makepassive

Enforce passivity of rational fit

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Syntax

pfit = makepassive(fit)
pfit = makepassive(fit,s)
pfit = makepassive(fit,s,'Display','on')

Description

pfit = makepassive(fit) produces a passive fit by modifying the input given using either the rational object or the rationalfit function.

pfit = makepassive(fit,s) produces a passive fit by modifying the input, fit while optimally matching the data of S-parameter input, s. makepassive function does modifies the residues of the fit to make it passive.

example

pfit = makepassive(fit,s,'Display','on') solves as above, but turns on the display of iteration information. The default for 'Display' is 'off'.

Examples

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Open Live Script

Read a file named passive.s2p and fit the 2x2 S-parameters.

 S = sparameters('passive.s2p');
 fit = rationalfit(S);

Plot the passivity of the 2x2 fit, noting the violations.

 figure
 passivity(fit)

Figure contains an axes object. The axes object with title Fit not passive, max norm(H) is 1+1.79e-02 at 17.7 GHz, xlabel Frequency (GHz), ylabel norm(H) contains 4 objects of type line. One or more of the lines displays its values using only markers

Optimize residues to produce a passive fit still close to S.

 pfit = makepassive(fit,S)
pfit = 
  2x2 rfmodel.rational array with properties:

    A
    C
    D
    Delay
    Name

To display iteration information:

  pfit = makepassive(fit,S,'Display','on' )
Iter	H-infinity norm	Frequency	Error (dB)	Constraints
0		1+1.79e-02		17.7 GHz		-40.4702
1		1+2.69e-04		282 MHz		-40.9169	5
2		1+6.96e-05		378 MHz		-40.9076	8
3		1+1.86e-06		361 MHz		-40.9067	9
4		1-1.53e-06		367 MHz		-40.9062	10

pfit = 
  2x2 rfmodel.rational array with properties:

    A
    C
    D
    Delay
    Name

Plot the passivity of the new fit.

 figure
 passivity(pfit)

Figure contains an axes object. The axes object with title Fit passive, max norm(H) is 1-1.53e-06 at 367 MHz, xlabel Frequency (GHz), ylabel norm(H) contains an object of type line.

Input Arguments

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Rational fit object, specified as an N-by-N array of a rational or rationalfit object.

S-parameters, specified as an RF Toolbox™ network parameter object. To create this type of object, use the sparameters function.

Output Arguments

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rfmodel.rational objects, returned as N-by-N array.

Version History

Introduced in R2019a

See Also

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