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

Single-flux-quantum logic

T. Van Duzer

Published Mar 1, 1992• 0 citations
Publisher

Abstract

This paper reviews the several families of single-flux-quantum logic that have appeared in the literature as well as a new one designed in our Laboratory. Some of these have been evaluated in full-adder circuits and found to have approximately the same latency (time between input and output) as a voltage-state circuit. It is pointed out that the throughput of single-flux-quantum circuits can be much higher than with voltage-state circuits because of a much shorter reset time. The applications for these circuits are greatest in data-independent computation such as signal processing. The prospects and problems for these kinds of circuits are discussed both for low- and high-temperature superconductors.

DOI
10.1117/12.2321840

Related papers

Single-flux-quantum logic

T. Van Duzer

ABSTRACT This paper reviews the several families of single-flux-quantum logic that haveappeared in the literature as well as a new one designed in our Laboratory. Some ofthese have been evaluated in full-adder circuits and found to have approximately the same latency (time between input and output) as a voltage-state circuit. It is pointed out that the throughput of single-flux-quantum circuits can be much higherthan with voltage-state circuits because of a much shorter reset time. The applica-tions for these circuits are greatest in data-independent computation such as signalprocessing. The prospects and problems for these kinds of circuits are discussed bothfor low- and high-temperature superconductors. 1. LOGIC FAMILIES The several families of single-flux-quantum logic that have been reported can be divided into two groups. One type transfers clock current from one branch of acircuit to another and typically has a three-phase clock. The other type of flux quantum logic employs single-flux-quantum pulses that propagate between gates to rep-resent logic signals. The clock also consists of pulses, and they can be generatedon-chip.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Mar 1, 1992•1 citation

Single flux, quantum B flip-flop and its possible applications

Stanislav V. Polonsky, Vasili K. Semenov, Alex F. Kirichenko

We are introducing a new subfamily of rapid single-flux-quantum (RSFQ) digital cells, based on a single B flip-flop template. The template can be considered as an SFQ flip-flop with up to 4 inputs and 6 outputs. Each input SFQ pulse can change the flip-flop's internal state. Each output presents (in the form of SFQ pulses a specific logic function of the initial state of the cell and input signals. Simple connection of various inputs and/or outputs, combined with shortening or opening of certain branches of the template allows one to implement a variety of RSFQ cells with wide margins. Of these various RSFQ cells, we have designed and successfully tested the T1 cell (asynchronous toggle flip-flop with synchronous destructive readout), single-bit full adder, and single-bit stage of an up-down counter. Experimentally measured margins for dc power supply voltage for these circuits were /spl plusmn/24%, /spl plusmn/24%, and /spl plusmn/17%, respectively.>

IEEE Transactions on Applied Superconductivity•Mar 1, 1994•75 citations

New multi-flux-quantum logic family

V.K. Kaphmenko, E. Wikborg

We report on a voltage-state logic family based on shunted Josephson junctions and on the Rapid Single Flux Quantum (RSFQ) concept. Storing information in a voltage-state form makes this Multi-Flux-Quantum Logic (MFQL) easier to match to complementary metal-oxide semiconductor (CMOS) circuits. The switching of MFQL element between the voltage and zero-voltage states takes a minimum of two SFQ pulses, and the switching time of this logic is comparable to that of RSFQ logic. The key logic element is an inverter in the form of an asymmetric interferometer, and the underlying idea is to use a separate superconducting wire to supply a standard dc output voltage for the elements. The asymmetric interferometer, directly coupled to the other elements, is actually a Josephson junction based three-terminal device or transistor. Elements such as NOT, OR, NOR, XOR, XNOR, a toggle flip-flop, and an RS trigger have been simulated, and show margins better than /spl plusmn/24%. The performance of this logic with current circuit fabrication technologies is also discussed.

