Characterization of HTS SFQ circuits using interface-engineered Josephson junctions

Saitoh, Kazuo; Soutome, Y.; Fukazawa, T.; Tarutani, Y.; Takagi, K

doi:10.1109/77.919464

Cited by 17 publications

(5 citation statements)

References 16 publications

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“…The recent transmission electron microscopy (TEM) observation for the high-quality junctions demonstrated that quite smooth barrier-electrode interfaces were realized [5]. The junctions of this type have been widely studied for application to digital electronic devices, such as SFQ circuits [6], [7]. It is necessary to fabricate high-quality junctions with higher products and smaller spreads in order to enable operation of large-scale circuits at a higher clock frequency.…”

Section: Introductionmentioning

confidence: 98%

Ramp-edge junctions with interface-modified barriers fabricated on YBCO thick films

Wakana

Adachi

Sugiyama

et al. 2003

IEEE Trans. Appl. Supercond.

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We fabricated ramp-edge junctions with an interface-modified barrier on YBa 2 Cu 3 O (YBCO) liquid phase epitaxy (LPE) thick films. The LPE thick films were used as ground-planes. For the insulating layer between the ground plane and base electrode, a SrTiO 3 (STO)/(LaAlO 3 ) 0 3 -(SrAl 0 5 Ta 0 5 O 3 ) 0 7 (LSAT)/STO multilayer with the dielectric constant of approximately 32 was employed. We fabricated ramp-edge junctions with La-doped YBa 2 Cu 3 O (La-YBCO) and La-doped YbBa 2 Cu 3 O (La-YbBCO) as base and counter electrodes, respectively. The fabricated junctions exhibited resistively and capacitively shunted junction (RCSJ)-like characteristics and typical c n products of 2.6 and 1.1 mV at 4.2 and 40 K, respectively. The 1 -spread in c as small as 8.1% was obtained for 100-junction series-arrays. The use of ground plane reduced the sheet inductance of electrodes to a value of 0.76-0.94 pH/square at 4.2 K.

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Section: Introductionmentioning

confidence: 98%

Ramp-edge junctions with interface-modified barriers fabricated on YBCO thick films

Wakana

Adachi

Sugiyama

et al. 2003

IEEE Trans. Appl. Supercond.

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“…These projected performances are owing to the high of the oxide electrodes and a high output voltage of the ramp-edge junction having a high critical current density , respectively. In reality, operating frequencies more than 100 GHz have been demonstrated for a toggle flip-flop(t-FF) [2] and comparators [3], [4]. The operating frequencies have been estimated from the voltage induced by the SFQs that successively propagate in the Josephson transmission line (JTL).…”

Section: Introductionmentioning

confidence: 99%

Fabrication and Logic Operation of Oxide SFQ-Circuit-Components

Tarutani

Ishimaru

Wakana

et al. 2005

IEEE Trans. Appl. Supercond.

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Basic SFQ circuit components, such as SFQ-dc converter, set-reset flip-flop (RS-FF), confluence buffer and splitter, have been fabricated by the YBa 2 Cu 3 O 7 x -ramp-edge-junction technology and their logic operations were investigated. Circuit parameters were optimized in order to widen the margins of these oxide SFQ circuit components. The SFQ-dc converter that comprised double SQUIDs connected in series showed the output voltage as much as 0.3 mV at 22 K owing to high value of the ramp-edge junction. Logic operations of the RS-FF, the confluence buffer and the splitter were correctly performed by using the SFQ-dc converter. Finite operating margins were obtainable for these circuits up to the temperature near 30 K. Index Terms-Confluence buffer, oxide SFQ circuit, RS flip-flop, SFQ-dc converter, splitter, YBa 2 Cu 3 O 7 x ramp-edge junction.

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“…20-40 K, junctions with high I c R n product are required. In a previous paper, we demonstrated that I c R n product should be larger than 0.7 mV to obtain 100 GHz operation at 30 K [11]. We determined this based on circuit simulation with a thermal noise effect.…”

Section: Dc-characteristics Of a Balanced Comparatormentioning

confidence: 99%

“…Although the fabrication of this junction is not as mature as that of the lowtemperature superconductive Josephson junction, the recent development of a new type of HTS Josephson junction, the 'interface-engineered-junction (IEJ)', has opened the door to the demonstration of HTS SFQ circuits [8][9][10][11]. In fact, the typical spread of the critical current with IEJ technology is 10%, and the junction characteristics are quite reproducible [10].…”

Section: Introductionmentioning

confidence: 99%

Dc-characteristics of a high-T_csuperconducting sigma–delta modulator using interface-engineered Josephson junctions

Saitoh

Soutome

Fukazawa

et al. 2002

Supercond. Sci. Technol.

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We fabricated and tested a high-temperature superconducting (HTS) sigma-delta modulator using interface-engineered Josephson junctions. Proper dc-characteristics were obtained with a sampling frequency of 100 GHz at 20 K. To achieve high-speed sampling, Josephson junctions with a higher critical-current normal-resistance product were used. Circuit simulations with thermal noise were performed for the analysis of switching characteristics and SFQ dynamics.

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Characterization of HTS SFQ circuits using interface-engineered Josephson junctions

Cited by 17 publications

References 16 publications

Ramp-edge junctions with interface-modified barriers fabricated on YBCO thick films

Ramp-edge junctions with interface-modified barriers fabricated on YBCO thick films

Fabrication and Logic Operation of Oxide SFQ-Circuit-Components

Dc-characteristics of a high-T_csuperconducting sigma–delta modulator using interface-engineered Josephson junctions

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Characterization of HTS SFQ circuits using interface-engineered Josephson junctions

Cited by 17 publications

References 16 publications

Ramp-edge junctions with interface-modified barriers fabricated on YBCO thick films

Ramp-edge junctions with interface-modified barriers fabricated on YBCO thick films

Fabrication and Logic Operation of Oxide SFQ-Circuit-Components

Dc-characteristics of a high-Tcsuperconducting sigma–delta modulator using interface-engineered Josephson junctions

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Product

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Dc-characteristics of a high-T_csuperconducting sigma–delta modulator using interface-engineered Josephson junctions