Simulation of a quantum Hall cryogenic current comparator resistance bridge

A servo model of MSL's CCC resistance bridge has been developed that predicts a number of resonance peaks in the response not obvious from a trivial analysis and may explain some observed instability. Such a model is useful for exploring subtle frequency-dependant effects and is valuable for optimising servo performance. Changes to some component values and operating procedures are predicted to limit the measured resistance ratio error to <0.002 ppm.