Chapter 6 - Digital filter structures and their implementation

Abstract

Here we focus on robust digital filter structures suitable for implementation using field-programmable gate arrays, i.e., nonrecursive FIR filters and wave digital filters. Of further interest are digital filter implementations that are power-efficient. First, we discuss the computer-aided design of regular FIR filters and their realization. However, these structures become expensive for filters with narrow transition bands. We, therefore, discuss frequency response masking techniques that are suitable for such cases. Wave digital filters are derived from analog filter structures from which they inherit their properties, e.g., robustness, suppressing parasitic oscillations, and low passband sensitivity to element errors. We, therefore, discuss the design of analog filters, compare the standard approximations, and propose some novel approximations that yield low passband sensitivity. In addition, we discuss the realization of analog filters and how to obtain low passband sensitivity. Next, we discuss some building blocks for wave digital filters and the design of ladder, lattice, and circulator-tree wave digital filters. We also compare these structures with respect to passband sensitivity. Finally, we discuss some techniques, e.g., multiple-constant multiplication and distributed arithmetic, to reduce the implementation cost, i.e., power consumption, reduced and simplified arithmetic, and chip area. We also discuss hardware architecture and cyclic scheduling techniques. Numerous programs using MATLAB® and an available toolbox are used for the design of the filters.