Design Recipes for FPGAs
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useful to introduce some key concepts at this stage of the two main
types of digital filter in common usage today. These are the recur-
sive (or Infinite Impulse Response – IIR) filters and non-recursive
(or Finite Impulse Response – FIR) filters.
FIR filters
FIR filters are characterized by the fact that they use only delayed
versions of the input signal to filter the input to the output. For
example, if we take the expression for a general FIR filter below,
we can see that the output is a function of a series of delayed,
scaled versions of the input:
Where A
i
is the scale factor for the ith delayed version of the input.
We can ...