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s2sdd

Convert 4-port, single-ended S-parameters to 2-port, differential-mode S-parameters (Sdd)

Syntax

sdd_params = s2sdd(s_params)
sdd_params = s2sdd(s_params,option)

Description

sdd_params = s2sdd(s_params) converts the 2N-port, single-ended S-parameters, s_params, to N-port, differential-mode S-parameters, sdd_params. sdd_params is a complex N-by-N-by-M array that represents M N-port, differential-mode S-parameters (Scd).

sdd_params = s2sdd(s_params,option) converts S-parameters based on the optional option argument, which indicates the port-ordering convention of the S-parameters.

Input Arguments

collapse all

S-parameters, specified as a complex 4-by-4-by-M array, that represents M 4-port S-parameters.

Port order, specified as 1, 2, 3, determines how the function orders the ports:

  • 1s2sdd 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 differential-mode pair 1.

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

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

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

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

  • 2s2sdd pairs the input and output ports in ascending order. For example, in a single-ended, 8-port network:

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

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

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

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

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

  • 3s2sdd 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 differential-mode pair 1.

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

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

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

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

Examples

Convert network data to differential-mode S-parameters using the default port ordering:

 ckt = read(rfckt.passive,'default.s4p'); 
 s4p = ckt.NetworkData.Data; 
 s_dd = s2sdd(s4p);

Read a data file, transform the data into differential-mode S-parameters, analyze the new data, and write the new data to a file:

% Create a circuit object from a data file
ckt = read(rfckt.passive,'default.s4p');
data = ckt.AnalyzedResult;
% Create a data object to store the
% differential S-parameters
diffSparams = rfdata.network;
diffSparams.Freq = data.Freq;
diffSparams.Data = s2sdd(data.S_Parameters);
diffSparams.Z0 = 2*data.Z0;
% Create a new circuit object with the data
% from the data object
diffCkt = rfckt.passive;
diffCkt.NetworkData = diffSparams;
% Analyze the new circuit object
frequencyRange = diffCkt.NetworkData.Freq;
ZL = 50;
ZS = 50;
Z0 = diffSparams.Z0;
analyze(diffCkt,frequencyRange,ZL,ZS,Z0);
diffData = diffCkt.AnalyzedResult;
% Write the differential S-parameters into a
% Touchstone data file
write(diffCkt,'diffsparams.s2p');

References

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.

See Also

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