Recursive Filters

Recursive filters are an efficient way of achieving a long impulse response, without having to
perform a long convolution. They execute very rapidly, but have less performance and flexibility
than other digital filters. Recursive filters are also called Infinite Impulse Response (IIR) filters,
since their impulse responses are composed of decaying exponentials. This distinguishes them
from digital filters carried out by convolution, called Finite Impulse Response (FIR) filters. This
chapter is an introduction to how recursive filters operate, and how simple members of the family
can be designed. Chapters 20, 26 and 33 present more sophisticated design methods.
CHAPTER
Recursive Filters
19

Recursive filters are an efficient way of achieving a long impulse response, without having to
perform a long convolution. They execute very rapidly, but have less performance and flexibility
than other digital filters. Recursive filters are also called Infinite Impulse Response (IIR) filters,
since their impulse responses are composed of decaying exponentials. This distinguishes them
from digital filters carried out by convolution, called Finite Impulse Response (FIR) filters. This
chapter is an introduction to how recursive filters operate, and how simple members of the family
can be designed. Chapters 20, 26 and 33 present more sophisticated design methods.




The Recursive Method
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