Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

IEICE Technical Report; IEICE Tech. Rep.

Design and demonstration of a 5-bit flash-type SFQ A/D converter with error correction circuits

Hideo Suzuki, M. Oikawa, Kenichiro Nishii, Kazumasa Ishihara, 睦夫 日高

Published Feb 11, 2011• 0 citations
OpenAlex

Related papers

Novel serial–parallel converter using SFQ logic circuits

H. Park, Yuki Yamanashi, K. Taketomi +3 more

Physica C Superconductivity•May 29, 2008•4 citations

Design and Demonstration of a 5-Bit Flash-Type SFQ A/D Converter Integrated With Error Correction and Interleaving Circuits

Hideo Suzuki, M. Oikawa, K. Nishii +4 more

We have designed a fully integrated 5-bit flash-type single-flux quantum (SFQ) analog-to-digital converter (ADC), in which an error correction and a bit-interleaving circuit are integrated with complementary quasi-one-junction SQUID (CQOS) comparators, and we verified its operation in experiments. Two types of look-back error correction circuits with different clock schemes were designed for the integrated ADCs to avoid the gray zone in comparators and to convert gray code to binary code. The interleaving circuit was also used in the ADC to add one extra bit. A binary 5-bit A/D converter was integrated into an IC chip. Then, input waveforms at low frequencies were successfully retrieved from the binary data of the A/D converter without any errors. We also confirmed that the A/D converter operated properly by conducting tests in our cryocooling system using a 4K-GM cryocooler after the chip was flip-chip bonded onto a multi-chip-module (MCM) carrier. We also used the beat frequency method to test and confirm that the CQOS comparator operated effectively at high frequency, i.e., 3 bits at 15 GHz in the binary code operation and 4 bits at 15 GHz in the gray code operation. Furthermore, operations at sampling frequencies of up to 32 and 50 GHz with a low-frequency analog input signal were experimentally confirmed for a 4-bit comparator circuit with a critical current density Jcof 2.5 kA/cm2and 10 kA/cm2, respectively.

IEEE Transactions on Applied Superconductivity•Dec 22, 2010•15 citations

Improvement of SFQ pulse frequency in an SFQ-D/A converter

Yuma Arai, Tomoki Watanabe, Kazunao Sawada +2 more

The Japan Society of Applied Physics•Jul 22, 2016•1 citation

Investigation of a 5-bit Flash-Type SFQ A/D Converter Using 10 $\hbox{kA/cm}^{2}$ Niobium Process and Locally Isolated Grounds

Hideo Suzuki, M. Oikawa, K. Nishii +1 more

We have investigated technologies for high-frequency and stable operation in a 5-bit flash-type single-flux quantum analog-to-digital (A/D) converter. We designed and evaluated several comparators with different designs of the transformer and found that the length of the primary line was the principal factor to determine the bandwidth, which was improved from 7 to 13 GHz by reducing the length from 860 to 290 μm. We have also investigated methods to avoid incorrect operation caused by ground return current of the bias current: one is locally extracting the return current around the component circuits, and the other is to use locally isolated ground for each component circuit. An integrated 5-bit A/D converter with an error correction circuit was designed using the locally isolated ground structure, which can avoid ground return current inflow from other component circuits. The A/D converter was operated without extracting ground return current and 10 GHz operation was carried out by means of the beat frequency method in our cryocooling system. Operation for an optical input signal was also observed. In addition, 100 GHz sampling clock operation with 1 kHz input signal was confirmed.

IEEE Transactions on Applied Superconductivity•Jan 25, 2013•8 citations

New type of SFQ-dc converter for use in oxide circuits

Y. Tarutani, Yoshihiro Ishimaru, H. Wakana +6 more

Physica C Superconductivity•Jun 3, 2004•13 citations

Possible Application of Flash-Type SFQ A/D Converter to Optical Communication Systems and Their Measuring Instruments

