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

IEEE Asian Solid-State Circuits Conference (A-SSCC)

A 57.2GHz 11.2mW 8-bit General Purpose Superconductor Microprocessor with Dual-Clocking Scheme

Ikki Nagaoka, Ryota Kashima, Tomoki Nakano, Masamitsu Tanaka, Taro Yamashita, Koji Inoue, Akira Fujimaki

Published Nov 6, 2022• 10 citations
Publisher

Abstract

A superconductor single-flux-quantum (SFQ) logic 8-bit microprocessor is demonstrated up to 57.2 GHz with a measured power consumption of 11.2 mW. The microprocessor has an ultradeep, gate-level pipelining containing many feedback paths and communications between components. The arrival clock timings at all the logic gates are ultra-precisely tuned using two different clocking schemes, called “concurrent-flow” and “counter-flow,” to achieve extremely high clock frequency operation over 50 GHz. Low-temperature circumstances enable us to conduct super delay-intensive layout design by controlling delays of all waveguide interconnects in the order of sub-picosecond precision.

DOI
10.1109/a-sscc56115.2022.9980802

Related papers

64-GHz Datapath Demonstration for Bit-Parallel SFQ Microprocessors Based on a Gate-Level-Pipeline Structure

Ryota Kashima, Ikki Nagaoka, Masamitsu Tanaka +2 more

We successfully demonstrated an 8-bit-wide, bit-parallel datapath composed of an arithmetic logic unit and register files for high-throughput oriented SFQ microprocessors based on a gate-level-pipeline structure. Achieving high-speed operation in the bit-parallel datapath is difficult because of feedback paths. We used concurrent-flow clocking and counter-flow clocking in combination to solve the timing problem at the feedback path in the datapath, and we optimized the number of JJs and pipeline stages in the register file for solving the timing issue. We designed the datapath with the cell library for the AIST 10 kA/cm$^2$Advanced Process. The total number of pipeline stages, Josephson junctions, and circuit area of the designed datapath were 52, 18448, and 3.81 mm × 4.05 mm, respectively. We obtained a relatively wide bias margin of the designed datapath at the target clock frequency of 50 GHz, and it operated up to 64 GHz in on-chip high-speed testing.

IEEE Transactions on Applied Superconductivity•Feb 23, 2021•37 citations

32 GHz 6.5 mW Gate-Level-Pipelined 4-Bit Processor using Superconductor Single-Flux-Quantum Logic

Koki Ishida, Masamitsu Tanaka, Ikki Nagaoka +5 more

A Single-Flux-Quantum (SFQ) 4-bit throughput-oriented processor has successfully been demonstrated at up to 32 GHz with the measured power consumption of 6.5 mW. This is the first implementation of the gate-level-pipelined processor, and it achieves 2.5 Tera-Operations Per Watt (TOPS/W) by circuit and architectural optimizations.

Symposium on VLSI Circuits•Jun 1, 2020•39 citations

29.3 A 48GHz 5.6mW Gate-Level-Pipelined Multiplier Using Single-Flux Quantum Logic

Ikki Nagaoka, Masamitsu Tanaka, Koji Inoue +1 more

A multiplier based on superconductor single-flux-quantum (SFQ) logic is demonstrated up to 48GHz with the measured power consumption of 5.6 mW. The multiplier performs 8 × 8-bit signed multiplication every clock cycle. The design is based on a bit-parallel, gate-level-pipelined structure that exploits ultimately high-throughput performance of SFQ logic. The test chip fabricated using a 1.0-μm, 9-layer process consists of 20,251 Nb/AlOx/Nb Josephson junctions (JJs). The correctness of operation is verified by on-chip high-speed testing.

