filt2block

Generate Simulink filter block

Syntax

filt2block(b)

filt2block(b,'subsystem')

filt2block(___,'FilterStructure',structure)

filt2block(b,a)

filt2block(b,a,'subsystem')

filt2block(___,'FilterStructure',structure)

filt2block(sos)

filt2block(sos,'subsystem')

filt2block(___,'FilterStructure',structure)

filt2block(d)

filt2block(d,'subsystem')

filt2block(___,'FilterStructure',structure)

filt2block(___,Name,Value)

Description

filt2block(b) generates a Discrete FIR Filter block with filter coefficients, b.

filt2block(b,'subsystem') generates a Simulink^® subsystem block that implements an FIR filter using sum, gain, and delay blocks.

filt2block(___,'FilterStructure',structure) specifies the filter structure for the FIR filter.

filt2block(b,a) generates a Discrete Filter block with numerator coefficients, b, and denominator coefficients, a.

filt2block(b,a,'subsystem') generates a Simulink subsystem block that implements an IIR filter using sum, gain, and delay blocks.

filt2block(___,'FilterStructure',structure) specifies the filter structure for the IIR filter.

filt2block(sos) generates a Biquad Filter block with second order sections matrix, sos. sos is a K-by-6 matrix, where the number of sections, K, must be greater than or equal to 2. You must have the DSP System Toolbox™ software installed to use this syntax.

filt2block(sos,'subsystem') generates a Simulink subsystem block that implements a biquad filter using sum, gain, and delay blocks.

filt2block(___,'FilterStructure',structure) specifies the filter structure for the biquad filter.

filt2block(d) generates a Simulink block that implements a digital filter, d. Use the function designfilt to create d. The block is a Discrete FIR Filter block if d is FIR and a Biquad Filter block if d is IIR.

filt2block(d,'subsystem') generates a Simulink subsystem block that implements d using sum, gain, and delay blocks.

filt2block(___,'FilterStructure',structure) specifies the filter structure to implement d.

filt2block(___,Name,Value) uses additional options specified by one or more Name,Value pair arguments.

Examples

Generate Block from FIR Filter

Design a 30th-order FIR filter using the window method. Specify a cutoff frequency of π/4 rad/sample. Create a Simulink® block.

b = fir1(30,0.25);
filt2block(b)

Generate Block from IIR Filter

Design a 30th-order IIR Butterworth filter. Specify a cutoff frequency of π/4 rad/sample. Create a Simulink® block.

[b,a] = butter(30,0.25);
filt2block(b,a)

Generate FIR Filter with Direct Form I Transposed Structure

Design a 30th-order FIR filter using the window method. Specify a cutoff frequency of π/4 rad/sample. Create a Simulink® block with a direct form I transposed structure.

b = fir1(30,0.25);
filt2block(b,'FilterStructure','directFormTransposed')

Generate IIR Filter with Direct Form I Structure

Design a 30th-order IIR Butterworth filter. Specify a cutoff frequency of π/4 rad/sample. Create a Simulink® block with a direct form I structure.

[b,a] = butter(30,0.25);
filt2block(b,a,'FilterStructure','directForm1')

Generate Subsystem Block from Second-Order Section Matrix

Design a 5-th order Butterworth filter with a cutoff frequency of π/5 rad/sample. Obtain the filter in biquad form and generate a Simulink® subsystem block from the second order sections.

[z,p,k] = butter(5,0.2);
sos = zp2sos(z,p,k);
filt2block(sos,'subsystem')

Lowpass FIR Filter Block with Sample-Based Processing

Generate a Simulink® subsystem block that implements an FIR lowpass filter using sum, gain, and delay blocks. Specify the input processing to be elements as channels by specifying 'FrameBasedProcessing' as false.

B = fir1(30,.25);
filt2block(B,'subsystem','BlockName','Lowpass FIR',...
              'FrameBasedProcessing',false)

New Model with Highpass Elliptic Filter Block

Design a highpass elliptic filter with normalized stopband frequency 0.45 and normalized passband frequency 0.55. Specify a stopband attenuation of 40Design a highpass elliptic filter with normalized stopband frequency 0.45 and normalized passband frequency 0.55. Specify a stopband attenuation of 40 dB and a passband ripple of 0.5 dB. Implement the filter as a Direct Form II structure, call it "HP", and place it in a new Simulink® model.

d = designfilt('highpassiir','DesignMethod','ellip', ...
               'StopbandFrequency',0.45,'PassbandFrequency',0.55, ...
               'StopbandAttenuation',40,'PassbandRipple',0.5);

filt2block(d,'subsystem','FilterStructure','directForm2', ...
             'Destination','new','BlockName','HP')

Input Arguments

b — Numerator filter coefficients

row or column vector

Numerator filter coefficients, specified as a row or column vector. The filter coefficients are ordered in descending powers of z^–1 with the first element corresponding to the coefficient for z⁰.

