An adaptive backpropagation cascade IIR filter

Among the various linear infinite impulse response (IIR) structures for adaptive filters, cascade IIR filters are notable for easy stability monitoring and good sensitivity performance. However, their high cost for computing gradients is a problem. A novel technique of backpropagating the desired signal is proposed, and a cascade structure satisfying the requirements of this technique is developed, resulting in an efficient adaptive IIR filter. It is shown that the equation-error formulation is just a special case of this backpropagation idea