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PDL-IO-Touchstone-1.005
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NAME

PDL::IO::Touchstone - Read and manipulate Touchstone .s2p (and .sNp) files.

DESCRIPTION

A simple interface for reading and writing RF Touchstone files (also known as ".sNp" files). Touchstone files contain complex-valued RF sample data for a device or RF component with some number of ports. The data is (typically) measured by a vector network analyzer under stringent test conditions.

The resulting files are usually provided by manufacturers so RF design engineers can estimate signal behavior at various frequencies in their circuit designs. Examples of RF components include capacitors, inductors, resistors, filters, power splitters, etc.

SYNOPSIS

    use PDL::IO::Touchstone;

    # Read input matrix:
    ($f, $m, $param_type, $z0, $comments, $fmt, $funit, $orig_f_unit) =
            rsnp('input-file.s2p', { units => 'MHz' }); 


    # Write output file:
    wsnp('output-file.s2p',
            $f, $m, $param_type, $z0, $comments, $fmt, $from_hz, $to_hz);

You can reproduce the same output file from an input as follows:

    @data = rsnp('input-file.s2p');
    wsnp('output-file.s2p', @data);

You may convert between output formats or frequency scale by changing the $fmt and $to_hz fields when writing:

    @data = rsnp('input-file.s2p');
    $data[5] = 'DB'; # $fmt
    $data[7] = 'MHz' # $to_hz in wsnp() or $orig_f_unit from rsnp().
    wsnp('output-file.s2p', @data);

Note that you may change neither $param_type nor $z0 unless you have done your own matrix transform from one parameter type (or impedance) to another. This is because while wsnp knows how to convert between RA, MA, and DB formats, it does not manipulate the matrix to convert between parameter types (or impedances). Use the P_to_Q() functions below to transform between matrix types.

IO Functions

rsnp($filename, $options) - Read touchstone file

Arguments:

Return values

The first set of parameters ($f, $m, $param_type, $z0) are required to properly utilize the data loaded by rsnp():

The remaining parameters ($comments, $fmt, $funit) are useful only if you wish to re-create the original file format by calling wsnp():

wsnp($filename, $f, $m, $param_type, $z0, $comments, $fmt, $from_hz, $to_hz)

Arguments

Except for $filename (the output file), the arguments to wsnp() are the same as those returned by rsnp().

When writing it is up to you to maintain consistency between the output format and the data being represented. Except for complex value representation in $fmt and frequency scale in $f, this PDL::IO::Touchstone module will not make any mathematical transform on the matrix data.

Changing $to_hz will modify the frequency format in the resultant Touchstone file, but the represented data will remain correct because Touchstone knows how to scale frequencies.

Roughly speaking this should create an identical file to the input:

    wsnp('output.s2p', rsnp('input.s2p'));

However, there are a few output differences that may occur:

wsnp_fh($fh, $f, $m, $param_type, $z0, $comments, $fmt, $from_hz, $to_hz)

Same as wsnp() except that it takes a file handle instead of a filename. Internally wsnp() uses wsnp_fh() and wsnp_fh() can be useful for building MDF files, however MDF files are much more complicated and outside of this module's scope. Consult the "SEE ALSO" section for more about MDFs and optimizing circuits.

S-Parameter Conversion Functions

$Y = s_to_y($S, $z0): Convert S-paramters to Y-parameters.

$S = y_to_s($Y, $z0): Convert Y-paramters to S-parameters.

$Z = s_to_z($S, $z0): Convert S-paramters to Z-parameters.

$S = z_to_s($Z, $z0): Convert Z-paramters to S-parameters.

$ABCD = s_to_abcd($S, $z0): Convert S-paramters to ABCD-parameters.

$S = abcd_to_s($ABCD, $z0): Convert ABCD-paramters to S-parameters.

S-Paramter Calculaction Functions

All functions prefixed with "s_" require an S-parameter matrix.

$z0n = s_port_z($S, $z0, $n) - Return the complex port impedance vector for all frequencies given:

In a 2-port, this will provide the input or output impedance as follows:

$z_in  = s_port_z($S, 50, 1);
$z_out = s_port_z($S, 50, 2);

Helper Functions

$n = n_ports($S) - return the number of ports represented by the matrix.

Given any matrix (N,N,M) formatted matrix, this function will return N.

SEE ALSO

AUTHOR

Originally written at eWheeler, Inc. dba Linux Global Eric Wheeler to transform .s2p files and build MDF files to optimize with Microwave Office for amplifer impedance matches.

COPYRIGHT

Copyright (C) 2022 eWheeler, Inc. https://www.linuxglobal.com/

This module is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This module is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this module. If not, see <http://www.gnu.org/licenses/>.