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Digital security concept

High resolution digitisers are used to convert analogue electrical signals from sensors into a digital form with the highest precision. They were first developed for metrology applications but are now used for signal analysis in a wide range of applications including in the manufacturing, automotive, aerospace, communications and medical fields. Extending the performance of digitisers beyond the current state-of-the-art, to deliver accuracy levels below the part per million level, will widen the range of signals accessible to traceable, reliable, and accurate measurement.

Metrology Partnership project Towards a true 8-digit digitiser (22RPT02, True8DIGIT) is working to address the development of a digitiser based on state-of-the-art analogue-to-digital converters  (ADCs) operating from direct current to 100 kHz. This will meet the demands for linearity, noise, and overall accuracy of high-level measurement applications that cannot be met using currently available digitisers. Research on the key techniques and technologies needed to underpin a follow-up full-scale project will be carried out.

The knowledge gained in the project will be shared with less experienced partners, such as CMI, IPQ and FER, allowing them to participate in the anticipated follow on-project with the aim of developing a metrology-grade digitiser.

Barrier braking research

The project consortium has succeeded in breaking a barrier in the characterisation of nonlinear behaviour in nominally linear devices like capacitors and resistors. While the project objective was to demonstrate distortion measurements down to and below -120 dBc or 1 part in 10⁶, this limit has been extended to -170 dBc or 3 parts in 10⁹ across the whole audio frequency band. This improves the critical selection of components for most precision room-temperature instrumentation, like ultra-precision digitisers.

A newly developed detailed model can already use these results and show the impact of the non-ideal behaviour of even the highest quality components on the conversion linearity of an ADC. By measuring resistor non-linearity down to –170 dBc,  a key requirement for developing a new generation of ultra-accurate digitisers based on ultra-linear resistor networks was unlocked—advances that will also benefit a wide range of high-precision electronic designs.

By resolving resistor non-linearity at the –170 dBc level, the project now provides the basis for selecting ultra-linear resistor and resistor networks essential to high-performance integrating ADCs and advanced metrology circuits.

Project coordinator Oliver Power from NSAI said

‘The project outcomes, particularly in the area of ADC modelling, component characterisation and timing, provide a solid basis for the realisation of a prototype digitiser with a DC performance at the level of a few parts in 10⁸.’
 

This Metrology Partnership project has received funding from the European Partnership on Metrology, co-financed by the European Union Horizon Europe Research and Innovation Programme and from the Participating States.

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