Digest of technical papers/Digest of technical papers - IEEE International Solid-State Circuits Conference•Feb 1, 2019•45 citations

ARCHITECTURE AND DESIGN OF AN 8-BIT FLUX-1 SUPERCONDUCTOR RSFQ MICROPROCESSOR

M. Dorojevets

The first single-chip superconductor FLUX-1 microprocessor has been designed in the Rapid Single Flux Quantum (RSFQ) logic and fabricated using 4 kA/cm2, 1.75-μm Nb/AlOx/Nb Josephson junction technology as a result of the collaboration between SUNY Stony Brook and TRW, Inc. A FLUX-1 chip represents an 8-bit deeply pipelined microprocessor prototype with a target clock frequency of 17-20 GHz. A new parallel partitioned architecture has been developed in order to tolerate interconnect delays and fill long FLUX-1 processor pipelines with useful instructions. The processor includes the 16 × 32-bit pipelined instruction memory, 8 integer arithmetic-logic units interleaved with 8 registers, the branch unit, and I/O ports for 5-GHz chip-to-chip communication over Nb microstrip lines on a chip carrier. The FLUX-1 instruction set consists of ~25 arithmetic, logical, and control instructions. A FLUX-1 microprocessor chip contains 65,759 Josephson junctions on a 10.6 mm × 13.2 mm die with flip-chip packaging. First FLUX-1 chips fabricated in August 2001 are currently under testing at TRW, Inc.

International Journal of High Speed Electronics and Systems•Jun 1, 2002•8 citations

A 20-GHz FLUX-1 superconductor RSFQ microprocessor

M. Dorojevets

The first single-chip superconductor FLUX-1 microprocessor prototype with a target clock frequency of 17-20 GHz has been designed in the Rapid Single Flux Quantum (RSFQ) logic and fabricated using low-temperature 4 kA/cm 2 , 1.75-μm Nb/AlOx/Nb Josephson junction technology. A FLUX-1 chip represents an 8-bit deeply pipelined microprocessor with a new parallel partitioned architecture that has been developed to tolerate interconnect delays and fill long FLUX-1 pipelines with operations. A FLUX-1 chip contains 65,759 Josephson junctions on a 10.6 mm x 13.2 mm die with flip-chip packaging. First FLUX-1 chips fabricated in 2001 are currently under testing at TRW.

Journal de Physique IV (Proceedings)•May 1, 2002•4 citations

Design and Implementation of a Pipelined Bit-Serial SFQ Microprocessor, ${\rm CORE}1\beta$

Yuki Yamanashi, Masamitsu Tanaka, A. Akimoto +7 more

A pipelined 8-bit-serial single-flux-quantum (SFQ) microprocessor, called CORE1beta, was designed and tested. The CORE1beta has two cascaded arithmetic logic units (ALUs) based on forwarding architecture, which can perform two register operations from one instruction. Pipelining is also extensively adopted to enhance the performance. A new design method, known as one-hot encoding, has been introduced into the design of the control circuit. The 4-stage-pipelined SFQ microprocessors, CORE1beta8, have been implemented using the CONNECT cell library and the SRL 2.5 kA/cm2Nb process. The frequency for the instruction fetch is 25 GHz, and 20 GHz for the bit-serial data operation. The peak performance and the power consumption of the CORE1beta8 are estimated to be 1400 MOPS (million instructions per second) and 3.4 mW, respectively. We have experimentally demonstrated 4-stage pipelining and all functionalities of the CORE1beta8 microprocessors by on-chip high-speed tests.

