- TITLE:
-
Cascaded Coefficient Number Systems Lead to
FIR Filters of Striking Computational Efficiency
- AUTHORS:
- J. O. Coleman
- ABSTRACT:
-
Multiplierless FIR filters (or other fixed linear
combiners) are built as add/subtract networks
operating on bit-shifted input data. Classically, the
computational structure required is determined by
simply expressing the coefficients in
canonical-signed-digit (CSD) form. In this paper,
expressing coefficients in a higher-radix number
system instead results in a computational structure
for a partial solution, one that reduces a large
linear-combination problem to a smaller one. A
well-chosen sequence of such number systems then leads
to a cascade of these problem-reducing networks that
together solve the original problem with remarkable
overall computational efficiency, especially for
larger filters. An example FIR filter with a real
chirp impulse response 3000 samples in length (a
matched filter for a pulse-compression radar) was
easily realized with -95 dB rms approximation error
using less than two add or subtract operations per
coefficient. This is a reduction of approximately 60%
relative to the usual CSD method.
- DOWNLOADABLE PREPRINT:
-
PDF (97K),
- STATUS:
- Accepted for presentation to the The 2001 Int'l IEEE
Conf. on Electronics, Circuits, and Systems (ICECS
'01), Malta, September 2001.
- DATE OF ENTRY:
-
May 2001.