Output Port

Connection block from RF physical blocks to Simulink environment

• Library:

• RF Blockset / Equivalent Baseband / Input / Output Ports

• 

Description

The Output Port block produces the baseband-equivalent time-domain response of an input signal traveling through a series of RF physical components. The Output Port block

1. Partitions the RF physical components into linear and nonlinear subsystems.

2. Extracts the complex impulse response of the linear subsystem for baseband-equivalent modeling of the RF linear system.

3. Extracts the nonlinear AMAM/AMPM modeling for RF nonlinearity.

The Output Port block also serves as a connecting port from an RF physical part of the model to the Simulink^®, or mathematical, part of the model. For more information about how the Output Port block converts the physical modeling environment signals to mathematical Simulink signals, see Convert to and from Simulink Signals.

Note

Some RF blocks require the sample time to perform baseband modeling calculations. To ensure the accuracy of these calculations, the Input Port block, as well as the mathematical RF blocks, compare the input sample time to the sample time you provide in the mask. If they do not match, or if the input sample time is missing because the blocks are not connected, an error message appears.

Parameters

Main Tab

Load impedance(ohms) — Load impedance of RF network

50 (default) | scalar

Load impedance of the RF network described in the physical model to which it connects, specified as scalar in ohms.

Visualization Tab

Source of frequency data — Frequency data source

Derived from Input Port parameter (default) | User-specified

Frequency data source in specified based on one of the following:

• When Source of frequency data is Derived from Input Port parameter, frequency data source will be derived from the parameters set on the Input Port.

• When Source of frequency data is User-specified, specify as a vector of frequencies in the Frequency data parameter.

Frequency data — Frequency data range

[1e9:1e6:3e9] (default) | vector

Frequency data range, specified as a vector in hertz.

Dependencies

To set this parameter, first select User-specified in Source of amplifier gain. This selection activates the Visualization Tab which contains Source of frequency data

Reference impedance (ohms) — Reference impedance

50 (default) | scalar

Reference impedance of the coaxial transmission line, specified as a scalar in ohms.

Plot type — Type of data plot

X-Y plane (default) | Composite data | 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:

• X-Y plane — Generate a Cartesian plot of your data versus frequency. To create linear, semi-log, or log-log plots, set the Y scale and X scale accordingly.

• Composite data—The composite data plot automatically generates four separate plots in one figure window, showing the frequency dependence of several parameters.

• 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, and ZY Smith chart — Generate a Smith^® chart of your data. The block plots only the range of data corresponding to the specified frequencies.

Y Parameter1 — Type of parameters to plot

S21 (default) | S11 | S12 | S22 | GroupDelay | GammaIn | GammaOut | VSWRIn | VSWROut | OIP3 | IIP3 | NF | NFactor | NTemp | TF1 | TF2 | TF3 | Gt | Ga | Gp | Gmag | Gmsg | GammaMS | GammaML | K | Delta | Mu | MuPrime

Type of parameters to plot, specified as one of the following S11, S12, S21, S22, GroupDelay, GammaIn, GammaOut, VSWRIn, VSWROut, OIP3, IIP3, TF1, TF2, TF3, Gt, Ga, Gp, Gmag, Gmsg, GammaMS, GammaML, K, Delta, Mu or MuPrime. When noise is spectral NF, NFactor and NTemp plotting is possible.

Y Parameter2 — Type of parameters to plot

S11 (default) | S12 | S21 | S22 | GroupDelay | GammaIn | GammaOut | VSWRIn | VSWROut | OIP3 | IIP3 | NF | NFactor | NTemp | TF1 | TF2 | TF3 | Gt | Ga | Gp | Gmag | Gmsg | GammaMS | GammaML | K | Delta | Mu | MuPrime

Type of parameters to plot, specified as one of the following S11, S12, S21, S22, GroupDelay, GammaIn, GammaOut, VSWRIn, VSWROut, OIP3, IIP3, TF1, TF2, TF3, Gt, Ga, Gp, Gmag, Gmsg, GammaMS, GammaML, K, Delta, Mu or MuPrime. When noise is spectral NF, NFactor and NTemp plotting is possible.

Y Format1 — Plot format

Angle (degrees) (default) | dB | Magnitude (decibels) | Abs | Mag | Magnitude (linear) | Angle | Angle (radians) | Real | Imag | Imaginary

Plot format, specified as one of the following Magnitude (decibels), Angle (degrees), Real, or Imaginary.

