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Filter Design Methods

The Filter Designer app is a user interface for designing and analyzing filters quickly. The app enables you to design digital FIR or IIR filters by setting filter specifications, by importing filters from your MATLAB® workspace, or by adding, moving or deleting poles and zeros. It also provides tools for analyzing filters, such as magnitude and phase response and pole-zero plots.

The Filter Designer app gives you access to the following Signal Processing Toolbox™ filter design methods.

Design Method

Function

Butterworth

butter

Chebyshev Type I

cheby1

Chebyshev Type II

cheby2

Elliptic

ellip

Maximally Flat

maxflat

Equiripple

firpm

Least-squares

firls

Constrained least-squares

fircls

Complex equiripple

cfirpm

Window

fir1

When using the window method, all Signal Processing Toolbox window functions are available, and you can specify a user-defined window by entering its function name and input parameter.

Advanced Filter Design Methods

The following advanced filter design methods are available if you have DSP System Toolbox™ software.

Design Method

Function

Constrained equiripple FIR

firceqrip (DSP System Toolbox)

Constrained-band equiripple FIR

fircband (DSP System Toolbox)

Generalized remez FIR

firgr (DSP System Toolbox)

Equiripple halfband FIR

firhalfband (DSP System Toolbox)

Least P-norm optimal FIR

firlpnorm (DSP System Toolbox)

Equiripple Nyquist FIR

firnyquist (DSP System Toolbox)

Interpolated FIR

ifir (DSP System Toolbox)

IIR comb notching or peaking

iircomb (DSP System Toolbox)

Allpass filter (given group delay)

iirgrpdelay (DSP System Toolbox)

Least P-norm optimal IIR

iirlpnorm (DSP System Toolbox)

Constrained least P-norm IIR

iirlpnormc (DSP System Toolbox)

Second-order IIR notch

iirnotch (DSP System Toolbox)

Second-order IIR peaking (resonator)

iirpeak (DSP System Toolbox)