Digital Filter Design

FIR, IIR, windowing, equiripple, least squares, Butterworth, Chebyshev, elliptic, pulse shaping

Design digital filters using as a starting point a set of specifications (designfilt) or a design algorithm (butter, fir1). Generate FIR differentiators and Hilbert filters.

Apps

Filter Analyzer	View, analyze, and compare filters (Since R2024a)
Filter Designer	Design filters starting with algorithm selection

Live Editor Tasks

Design Filter

Design a digital filter in the Live Editor (Since R2021b)

Functions

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IIR Filters

`butter`	Butterworth filter design
`buttord`	Butterworth filter order and cutoff frequency
`cheby1`	Chebyshev Type I filter design
`cheb1ord`	Chebyshev Type I filter order
`cheby2`	Chebyshev Type II filter design
`cheb2ord`	Chebyshev Type II filter order
`designfilt`	Design digital filters
`ellip`	Elliptic filter design
`ellipord`	Minimum order for elliptic filters
`yulewalk`	Recursive digital filter design

FIR Filters

`cfirpm`	Complex and nonlinear-phase equiripple FIR filter design
`designfilt`	Design digital filters
`fir1`	Window-based FIR filter design
`fir2`	Frequency sampling-based FIR filter design
`fircls`	Constrained-least-squares FIR multiband filter design
`fircls1`	Constrained-least-squares linear-phase FIR lowpass and highpass filter design
`firls`	Least-squares linear-phase FIR filter design
`firpm`	Parks-McClellan optimal FIR filter design
`firpmord`	Parks-McClellan optimal FIR filter order estimation
`gaussdesign`	Gaussian FIR pulse-shaping filter design
`intfilt`	Interpolation FIR filter design
`kaiserord`	Kaiser window FIR filter design estimation parameters
`maxflat`	Generalized digital Butterworth filter design
`rcosdesign`	Raised cosine FIR pulse-shaping filter design
`sgolay`	Savitzky-Golay filter design

Filter Utilities

`digitalFilter`	Digital filter
`double`	Cast coefficients of digital filter to double precision
`dspfwiz`	Create Simulink filter block using Realize Model panel
`filt2block`	Generate Simulink filter block
`filterAnalyzer`	Analyze filters with Filter Analyzer app (Since R2024a)
`info`	Information about digital filter
`isdouble`	Determine if digital filter coefficients are double precision
`issingle`	Determine if digital filter coefficients are single precision
`polyscale`	Scale roots of polynomial
`polystab`	Stabilize polynomial
`scaleFilterSections`	Scale cascaded transfer functions with scale values (Since R2023b)
`single`	Cast coefficients of digital filter to single precision

Topics

IIR Filter Design
This example compares classical Butterworth, Chebyshev, and elliptic designs; and explores Bessel, Yule-Walker, and generalized Butterworth filters.
FIR Filter Design
This example shows how to use windowing, least squares, or the Parks-McClellan algorithm to design lowpass, highpass, multiband, or arbitrary-response filters, differentiators, or Hilbert transformers.
Filter Implementation
Filter signals using the filter function.
Anti-Causal, Zero-Phase Filter Implementation
Eliminate the phase distortion introduced by an IIR filter.
Compensate for the Delay Introduced by an FIR Filter
Use indexing to counteract the time shifts introduced by filtering.
Compensate for the Delay Introduced by an IIR Filter
Remove delays and distortion introduced by filtering, when it is critical to keep phase information intact.
Take Derivatives of a Signal
Use a differentiator filter to differentiate a signal without amplifying the noise.
Filter Builder Design Process
filterBuilder is a graphical interface that speeds up the filter design process.
Generating Guitar Chords Using the Karplus-Strong Algorithm
Generate realistic guitar chords using the Karplus-Strong algorithm and discrete-time filters.

Related Information

Filter Design in MATLAB

Featured Examples

Practical Introduction to Digital Filter Design

Use the designfilt function to design FIR and IIR filters based on frequency response specifications.

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Practical Introduction to Digital Filtering

Design, analyze, and apply digital filters to remove unwanted content from a signal without distorting the data.

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Filter Design Gallery

Identify a filter response of interest, see how it is designed using the designfilt function, and use it in your own project.

Open Live Script