers and adders. By including a simple circuit that removes erroneous induced constants in the output of the adaptive filter, adaptive fault tolerance can be extended to a broader class of hardware failures.