IEEE Transactions on Applied Superconductivity•Jun 1, 1997•1 citation

Superconducting digital electronics

H. Hayakawa, Nobuyuki Yoshikawa, Shinichi Yorozu +1 more

Single-flux quantum logic (SFQ) circuits, in which a flux quantum is used as an information carrier, have the possibility for opening the door to a new digital system operated at over 100-GHz clock frequency at extremely low power dissipation. The SFQ logic system is a so-called pulse logic, which is completely different from the level logic for semiconductors like CMOS, so circuit design technologies for SFQ logic circuits have to be newly developed. Recently, much progress in basic technologies for designing SFQ circuits and operating circuits at high speeds has been made. With advances in these design tools, large-scale circuits including more than several thousand junctions can be easily operated with the clock frequency of more than several tens of gigahertz. High-end routers and high-end computers are possible applications of SFQ logic circuits because of their high throughput nature and the low power dissipation of SFQ logic. In this paper, recent advances of SFQ circuit design technologies and recent developments of switches for high-end routers and microprocessors for high-end computers that are considered possible applications for SFQ logic will be described.

Proceedings of the IEEE•Sep 20, 2004•72 citations

A New Design Approach for High-Throughput Arithmetic Circuits for Single-Flux-Quantum Microprocessors

Masamitsu Tanaka, Yuki Yamanashi, Yoshiaki Kamiya +7 more

We propose a new design approach for high- throughput arithmetic circuits based on state transitions using single-flux-quantum (SFQ) logic circuits. Microprocessors have several complex interconnects in datapath including loops of data, to which only one SFQ pulse is allowed to be confined, and the loops can spoil the high-throughput nature of SFQ circuits. In our new approach, we regard an arithmetic circuit with loops as a sequential logic circuit, and we use nondestructive readout gates (NDROs) as storage elements of the internal state. We can eliminate the loops and achieve high throughput by translating calculations into transitions of the state stored in the NDROs. We have implemented a bit-serial adder with the proposed approach, and demonstrated 36-GHz operations using the niobium 2.5-kA/cm2standard process technology.

IEEE Transactions on Applied Superconductivity•Jun 1, 2007•11 citations

Superconducting digital electronics

Shuichi Tahara, Shinichi Yorozu, Y. Kameda +5 more

Superconducting devices have intrinsically superior characteristics to those of semiconductor devices. Presently, we can fabricate more than twenty thousand junctions on one chip using niobium technology. We have demonstrated the operation of a network system with a superconducting interconnection chip using voltage-state logic. Single flux quantum devices are promising for future superconducting applications because the clock frequency of SFQ logic is higher than that of voltage-state. We have proposed a high-end switch based on hybrid architecture using optical devices, semiconductors and SFQ devices. To demonstrate the high-speed operation of SFQ circuits, we developed an arbiter circuit that uses SFQ components and the arbiter circuit operates at 60 GHz. We also have developed a high Tc superconducting (HTS) SFQ sampler system for observing ultra-fast signal waveforms. In addition, we will discuss the prospects of future superconducting devices based on the fabrication technologies we developed.