Y Format2 — Plot format

dB (default) | Magnitude (decibels) | Abs | Mag | Magnitude (linear) | Angle | Angle (degrees) | Angle (radians) | Real | Imag | Imaginary

Plot format, specified as one of the following Magnitude (decibels), Angle(degrees), Real, or Imaginary.

X parameter — X parameter

Freq (default)

Parameter, specified as Freq. This parameter determines the data for x-axes on the X-Y plane plot.

X format — Plot format

Hz (default) | Auto | KHz | MHz | GHz | THz

Plot format, specified as one of the following Hz, Auto, KHz, MHz, GHz or THz.

Y scale — Y-axis scale

Linear (default) | Log

Y-axis scale, specified as Linear or Log.

X scale — X-axis scale

Linear (default) | Log

X-axis scale, specified as Linear or Log.

Plot — Plot specified data

button

Plot the specified data using the plot button.

Dependencies

The Visualization tab shows parameters for creating plots if you display the Output Port mask after you perform one or more of the following actions:

• Run a model with two or more blocks between the Input Port block and the Output Port block.

• Click the Update Diagram button to initialize a model with two or more blocks between the Input Port block and the Output Port block.

For information about plotting, see Create Plots.

More About

Linear Subsystem

For the linear subsystem, the Output Port block uses the Input Port block parameters and the interpolated S-parameters calculated by each of the cascaded physical blocks to calculate the baseband-equivalent impulse response. Specifically, it

1. Determines the modeling frequencies f as an N-element vector. The modeling frequencies are a function of the center frequency f_c, the sample time t_s, and the finite impulse response filter length N, all of which you specify in the Input Port block dialog box.

   The nth element of f, f_n, is given by

   $$\begin{array}{cc}{f}_n=f_{\min }+\frac{n-1}{t_{s}N}& n=1,\mathrm{...},N\end{array}$$

   where

   $$f_{\min }=f_c-\frac{1}{2t_s}$$

2. Calculates the passband transfer function for the frequency range as

   $$H(f)=\frac{V_L(f)}{V_S(f)}$$

   where V_S and V_L are the source and load voltages, and f represents the modeling frequencies. More specifically,

   $$H(f)=\frac{S_{21}\left(1+{\Gamma }_l\right)\left(1-{\Gamma }_s\right)}{2\left(1-S_{22}{\Gamma }_l\right)\left(1-{\Gamma }_{in}{\Gamma }_s\right)}$$

   where

   $$\begin{array}{l}{\Gamma }_l=\frac{Z_l-Z_o}{Z_l+Z_o}\\ {\Gamma }_s=\frac{Z_s-Z_o}{Z_s+Z_o}\\ {\Gamma }_{in}=S_{11}+\left(S_{12}{S}_{21}\frac{{\Gamma }_l}{\left(1-S_{22}{\Gamma }_l\right)}\right)\end{array}$$

   and

   • Z_S is the source impedance.

   • Z_L is the load impedance.

   • S_ij are the S-parameters of a two-port network.

   The blockset derives the passband transfer function from the Input Port block parameters as shown in the following figure:

   

3. Translates the passband transfer function to baseband as H(f – f_c), where f_c is the specified center frequency.

   The baseband transfer function is shown in the following figure.

   

4. Obtains the baseband-equivalent impulse response by calculating the inverse FFT of the baseband transfer function. For faster simulation, the block calculates the IFFT using the next power of 2 greater than the specified finite impulse response filter length. Then, it truncates the impulse response to a length equal to the filter length specified.

For the linear subsystem, the Output Port block uses the calculated impulse response as input to the DSP System Toolbox™ Digital Filter Design (DSP System Toolbox) block to determine the output.

Nonlinear Subsystem

The nonlinear subsystem is implemented by AM/AM and AM/PM nonlinear models, as shown in the following figure.

The nonlinearities of AM/AM and AM/PM conversions are extracted from the power data of an amplifier or mixer by the equations

$$\begin{array}{c}A{M}_{out}=\sqrt{R_l{P}_{out}}\\ P{M}_{out}=\phi \\ A{M}_{in}=\sqrt{R_s{P}_{in}}\end{array}$$

where AM_in is the AM of the input voltage, AM_out and PM_out are the AM and PM of the output voltage, R_s is the source resistance (50 ohms), R_l is the load resistance (50 ohms), P_in is the input power, P_out is the output power, andϕ is the phase shift between the input and output voltage.

Note

You can provide power data via a .amp file. See AMP File Data Sections for information about this format.

The following figure shows the original power data of an amplifier.

This figure shows the extracted AM/AM nonlinear conversion.