Applied Physics Letters

Multiple-quantum interference superconducting analog-to-digital converter

R. Harris, C.A. Hamilton, Frances L. Lloyd

Published Nov 1, 1979• 31 citations

Abstract

Multiple-quantum interference in a superconducting interferometer is used for analog-to-digital conversion. The simple fully parallel four-bit converter which is described is the first known use of this effect in a digital circuit. Sampling rates of 2×108 per second were achieved, and much higher rates appear possible.

DOI: 10.1063/1.91238

Related papers

Multiple-quantum interference superconducting analog-to-digital converter. [Patent application]

R. Harris, C.A. Hamilton

Disclosed is an analog-to-digital converter using superconducting interferometers connected in parallel, each interferometer being identical. The coupling of the analog signal to each successive interferometer is increased in the ratio of 1:2:4:8:16:32:, etc. The application of a pulsed power supply to the parallel connected interferometer generates output voltages on the interferometers. The output voltages are a Gray Code representation of the analog signal.

May 7, 19810 citations

A superconducting 6-bit analog-to-digital converter with operation to 2 × 109samples/second

C.A. Hamilton, Frances L. Lloyd

The design and performance of a 6-bit superconducting A/D converter are described. The converter is based on double junction interferometers used as current comparators. The unique periodic response of these comparators makes possible a fully parallel N-bit converter requiring only N comparators. Conversion rates up to 2 × 109samples per second have been demonstrated.

IEEE Electron Device LettersMay 1, 198026 citations

Multigigahertz performance of a superconducting analog-to-digital converter

Howard Cam Luong, T. Van Duzer

This paper presents the progress we have made on our design, fabrication, and testing of a fully parallel superconducting analog-to-digital converter (ADC) with multi-GHz clock frequencies and input bandwidth. To our best knowledge, this converter is the first flash-type analog-to-digital converter ever reported in Josephson technology that fully integrates a quantizer and a thermometer-to-binary encoder to achieve binary outputs. In this design, the quantizer consists of 2(superscript N-1 comparators, each of which is realized using a hysteretic one- junction sampling SQUID driving a two-junction readout SQUID. A new logic family has been designed based on the same comparator building block and has been used to implement the thermometer-to- binary encoder. Taking advantage of the fact that the encoder's input is thermometer-coded, we have designed three-input and four-input quasi-XOR gates with only three NAND gates and therefore reduced significantly the total gate count. Functionalities of all the sub-circuits have been verified experimentally at clock frequencies up to 3 GHz, which is limited by our currently available testing equipment.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIEJul 2, 19940 citations

Analog measurement applications for high speed Josephson switches

C. Hamilton, Frances L. Lloyd, Richard L. Kautz

This paper reviews high speed analog applications of Josephson switching devices. The design and performance of two different analog sampling circuits is described. A method is proposed for delivering room temperature signals to these samplers with 30 GHz or more of bandwidth. An analog-to-digital converter based on quantum interference comparators is also described. This device has achieved conversion rates of 2 × 109samples per second.

IEEE Transactions on MagneticsJan 1, 198136 citations

Superconductor analog-to-digital converters

Oleg A. Mukhanov, Deepnarayan Gupta, Alan M. Kadin +1 more

Ultrafast switching speed, low power, natural quantization of magnetic flux, quantum accuracy, and low noise of cryogenic superconductor circuits enable fast and accurate data conversion between the analog and digital domains. Based on rapid single-flux quantum (RSFQ) logic, these integrated circuits are capable of achieving performance levels unattainable by any other technology. Two major classes of superconductor analog-to-digital converters (ADCs) are being developed - Nyquist sampling and oversampling converters. Complete systems with digital sampling at rates of /spl sim/20 GHz and above have been demonstrated using low-temperature superconductor device technology. Some ADC components have also been implemented using high-temperature superconductors. Superconductor ADCs have unique applications in true digital-RF communications, broadband instrumentation, and digital sensor readout. Their designs, test results, and future development trends are reviewed.

Proceedings of the IEEESep 20, 2004185 citations

Superconducting Analog-to-Digital Converters

Alan M. Kadin, Oleg A. Mukhanov

Analog-to-digital converters (ADCs) are electronic circuits that convert an electrical signal from the analog domain to the digital domain of binary numbers, which can then be processed by computers. A digital-to-analog converter (DAC) functions in the reverse direction, converting a sequence of binary numbers into a continuous electrical signal, and high-performance superconducting DACs are still being developed. A time-to-digital converter (TDC) digitizes time and resembles in some ways ADCs. Superconducting TDCs are simpler than ADCs and are being developed mostly for integration with cryogenic sensor arrays. Quantization refers to the selection of a discrete value for the magnitude when the signal is sampled, and is carried out by a quantizer. A high sampling rate with good linearity is necessary for high fidelity to the desired signal, and a DAC can be characterized by parameters of SNR and SFDR in much the same way as an ADC.

CRC Press eBooksMay 17, 20220 citations