Process File Data for Analysis

This topic shows you how to process RF data for analysis. After you import your data, you can process it using one of the following methods:

Convert single-ended S-parameters to mixed-mode S-parameters.
Extract M-port S-parameters from N-Port S-parameters.
Cascade N-port S-parameters

Convert Single-Ended S-Parameters to Mixed-Mode S-Parameters

This section contains the following topics:

Functions for Converting S-Parameters
Convert S-Parameters

Functions for Converting S-Parameters

To convert between 4-port single-ended S-parameter data and 2-port differential-, common-, and cross-mode S-parameters, use one of these functions:

s2scc — Convert 4-port, single-ended S-parameters to 2-port, common-mode S-parameters (S_cc).
s2scd — Convert 4-port, single-ended S-parameters to 2-port, cross-mode S-parameters (S_cd).
s2sdc — Convert 4-port, single-ended S-parameters to cross-mode S-parameters (S_dc).
s2sdd — Convert 4-port, single-ended S-parameters to 2-port, differential-mode S-parameters (S_dd).

To perform the above conversions all at once, or to convert larger data sets, use one of these functions:

s2smm — Convert 4N-port, single-ended S-parameters to 2N-port, mixed-mode S-parameters.
smm2s — Convert 2N-port, mixed-mode S-parameters to 4N-port, single-ended S-parameters.

Conversion functions support a variety of port orderings. For more information on these functions, see the corresponding reference pages.

Convert S-Parameters

In this example, use the toolbox to import 4-port single-ended S-parameter data from a file, convert the data to 2-port differential S-parameter data, and create a new circuit object to store the converted data for analysis.

At the MATLAB^® prompt:

Type this command to import data from the file default.s4p:
```
singleEnded4PortSparam = sparameters('default.s4p');
```

Type these commands to convert 4-port single-ended S-parameters to 2-port mixed-mode S-parameters:

differential2PortData = s2sdd(singleEnded4PortSparam.Parameters);
differential2PortSparam = sparameters(differential2PortData, ...
    singleEnded4PortSparam.Frequencies,2*singleEnded4PortSparam.Impedance);

Type this command to create an nport object that stores the 2-port differential S-parameters for addition to a circuit or rfbudget object:
```
differential2Port = nport(differential2PortSparam);
```

Extract M-Port S-Parameters from N-Port S-Parameters

After you import file data (as described in Import Property Values from Data Files), you can extract a set of data with a smaller number of ports by terminating one or more ports with a specified impedance.

This section contains the following topics:

Extract S-Parameters
Extract S-Parameters from Imported File Data

Extract S-Parameters

To extract M-port S-parameters from N-port S-parameters, use the snp2smp function with the following syntax: To extract M-port S-parameter data from N-port S-parameter data, use the snp2smp.

The following figure illustrates how to specify the ports for the output data and the termination of the remaining ports.

Ports for the output data and the termination of the remaining ports.

For more details about the arguments to this function, see the snp2smp reference page.

Extract S-Parameters from Imported File Data

In this example, use the toolbox to import 16-port S-parameter data from a file, convert the data to 4-port S-parameter data by terminating the remaining ports, and create a new sparameters object to store the extracted data for analysis.

At the MATLAB prompt:

Type this command to import data from the file default.s16p into an sparameters object,
```
singleEnded16PortData:singleEnded16PortSparam = sparameters('default.s16p');
```
Type these commands to convert 16-port S-parameters to 4-port S-parameters by using ports 1, 16, 2, and 15 as the first, second, third, and fourth ports, and terminating the remaining 12 ports with an impedance of 50 ohms:
```
N2M_index = [1 16 2 15];
fourPortData = snp2smp(singleEnded16PortSparam.Parameters, ...
    singleEnded16PortSparam.Impedance, N2M_index, 50);
fourPortSparam = sparameters(fourPortData, ...
    singleEnded16PortSparam.Frequencies,singleEnded16PortSparam.Impedance);
```
Alternatively, apply the snp2smp function to the sparameters object:
```
fourPortSparam = snp2smp(singleEnded16PortSparam, N2M_index, 50);
```

Cascade N-Port S-Parameters

Cascade two or more networks of N-port S-parameters using the cascadesparams function.

Import and Cascade N-Port S-Parameters

In this example, use the toolbox to import 16-port and 4-port S-parameter file data and cascade the two S-parameter networks by connecting the last three ports of the 16-port network to the first three ports of the 4-port network. Then, create a new sparameters object to store the resulting network for analysis.

At the MATLAB prompt:

Type these commands to import data from the files default.s16p and default.s4p, and create the 16- and 4-port networks of S-parameters:
```
S_16Port = sparameters('default.s16p');
S_4Port = sparameters('default.s4p');
freq = [2e9 2.1e9];
sparams_16p = rfinterp1(S_16Port,freq);
sparams_4p = rfinterp1(S_4Port,freq);
```
Type this command to cascade 16-port S-parameters and 4-port S-parameters by connecting ports 14, 15, and 16 of the 16-port network to ports 1, 2, and 3 of the 4-port network:
```
sparams_cascaded = ...
    cascadesparams(sparams_16p.Parameters, sparams_4p.Parameters,3);
```
cascadesparams creates a 14-port network. Ports 1–13 are the first 13 ports of the 16-port network. Port 14 is the fourth port of the 4-port network.
Type this command to create an sparameter object that stores the 14-port S-parameters for simulation:
```
Ckt14 = sparameters(sparams_cascaded,freq);
```