文档介绍：Digital Filter Structures Digital Filter Structures
• The convolution sum description of an LTI • Here the input-output relation involves a
discrete-time system can, in principle, be finite sum of products:
used to implement the system N M
y[n] = ­åk=1dk y[n ­ k] + åk=0 pk x[n ­ k]
• For an IIR finite-dimensional system this • On the other hand, an FIR system can be
approach is not practical as here the impulse implemented using the convolution sum
response is of infinite length which is a finite sum of products:
• However, a direct implementation of the IIR N
y[n] = åk =0 h[k]x[n ­ k]
finite-dimensional system is practical
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Copyright © 2001, S. K. Mitra Copyright © 2001, S. K. Mitra
Digital Filter Structures Digital Filter Structures
• However, a direct implementation of a digital
• The actual implementation of an LTI digital filter based on either the difference equation
filter can be either in software or hardware or the finite convolution sum may not
form, depending on applications provide satisfactory performance due to the
• In either case, the signal variables and the finite precision arithmetic
filter coefficients cannot be represented • It is thus of practical interest to develop
with finite precision alternate realizations and choose the structure
that provides satisfactory performance under
finite precision arithmetic
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