Analog Filter Design

Design and implement analog filters

  • Library:
  • DSP System Toolbox / Filtering / Filter Implementations

Description

The Analog Filter Design block designs and implements a Butterworth, Chebyshev type I, Chebyshev type II, elliptic, or bessel filter in a highpass, lowpass, bandpass, or bandstop configuration.

You select the design and band configuration of the filter from the Design method and Filter type drop-down lists in the dialog box. For each combination of design method and band configuration, an appropriate set of secondary parameters is displayed. For more details, see Design/Band Combination Table.

The Analog Filter Design block uses a state-space filter representation, and applies the filter using the State-Space block in the Simulink® Continuous library. All of the design methods use Signal Processing Toolbox™ functions to design the filter.

The Analog Filter Design block is built on the filter design capabilities of Signal Processing Toolbox software.

Note

The Analog Filter Design block does not work with the Simulink discrete solver, which is enabled when you set the Solver list to Discrete (no continuous states) in the Solver pane of the Model Configuration Parameters dialog box. Select one of the continuous solvers (such as ode4) instead.

Ports

Input

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Input signal to filter, specified as a sample-based, continuous-time, real-valued scalar value.

Data Types: double

Output

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Filtered signal, returned as a real double scalar value.

Data Types: double

Parameters

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The filter design methods are:

  • Butterworth — The magnitude response of a Butterworth filter is maximally flat in the passband and monotonic overall. The Butterworth design uses the toolbox function butter.

  • Chebyshev I — The magnitude response of a Chebyshev I filter is equiripple in the passband and monotonic in the stopband. The Chebyshev I design uses the toolbox function cheby1.

  • Chebyshev II — The magnitude response of a Chebyshev II filter is monotonic in the passband and equiripple in the stopband. The Chebyshev II design uses the toolbox function cheby2.

  • Elliptic — The magnitude response of an elliptic filter is equiripple in both the passband and the stopband. The elliptic design uses the toolbox function ellip.

  • Bessel — The magnitude response of a bessel filter is maximally flat in the passband and monotonic overall. The filter has a maximally flat linear phase response. The bessel design uses the function besself.

Tunable: Yes

The type of filter to design:

  • Lowpass

  • Highpass

  • Bandpass

  • Bandstop

Tunable: Yes

The order of the filter when Filter type is set to:

  • Lowpass

  • Highpass

The order of the final filter is twice the value of Filter order when Filter type is set to:

  • Bandpass

  • Bandstop

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The passband edge frequency, in rad/s.

Tunable: Yes

Dependencies

This parameter appears only when Design method is set to:

  • Butterworth

  • Chebyshev I

  • Elliptic

  • Bessel

and Filter type is set to:

  • Lowpass

  • Highpass

The lower passband edge frequency, specified in rad/s.

Tunable: Yes

Dependencies

This parameter appears only when Design method is set to:

  • Butterworth

  • Chebyshev I

  • Elliptic

  • Bessel

and Filter type is set to:

  • Bandpass

  • Bandstop

The upper passband edge frequency, specified in rad/s.

Tunable: Yes

Dependencies

This parameter appears only when Design method is set to:

  • Butterworth

  • Chebyshev I

  • Elliptic

  • Bessel

and Filter type is set to:

  • Bandpass

  • Bandstop

The stopband edge frequency, specified in rad/s.

Tunable: Yes

Dependencies

This parameter appears only when Design method is set to:

  • Chebyshev II

and Filter type is set to:

  • Lowpass

  • Highpass

The lower stopband edge frequency, in rad/s.

Tunable: Yes

Dependencies

This parameter appears only when Design method is set to:

  • Chebyshev II

and Filter type is set to:

  • Bandpass

  • Bandstop

The upper stopband edge frequency, specified in rad/s.

Tunable: Yes

Dependencies

This parameter appears only when Design method is set to:

  • Chebyshev II

and Filter type is set to:

  • Bandpass

  • Bandstop

The passband ripple, specified in dB.

Tunable: Yes

Dependencies

This parameter appears only when Design method is set to:

  • Chebyshev I

  • Elliptic

The stopband attenuation, in dB.

Tunable: Yes

Dependencies

This parameter appears only when Design method is set to:

  • Chebyshev II

  • Elliptic

Block Characteristics

Data Types

double

Multidimensional Signals

No

Variable-Size Signals

No

More About

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References

[1] Antoniou, A. Digital Filters: Analysis, Design, and Applications. 2nd ed. New York, NY: McGraw-Hill, 1993.

Extended Capabilities

Introduced before R2006a