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 Transactions on Applied Superconductivity

HTS Pulse-Stretcher and Second Order Modulator: Design and First Results

Agnès Roussy, S. Karthikeyan, Ingrid Oomen, Thomas Ortlepp, Eko Hadi Sujiono, Alexander Brinkman, Horst Rogalla

Published Jun 1, 2005• 6 citations
Publisher

Abstract

One of the remaining challenges in the application of superconducting electronics is the interfacing between superconducting and semiconducting environments. The voltage and speed mismatch between RSFQ pulses and semiconducting read-out electronics makes it necessary to amplify as well as stretch the RSFQ pulses. Moreover, circuits based on HTS (High Temperature Superconductor) technology are very attractive since they can operate under considerably relaxed cooling effort, which is one of the main problems with LTS (Low Temperature Superconductor) circuits. Within the European project SuperADC, a HTS second order sigma delta modulator and a pulse stretcher, used as an interface between the modulator and the first semi-conducting amplifier stage, have been designed at Twente University and will be presented here.

DOI
10.1109/tasc.2005.849873

Related papers

Superconducting modulators for analog-to-digital converters

Peter Magnusson

The main topic of this thesis is the evaluation of performance of super-conducting rst- and second-order low-pass sigma-delta modulators. Superconducting electronics comprise characteristics such as very high switching speed, natural quantization, high sensitivity and low noise, proper-ties that are all essential for modulators used in high performance analog-to-digital converters (ADC). Sigma-delta modulators trade speed for improved resolution using feedback mechanisms making superconducting electronics an interesting alternative technology for the implementation. With linear models and device-level simulations the performance of these modulators have been evaluated. The linear model of the rst-order sigma-delta modulator shows that the performance, for a given oversampling ratio, only depends on the cut-o frequency of the RL-lter used. This is veried by device-level simulations and the results from the two methods are in good agreement. Device-level simulations of the second-order sigma-delta modu-

•Jan 1, 2005•1 citation

Superconducting second-order sigma-delta modulators utilizing multi-flux-quantum generators

T. Hashimoto, H. Hasegawa, Shuichi Nagasawa +3 more

We have been developing a superconducting second-order sigma-delta analog-to-digital converter with a large bandwidth and a large dynamic range for software radio applications. In a superconducting second-order sigma-delta modulator utilizing a passive integrator and single-flux-quantum (SFQ) feedback, gain to compensate the large attenuation in the passive integrator of the modulator is required to obtain a large dynamic range. In this paper, a second-order modulator utilizing multi-flux-quantum (MFQ) generators creating the needed gain is reported and the design and experimental test results of the elementary circuits including a comparator, a first-order modulator, and the MFQ generator are described. The digital outputs of the comparator and the first-order modulator were experimentally evaluated, where the input dependence of the comparator switching probability and the noise-shaping properties of the modulator were clearly observed. The low speed operation of the MFQ generator creating three SFQ pulses was experimentally confirmed. The other circuits were also tested at low frequencies.

IEEE Transactions on Applied Superconductivity•Mar 1, 2001•12 citations

Analogue demonstration of a high temperature superconducting sigma-delta modulator with 27 GHz sampling

Martin G. Forrester, B. D. Hunt, Donald L. Miller +2 more

We have successfully fabricated and tested a high temperature superconducting (HTS) sigma-delta modulator for analogue-to-digital conversion. This is the first demonstration of a GHz sampling A-to-D in HTS. The 15-junction single-flux-quantum (SFQ) circuit, fabricated using an epitaxial multilayer HTS process with YBCO/Co-YBCO/YBCO edge junctions, was internally clocked at 27 GHz and used to convert a 5.01 MHz signal. The modulator demonstrated a spur-free dynamic range of more than 75 dB. Two-tone measurements with 5.01 MHz and 5.51 MHz signals demonstrated third-order intermodulation products to be lower than -59 dBc. Demonstration of a functional HTS modulator represents a significant milestone in the development of high dynamic range ADCs suitable for such applications as surveillance radar.

