S-Parameters
Model S-parameter network
Libraries:
RF Blockset /
Circuit Envelope /
Elements
Description
The S-parameters block models a network defined by S-parameters in the RF Blockset™ circuit envelope simulation environment. The device can have up to 65 ports. For an introduction to RF simulation, see the example, Simulate High Frequency Components.
The block models S-parameter data in the RF Blockset environment by fitting a rational function to the specified data. For more
information about rational fitting of S-parameters, see the RF Toolbox™
rational
function.
Note
During the fitting procedure, the block sets the
TendsToZero
and Qlimit
properties
of the rational
object to false
and
inf
, respectively.
S-parameters block mask icons are dynamic and indicate the current state of the applied noise parameter. This table shows you how the icons on this block vary based on the state of the Simulate noise parameter on the block.
Simulate noise: on | Simulate noise: off |
---|---|
|
|
To model RF complex baseband S-parameters in Simulink, use the Idealized Baseband S-parameters block.
Examples
Architectural Design of a Low IF Receiver System
Use the RF Blockset™ Circuit Envelope library to simulate the performance of a Low IF architecture with the following RF impairments:
Compare Time and Frequency Domain Simulation Options for S-parameters
Model S-parameters using time and frequency domain simulation modes.
Parameters
Data source — Data source
Data file
(default) | Network-parameters
| Rational model
Data source for S-parameters behavior, specified as one of the following:
Data file
— Name of a Touchstone file with the extension.s2p
. The block ignores noise and nonlinearity data in imported files.Network-parameters
— Provide Network parameter data such asS-parameters
,Y-parameters
, andZ-parameters
with corresponding Frequency and Reference impedance (ohms) for the s-parameters.Rational model
— Provide values for Residues, Poles, and Direct feedthrough parameters which correspond to the equation for a rational model.In this rational model equation, each Ck is the residue of the pole Ak. If Ck is complex, a corresponding complex conjugate pole and residue must also be enumerated. This object has the properties
C
,A
, andD
. You can use these properties to specify the Residues, Poles, and Direct feedthrough parameters.
Data file — Name of network parameter data file
simrfV2_unitygain.s2p
(default) | character vector
Name of network parameter data file, specified as a character vector.
Dependencies
To enable this parameter, select Data file
in Data
source tab.
Network-parameter object — Network parameter objects as data source
off
(default) | on
Select this parameter to use a network parameter object as the data source to model the S-parameters.
Once you select this parameter, in the text box that opens, specify one of these:
Network parameter object.
MATLAB® base workspace variable or a Simulink® model workspace variable. The block evaluates if the specified variable is a network parameter object.
sparameters('default.s2p')
is the default network
parameter object when you select this parameter.
The network parameter objects that you can specify include:
Dependencies
To enable this parameter, set Data source to
Network-parameters
.
Network parameter type — Network parameter type
S-parameters
(default) | Y-parameters
| Z-parameters
Network parameter type, specified as S-parameters
, Y-parameters
,
or Z-parameters
.
Dependencies
To enable this parameter, set Data source to
Network-parameters
.
Network-parameters — Network parameter values
[0 0;1 0]
(default) | multidimensional array | scalar
Network parameter values specified as a multidimensional array or a scalar. When you specify Network parameters as a multi-dimensional array, the third dimension of the S-parameter array must be of the same length as the frequencies vector specified in the Frequency (dB) parameter.
Dependencies
To enable this parameter, set Data source to
Network-parameters
.
Frequency (dB) — Frequency of network parameters
1e9 Hz
(default) | scalar | vector | Hz
| kHz
| MHz
| GHz
Frequency of network parameters, specified as a scalar or a vector in Hz.
Dependencies
To enable this parameter, set Data source to
Network-parameters
.
Reference Impedance(Ohm) — Reference impedance of network parameters
50
(default) | positive scalar | vector of positive scalars
Reference impedance of network parameters, specified as a positive scalar or vector of positive scalars in ohms.
Note
The reference impedance of all ports must be equal when you specify it as a vector of positive scalars.
Dependencies
To enable this parameter, set Data source to
Network-parameters
.
Use rational object — Rational object as data source
off
(default) | on
Select this parameter to use a rational
object as the
data source to model S-parameter.
Once you select this parameter, in the text box that opens, specify one of these:
rational
object.MATLAB base workspace variable or a Simulink model workspace variable. The block evaluates if the specified variable is a rational object."
rational('default.s2p')
is the default
rational
object when you select this parameter.
The rational
objects that you can specify include:
Dependencies
To enable this parameter, set Data source to
Rational model
.
