Browse Prior Art Database

Improved Speed Technique for Infinite-impulse-response Digital Filters

IP.com Disclosure Number: IPCOM000099517D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Coker, JD: AUTHOR [+3]

Abstract

This disclosure addresses the design of high-speed digital filters implementing an infinite-impulse-response (IIR). The invention significantly improves the speed performance of an IIR filter.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 66% of the total text.

Improved Speed Technique for Infinite-impulse-response Digital Filters

       This disclosure addresses the design of high-speed digital
filters implementing an infinite-impulse-response (IIR). The
invention significantly improves the speed performance of an IIR
filter.

      Classical techniques involving pipelining are possible in
finite- impulse-response (FIR) filters because the output of the
filter is dependent only on input values.  In the IIR case, however,
output values depend not only on input values, but also on previous
output values.  In a real-time recursion, this means a new output
value must be calculated within a single clock period to begin the
next recursion. This is the time constraint in classical
implementations of an IIR filter.

      Let xn be a sequence of input values to be filtered and yn be
the sequence of output values.  An Nth order IIR filter is described
by the recursion

                            (Image Omitted)

    where ak and bk are the tap weights.
    The conceptual heart of the invention is to take M input values
as a group and to calculate M new output values.  This transforms the
serial recursion into a hybrid parallel/serial recursion of the
following form:
    (n)      (n)
    where ak   and bk   are, in general, nonlinear combinations of
the

      (n)      (n) original tape weights ak and bk .  Each ak   and
bk   is a unique real number that may be t...