Touchstone file
A Touchstone file was originally a proprietary file format for the eponymous frequency-domain linear circuit simulator[1] from EEsof, launched in 1984 and now owned by Agilent Technologies.
The Touchstone simulator has long since been superseded[2], but its file format lives on.
A Touchstone file (also known as an SnP file after its set of file extensions[3]) is an ASCII text file used for documenting the n-port network parameter data and noise data of linear active devices, passive filters, passive devices, or interconnect networks. An example of the format of the S-parameter section is given in the article about S-parameters. In addition to S-parameters, other representations such as Y-parameters and Z-parameters can be recorded.
It later became a de facto industry-standard file format not only for circuit simulators but also for measurement equipment (e.g. vector network analyzers, or VNAs), then later still an EIA standard as part of the Input/output Buffer Information Specification (IBIS) project[4]. On April 24, 2009, the IBIS Open Forum ratified version 2.0[5], superseding Version 1.1[6]. Version 2.0 adds IBIS-style keywords such as [Reference], which permits per-port definition of the reference environment.
Several further enhancements to the file format that allow description of the non-linear behavior of the component have been developed under the P2D and S2D pair of formats[7], but these too have been superseded by the X-parameters functionality.
[edit] Notes
- ^ "History of EEsof and Touchstone at Microwaves 101". http://www.microwaves101.com/encyclopedia/historyCAD.cfm#touchstone.
- ^ "W2200 Advanced Design System (ADS) Core". http://www.home.agilent.com/agilent/redirector.jspx?action=ref&cname=PRODUCT&ckey=1385381&cc=US&lc=eng.
- ^ .S1P for one-port (e.g. termination), .S2P for two-port (e.g. transmission line), .S3P for three-port (e.g. a mixer), .S4P for four-port (e.g. a differential transmission line) and so on.
- ^ "IBIS (I/O Buffer Information Specification)". http://www.eda.org/ibis/.
- ^ "Touchstone File Format Specification Version 2.0" (PDF). http://www.eda.org/ibis/touchstone_ver2.0/touchstone_ver2_0.pdf.
- ^ "Touchstone File Format Specification Rev 1.1" (PDF). http://www.eda.org/pub/ibis/connector/touchstone_spec11.pdf.
- ^ "E8854A RF System, now part of W2200 Advanced Design System (ADS) Core". http://www.home.agilent.com/agilent/redirector.jspx?action=ref&cname=PRODUCT&ckey=1375687&cc=US&lc=eng.
