Improved Cryogenic Current Comparator Setup With Digital Current Sources

Götz, Martín; Drung, D.; Pesel, Eckart; Barthelmess, H.-J.; Hinnrichs, C.; Assmann, C.; Peters, M.; Scherer, H.; Schumacher, B.; Schurig, T.

doi:10.1109/tim.2008.2012379

Cited by 49 publications

(35 citation statements)

References 7 publications

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“…The traceable calibration is performed with a state-ofthe art CCC resistance bridge developed in collaboration between PTB and the company Magnicon [9,14]. The suitability of this special setup has been experimentally proven (see chapter 3), but other CCC resistance bridges may alternatively be used if the required turns ratios are available.…”

Section: Traceable Calibrationmentioning

confidence: 99%

“…The currents I 1 and I 2 flow through the respective CCC windings N 1 and N 2 that are coupled to a SQUID. A so-called external feedback loop is realized that keeps the flux in the SQUID constant by controlling one of the current sources [9]. The constant dc flux offset is suppressed by applying current reversal.…”

Section: Traceable Calibrationmentioning

confidence: 99%

“…Uncertainty budget for the calibration of the 3 GΩ input stage. Unless otherwise noted, the quoted uncertainties are standard uncertainties (coverage factor k = 1) obtained with PTB's 14-bit CCC [8]; values for the 12-bit CCC [9] are given in parentheses if they differ from those for the 14-bit CCC. Nonlinearity of the NiCr thin-film resistors has also to be considered (amplifier effects can be neglected because of the high open-loop gain >10 9 ).…”

Section: Uncertainty Analysismentioning

confidence: 99%

See 2 more Smart Citations

Ultrastable low-noise current amplifier

Drung

Krause

Becker

et al. 2014

29th Conference on Precision Electromagnetic Measurements (CPEM 2014)

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An ultrastable low-noise current amplifier (ULCA) is presented. The ULCA is a non-cryogenic instrument based on specially designed operational amplifiers and resistor networks. It involves two stages, the first providing a 1000-fold current gain and the second performing a current-to-voltage conversion via an internal 1 MΩ reference resistor or, optionally, an external standard resistor. The ULCA's transfer coefficient is extremely stable versus time, temperature and current amplitude within the full dynamic range of ±5 nA. A low noise level of 2.4 fA/√Hz helps to keep averaging times low at small input currents. A cryogenic current comparator is used to calibrate both input current gain and output transresistance, providing traceability to the quantum Hall effect. Typically, within one day after calibration, the uncertainty contribution from short-term fluctuations of the transresistance is below one part in 10 7 . The long-term stability is expected to be better than one part in 10 5 over a year. A high-precision variant is available that shows a substantially improved stability at the expense of a higher noise level of 7.5 fA/√Hz. The ULCA also allows the traceable generation of small electrical currents or the calibration of high-ohmic resistors.

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Section: Traceable Calibrationmentioning

confidence: 99%

Section: Traceable Calibrationmentioning

confidence: 99%

Section: Uncertainty Analysismentioning

confidence: 99%

See 1 more Smart Citation

Ultrastable low-noise current amplifier

Drung

Krause

Becker

et al. 2014

29th Conference on Precision Electromagnetic Measurements (CPEM 2014)

Self Cite

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“…Benefitting from a kind of complementarity [5], the binary compensation unit can be calibrated in a very convenient and fast way by means of a binary CCC as, for example, our 12-bit comparator described elsewhere [7]. Furthermore, the calibration is performed using the same measurement hardware and software as for a standard CCC-based resistance comparison.…”

Section: B Calibrationmentioning

confidence: 99%

“…First, we have performed a series of comparisons between the QHR and a 100 standard resistor with two different N 1 /N 2 ratios: the very common 2065/16 ratio and additionally the 4001/31 ratio, which became available for us with the 12-bit CCC [7]. For these ratios, the respective sign and absolute value of the compensation k · N A /N 1 differ significantly.…”

Section: Balancing Capabilitiesmentioning

confidence: 99%

Aspects of Application and Calibration of a Binary Compensation Unit for Cryogenic Current Comparator Setups

Drung

Götz

Pesel

et al. 2013

IEEE Trans. Instrum. Meas.

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We have developed a binary compensation unit for balancing measurement bridges with cryogenic current comparators (CCCs) commonly used in resistance metrology. We present the basic design ideas for the new microcontroller-operated module. It offers balance over a gapless range of resistance ratios of the resistors to be compared. The binary setup allows for convenient calibration when being combined with a binary CCC. The calibration can be performed using the CCC's control electronics and software. Examples of measurements demonstrate the unit's high flexibility and stability of resistance calibration well below one part in 10 9 over a period of 21 hours.

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