Digital to analog convertors generate bipolar voltages when coupled to a polarity switchable double flux amplifier

June 27, 2017, University of Electro Communications
Sinusoidal waves indicative of bipolar outgoing voltages generated using the 8-bit variable pulse number multiplier. Credit: University of Electro Communications

Digital to analog convertors (DACs) are devices that convert digital, typically binary signals to outputs in the form of voltage. The voltage generated can then be used to produce light, as in video and television or sound, as in MP3 players. Single-flux-quantum (SFQ)-based DACs fabricated using superconducting Josephson junctions generate voltages of quantum accuracy, which would be applied for metrological applications, i.e., realization of AC voltage standards.

A group led by Yoshinao Mizugaki at the University of Electro-Communications in Tokyo has developed SFQ-based DACs producing only unipolar voltages, with positive polarity. This makes them less advanced than other available DACs for metrology. Their previous attempts to resolve the issue of unipolarity were quite exhaustive. The team has now attempted to develop their device by adding a simple fixture to the circuit.

A DAC was designed using a so-called polarity-switchable double flux amplifier (PS-DSQA). The PS-DSQA consisted of three-junction loops, or stacks of cells, that produced output voltages with polarities corresponding to the polarity of deliberately applied (bias) currents. Thus switching the polarity of the bias current resulted in switching of the generated voltage. When an 8-bit digital input code was applied, in the form of a variable pulse number multiplier, the voltage generated was measured using an oscilloscope. The bias current was forwarded to a PS-DSQA capable of ±500 and ±8 fold magnification of .

Notably, the PS-DSQA produced positive and negative currents, albeit not of equal magnitude at ±500 fold. However, at ±8 fold, bias current conditions were more feasible for equivalent bipolar voltages. Sinusoidal waves were observed, indicating proper functioning and generation of bipolar voltages. Mizugaki and co-workers successfully built on their previous work, creating DACs with performances equivalent to devices currently available.

Explore further: Road to AC voltage standard leads to important junction

More information: Yoshinao Mizugaki et al. Single-Flux-Quantum Bipolar Digital-to-Analog Converter Comprising Polarity-Switchable Double-Flux-Quantum Amplifier, IEEE Transactions on Applied Superconductivity (2016). DOI: 10.1109/TASC.2016.2625739

Related Stories

Road to AC voltage standard leads to important junction

July 20, 2006

After 10 years of research, the National Institute of Standards and Technology (NIST) has unveiled the world's first precision instrument for directly measuring alternating current (AC) voltages. The instrument is being tested ...

NIST ships first programmable AC/DC 10-volt standard

October 27, 2010

Extending its 26-year tradition of innovative quantum voltage standards, researchers at the National Institute of Standards and Technology (NIST) have begun shipping a new 10-volt standard to users around the world. The programmable ...

Efficient power converter for internet of things

February 17, 2017

The "internet of things" is the idea that vehicles, appliances, civil structures, manufacturing equipment, and even livestock will soon have sensors that report information directly to networked servers, aiding with maintenance ...

Recommended for you

A better way to control crystal vibrations

May 21, 2018

The vibrational motion of an atom in a crystal propagates to neighboring atoms, which leads to wavelike propagation of the vibrations throughout the crystal. The way in which these natural vibrations travel through the crystalline ...

Turning entanglement upside down

May 21, 2018

A team of physicists from ICTP-Trieste and IQOQI-Innsbruck has come up with a surprisingly simple idea to investigate quantum entanglement of many particles. Instead of digging deep into the properties of quantum wave functions, ...

Quantum effects observed in photosynthesis

May 21, 2018

Molecules that are involved in photosynthesis exhibit the same quantum effects as non-living matter, concludes an international team of scientists including University of Groningen theoretical physicist Thomas la Cour Jansen. ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.