Residues — Residues in order of rational model
0
(default) | vector
Residues in order of rational model, specified as a vector.
Dependencies
To enable this parameter, set Data source to
Rational model
.
Poles — Residues in order of rational model
0
(default) | vector
Poles in order of rational model, specified as a vector.
Dependencies
To enable this parameter, set Data source to
Rational model
.
Direct feedthrough — Direct feedthrough
{0 0:1 0}
(default) | array of vectors
Direct feedthrough, specified as an array vector.
Dependencies
To enable this parameter, set Data source to
Rational model
.
Simulate noise — Simulate thermal noise waves
off
(default) | on
Select this parameter to simulate thermal noise waves [1]. For more information see, Generate Thermal Noise.
The S-Parameter block simulates thermal noise of an S-parameter network with up to 65 ports. (since R2023b)
Ground and hide negative terminals — Ground RF circuit terminals
on
(default) | off
Select this parameter to ground and hide the negative terminals. Clear this parameter to expose the negative terminals. By exposing these terminals, you can connect them to other parts of your model.
Modeling options — Model S-parameters
Time domain
(default) | Frequency domain
Model S-parameters, specified as:
Time domain
technique creates an analytical rational model that approximates the whole range of the data. When modeling usingTime domain
, the Plot inVisualization
tab plots the data defined inData Source
and the values in therational
function.Frequency domain
computes the baseband impulse response for each carrier frequency independently. This technique is based on convolution. There is an option to specify the duration of the impulse response. For more information, see Compare Time and Frequency Domain Simulation Options for S-parameters.For the Amplifier, Antenna, and S-parameters blocks, the default value is
Time domain
. For the Transmission Line block, the default value isFrequency domain
.
Dependencies
To enable this parameter, set Data source to either Data
file
or
Network-parameters
.
Fitting options — Rational fit fitting options
Fit individually
(default) | Share poles by column
| Share all poles
Rational fit fitting options, specified as Fit
individually
, Share poles by
column
, or Share all
poles
.
Rational fitting results shows values of Number of independent fits, Number of required poles, and Relative error achieved (dB).
Dependencies
To set this parameter, select Time domain
in Modeling options.
Relative error desired (dB) — Relative error acceptable for the rational fit
-40
(default) | scalar
Relative error acceptable for the rational fit, specified as a scalar.
Dependencies
To set this parameter, select Time domain
in Modeling
options.
Maximum number of poles — Maximum number of poles
48
(default) | positive scalar
Maximum number of poles to control over the fitting procedure, specified
as a positive scalar. You can specify up to 99
poles.
Dependencies
To set this parameter, select Time domain
in Modeling options.
Automatically estimate impulse response duration — Automatically calculate impulse response
on
| off
Select this parameter to automatically calculate impulse response. Clear this parameter to manually specify the impulse response duration using Impulse response duration.
Dependencies
To set this parameter, select Frequency domain
in Modeling
options.
Impulse response duration — Impulse response duration
1e-10
(default) | scalar
Impulse response duration, specified as a scalar.
Dependencies
To set this parameter, first select Frequency domain
in Modeling
options. Then, clear Automatically estimate impulse
response duration
.
Use only S-parameter magnitude with appropriate delay — Use only S-parameter magnitude with appropriate delay
off
(default) | on
Select this parameter to ignore the S-parameter phase and to delay the impulse response by half its length. You can use this parameter to shape spectral content with filter effects by specifying only magnitude.
This parameter uses the magnitude of the original data to obtain the impulse response of the block. This impulse response is centered about the time sequence and adds an inherent delay of half the duration of the impulse response. In the frequency domain, this translates to a linear monotonic decrease in phase throughout the given spectrum.
Note
This parameter is applicable only for S-parameter data modeled in the frequency domain and introduces an artificial delay to the system.
Adding a time delay (or frequency phase variation) to the system can result in unexpected behaviors. For example, in an unmatched system, delayed signals are bounced back and added to the original signals.
Dependencies
To enable this parameter, set Modeling options to
Frequency domain
.
Source of frequency data — Frequency data source
Extracted from data source
(default) | User-defined
Frequency data source, specified as:
When Source of frequency data is Extracted
from data source
, the Data source must
be set to Data file
. Verify that the specified Data
file contains frequency data.
When Source of frequency data is User-specified
,
specify a vector of frequencies in the Frequency data parameter.
Also, specify units from the corresponding drop-down list.
Frequency data — Frequency data range
[1e9:1e6:3e9]
Hz (default) | vector | scalar
Frequency data range, specified as a vector or a scalar in Hz, kHz, MHZ, or GHz. Specify Frequency data as a scalar when you want to visualize a singe frequency S-parameter data.
