Digital Filter Design

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

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 the 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
Compare classical Butterworth, Chebyshev, and elliptic designs. Explore Bessel, Yule-Walker, and generalized Butterworth filters.
FIR Filter Design
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

Featured Examples

Practical Introduction to Digital Filter Design

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