FIR vs IIR

Posted 2021-02-20 hongxiwong

内容截取自：https://community.sw.siemens.com/s/article/introduction-to-filters-fir-versus-iir

内容截取自：https://community.sw.siemens.com/s/article/introduction-to-filters-fir-versus-iir

内容截取自：https://community.sw.siemens.com/s/article/introduction-to-filters-fir-versus-iir

---

The FIR methods use different spectral windows when transforming from the frequency to time domain. Some of the window methods include:

• Chebyshev – Has the lowest amount of ripple in stop band, but widest transition band.
• Hamming – Narrow transition zone, smaller ripple than Hanning. Developed by Richard Hamming, who was a member of the Manhattan Project.
• Kaiser – Developed by James Kaiser at Bell Laboratories, the Kaiser window has small amplitude ripple in stop zone, only the wide transition width Chebyshev has lower amplitude ripple.
• Hanning – Narrowest transition band, but large ripple in stop band.
• Rectangular – Largest amount of ripple/lobes, even affects pass band.

Attributes of the different IIR filter methods:

• Butterworth – Flat response in both the pass and stop band, but has a wide transition zone. First described by British physicist Stephen Butterworth in 1930.
• Inverse Chebyshev – Flat in the pass band, with a narrower transition width than the Butterworth filter, but has ripple in the stop band. If ripple in the stop band is not a problem, might be preferred for a given application over the Butterworth filter.
• Chebyshev – Can have ripple in pass band, but has steeper rolloff than Inverse Chebyshev.
• Cauer – Narrowest transition zone. Ripple in both stop and pass bands. Sometimes called an Elliptic filter.
• Bessel – Sloping amplitude in both the pass and stop band, with a very wide transition zone. The delay versus frequency in the filter is the flattest in this list. The Bessel filter was named for Freidrich Bessel (1784-1846), a German mathematician.