S-parameters

Model RF complex baseband S-parameters in Simulink

Since R2023a

• 

Libraries:
RF Blockset / Idealized Baseband

Description

Use the Idealized Baseband S-parameter block to model RF complex baseband S-parameters in Simulink^®. You can input your S-parameters as a Touchstone file, an sparameters object, or as a rational object. If you describe the S-parameters using a Touchstone file or an sparameters object, the software uses rational fitting to derive a rational object. You can also model your S-parameters data in either the time or frequency domain and plot the S-parameters characteristics.

If you want to design S-parameters with impedance mismatches, use the Circuit Envelope S-Parameters block.

Examples

Model RF Complex Baseband S-Parameters in Simulink

Compare Idealized Baseband and Circuit Envelope S-parameters blocks.

• Open Script

Ports

Input

Port_1 — Time-dependent input signal

real scalar | real column | complex scalar | complex column

Time-dependent input signal, specified as a real scalar, real column, complex scalar, or complex column. A column represents consecutive points in time.

Data Types: double | single

Output

Port_1 — Time-dependent output signal

complex scalar | complex column

Time-dependent output signal, returned as a complex scalar or complex column. The output time-dependent signal is equal in size to the input time-dependent signal.

Data Types: double | single

Parameters

Main

Data source — Data source to model RF complex baseband S-parameters

file (default) | sparameters | rational

Data source to model RF complex baseband S-parameters, specified as one of the following:

• file — Select this option to specify a Touchstone file with the extension .s2p. The block ignores noise and nonlinearity data in imported files.

• sparameters — Select this option to specify an sparameters object.

• rational — Select this option to specify a rational object.

File — Two-port Touchstone data file

unitygain.s2p (default) | character vector

Name of the two-port Touchstone file, specified as a character vector.

Dependencies

To enable this parameter, set Data source to file.

Sparameter object — Use sparameters object as data source

sparameters('unitygain.s2p') (default)

Select this parameter to use an sparameters object as the data source to model the S-parameters.

Dependencies

To enable this parameter, set Data source to sparameters.

Rational object — Use rational object as data source

rational('unitygain.s2p','TendsToZero',false) (default)

Select this parameter to use a rational object as the data source to model the S-parameters.

Dependencies

To enable this parameter, set Data source to rational.

RF frequency (Hz) — Carrier frequency at which S-parameters are modeled

1000000000 (default) | positive real scalar

Carrier frequency at which the S-parameters are modeled, specified as a positive real scalar in Hz.

Simulate using — Type of simulation to run

Interpreted execution (default) | Code generation

Type of simulation to run, specified as one of the following:

• Interpreted execution — Simulate the model using the MATLAB^® interpreter. This option shortens the startup time, but the speed of the subsequent simulations is slower than when you use the Code generation option. Use this mode to debug the source code of the block.

• Code generation — Simulate the model using generated C code. The first time you run a simulation, Simulink^® generates C code for the block. The C code is reused for subsequent simulations as long as the model does not change. This option requires additional startup time, but the speed of the subsequent simulations is faster than when you use the Interpreted execution option.

Modeling

Modeling domain — Modeling domain

Time (Fixed step) (default) | Time (Continuous) | Frequency (Digital filter)

Modeling domain, specified as one of the following:

• Time(Fixed step) — Model using fixed-step solvers (NDF2, Trapezoidal, and Backward Euler)

• Time(Continuous) — Model using continuous or stiff solvers (ode15s, ode23s, ode23t, and ode23tb)

• Frequency (Digital filter) — model using a 1-D digital filter.

Solver — Time-domain solvers

NDF2 (default) | Trapezoidal | Backward Euler | ode15s | ode23s | ode23t (trap) | ode23tb (trap+BE)

Fixed-step and continuous time-domain solvers, specified as one of the following:

Fixed-step Solvers

• NDF2 — Balance narrowband and wideband accuracy. This solver is suitable for situations where the frequency content of the signals in the system is unknown relative to the Nyquist rate.

• Trapezoidal — Perform narrowband simulations. Frequency warping and the lack of damping effects make this method inappropriate for most wideband simulations.

• Backward Euler — Simulate the largest class of systems and signals. Damping effects make this solver suitable for wideband simulation, but overall accuracy is low.

Continuous Solvers

• ode15s — Solve stiff differential equations and DAEs using a variable order method

• ode23s — Solve stiff differential equations using a low-order method

• ode23t (trap) — Solve moderately stiff ODEs and DAEs using a trapezoidal rule

• ode23tb (trap+BE) — Solve stiff differential equations using a trapezoidal rule and backward differentiation formula

Dependencies

To enable:

• Fixed-step time-domain solvers, set Modeling domain to Time(Fixed step).

