Abstract: A system and method for receiving a radio frequency signal, comprising a device for digitizing, without prior alteration of frequency, an analog radio frequency representation of each of a plurality of radio frequency signals to produce a respective plurality of digital radio frequency signals having a respective associated radio frequency digital clock, the plurality of digital radio frequency signals having a sufficiently high respective associated clock rate to preserve an information content of an information communication present in the analog radio frequency representation; a switch matrix adapted to concurrently switch the plurality of digital radio frequency signals and associated digital radio frequency clock to ones of a plurality of digital signal processors; and a control adapted to selectively automatically control the concurrent switching of a plurality of digital signals and associated digital clock to the respective plurality of digital signal processors; wherein the digital signal processors

Abstract: Superconductor analog-to-digital converters (ADC) offer high sensitivity and large dynamic range. One approach to increasing the dynamic range further is with a subranging architecture, whereby the output of a coarse ADC is converted back to analog and subtracted from the input signal, and the residue signal fed to a fine ADC for generation of additional significant bits. This also requires a high-gain broadband linear amplifier, which is not generally available within superconductor technology. In a preferred embodiment, a distributed digital fluxon amplifier is presented, which also integrates the functions of integration, filtering, and flux subtraction. A subranging ADC design provides two ADCs connected with the fluxon amplifier and subtractor circuitry that would provide a dynamic range extension by about 30-35 dB.

Abstract: A radio frequency receiver subject to a large in-band interferor employs active cancellation with coarse and at least one fine cancellation signal, each with a respective radio frequency combiner, in order to increase the effective dynamic range of the receiver for weak signals of interest. One or both can be digitally synthesized. This is particularly applicable for co-site interference, whereby the interfering transmit signal is directly accessible. A similar system and method may also be applied to external interferors such as those produced by deliberate or unintentional jamming signals, or by strong multipath signals. An adaptive algorithm may be used for dynamic delay and gain matching. In a preferred embodiment, a hybrid technology hybrid temperature system incorporates both superconducting and semiconducting components to achieve enhanced broadband performance.

Abstract: A magnetic resonance system, comprising at least one SQUID, configured to receive a radio frequency electromagnetic signal, in a circuit configured to produce a pulsatile output having a minimum pulse frequency of at least 1 GHz which is analyzed in a processor with respect to a timebase, to generate a digital signal representing magnetic resonance information. The processor may comprise at least one rapid single flux quantum circuit. The magnetic resonance information may be image information. A plurality of SQUIDs may be provided, fed by a plurality of antennas in a spatial array, to provide parallel data acquisition. A broadband excitation may be provided to address a range of voxels per excitation cycle. The processor may digitally compensate for magnetic field inhomogeneities.

Abstract: Signals of interest in magnetic resonance imaging (MRI) systems comprise narrowband, circularly polarized (CP) radio-frequency magnetic fields from rotating atomic nuclei. Background “body noise” may comprise broadband, linearly polarized (LP) magnetic fields from thermally-activated eddy currents, and may exceed the signal in a band of interest, limiting the imaging resolution and requiring excessive averaging times. Noise may be selectively detected and substantially suppressed, while enhancing the signal of interest, using appropriate digital time-domain algorithms. At least two quadrature receiving antennas may be employed to distinguish and separate the LP noise from the CP signal. At least one broadband receiver may be used to identify and localize fast noise sources and to digitally filter the representation of their radio-frequency magnetic fields in the signal.

Abstract: A superconducting circuit is disclosed for fast digital readout of on-chip diagnostics in an array of devices in an integrated circuit. The digital readout comprises a digital RSFQ multiplexer to select the readout channel. This permits a large number of devices to be tested with a minimum of input and output lines. The devices may comprise digital devices (such as elementary RSFQ cells), or analog devices (such as inductors, resistors, or Josephson junctions) with a SQUID quantizer to generate a digital signal. The diagnostic array and the digital multiplexer are preferably configured to operate as part of the same integrated circuit at cryogenic temperatures.

