# s2scd

Convert 4-port, single-ended S-parameters to 2-port, cross-mode S-parameters (Scd)

## Syntax

``scd_params = s2scd(s_params)``
``scd_params = s2scd(s_params,option)``

## Description

example

````scd_params = s2scd(s_params)` converts the 2N-port single-ended S-parameters to N-portcross-mode S-parameters. ```
````scd_params = s2scd(s_params,option)` converts S-parameters based on the optional `option` argument, which indicates the port-ordering convention of the S-parameters.```

## Examples

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Convert network data to cross-mode S-Parameters using the default port ordering.

``` S = sparameters('default.s4p'); s4p = S.Parameters; s_cd = s2scd(s4p);```

Display the cross-mode S-Parameters at the first frequency.

` s_cd_new = s_cd(:,:,1)`
```s_cd_new = 2×2 complex 0.0015 - 0.0029i -0.0005 + 0.0014i 0.0003 - 0.0009i 0.0019 - 0.0027i ```

## Input Arguments

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2N-port S-parameters, specified as a 2N-by-2N-by-M array of complex numbers, where M represents the number of frequency points of 2N-port S-parameters.

Port order, a scalar, specified as `1`, `2`, or `3`. Port order determines how the function orders the ports:

• `1``s2scd` pairs the odd-numbered ports together first, followed by the even-numbered ports. For example, in a single-ended, 8-port network:

• Ports 1 and 3 become cross-mode pair 1.

• Ports 5 and 7 become cross-mode pair 2.

• Ports 2 and 4 become cross-mode pair 3.

• Ports 6 and 8 become cross-mode pair 4.

The following figure illustrates this convention for an 8-port device.

• `2``s2scd` pairs the input and output ports in ascending order. For example, in a single-ended, 8-port network:

• Ports 1 and 2 become cross-mode pair 1.

• Ports 3 and 4 become cross-mode pair 2.

• Ports 5 and 6 become cross-mode pair 3.

• Ports 7 and 8 become cross-mode pair 4.

The following figure illustrates this convention for an 8-port device.

• `3``s2scd` pairs the input ports in ascending order and the output ports in descending order. For example, in a single-ended, 8-port network:

• Ports 1 and 2 become cross-mode pair 1.

• Ports 3 and 4 become cross-mode pair 2.

• Ports 8 and 7 become cross-mode pair 3.

• Ports 6 and 5 become cross-mode pair 4.

The following figure illustrates this convention for an 8-port device.

## Output Arguments

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N-port cross-mode S-Parameters, returned as a complex N-by-N-by-M array of complex numbers where M represents the number of frequency points of N-port cross-mode S-parameters.

## References

[1] Fan, W., A. C. W. Lu, L. L. Wai, and B. K. Lok. "Mixed-Mode S-Parameter Characterization of Differential Structures."Electronic Packaging Technology Conference. pp. 533–537, 2003.

## Version History

Introduced in R2006a