Conversion of a 2-terminal-pair bridge to a 4-terminal-pair bridge for increased range and precision in impedance measurements

NIST comparison of the quantized Hall resistance and the realization of the SI OHM through the calculable capacitor

“…Choke corrections were measured for each choke and applied to the bridge measurements. The sum of relative choke errors for any of the bridges was not larger than f) The relative standard uncertainty due to harmonics in the quadrature bridge (1000 pF to 100 k ) was measured and found to be less than g) A new 4-terminal-pair bridge has been constructed at NIST [6]. This was compared with the present 4-terminal-pair bridge used in the SI determination.…”

“…Comparisons with previous measurements [5] of the nonlinearities showed them to be relatively constant. A quick check of the magnitude of the bridge adjustments was made in the current series of measurements through a comparison with a newly constructed 4-terminal-pair bridge (see item g) for a 10 : 1 setup with 1000 pF and 100 pF capacitance standards [6]. A 0.17 pF capacitor was added in parallel on the low side to create a significant change in the bridge reading.…”

Impedance bridges: from Wheatstone to Josephson

“…When an impedance standard of smaller value has to be calibrated with the highest accuracy, the four terminalpair definition of the impedance needs to be realized. Therefore, either extrapolation techniques [53] have to be applied with the use of a two terminalpair bridge or the bridge network needs to be expanded with supplementary components (like variable capacitors, variable resistors or IVDs) to comply with the four terminalpair definition of the standards [62,66]. However, it is worth to precise that once the bridge is balanced, the main balance equation is still simply given by equation (4) [79,169].…”

NIST comparison of the quantized Hall resistance and the realization of the SI ohm through the calculable capacitor

“…Choke corrections were measured for each choke and applied to the bridge measurements. The sum of relative choke errors for any of the bridges was not larger than f) The relative standard uncertainty due to harmonics in the quadrature bridge (1000 pF to 100 k ) was measured and found to be less than g) A new 4-terminal-pair bridge has been constructed at NIST [6]. This was compared with the present 4terminal-pair bridge used in the SI determination.…”