Superconductor microelectronics (SME) enables the realization of the true digital-RF architecture, extending the flexibility and fidelity of digital processing up to multi-GRz speeds. HYPRES is developing digital-RF subsystems that provide wideband and narrowband OBJECTIVE-level performance for WIN-T, FCS, TCA and JTRS communications systems. These subsystems are designed for near-term insertion into existing and future systems providing dramatic performance improvements and major reductions in SWaP and life cycle cost. This quantum electronics technology provides a quantum leap in performance ypassing the slow incremental improvements of traditional mostly analog electronics - to revolutionize future RF systems. This revolutionary SME technology provides unparalleled accuracies, spectral purities and ultra fast speeds that are otherwise unattainable with competing semiconductor technologies. The advantages and features of SME technology can be applied to a wide range of military satellite communications applications to include an extended family of JTRS SCA compliant radios in the 2 GHz to 55 GHz band and digital beamforming (DBF) phased arrays that make SATCOM-On-The-Move (SOTM) viable.
Superconductor microelectronics (SME) enables the realization of the true digital-RF architecture, extending the flexibility and fidelity of digital processing up to multi-GRz speeds. HYPRES is developing digital-RF subsystems that provide wideband and narrowband OBJECTIVE-level performance for WIN-T, FCS, TCA and JTRS communications systems. These subsystems are designed for near-term insertion into existing and future systems providing dramatic performance improvements and major reductions in SWaP and life cycle cost. This quantum electronics technology provides a quantum leap in performance ypassing the slow incremental improvements of traditional mostly analog electronics - to revolutionize future RF systems. This revolutionary SME technology provides unparalleled accuracies, spectral purities and ultra fast speeds that are otherwise unattainable with competing semiconductor technologies. The advantages and features of SME technology can be applied to a wide range of military satellite communications applications to include an extended family of JTRS SCA compliant radios in the 2 GHz to 55 GHz band and digital beamforming (DBF) phased arrays that make SATCOM-On-The-Move (SOTM) viable.
Superconductor microelectronics (SME) are rapidly redefining the state-of-the-art in wireless RF performance. SME-based digital RF subsystems, enabled by compact cryocoolers, have the potential to achieve all JTRS objective requirements (not just the thresholds) for performance, SWaP, and Cost as an Independent Variable (CAIV) targets for clusters 1, 3 and 4. Compact cryo-packaging is the key to deploying SME-based digital RF subsystems in JTRS and other wireless radio systems. A compact cryocooler provides the cryogenic environment for the superconductor multi-chip modules (MCM). The cryo-package (comprising the MCM and compact cryocooler) includes the mechanical and electrical interfaces to the JTRS radio. For example, a single SME-based digital RF subsystem provides a 10-channel full-duplex transceiver in less than 500 in/sup 3/, 30 lbs, and 150 watts; and an availability (up time) on the order of 99.998%. This paper discusses all aspects of cryopackaging, which include compact closed-cycle refrigerators or cryocoolers, methods of building and cooling superconductor multi-chip modules, managing thermal loads of input-output leads between warm ambient temperature electronics and cold superconductor electronics, and electromagnetic shielding.
Wireless applications would be less expensive, more flexible, and more robust if they had more digital and less analog circuitry. The problem is implementing digital signal processing at radio frequencies. Conventional data converters (ADCs and DACs) and digital circuits are simply not fast enough, especially at SATCOM frequencies. However, superconductors can provide ultra fast mixed signal and digital circuits with the linearity and dynamic range required for true direct, digital-RF processing. These superconducting circuits are digital ICs based on Josephson junctions and "rapid-single-flux-quantum" logic (RSFQ), where simple circuit switching speeds up to 750 GHz have been demonstrated. This permits direct conversion between analog RF and digital baseband signals, replacing frequency and protocol-specific analog hardware with flexible digital processors. HYPRES recently developed and delivered an X-band All Digital RF Receiver (XADR) prototype system for the US Army CERDEC and PM DCATS. The concept of this ADR is to replace the entire analog RF receive chain between the antenna and the baseband demodulator with a high performance digital RF equivalent. The first XADR prototype system has been successfully demonstrated at the Joint SATCOM engineering Center (JSEC). End to end link testing, over the satellite has been successfully completed using an existing AN/GSC-39 X-band earth terminal, an XTAR satellite, the X-band ADR and a SATCOM modem.
Superconductive technology offers unparalleled digital and mixed-signal circuit performance, advancing digital processing from baseband to RF stages. This allows elimination of analog filters and mixers with generally poorly controlled phase performance, causing intersymbol interference limiting an overall communication system performance. HYPRES has been developing superconducting circuit components for application to digital RF communication transceivers. The components include low-pass and band-pass analog-to-digital converters, digital decimation and correlation-based filters, digital up/down-converters, and low-time-jitter clock sources. All of these are based on ultra-fast Rapid Single Flux Quantum (RSFQ) digital circuits, with clock rates up to 20 GHz demonstrated with 3-micron technology, and being scaled to 40 GHz and above. In this paper, we will discuss design and performance of some of these components. 1.