Dependencies
To enable this parameter, set Source of frequency
data to User-specified
.
Plot type — Type of data plot
X-Y plane
(default) | Polar plane
| Z Smith chart
| Y Smith chart
| ZY Smith chart
Type of data plot that you want to produce with your data specified as one of the following:
X-Y plane
— Generate a Cartesian plot of your data versus frequency. To create linear, semilog, or log-log plots, set the Y-axis scale and X-axis scale accordingly.Polar plane
— Generate a polar plot of your data. The block plots only the range of data corresponding to the specified frequencies.Z smith chart
,Y smith chart
, andZY smith chart
— Generate a Smith® chart. The block plots only the range of data corresponding to the specified frequencies.
Parameter 1 — Type of S-Parameters to plot
S11
(default) | SNN
Type of S-Parameters to plot, specified as SNN
, where N
is the number of ports in the s-parameters block.
Parameter 2 — Type of S-Parameters to plot
None
(default) | SNN
Type of S-Parameters to plot, specified as SNN
, where
N is the number of ports in the s-parameters
block.
Format1 — Plot format
Magnitude (decibels)
(default) | Angle(degrees)
| Real
| Imaginary
Plot format, specified as Magnitude (decibels)
, Angle(degrees)
, Real
,
or Imaginary
.
Format2 — Plot format
Magnitude (decibels)
(default) | Angle(degrees)
| Real
| Imaginary
Plot format, specified as Magnitude (decibels)
, Angle(degrees)
, Real
,
or Imaginary
.
Y-axis scale — Y-axis scale
Linear
(default) | Logarithmic
Y-axis scale, specified as Linear
or Logarithmic
.
X-axis scale — X-axis scale
Linear
(default) | Logarithmic
X-axis scale, specified as Linear
or Logarithmic
.
Plot — Plot specified data
button
Plot specified data using plot button.
More About
Generate Thermal Noise
You can only generate thermal noise if the given S-parameters multiport components are passive.
To include the noise waves, the block augments the S-parameters equation:
a and b — Customary wave vectors
c — Noise wave vector
The noise wave vector, noise correlation matrix, and S-parameters have these relationships:
where:
K
— Boltzmann's constantT
— System temperaturec
— Noise wave vector
References
[1] Wedge, Scott, and David Rutledge. “Wave Techniques for Noise Modeling and Measurement.” IEEE Transactions on Microwave Theory and Techniques 40, no. 11 (November 1992): 2004–12. https://doi.org/10.1109/22.168757.
Version History
Introduced in R2010bR2024b: Time domain (rationalfit)
parameter renamed
The Time domain (rationalfit)
parameter value in the
Modeling options parameter has been renamed to
Time domain
in the S-parameters
block.
When you open a model created before R2024b containing an
S-parameters block, the parameter name displays as
Time domain
.
R2023b: Simulate noise in S-parameters block
Starting this release, you can use the Simulate noise parameter in the S-Parameters block to simulate the noise of an S-parameter network with more than eight ports. In earlier releases, you could use the block to simulate the noise of networks with up to eight ports.
R2022b: Use Network parameter and rational objects to model S-parameters
Use network parameter and rational
objects created at the MATLAB
command line as the data source to model S-parameters by setting Data
Source to Network parameters
and
Rational model
. For more information, see
Network-parameter
object and Use rational
object.
R2022b: Visualize single-frequency S-parameter data
Visualize single-frequency S-parameter data by specifying single-frequency S-parameter data in the Frequency data parameter.
R2022b: Block parameter renamed
The Frequency data parameter in the S-parameter block has been renamed to Source of frequency data.
When you open a model created before R2022b containing the S-parameter block, the software replaces the Frequency data parameter with the Source of frequency data parameter.
R2021b: S-parameter network data construction in S-parameter block
Starting in R2021b, the Circuit Envelope library S-Parameters block uses the rational
function to perform rational fitting to complex frequency-dependent data. The
rational
object provides improved fitting speed. The block
also has a new parameter, Maximum number of poles, to provide
additional control over the fitting procedure. You can specify up to 99
poles.
When you open a model created before R2021b containing the Circuit Envelope library S-parameter block, the software updates the extraction method to perform a rational fit with the new Maximum number of poles parameter. The output of the model gets refitted and the refitted output might differ from the output in previous releases.
R2021b: S-parameter block icon updated
Starting in R2021b, the S-parametrs block icon has updated. The block icons are now dynamic and show the current state of the noise parameter.
When you open a model created before R2021b containing a S-parametrs block, the software replaces the block icon with the R2021b version.
See Also
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