S. Samadi et al., INTERVAL PROPERTIES OF LATTICE ALLPASS FILTERS WITH APPLICATIONS, IEICE transactions on fundamentals of electronics, communications and computer science, E76A(10), 1993, pp. 1775-1780
In practical applications of digital filters it is more realistic to t
reat multiplier coefficients as finite intervals than restricting them
to infinite or very long word-length representations. However, this c
an not be done if the frequency response performance under interval as
sumption is difficult to analyze. In this paper, it is proved that sta
ble lattice allpass filters possess bounded continuous phase response
when lattice parameters vary in bounded intervals. It is shown that sh
arp bounds on the interval phase response can be computed easily at an
arbitrary frequency using a simple recursive procedure. Application o
f this property to the problem of finite word-length lattice allpass f
ilter design is also discussed. By formulating this problem as an inte
rval design it is possible to solve it efficiently independent of the
number system used to represent multiplier coefficients.