A Two-Stage, Guarded Inductive Voltage Divider with Small Ratio Errors for Coaxial Bridge Applications

The traceability chain to derive the capacitance unit from the quantum Hall resistance comprises some coaxial bridges. These bridges employ a main two-stage inductive voltage divider to provide the voltage ratio needed. One such divider has been recently constructed and calibrated at Inmetro. The design techniques responsible for the small ratio errors of the device and the calibration method employed are both detailed. The new divider was installed in Inmetro's two terminal-pair coaxial capacitance bridge with significant improvements in the bridge resolution and accuracy.