Self-compensating networks for four terminal-pair impedance definition in current comparator bridges

The four terminal-pair definition of standards allows to reach ultimate accuracy in impedance metrology. The four terminal-pair definition requires dedicated circuitry to be included in the bridge network, and the reach of auxiliary bridge balances during the measurement. A careful choice of the network topology allows the bridge to be self-compensating: the four terminal-pair definition is in large part achieved by the behaviour of the network itself, without any adjustment. The additional circuitry required for impedance definition can therefore be simpler, the balancing procedure becomes easier, and a more robust four terminal-pair definition is achieved. This paper analyses a current comparator bridge network with a topology featuring self-compensation. A digitally-assisted test implementation was realized; test measurements on ac resistance comparison in the 25Ω to 100Ω range, at kHz frequency, are reported.

[1]  N. Kusters.  The Precise Measurement of Current Ratios , 1964 .

[2]  N. L. Kusters.  Current comparators - a new class of transformer-like devices , 1968 .

[3]  Luca Callegaro,et al.  A Three-Arm Current Comparator Bridge for Impedance Comparisons Over the Complex Plane , 2015, IEEE Transactions on Instrumentation and Measurement.

[4]  R. D. Cutkosky.  Four-terminal-pair networks as precision admittance and impedance standards , 1964, IEEE Transactions on Communication and Electronics.

[5]  Luca Callegaro,et al.  Electrical Impedance: Principles, Measurement, and Applications , 2012 .

[6]  Luca Callegaro,et al.  Automatic compensation technique for alternating current metrology based on synchronous filtering , 1998 .

[7]  Rudiger Hanke.  Precise Kelvin Double Bridge for Measuring Dissipation Factors and Capacitances up to 1 F , 1978, IEEE Transactions on Instrumentation and Measurement.

[8]  Bruno Trinchera,et al.  Realization of the farad from the dc quantum Hall effect with digitally-assisted impedance bridges , 2010 .

[9]  R. Hanke,et al.  Reduction of Kelvin Ratio Arm Errors in an AC Double Bridge Using Electronic Control , 1983, IEEE Transactions on Instrumentation and Measurement.

[10]  Blaise Jeanneret,et al.  Digitally assisted coaxial bridge for automatic quantum Hall effect measurements at audio frequencies , 2014, 29th Conference on Precision Electromagnetic Measurements (CPEM 2014).

[11]  Luca Callegaro.  On strategies for automatic bridge balancing , 2004, IEEE Transactions on Instrumentation and Measurement.

[12]  Luca Callegaro,et al.  A three-arm current comparator bridge for two terminal-pair impedance comparisons over the complex plane , 2014, 29th Conference on Precision Electromagnetic Measurements (CPEM 2014).

[13]  Bruno Trinchera,et al.  A Digitally Assisted Current Comparator Bridge for Impedance Scaling at Audio Frequencies , 2013, IEEE Transactions on Instrumentation and Measurement.

[14]  Jonathan M. Williams,et al.  Automation of a Coaxial Bridge for Calibration of AC Resistors , 2007, IEEE Transactions on Instrumentation and Measurement.

[15]  Jaroslav Bohacek,et al.  The European ACQHE project: modular system for the calibration of capacitance standards based on the quantum Hall effect , 2002, Conference Digest Conference on Precision Electromagnetic Measurements.

[16]  Bruno Trinchera,et al.  Quadrature Bridge for R-C Comparisons based on Polyphase Digital Synthesis , 2007, IMTC 2007.

[17]  S. K. Basu,et al.  A Direct-Reading Current-Comparator Bridge for Scaling Four-Terminal Impedances at Audio Frequencies , 1966 .

[18]  Awan,et al.  Coaxial Electrical Circuits for Interference-Free Measurements , 2011 .

[19]  L. Callegaro,et al.  A precise two-channel digitally synthesized AC voltage source for impedance metrology , 2014, 29th Conference on Precision Electromagnetic Measurements (CPEM 2014).

[20]  N. L. Kusters,et al.  The Development and Performance of Current Comparators for Audio Frequencies , 1965 .