Superconductor Science and Technology•Nov 1, 1999•11 citations

Superconducting modulators for high dynamic range delta-sigma analog-to-digital converters

A. Hodge Worsham, Donald L. Miller, Paul D. Dresselhaus +2 more

Superconducting digital circuits are capable of producing high dynamic range analog-to-digital converters (ADCs). We present sigma-delta architectures using large (>100) oversampling ratios to give signal-to-noise ratios of greater than 100 dB in simulation. Three distinct designs, using two distinct mechanisms for feedback, are presented. All of the designs use only shunted junctions, and are therefore compatible with HTS SNS junctions. Simulations are presented for a modulator which creates feedback pulses by SQUID lobe-crossings, a modulator which uses the transresistance of a SQUID for feedback, and a modulator which uses threshold crossings in both the first and second loops for feedback.

IEEE Transactions on Applied Superconductivity•Jun 1, 1999•26 citations

Magneto-optical modulator for the superconducting digital output interface

Roberto Rey-de-Castro

Josephson-junction-based low temperature rapid single flux quantum (RSFQ) superconducting electronics is already a mature technology, which is expected to perform at speeds exceeding 100 GHz [1]. However, the RSFQ technology still lacks a fast enough output interface between its operating circuit temperature T = 4.2 K and the room temperature electronic environment. RSFQ circuits work at liquid helium temperatures and the direct interconnection of these circuits and room temperature circuits using, e.g., copper transmission lines would consume too much of the cooling power [2]. To solve this problem a magneto-optical (MO) output interface has been proposed [3], in which the output current pulse from the RSFQ circuit is converted into an optical pulse and delivered to room temperature readout circuitry via an optical fiber.

Opto-Canada: SPIE Regional Meeting on Optoelectronics, Photonics, and Imaging•Aug 29, 2017•1 citation

Interfacing Superconductor and Semiconductor Digital Electronics

Yerzhan Mustafa, Selçuk Köse

Interface circuits are the key components that enable the hybrid integration of superconductor and semiconductor digital electronics. The design requirements of superconductor-semiconductor interface circuits vary depending on the application, such as high-performance classical computing, superconducting quantum computing, and digital signal processing. In this survey, various interface circuits are categorized based on the working principle and structure. The superconducting output drivers are explored, which are capable of converting and amplifying, e.g., single flux quantum (SFQ) voltage pulses, to voltage levels that semiconductor circuits can process. Several trade-offs between circuit- and system-level design parameters are examined. Accordingly, parameters such as the data rate, output voltage, power dissipation, layout area, thermal/heat load of cryogenic cables, and bit-error rate are considered.

