EMRP-SIB62: Metrology for new electrical Measurement Quantities in High-Frequency Circuits

• Research unit: METAS
• Project number: F-5217.30026

Key words (English)

Rf, microwave, millimeter wave, high frequency, S-parameter, vector network analyzer, re-flection, transmission, coaxial lines, metallic wave guide, multiport VNA, electronic calibration units, differential, planar circuits, signal integrity, nonlinear measurements, extreme load impedances, vector measurement uncertainties, verification, international guides and standards

Short description (English)

The capability and functionality of test instrumentation enabling state-of-the-art high-frequency electrical circuit analysis has advanced dramatically during the past 5 to 10 years, but traceability to the SI has lagged behind these technical developments. These advancements have introduced new measurement quantities, and evolved existing measurement quantities, that are being used in radio frequency (RF), microwave, millimetre-wave and submillimetre-wave areas of technology. However, these quantities (e.g. mixed-mode S-parameters, X-parameters and S-parameters at millimetre- and submillimetre-wave frequencies) fall outside the scope of existing SI units and the traceability currently provided by the world’s National Measurement Institutes (NMIs). The lack of traceability for the newly developed instrumentation introduces a barrier to the use of this instrumentation in high value, high impact, fields – for example, medical, security, consumer electronics and environmental monitoring uses. The advancements in instrumentation have been required to meet the needs of existing and next-generation end-user applications, e.g. in industry and elsewhere. The challenge that this project addresses is to put in place traceability and dissemination mechanisms for these measurement quantities and to ensure maximum impact on the end-user community.
The project will establish traceability to the International System of units (SI) for these new and evolving quantities and units.

This project is part of the European Metrology Research Programme (EMRP, http://www.euramet.org/index.php?id=emrp); it is partly funded by the European Union on the basis of Decision No 912/2009/EC.

Project aims (English)

New advanced techniques will be developed for implementing and disseminating measurement traceability to users of metrology services – i.e. other NMIs, accredited laboratories, instrumentation manufacturers and end-users. The project will achieve this by addressing the following key scientific and technical objectives:

• Traceability and verification techniques to support millimetre-wave and submillimetre-wave electronics and electromagnetics in coaxial line and waveguide
• Traceability and verification techniques to support high-speed digital PCBs for Signal Integrity applications, and multi-port configurations including electronic calibration and differential transmission lines
• Traceability and verification techniques to support large-signal / nonlinear device characterisation - e.g. high power transistors and power amplifiers (PAs) - and nano-scale devices, such as CNTs, graphene-related electronics, organic macromolecules, etc
• Input to a revised version of the EURAMET Guide; the development of IEEE standard P1785; and the revision of IEEE standard P287. Input will also be made to a third IEEE standard-making activity (via a Special Interest Group), in the area of defining nonlinear measurement quantities, which will be initiated during the lifetime of this project.

The underlined parts involve METAS.

Abstract (English)

METAS has contributed to the following results:

• New elegant method to determine the propagation constant in coaxial transmission lines with rough surfaces.

• Characterization of calibration standards for 1mm connectors, resulting in the SI traceability of 1mm measurements.

• New characterization procedures for VNA setups.

• Measurement comparison (EURAMET project) in coaxial S-parameters up to 67 GHz (1.85 mm connector).

• Short and long term studies of VNA electronic calibration units (ECUs), resulting in a best practice guide for the use of ECUs.

• New data formats for S-parameter data, allowing for the expression of uncertainties including correlations. The new data formats have been described in a document.

• Improved concepts in VNA verification.

• Extensive study on the characterisation of all major metrology grade coaxial connector interfaces, including mechanical parametrization and reflection and sensitivity coefficients of connector pairs. This resulted in a report to the standards committee IEEE P287 (coaxial connectors) for inclusion in the next version of the standard.

• Rewrite of VNA guide EURAMET cg-12. The old outdated guide was replaced by completely new guide. METAS had the lead in this activity and wrote most parts of the new guide. The new guide is wider applicable (higher frequencies in particular) and takes the developments in VNA metrology over the last years into account. The final draft of the guide has been submitted to the EURAMET TCEM SC-RF&MW for further review and final approval.

• Six European ANAMET workshops were provided, one of them hosted by METAS. 13 ANAMET presentations were delivered by METAS.

Transfer and application (English)

Many of the results in this project are of practical importance. They are used to extend the scope and to improve quality and accuracy of VNA measurement Services. The study on coaxial connector pairs will appear as an annex in the revised standard document IEEE P287. This will further raise the awareness for the influence of the connector interface in VNA measurements. With the project activities over the last years, METAS has positioned itself as the leading lab in coaxial VNA metrology, proposing new improved approaches and questioning some of the old established practices. But old habits die hard. The new VNA guide EURAMET cg-12 should help to gain wider acceptance of the new methods.

Publications / Results (English)

1. M. Zeier, J Hoffmann, P. Hürlimann, J. Rüfenacht, M. Wollensack, R. Judaschke, K. Kuhlmann, Stability tests of electronic calibration units, CPEM 2014 Conference Digest, pp 16 – 17, 2014.
2. J. Hoffmann, J. Ruefenacht, M. Zeier, The Propagation Constant of Coaxial Offset Shorts with Rough Surfaces, CPEM 2014 Conference Digest, pp 14 – 15, 2014
3. J. Hoffmann, M. Wollensack, J. Ruefenacht, M. Zeier, Extended S-parameters for imperfect test ports, Metrologia 52 (2015) 121-129.
4. J. Hoffmann, M. Wollensack, J. Ruefenacht, M. Zeier, Comparison of Methods for Measurement of Equivalent Source Match, Proceedings of the 45th European Microwave Conference, p 730 – 733, 2015.
5. M. Zeier, Messunsicherheiten in der Vektornetzwerkanalyse – Die neue Richtlinie EURAMET cg-12.
6. Messunsicherheit praxisgerecht bestimmen, VDI Berichte 2269, p. 29 – 38, 2015
7. F. Mubarak, J. Hoffmann, Effects of Connectors and Improper Mounting of Air Lines in TRL Calibration, CPEM 2016 conference digest, 2016.
8. F. Mubarak, M. Zeier J. Hoffmann, N. M. Ridler, M. J. Salter, K. Kuhlmann, Verification concepts in S-parameter measurements, CPEM 2016 conference digest, 2016.
9. C. Eiø, D. Allal, P. Huerlimann, J. Ruefenacht, S. Zinal, Measurement Comparison up to 65 GHz in Coaxial 1.85 mm Line, CPEM 2016 conference digest, 2016.