Hideo Suzuki, Michitaka Maruyama, Y. Hashimoto +2 more

We propose a possible application of a high-speed flash type single flux quantum (SFQ) analogue-to-digital converter (ADC) to optical communication systems and their measuring instruments. One of the problems in optical networks is the chromatic dispersion over a standard single mode fiber, which has to be recovered by optical dispersion compensation. Recently, there has been great interest in 100-Gbit/s Ethernet technologies as next generation optical networks in which chromatic dispersion is more severe. Among several types of architectures, digital coherent optical communication system is a promising technology. Correction of the dispersion is performed electrically after digital conversion without any optical compensation, which would ease system construction. Digital storage oscilloscopes with high-speed ADCs are crucial for investigating the architecture and for constructing 100-GbE systems. A flash-type SFQ ADC is attractive for its high-speed sampling clock capability, especially as an instrument for a digital coherent receiver. The maximum operating frequency of the comparator in ADCs was studied by simulation for various critical current densities (Jc). The simulation suggested that using Jcof 20-40 kA/cm2enables the comparator to operate at a clock frequency of more than 100 GHz. An O/E converter, a uni-traveling-carrier photodiode, operable at low-temperature, has been developed and 40-GHz operation was confirmed at 5 K. We have also designed a 1-bit slice of a superconducting quantum interference device-(SQUID) wheel-type ADC and its test circuit including a doubler circuit and two driver types.

IEEE Transactions on Applied Superconductivity•Jun 1, 2009•10 citations
We have designed a fully integrated 5-bit flash-type single-flux quantum (SFQ) analog-to-digital converter (ADC), in which an error correction and a bit-interleaving circuit are integrated with complementary quasi-one-junction SQUID (CQOS) comparators, and we verified its operation in experiments. Two types of look-back error correction circuits with different clock schemes were designed for the integrated ADCs to avoid the gray zone in comparators and to convert gray code to binary code. The interleaving circuit was also used in the ADC to add one extra bit. A binary 5-bit A/D converter was integrated into an IC chip. Then, input waveforms at low frequencies were successfully retrieved from the binary data of the A/D converter without any errors. We also confirmed that the A/D converter operated properly by conducting tests in our cryocooling system using a 4K-GM cryocooler after the chip was flip-chip bonded onto a multi-chip-module (MCM) carrier. We also used the beat frequency method to test and confirm that the CQOS comparator operated effectively at high frequency, i.e., 3 bits at 15 GHz in the binary code operation and 4 bits at 15 GHz in the gray code operation. Furthermore, operations at sampling frequencies of up to 32 and 50 GHz with a low-frequency analog input signal were experimentally confirmed for a 4-bit comparator circuit with a critical current density Jcof 2.5 kA/cm2and 10 kA/cm2, respectively.
Investigation of a 5-bit Flash-Type SFQ A/D Converter Using 10 kA/cm2\hbox{kA/cm}^{2}kA/cm2 Niobium Process and Locally Isolated Grounds
We have investigated technologies for high-frequency and stable operation in a 5-bit flash-type single-flux quantum analog-to-digital (A/D) converter. We designed and evaluated several comparators with different designs of the transformer and found that the length of the primary line was the principal factor to determine the bandwidth, which was improved from 7 to 13 GHz by reducing the length from 860 to 290 μm. We have also investigated methods to avoid incorrect operation caused by ground return current of the bias current: one is locally extracting the return current around the component circuits, and the other is to use locally isolated ground for each component circuit. An integrated 5-bit A/D converter with an error correction circuit was designed using the locally isolated ground structure, which can avoid ground return current inflow from other component circuits. The A/D converter was operated without extracting ground return current and 10 GHz operation was carried out by means of the beat frequency method in our cryocooling system. Operation for an optical input signal was also observed. In addition, 100 GHz sampling clock operation with 1 kHz input signal was confirmed.
We propose a possible application of a high-speed flash type single flux quantum (SFQ) analogue-to-digital converter (ADC) to optical communication systems and their measuring instruments. One of the problems in optical networks is the chromatic dispersion over a standard single mode fiber, which has to be recovered by optical dispersion compensation. Recently, there has been great interest in 100-Gbit/s Ethernet technologies as next generation optical networks in which chromatic dispersion is more severe. Among several types of architectures, digital coherent optical communication system is a promising technology. Correction of the dispersion is performed electrically after digital conversion without any optical compensation, which would ease system construction. Digital storage oscilloscopes with high-speed ADCs are crucial for investigating the architecture and for constructing 100-GbE systems. A flash-type SFQ ADC is attractive for its high-speed sampling clock capability, especially as an instrument for a digital coherent receiver. The maximum operating frequency of the comparator in ADCs was studied by simulation for various critical current densities (Jc). The simulation suggested that using Jcof 20-40 kA/cm2enables the comparator to operate at a clock frequency of more than 100 GHz. An O/E converter, a uni-traveling-carrier photodiode, operable at low-temperature, has been developed and 40-GHz operation was confirmed at 5 K. We have also designed a 1-bit slice of a superconducting quantum interference device-(SQUID) wheel-type ADC and its test circuit including a doubler circuit and two driver types.