IEICE Electronics Express
Online ISSN : 1349-2543
ISSN-L : 1349-2543
100GHz operation of a 4-bit single-flux-quantum pulse-frequency modulator designed for bipolar D/A conversion
Yoshinao MizugakiNaonori SegaHiroshi Shimada
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2022 Volume 19 Issue 12 Pages 20220194


We designed and operated a 4-bit single-flux-quantum pulse-frequency modulator for bipolar D/A conversion. It was based on our previously-proposed “sum of selected bit sequence” configuration. Two functions, a synchronization scheme with a reference signal source and a complement number system for realization of bipolar output voltage, were implemented. A test circuit excluding the output analog stage (dual double-flux-quantum amplifier) was fabricated using a 10kA/cm2 Nb/AlOx/Nb integration process. The synchronization function was evaluated in terms of the average voltages, which agreed well with the expected values. The bipolar D/A conversion was successfully emulated by using the positive and negative output signals. The maximum over-biased input voltage was determined to be 230µV, of which the corresponding SFQ repetition frequency was 111GHz.

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© 2022 by The Institute of Electronics, Information and Communication Engineers
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