Antti Manninen | Searcharxiv

arXiv2020

Realisation of a quantum current standard at liquid helium temperature with sub-ppm reproducibility

A silicon electron pump operating at the temperature of liquid helium has demonstrated repeatable operation with sub-ppm accuracy. The pump current, approximately 168 pA, is measured by three laboratories, and the measurements agree with the expected current ef within the uncertainties which range from 0.2 ppm to 1.3 ppm. All the measurements are carried out in zero applied magnetic field, and the pump drive signal is a sine wave. The combination of simple operating conditions with high accuracy demonstrates the possibility that an electron pump can operate as a current standard in a National Measurement Institute. We also discuss other practical aspects of using the electron pump as a current standard, such as testing its robustness to changes in the control parameters, and using a rapid tuning procedure to locate the optimal operation point..

physics.ins-det↗

arXiv2007

Microelectromechanical components in electrical metrology

Microelectromechanical systems (MEMS) can offer a competitive alternative for conventional technology in electrical precision measurements. This article summarises recent work in development of MEMS solutions for electrical metrology. MEMS-based voltage references, RMS-to-DC converters, high frequency power sensors, and reference oscillators are discussed. The main principle of operation of the components is the balance between electrical forces and mechanical spring forces in micromachined silicon structures. In RMS sensors and RMS-to-DC converters, the quadratic voltage dependence of the force between plates of a moving-plate capacitor is utilised, and the operation of the MEMS voltage reference is based on the pull-in phenomenon of a moving-plate capacitor. Advantages of MEMS devices compared to more conventional solutions include small size, low power consumption, low price in mass production, and stability. The drift caused by electrostatic charging effects has turned out to be a major problem. This problem has not yet been solved in DC applications, but it can be circumvented by using AC actuation instead of DC and by compensating the internal DC voltages of the component. In this way, an AC voltage reference with relative drift rate below 2 ppm during a three-week test period has been constructed. Even better stability has been demonstrated with a MEMS-based reference oscillator: no changes in resonance frequency were observed at relative uncertainty level of about 0.01 ppm in a measurement which was continued for more than a month. MEMS components have also been developed for measuring RF and microwave power up to frequencies of about 40 GHz. Unlike conventional high frequency power sensors, which measure the absorbed power, the MEMS device measures the power that is transmitted through the sensor.

physics.ins-det↗