| Presentation | 2012-07-19 Design of Circuits Controlling Dependence of Signal Propagation Time on Bias Voltage for Expanding the Operating Margin of SFQ Circuits Mikio OTSUBO, Yuki YAMANASHI, Nobuyuki YOSHIKAWA, |
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| Abstract(in Japanese) | (See Japanese page) |
| Abstract(in English) | Superconductive single flux quantum (SFQ) digital circuits can operate at a clock frequency of several tens GHz. However, the operating margin of the SFQ digital circuit decreases with increase of the operating frequency because timing error occurs at low bias voltage. In this study, a novel design method, which enables us to obtain wide operating margin at high operating frequency, has been investigated. In the proposed design method, timing error can be avoided by controlling dependences of signal propagation delay of Josephson transmission lines (JTLs) on the bias voltage. The proposed JTLs to control the dependence of propagation delay on the bias voltage has extra bias feeding line in addition to conventional bias feeding lines of the conventional JTLs. By adjusting resistance of the bias resistors in the extra bias feeding lines and the critical current of the Josephson junctions, the dependence of propagation delay on the bias voltage can be arbitrarily adjusted and we can avoid timing error occurs at low bias region. In measuring characteristics of proposed circuits, dependence of signal transmission time on bias voltage of proposed circuits changed between 0.87 ps and -0.21 ps in comparison with normal transmission lines. Circuit simulation results indicate that bias margin of a full adder, designed assuming the 2.5 kA/cm^2 Nb process, can be improved by 20% compared to a conventional design at a frequency of 20 GHz by employing our novel design method. |
| Keyword(in Japanese) | (See Japanese page) |
| Keyword(in English) | Single flux quantum circuits / Josephson transmission line / Timing error / Full adder |
| Paper # | SCE2012-10 |
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| Conference Information | |
| Committee | SCE |
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| Conference Date | 2012/7/12(1days) |
| Place (in Japanese) | (See Japanese page) |
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| Topics (in Japanese) | (See Japanese page) |
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| Paper Information | |
| Registration To | Superconductive Electronics (SCE) |
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| Language | JPN |
| Title (in Japanese) | (See Japanese page) |
| Sub Title (in Japanese) | (See Japanese page) |
| Title (in English) | Design of Circuits Controlling Dependence of Signal Propagation Time on Bias Voltage for Expanding the Operating Margin of SFQ Circuits |
| Sub Title (in English) | |
| Keyword(1) | Single flux quantum circuits |
| Keyword(2) | Josephson transmission line |
| Keyword(3) | Timing error |
| Keyword(4) | Full adder |
| 1st Author's Name | Mikio OTSUBO |
| 1st Author's Affiliation | Yokohama National University() |
| 2nd Author's Name | Yuki YAMANASHI |
| 2nd Author's Affiliation | Faculty of Engineering, Yokohama National University |
| 3rd Author's Name | Nobuyuki YOSHIKAWA |
| 3rd Author's Affiliation | Faculty of Engineering, Yokohama National University |
| Date | 2012-07-19 |
| Paper # | SCE2012-10 |
| Volume (vol) | vol.112 |
| Number (no) | 138 |
| Page | pp.pp.- |
| #Pages | 5 |
| Date of Issue | |