• Continuous time-domain solvers, set Modeling domain to Time (Continuous).

Pole fitting options — Rational fit fitting options

Share all poles (default) | Fit individually | Share poles by columns

Rational fit fitting options to control the complex frequency-dependent data fitting process, specified as Share all poles, Fit individually, or Share poles by columns.

Dependencies

To set this parameter, set Data source to either file or sparameters.

Rational arguments — Rational fit arguments to control the fit

{ 'Tolerance',-40,'TendsToZero',false,'MaxPoles',48,'Qlimit',inf } (default) | cell array

Rational fit fitting arguments to control the fit, specified as a cell array.

Dependencies

To set this parameter, set Data source to either file or sparameters.

FIR filter length — Filter length of 1-D digital filter

128 (default) | real positive integer

Filter length of the 1-D digital filter or impulse response duration, specified as a real positive integer.

Dependencies

To set this parameter, set Modeling domain to Frequency (Digital filter).

Visualization

First plot type — Plot type

S21 (default) | Phase delay | Group delay | Impulse response | Step response

Plot type of the first plot, specified as one of the following:

• S21

• Phase delay

• Group delay

• Impulse response

• Step response

Impulse response arguments — Input arguments to plot impulse response

[ 1e-11, 1e4] (default) | two-element vector

Input arguments to plot the impulse response, specified as a two-element vector. Plot the impulse response by specifying the sample time of the input signal and the number of samples in this parameter. For more information, see impulse.

Dependencies

To set this parameter, set First plot type or Second plot type to Impulse response.

Step response arguments — Input arguments to plot step response

[ 1e-11, 1e4, 1e-10 ] (default) | three-element vector

Input arguments to plot the step response, specified as a three-element vector. Plot the step response by specifying the sample time of the input signal, the number of samples, and the amount of time required for the step signal to reach the maximum value in this parameter. For more information, see stepresp.

Dependencies

To set this parameter, set First plot type or Second plot type to Step response.

First plot y-axis units — Y-axis units of first plot

Magnitude (dB) (default) | Magnitude (linear) | Angle (degrees) | Real | Imaginary

Y-axis units of the first plot, specified as one of the following:

• Magnitude (dB)

• Magnitude (linear)

• Angle (degrees)

• Real

• Imaginary

Dependencies

To set this parameter, set First plot type to S21.

Second Plot type — Plot type of second plot

None (default) | S21 | Phase delay | Group delay | Impulse response | Step response

Plot type of the second plot, specified as one of the following:

• None

• S21

• Phase delay

• Group delay

• Impulse response

• Step response

Second plot y-axis units — Y-axis units of second plot

Magnitude (dB) (default) | Magnitude (linear) | Angle (degrees) | Real | Imaginary

Y-axis units of the second plot, specified as one of the following:

• Magnitude (dB)

• Magnitude (linear)

• Angle (degrees)

• Real

• Imaginary

Dependencies

To set this parameter, set Second plot type to S21.

X-axis frequency points (Hz) — Frequency points to plot S-parameter data

logspace(8,10,2001) (default) | positive real vector

Frequency points to plot the S-parameter data, specified as a positive real vector in Hz.

X-axis scale — Linear or logarithmic X-axis scale

Linear (default) | Logarithmic

Select this parameter to plot your data on a linear or logarithmic X-axis scale. Specify Linear or Logarithmic.

Y-axis scale — Linear or logarithmic Y-axis scale

Linear (default) | Logarithmic

Select this parameter to plot your data in a linear or logarithmic Y-axis scale. Specify Linear or Logarithmic.

Plot Sparameter characteristics — Plot S-parameters data

button

Select this button to plot the characteristics of the S-parameters data.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2023a

R2024b: Parameters of S-parameters block from idealized baseband library have been renamed

The following parameters in the S-parameters block in the idealized baseband library have been renamed.

Parameter Name Before R2024b	Parameter Name Since R2024b
Data File	File
Carrier frequency (Hz)	RF frequency (Hz)

The following parameter values in the S-parameters block in the idealized baseband library have been changed.

Parameter	Values Before R2024b	Values Since R2024b
Data source	Data file	file
	S-parameters object	sparameters
	Rational object	rational
Modeling domain	Time domain (Fixed step)	Time (Fixed step)
	Time domain (Continuous)	Time (Continuous)
	Frequency domain (Digital filter)	Frequency (Digital filter)

When you open a model created before R2024b containing the S-parameters block, the software replaces the parameter names and values as shown in the table.