Digital superconductor electronics has been experiencing rapid maturation with the emergence of smaller-scale, lower-cost communications applications which became the major technology drivers. These applications are primarily in the area of wireless communications, radar, and surveillance as well as in imaging and sensor systems. In these areas, the fundamental advantages of superconductivity translate into system benefits through novel Digital-RF architectures with direct digitization of wide band, high frequency radio frequency (RF) signals. At the same time the availability of relatively small 4K cryocoolers has lowered the foremost market barrier for cryogenically-cooled digital electronic systems. Recently, we have achieved a major breakthrough in the development, demonstration, and successful delivery of the cryocooled superconductor digital-RF receivers directly digitizing signals in a broad range from kilohertz to gigahertz. These essentially hybrid-technology systems combine a variety of superconductor and semiconductor technologies packaged with two-stage commercial cryocoolers: cryogenic Nb mixed-signal and digital circuits based on Rapid Single Flux Quantum (RSFQ) technology, room-temperature amplifiers, FPGA processing and control circuitry. The demonstrated cryocooled digital-RF systems are the world's first and fastest directly digitizing receivers operating with live satellite signals in X-band and performing signal acquisition in HF to L-band at ∼30GHz clock frequencies.
Superconducting microelectronics (SME) technology has the potential of realizing very high speed digital receivers capable of performing direct digitization of radio frequency signals with very low power consumption. The SME receiver is implemented on a single chip using Niobium based low temperature superconductive (LTS) Josephson Junction (JJ) technology by HYPRES. Analogue RF filters are still required at the receiver front end and are key components of the overall superconductor digital receiver. SME receivers usually require two types of RF filters; a wideband bandpass filter and a bandstop filter (a notch filter). The notch filter is required to eliminate interference and unwanted signals in the passband. In this thesis, design of highly miniaturized lumped element wideband and bandstop filters is investigated and some challenges are addressed. The filters are fabricated by the HYPRES process and therefore can be integrated with the SME receiver on the same chip. \nIn a wideband filter, the coupling between the adjacent resonators is high. Achieving such a strong coupling is one of the challenges of designing wideband filters. The wideband filters realized with distributed elements usually suffer from very low spurious frequency. As the bandwidth of the filter becomes wider, the spurious peak of the second harmonic gets closer to the passband of the filter. In the first part of this work, the possibility of realizing lumped element superconducting bandpass filters (BPF) with a relative bandwidth of 80% is investigated. \nIn the second part of the thesis, design and realization of lumped element superconducting bandstop filters (BSF) is discussed. The challenge for designing a bandstop filter is providing a good match over a wide frequency range. So narrowband inverters cannot be used. Instead, usually λ/4 matched transmission lines provide 90° phase shift between the resonators of a notch filter. The possibility of replacing the long transmission line with other means or eliminating the inverters and using both shunt and series resonators are investigated. Having both series and shunt resonators introduces some new challenges that are addressed in the thesis and discussed thoroughly. \nA tunable notch resonator is presented. The tunability is provided by a superconducting MEMS varactor that is realized in our group by doing some post processing on the device fabricated by HYPRES. The tunability range of the device at cryogenic temperatures is investigated. A 3-pole tunable BSF is also designed that uses the same tunable resonators. The tunability of the filter is investigated through simulation.
Wireless applications would be less expensive, more flexible, and more robust if they had more digital and less analog circuitry. The problem is implementing digital signal processing at radio frequencies. Conventional data converters (ADCs and DACs) and digital circuits are simply not fast enough. However, superconductors can provide ultra fast mixed signal and digital circuits with the linearity and dynamic range required for true direct, digital-RF processing. These superconducting circuits are digital ICs based on Josephson junctions and "rapid-single-flux-quantum" logic (RSFQ), where switching speeds up to 750 GHz have been demonstrated enabling true digital-RF architecture at clock speeds eventually up to 160 GHz. This permits direct conversion between analog RF and digital baseband signals, replacing frequency and protocol-specific analog hardware with flexible digital processors. Data conversion in high frequency wireless applications at frequencies up to 50 GHz will soon become practical. Hypres recently delivered a HF-VHF all digital RF receiver (ADR) prototype to ONR. Testing of this ADR has demonstrated the superior performance of superconducting ICs in cryocooled systems. A US Navy laboratory is now evaluating the world's first complete prototype digital RF receiver capable of direct digitization from DC to 2 GHz