physics.app-phCross-listedarXiv:2601.09969•Applied Physics Reviews•Jan 16, 2026•0 citations
One of the remaining challenges in the application of superconducting electronics is the interfacing between superconducting and semiconducting environments. The voltage and speed mismatch between RSFQ pulses and semiconducting read-out electronics makes it necessary to amplify as well as stretch the RSFQ pulses. Moreover, circuits based on HTS (High Temperature Superconductor) technology are very attractive since they can operate under considerably relaxed cooling effort, which is one of the main problems with LTS (Low Temperature Superconductor) circuits. Within the European project SuperADC, a HTS second order sigma delta modulator and a pulse stretcher, used as an interface between the modulator and the first semi-conducting amplifier stage, have been designed at Twente University and will be presented here.
The main topic of this thesis is the evaluation of performance of super-conducting rst- and second-order low-pass sigma-delta modulators. Superconducting electronics comprise characteristics such as very high switching speed, natural quantization, high sensitivity and low noise, proper-ties that are all essential for modulators used in high performance analog-to-digital converters (ADC). Sigma-delta modulators trade speed for improved resolution using feedback mechanisms making superconducting electronics an interesting alternative technology for the implementation. With linear models and device-level simulations the performance of these modulators have been evaluated. The linear model of the rst-order sigma-delta modulator shows that the performance, for a given oversampling ratio, only depends on the cut-o frequency of the RL-lter used. This is veried by device-level simulations and the results from the two methods are in good agreement. Device-level simulations of the second-order sigma-delta modu-
We have been developing a superconducting second-order sigma-delta analog-to-digital converter with a large bandwidth and a large dynamic range for software radio applications. In a superconducting second-order sigma-delta modulator utilizing a passive integrator and single-flux-quantum (SFQ) feedback, gain to compensate the large attenuation in the passive integrator of the modulator is required to obtain a large dynamic range. In this paper, a second-order modulator utilizing multi-flux-quantum (MFQ) generators creating the needed gain is reported and the design and experimental test results of the elementary circuits including a comparator, a first-order modulator, and the MFQ generator are described. The digital outputs of the comparator and the first-order modulator were experimentally evaluated, where the input dependence of the comparator switching probability and the noise-shaping properties of the modulator were clearly observed. The low speed operation of the MFQ generator creating three SFQ pulses was experimentally confirmed. The other circuits were also tested at low frequencies.
We have successfully fabricated and tested a high temperature superconducting (HTS) sigma-delta modulator for analogue-to-digital conversion. This is the first demonstration of a GHz sampling A-to-D in HTS. The 15-junction single-flux-quantum (SFQ) circuit, fabricated using an epitaxial multilayer HTS process with YBCO/Co-YBCO/YBCO edge junctions, was internally clocked at 27 GHz and used to convert a 5.01 MHz signal. The modulator demonstrated a spur-free dynamic range of more than 75 dB. Two-tone measurements with 5.01 MHz and 5.51 MHz signals demonstrated third-order intermodulation products to be lower than -59 dBc. Demonstration of a functional HTS modulator represents a significant milestone in the development of high dynamic range ADCs suitable for such applications as surveillance radar.
Superconducting digital circuits are capable of producing high dynamic range analog-to-digital converters (ADCs). We present sigma-delta architectures using large (>100) oversampling ratios to give signal-to-noise ratios of greater than 100 dB in simulation. Three distinct designs, using two distinct mechanisms for feedback, are presented. All of the designs use only shunted junctions, and are therefore compatible with HTS SNS junctions. Simulations are presented for a modulator which creates feedback pulses by SQUID lobe-crossings, a modulator which uses the transresistance of a SQUID for feedback, and a modulator which uses threshold crossings in both the first and second loops for feedback.
Josephson-junction-based low temperature rapid single flux quantum (RSFQ) superconducting electronics is already a mature technology, which is expected to perform at speeds exceeding 100 GHz [1]. However, the RSFQ technology still lacks a fast enough output interface between its operating circuit temperature T = 4.2 K and the room temperature electronic environment. RSFQ circuits work at liquid helium temperatures and the direct interconnection of these circuits and room temperature circuits using, e.g., copper transmission lines would consume too much of the cooling power [2]. To solve this problem a magneto-optical (MO) output interface has been proposed [3], in which the output current pulse from the RSFQ circuit is converted into an optical pulse and delivered to room temperature readout circuitry via an optical fiber.
Interface circuits are the key components that enable the hybrid integration of superconductor and semiconductor digital electronics. The design requirements of superconductor-semiconductor interface circuits vary depending on the application, such as high-performance classical computing, superconducting quantum computing, and digital signal processing. In this survey, various interface circuits are categorized based on the working principle and structure. The superconducting output drivers are explored, which are capable of converting and amplifying, e.g., single flux quantum (SFQ) voltage pulses, to voltage levels that semiconductor circuits can process. Several trade-offs between circuit- and system-level design parameters are examined. Accordingly, parameters such as the data rate, output voltage, power dissipation, layout area, thermal/heat load of cryogenic cables, and bit-error rate are considered.