Example: b = fir1(30,0.25);

Data Types: single | double
Complex Number Support: Yes

a — Denominator filter coefficients

row or column vector

Denominator filter coefficients, specified as a row or column vector. The filter coefficients are ordered in descending powers of z^–1 with the first element corresponding to the coefficient for z⁰. The first filter coefficient must be 1.

Data Types: single | double
Complex Number Support: Yes

sos — Second-order section matrix

K-by-2 matrix

Second order section matrix, specified as a K-by-2 matrix. Each row of the matrix contains the coefficients for a biquadratic rational function in z^–1. The Z-transform of the Kth rational biquadratic system impulse response is

$$H_k(z)=\frac{B_k(1)+B_k(2)z^{-1}+B_k(3)z^{-2}}{A_k(1)+A_k(2)z^{-1}+A_k(3)z^{-2}}$$

The coefficients in the Kth row of the matrix, sos, are ordered as follows:

$$\left[\begin{array}{cccccc}{B}_k(1)& B_k(2)& B_k(3)& A_k(1)& A_k(2)& A_k(3)\end{array}\right]$$

The frequency response of the filter is its transfer function evaluated on the unit circle with z = e^j2πf.

Data Types: single | double
Complex Number Support: Yes

d — Digital filter

digitalFilter object

Digital filter, specified as a digitalFilter object. Use designfilt to generate a digital filter based on frequency-response specifications.

Example: d = designfilt('lowpassiir','FilterOrder',3,'HalfPowerFrequency',0.5) specifies a third-order Butterworth filter with normalized 3 dB frequency 0.5π rad/sample.

structure — Filter structure

character vector | string scalar

Filter structure, specified as a character vector or string scalar. Valid options for structure depend on the input arguments. The following table lists the valid filter structures by input.

Input	Filter Structures
b	'directForm' (default), 'directFormTransposed', 'directFormSymmetric', 'directFormAntiSymmetric', 'overlapAdd'. The 'overlapAdd' structure is only available when you omit 'subsystem' and requires a DSP System Toolbox software license.
a	'directForm2' (default), 'directForm1', 'directForm1Transposed', 'directForm2', 'directForm2Transposed'
sos	'directForm2Transposed' (default), 'directForm1', 'directForm1Transposed', 'directForm2'
d	For FIR filters: 'directForm' (default), 'directFormTransposed', 'directFormSymmetric', 'directFormAntiSymmetric', 'overlapAdd'. The 'overlapAdd' structure is only available when you omit 'subsystem' and requires a DSP System Toolbox software license. For IIR filters: 'directForm2Transposed' (default), 'directForm1', 'directForm1Transposed', 'directForm2'

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: filt2block(...,'subsystem','BlockName','Lowpass FIR','FrameBasedProcessing',false)

Destination — Destination for Simulink filter block

'current' (default) | 'new' | character vector | string scalar

Destination for the Simulink filter block, specified as a character vector or string scalar. You can add the filter block to your current model with 'current', add the filter block to a new model with 'new', or specify the name of an existing model.

Example: filt2block([1 2 1],'Destination','MyModel','BlockName','New block')

Data Types: char | string

BlockName — Block name

character vector | string scalar

Block name, specified as a character vector or string scalar.

Data Types: char | string

OverwriteBlock — Overwrite block

false (default) | true

Overwrite block, specified as a logical false or true. If you use a value for 'BlockName' that is the same as an existing block, the value of 'OverwriteBlock' determines whether the block is overwritten. The default value is false.

Data Types: logical

MapCoefficientsToPorts — Map coefficients to ports

false (default) | true

Map coefficients to ports, specified as a logical false or true.

Data Types: logical

CoefficientNames — Coefficient variable names

cell array of character vectors | string array

Coefficient variable names, specified as a cell array of character vectors or a string array. This name-value pair is only applicable when 'MapCoefficientsToPorts' is true. The default values are {'Num'}, {'Num','Den'}, and {'Num','Den','g'} for FIR, IIR, and biquad filters.

Data Types: cell | string

FrameBasedProcessing — Frame-based or sample-based processing

true (default) | false

Frame-based or sample-based processing, specified as a logical true or false. The default is true and frame-based processing is used.

Data Types: logical

OptimizeZeros — Remove zero-gain blocks

true (default) | false

Remove zero-gain blocks, specified as a logical true or false. By default zero-gain blocks are removed.

Data Types: logical

OptimizeOnes — Replace unity-gain blocks with direct connection

true (default) | false

Replace unity-gain blocks with direct connection, specified as a logical true or false. The default is true.

Data Types: logical

OptimizeNegativeOnes — Replace negative unity-gain blocks with sign change

true (default) | false

Replace negative unity-gain blocks with a sign change at the nearest block, specified as a logical true or false. The default is true.

Data Types: logical

OptimizeDelayChains — Replace cascaded delays with a single delay

true (default) | false

Replace cascaded delays with a single delay, specified as a logical true or false. The default is true.

Data Types: logical

Version History

Introduced in R2013a