Direct-Form-I Implementation

The difference equation (Eq.(5.1)) is often used as the recipe for numerical implementation in software or hardware. As such, it specifies the direct-form I (DF-I) implementation of a digital filter, one of four direct-form structures to choose from. The DF-I signal flow graph for the second-order case is shown in Fig.5.1a. The direct-form II structure, another common choice, is depicted in Fig.5.1b. The other two direct forms are obtained by transposing direct forms I and II. Chapter 9 discusses all four direct-form structures.

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About the Author: Julius Orion Smith III
Julius Smith's background is in electrical engineering (BS Rice 1975, PhD Stanford 1983). He is presently Professor of Music and Associate Professor (by courtesy) of Electrical Engineering at Stanford's Center for Computer Research in Music and Acoustics (CCRMA), teaching courses and pursuing research related to signal processing applied to music and audio systems. See http://ccrma.stanford.edu/~jos/ for details.