IEEE Transactions on Applied Superconductivity•Jun 1, 2007•111 citations
A superconductor single-flux-quantum (SFQ) logic 8-bit microprocessor is demonstrated up to 57.2 GHz with a measured power consumption of 11.2 mW. The microprocessor has an ultradeep, gate-level pipelining containing many feedback paths and communications between components. The arrival clock timings at all the logic gates are ultra-precisely tuned using two different clocking schemes, called “concurrent-flow” and “counter-flow,” to achieve extremely high clock frequency operation over 50 GHz. Low-temperature circumstances enable us to conduct super delay-intensive layout design by controlling delays of all waveguide interconnects in the order of sub-picosecond precision.
We successfully demonstrated an 8-bit-wide, bit-parallel datapath composed of an arithmetic logic unit and register files for high-throughput oriented SFQ microprocessors based on a gate-level-pipeline structure. Achieving high-speed operation in the bit-parallel datapath is difficult because of feedback paths. We used concurrent-flow clocking and counter-flow clocking in combination to solve the timing problem at the feedback path in the datapath, and we optimized the number of JJs and pipeline stages in the register file for solving the timing issue. We designed the datapath with the cell library for the AIST 10 kA/cm2^22Advanced Process. The total number of pipeline stages, Josephson junctions, and circuit area of the designed datapath were 52, 18448, and 3.81 mm × 4.05 mm, respectively. We obtained a relatively wide bias margin of the designed datapath at the target clock frequency of 50 GHz, and it operated up to 64 GHz in on-chip high-speed testing.
A multiplier based on superconductor single-flux-quantum (SFQ) logic is demonstrated up to 48GHz with the measured power consumption of 5.6 mW. The multiplier performs 8 × 8-bit signed multiplication every clock cycle. The design is based on a bit-parallel, gate-level-pipelined structure that exploits ultimately high-throughput performance of SFQ logic. The test chip fabricated using a 1.0-μm, 9-layer process consists of 20,251 Nb/AlOx/Nb Josephson junctions (JJs). The correctness of operation is verified by on-chip high-speed testing.
The first single-chip superconductor FLUX-1 microprocessor has been designed in the Rapid Single Flux Quantum (RSFQ) logic and fabricated using 4 kA/cm2, 1.75-μm Nb/AlOx/Nb Josephson junction technology as a result of the collaboration between SUNY Stony Brook and TRW, Inc. A FLUX-1 chip represents an 8-bit deeply pipelined microprocessor prototype with a target clock frequency of 17-20 GHz. A new parallel partitioned architecture has been developed in order to tolerate interconnect delays and fill long FLUX-1 processor pipelines with useful instructions. The processor includes the 16 × 32-bit pipelined instruction memory, 8 integer arithmetic-logic units interleaved with 8 registers, the branch unit, and I/O ports for 5-GHz chip-to-chip communication over Nb microstrip lines on a chip carrier. The FLUX-1 instruction set consists of ~25 arithmetic, logical, and control instructions. A FLUX-1 microprocessor chip contains 65,759 Josephson junctions on a 10.6 mm × 13.2 mm die with flip-chip packaging. First FLUX-1 chips fabricated in August 2001 are currently under testing at TRW, Inc.
The first single-chip superconductor FLUX-1 microprocessor prototype with a target clock frequency of 17-20 GHz has been designed in the Rapid Single Flux Quantum (RSFQ) logic and fabricated using low-temperature 4 kA/cm 2 , 1.75-μm Nb/AlOx/Nb Josephson junction technology. A FLUX-1 chip represents an 8-bit deeply pipelined microprocessor with a new parallel partitioned architecture that has been developed to tolerate interconnect delays and fill long FLUX-1 pipelines with operations. A FLUX-1 chip contains 65,759 Josephson junctions on a 10.6 mm x 13.2 mm die with flip-chip packaging. First FLUX-1 chips fabricated in 2001 are currently under testing at TRW.
Design and Implementation of a Pipelined Bit-Serial SFQ Microprocessor, CORE1β{\rm CORE}1\betaCORE1β
A pipelined 8-bit-serial single-flux-quantum (SFQ) microprocessor, called CORE1beta, was designed and tested. The CORE1beta has two cascaded arithmetic logic units (ALUs) based on forwarding architecture, which can perform two register operations from one instruction. Pipelining is also extensively adopted to enhance the performance. A new design method, known as one-hot encoding, has been introduced into the design of the control circuit. The 4-stage-pipelined SFQ microprocessors, CORE1beta8, have been implemented using the CONNECT cell library and the SRL 2.5 kA/cm2Nb process. The frequency for the instruction fetch is 25 GHz, and 20 GHz for the bit-serial data operation. The peak performance and the power consumption of the CORE1beta8 are estimated to be 1400 MOPS (million instructions per second) and 3.4 mW, respectively. We have experimentally demonstrated 4-stage pipelining and all functionalities of the CORE1beta8 microprocessors by on-chip high-speed tests.