A synthesizer of precision AC waveforms based on a SINIS Josephson junction array has been developed. The array is divided into 15 segments in a binary series and the segments are individually biased using a high speed bias source with a 100 ns rise time. The design considerations and accuracy limitations of the system are discussed and comparisons between the synthesizer and thermal converters are presented.
"The electronics used to bias the array was developed at the NPL in order to facilitate high-speed operation . Up to 15 individually controllable bias modules are available to set the corresponding array segments to −V i , 0 or +V i , where V i is the Josephson voltage of the ith segment. "
[Show abstract][Hide abstract] ABSTRACT: A fully automated system has been developed for voltage calibrations where fast programmability and extremely low uncertainties are required. This system is based on a binary Josephson junction array with a smallest segment of one single junction. As an important application, the linearity of the 10 mV range of a digital nanovoltmeter was determined with a standard uncertainty better than 1 nV. As a further application of the fast programmability of the binary Josephson system, the standard uncertainty of voltage ratios measured by an -digit digital voltmeter in quantum Hall measurements was measured to be 10 × 10−9.
"In 1995, Hamilton et al. proposed a Josephson D/A converter based on binary sequence of series arrays . Investigations of this method—which produces an ac voltage by switching bias currents of selected sub-arrays—shows that the frequency of a synthesized ac voltage will be limited to frequencies clearly below 10 kHz because the undefined voltage transients between steps of quantized voltage enhance the uncertainty –. Benz and Hamilton have developed another approach that biases the array with Manuscript received October 5, 2004. A. S. Katkov and G. P. Telitchenko are with the Mendeleyev Institute for Metrology (VNIIM), 198000 St. Petersburg, Russia (e-mail: A.S.Katkov@vniim.ru). A. M. Klushin is with the Institut fuer Schichten und Grenzflaechen, 52428 Juelich, Germany (e-mail: firstname.lastname@example.org). "
[Show abstract][Hide abstract] ABSTRACT: Voltage pulses with a determined amplitude and width might be the basis for high-precision ac voltage measurements in the future. The pulse width modulation technique makes possible the generation of arbitrary waveforms. In this paper, arrays of SINIS Josephson junctions were investigated which produce a 1 V voltage step under irradiation at a frequency of the order of 70 GHz. This step has an amplitude of 1 mA whereof a region of 0.3 mA overlaps with the critical current. This allows the generation of a 1 V voltage pulse by switching the microwave power at constant dc bias current. The results of this investigation will be presented and also the array parameters which are required for obtaining a relative uncertainty of 0.1 ppm in ac voltage measurements.
[Show abstract][Hide abstract] ABSTRACT: The electrical characteristics of two different 1-V binary programmable Josephson arrays, an superconductor/insulator/normal conductor/insulator/superconductor-type Josephson array, and an externally shunted superconductor/insulator/superconductor-type Josephson array, were investigated at ten metrology institutes. Various operational parameters were evaluated and compared using different Josephson array voltage standard setups at microwave frequencies around 70 GHz. The results of the measurements show that both arrays have been working very well and the main differences were not imposed by the arrays themselves, but by the different measurement setups of the laboratories.
IEEE Transactions on Instrumentation and Measurement 05/2003; 52(2):524 - 528. DOI:10.1109/TIM.2003.811570 · 1.79 Impact Factor
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