An Improved 10 mA /10 V Standard for the CERN DC-current Calibrator

An improved 10 V / 10 mA standard is presented, which is part of the test infrastructure for direct current current transformers (DCCTs) for the High Luminosity Large Hadron Collider (HL-LHC) project at CERN. It serves primarily as a reference source for the 10 A CERN DC-current calibrator, but also as a 10 V source with extremely low noise at sub-Hz frequencies. Improvements were made in the internal voltage reference and voltage-to-current conversion circuits. Measurements against the PTB programmable Josephson voltage standard (PJVS) show 1/f noise-limited Allan deviation at 10 V on the order of 5•10
⁻⁸
V for measurement times of seconds to hours.