A compact 14-bit cryogenic current comparator

A cryogenic current comparator with an overall of 17,252 turns and windings including numbers of turns ranging from 2⁰ to 2¹³ has been realized. This system offers the possibility of resistance calibration at increased magnetic flux levels and allows for a direct calibration of 1 Ω to 100 MΩ normal resistors against the quantum Hall effect. Besides that, the very low-current measurements at PTB will benefit from the availability of this additional setup. Such applications include the use of this comparator as a current amplifier as well as for calibration of highly-stable transimpedance amplifiers.