Rational Fitting and Time Domain Analysis

Fit frequency domain data to rational function, calculate time, step, impulse, and frequency response

Use the rational function to fit data defined in the frequency domain with an equivalent Laplace transfer function. Using rational function fitting you can create simple models for a required accuracy, model order reduction, zero phase on extrapolation to DC, and causal modeling system among other advantages.

Functions

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Rational Fit

`rational`	Perform rational fitting on complex frequency-dependent data (Since R2020a)
`rfmodel.rational`	Perform rational fit using pole-residue representation of the component

Response Curves

`timeresp`	Time response for rational objects
`stepresp`	Step-signal response for rational object and `rationalfit` function object
`freqresp`	Frequency response of rational object and `rationalfit` function object
`pwlresp`	Calculate time response of piecewise linear input signal (Since R2021a)
`impulse`	Impulse response for rational function object

Passivity

`ispassive`	Return true if rational fit output is passive at all frequencies
`makepassive`	Enforce passivity of rational fit
`passivity`	Plot passivity of N-by-N rational fit output

Causality

iscausal Determine if data is causal at specified frequency (Since R2023a)

Transformation

`abcd`	Construct state-space matrices from `rational` object (Since R2020a)
`zpk`	Compute zeros, poles, and gain of rational object (Since R2020a)

External Simulator Codes

`writeva`	Generate Verilog-A description of `rational` object
`generateSPICE`	Generate SPICE file from `rationalfit` of S-parameters

S-parameter Checker

ieee370QualityCheckFrequencyDomain Check quality of measured S-parameter data using IEEE 370 standard (Since R2023b)

Topics

RF Model Objects
Discover the available RF model objects and learn their uses.

Featured Examples

Characterize High-Frequency Data and Interconnects Using IEEE P370 Standard

Use the IEEE P370 source code, its associated data files, and RF Toolbox™ functions to implement the following recommended practices for de-embedding the effect of fixtures when measuring a device under test (DUT).