A long settling time of the bridge voltage in resistance comparison setups with cryogenic current comparators might become crucial with respect to the type-A uncertainty, because it effectively limits the frequency of current reversals. Using a new bridge voltage detector with considerably increased bandwidth, we were able to trace the transient distortions caused by current reversal. Significant influence of the cabling is observed. Comparing a 12.9-kΩ quantum Hall resistor and a 100-Ω standard resistor, we achieved an expanded type-A uncertainty of about three parts in 10 10  after 24 min of measurement for current reversal frequencies down to 100 mHz.
['Martin Götz', 'Dietmar Drung', 'Eckart Pesel', 'Franz-Josef Ahlers']
Settling Behavior of the Bridge Voltage in Resistance Ratio Measurements With Cryogenic Current Comparators