IEEE Transactions on Applied Superconductivity•Mar 1, 2001•24 citations
This paper reviews the several families of single-flux-quantum logic that have appeared in the literature as well as a new one designed in our Laboratory. Some of these have been evaluated in full-adder circuits and found to have approximately the same latency (time between input and output) as a voltage-state circuit. It is pointed out that the throughput of single-flux-quantum circuits can be much higher than with voltage-state circuits because of a much shorter reset time. The applications for these circuits are greatest in data-independent computation such as signal processing. The prospects and problems for these kinds of circuits are discussed both for low- and high-temperature superconductors.
ABSTRACT This paper reviews the several families of single-flux-quantum logic that haveappeared in the literature as well as a new one designed in our Laboratory. Some ofthese have been evaluated in full-adder circuits and found to have approximately the same latency (time between input and output) as a voltage-state circuit. It is pointed out that the throughput of single-flux-quantum circuits can be much higherthan with voltage-state circuits because of a much shorter reset time. The applica-tions for these circuits are greatest in data-independent computation such as signalprocessing. The prospects and problems for these kinds of circuits are discussed bothfor low- and high-temperature superconductors. 1. LOGIC FAMILIES The several families of single-flux-quantum logic that have been reported can be divided into two groups. One type transfers clock current from one branch of acircuit to another and typically has a three-phase clock. The other type of flux quantum logic employs single-flux-quantum pulses that propagate between gates to rep-resent logic signals. The clock also consists of pulses, and they can be generatedon-chip.
We are introducing a new subfamily of rapid single-flux-quantum (RSFQ) digital cells, based on a single B flip-flop template. The template can be considered as an SFQ flip-flop with up to 4 inputs and 6 outputs. Each input SFQ pulse can change the flip-flop's internal state. Each output presents (in the form of SFQ pulses a specific logic function of the initial state of the cell and input signals. Simple connection of various inputs and/or outputs, combined with shortening or opening of certain branches of the template allows one to implement a variety of RSFQ cells with wide margins. Of these various RSFQ cells, we have designed and successfully tested the T1 cell (asynchronous toggle flip-flop with synchronous destructive readout), single-bit full adder, and single-bit stage of an up-down counter. Experimentally measured margins for dc power supply voltage for these circuits were /spl plusmn/24%, /spl plusmn/24%, and /spl plusmn/17%, respectively.>
We report on a voltage-state logic family based on shunted Josephson junctions and on the Rapid Single Flux Quantum (RSFQ) concept. Storing information in a voltage-state form makes this Multi-Flux-Quantum Logic (MFQL) easier to match to complementary metal-oxide semiconductor (CMOS) circuits. The switching of MFQL element between the voltage and zero-voltage states takes a minimum of two SFQ pulses, and the switching time of this logic is comparable to that of RSFQ logic. The key logic element is an inverter in the form of an asymmetric interferometer, and the underlying idea is to use a separate superconducting wire to supply a standard dc output voltage for the elements. The asymmetric interferometer, directly coupled to the other elements, is actually a Josephson junction based three-terminal device or transistor. Elements such as NOT, OR, NOR, XOR, XNOR, a toggle flip-flop, and an RS trigger have been simulated, and show margins better than /spl plusmn/24%. The performance of this logic with current circuit fabrication technologies is also discussed.
Single-flux quantum logic (SFQ) circuits, in which a flux quantum is used as an information carrier, have the possibility for opening the door to a new digital system operated at over 100-GHz clock frequency at extremely low power dissipation. The SFQ logic system is a so-called pulse logic, which is completely different from the level logic for semiconductors like CMOS, so circuit design technologies for SFQ logic circuits have to be newly developed. Recently, much progress in basic technologies for designing SFQ circuits and operating circuits at high speeds has been made. With advances in these design tools, large-scale circuits including more than several thousand junctions can be easily operated with the clock frequency of more than several tens of gigahertz. High-end routers and high-end computers are possible applications of SFQ logic circuits because of their high throughput nature and the low power dissipation of SFQ logic. In this paper, recent advances of SFQ circuit design technologies and recent developments of switches for high-end routers and microprocessors for high-end computers that are considered possible applications for SFQ logic will be described.
We propose a new design approach for high- throughput arithmetic circuits based on state transitions using single-flux-quantum (SFQ) logic circuits. Microprocessors have several complex interconnects in datapath including loops of data, to which only one SFQ pulse is allowed to be confined, and the loops can spoil the high-throughput nature of SFQ circuits. In our new approach, we regard an arithmetic circuit with loops as a sequential logic circuit, and we use nondestructive readout gates (NDROs) as storage elements of the internal state. We can eliminate the loops and achieve high throughput by translating calculations into transitions of the state stored in the NDROs. We have implemented a bit-serial adder with the proposed approach, and demonstrated 36-GHz operations using the niobium 2.5-kA/cm2standard process technology.
Superconducting devices have intrinsically superior characteristics to those of semiconductor devices. Presently, we can fabricate more than twenty thousand junctions on one chip using niobium technology. We have demonstrated the operation of a network system with a superconducting interconnection chip using voltage-state logic. Single flux quantum devices are promising for future superconducting applications because the clock frequency of SFQ logic is higher than that of voltage-state. We have proposed a high-end switch based on hybrid architecture using optical devices, semiconductors and SFQ devices. To demonstrate the high-speed operation of SFQ circuits, we developed an arbiter circuit that uses SFQ components and the arbiter circuit operates at 60 GHz. We also have developed a high Tc superconducting (HTS) SFQ sampler system for observing ultra-fast signal waveforms. In addition, we will discuss the prospects of future superconducting devices based on the fabrication technologies we developed.