A pEek on the lab

Instituto Português da Qualidade (Portugal)

Contacts: vcabral@ipq.pt

Web-site: http://www1.ipq.pt

LAB and RESEARCH

IPQ facilities located in Almada, in the Lisbon suburbs, on the south bank of the Tagus River.

IPQ – Portuguese Institute for Quality

IPQ is an institution directly under the Ministry of Economy of the Portuguese government.

It incorporates the Portuguese National Metrology Institute (NMI) which, with the support of two Designated Institutes (DI), guarantees the traceability to the International System of Units (SI) at national level. Is located in the suburbs of Lisbon and has technical skills in the fields of scientific, legal and applied metrology.

With the objective of guaranteeing the permanent support of the national network of calibration laboratories in emerging areas, IPQ has been actively involved in European metrological research and development projects.

IPQ Quantum Hall Effect experimental setup.

IPQ Experimental Equipment

IPQ Quantum Hall Effect (QHE) experimental setup

It is used to directly calibrate 10 kΩ standard resistors under a constant current of up to 100 µA.

Installed in 2005, it’s a 4-He Cryogenic Ltd 43 L cryostat with a 14 T magnetic field capability through a needle valve lambda plate refrigerator, a variable temperature insert and usually operated with LNE or DFM distributed GaAs/AlGaAs samples.

All instrumentation control is carried out through in-house developed software. The best uncertainties were achieved through the use of a potentiometric system using IPQ JAVS as a voltage measurement system.

IPQ Josephson Effect experimental setup.

IPQ Josephson Array Voltage Standard (JAVS) experimental setup

It is routinely used to directly calibrate zener diode-based standards and high precision nanovoltmeters, validated by a BIPM comparison.

It’s a 10 V SIS array, assembled by IPHT and biased by an NPL isolated programmable current source.

The whole system has been installed in 2005 and is operational since then.

Step biasing, array monitoring, instruments control, measurement readings and switching of UUT are automatically operated by an in-house developed software.

The 10 MHz disciplinary signal is provided by atomic clocks from IPQ Time and Frequency Laboratory optically distributed.

Metrological traceability to the SI.

The testing of the Memristive devices in order to verify the operating conductance states under specified electrical stimulation is a key activity in this project and requires the measurements of current and voltage with a well stated traceability chain and related uncertainties assured by the calibration of the measuring instrumentation involved.

As an example, in calibration of an electrometer used to measure the IV curves of Memristive devices in the operating states of interest, the traceable chain to Current and Voltage units can be established through indirect and direct methods.

For low current values, an indirect calibration method could be based on the reference current value obtained by the charge of a standard capacitor with a voltage variation measured over time.

For medium values of current, the calibration could be assured by the measurement of the voltage across a standard resistor.

For calibration of voltage quantities, the direct measuring of voltage with a calibrated reference multimeter might assure the needed uncertainty of measurement.

PEOPLE and LIFE

The IPQ team participating in this MEMQuD project, Vitor Cabral (vcabral@ipq.pt), Isabel Godinho (igodinho@ipq.pt) and Luís Ribeiro (lribeiro@ipq.pt) has been working in the field of electrical quantities for several years and has extensive experience in the field of high-accuracy DC and AC - LF measurements and in the model evaluation for uncertainties calculation.

Over the past years has also been involved in several EMRP/EMPIR projects.

IPQ MEMQuD team.