Josephson-Based Full Digital Bridge for High-Accuracy Impedance Comparisons
Frederic Overney, Nathan E. Flowers-Jacobs, Blaise Jeanneret, Alain Rufenacht, Anna E. Fox, Jason M. Underwood, Andrew D. Koffman, Samuel P. Benz
This paper describes a Josephson-based full digital impedance bridge capable of comparing any two impedances, regardless of type (R-C, R-L, or L-C), over a large frequency range. At the heart of the bridge are two Josephson arbitrary waveform synthesizer systems that offers unprecedented flexi-bility in high-precision impedance calibration, that is, it can compare impedances with arbitrary ratios and phase angles. This single bridge can thus fully cover the entire complex plane. In the near future, this type of instrument will considerably simplify the realization and maintenance of the various impedance scales in many National Metrology Institutes around the world.