A GENERALISED DESIGN METHOD FOR
Orthogonal Iir, Lattice Filters, Roy Albert Chapman · 1989
This paper investigates the practical problems involved in obtaining the signal flow graphs for orthogonal iir filters. A third polynomial derived from the numerator and denominator polynomials of the transfer function is required for such implementations. It is shown that the reflection coefficients of the lattices are extremely sensitive to roundoff errors in this polynomial and it consequently becomes difficult to implement many iir filters using orthogonal lattices. This paper assesses the transfer functions amenable to lattice realisations, introduces the basis of a CAD technique for orthogonal filter design and shows that if more complex structures can be tolerated lattice sections can be derived for any general transfer function.