Abstract: A transceiver architecture for wireless base stations wherein a broadband radio frequency signal is carried between at least one tower-mounted unit and a ground-based unit via optical fibers, or other non-distortive media, in either digital or analog format. Each tower-mounted unit (for both reception and transmission) has an antenna, analog amplifier and an electro-optical converter. The ground unit has ultrafast data converters and digital frequency translators, as well as signal linearizers, to compensate for nonlinear distortion in the amplifiers and optical links in both directions. In one embodiment of the invention, at least one of the digital data converters, frequency translators, and linearizers includes superconducting elements mounted on a cryocooler.

Abstract: A method for electrically interconnecting two substrates, each having a corresponding set of preformed electrical contacts, the substrates comprising an electronic circuit, and the resulting module, is provided. A liquid curable adhesive is provided over the set of contacts of a first substrate, and the set of electrical contacts of the second substrate is aligned with the set of electrical contacts of the first substrate. The sets of electrical contacts of the first and second substrate are compressed to displace the liquid curable adhesive from the inter-contact region, and provide electrical communication between the respective sets of electrical contacts. The liquid curable adhesive is then cured to form a solid matrix which maintains a relative compression between the respective sets of electrical contacts. One embodiment of the module comprises a high-speed superconducting circuit which operates at cryogenic temperatures.

Abstract: An important component in digital circuits is a phase rotator, which permits precise time-shifting (or equivalently, phase rotation) of a clock signal within a clock period. A digital phase rotator can access multiple discrete values of phase under digital control. Such a device can have application in digital clock synchronization circuits, and can also be used for a digital phase modulator that encodes a digital signal. A digital phase rotator has been implemented in superconducting integrated circuit technology, using rapid single-flux-quantum logic (RSFQ). This circuit can exhibit positive or negative phase shifts of a multi-phase clock. Arbitrary precision can be obtained by cascading a plurality of phase rotator stages. Such a circuit forms a phase-modulator that is the core of a direct digital synthesizer that can operate at multi-gigahertz radio frequencies.

Abstract: A system and method for receiving a signal, comprising an input adapted to receive a radio frequency signal having a strong interferer; a signal generator, adapted to produce a representation of the interferer as an analog signal generated based on an oversampled digital representation thereof; and a component adapted to cancel the strong interferer from radio frequency signal based on the generated analog signal to produce a modified radio frequency signal substantially absent the interferer. The system typically has a nonlinear component that either saturates or produces distortion from the strong interferer, which is thereby reduced. The system preferably employs high speed circuits which digitize and process radio frequency signals without analog mixers.

Abstract: A superconducting quantum interference devices (SQUID) comprises a superconducting inductive loop with at least two Josephson junction, whereby a magnetic flux coupled into the inductive loop produces a modulated response up through radio frequencies. Series and parallel arrays of SQUIDs can increase the dynamic range, output, and linearity, while maintaining bandwidth. Several approaches to achieving a linear triangle-wave transfer function are presented, including harmonic superposition of SQUID cells, differential serial arrays with magnetic frustration, and a novel bi-SQUID cell comprised of a nonlinear Josephson inductance shunting the linear coupling inductance. Total harmonic distortion of less than ?120 dB can be achieved in optimum cases.

Abstract: A method for increasing the integration level of superconducting electronic circuits, comprising fabricating a series of planarized electrically conductive layers patterned into wiring, separated by planarized insulating layers, with vias communicating between the conductive layers. Contrary to the standard sequence of patterning from the bottom up, the pattern of vias in at least one insulating layer is formed prior to the pattern of wiring in the underlying conductive layer. This enables a reduction in the number of planarization steps, leading to a fabrication process which is faster and more reliable. In a preferred embodiment, the superconductor is niobium and the insulator is silicon dioxide. This method can provide 10 or more wiring layers in a complex integrated circuit, and is compatible with non-planarized circuits placed above the planarized wiring layers.

Abstract: Superconductor analog-to-digital converters (ADC) offer high sensitivity and large dynamic range. One approach to increasing the dynamic range further is with a subranging architecture, whereby the output of a coarse ADC is converted back to analog and subtracted from the input signal, and the residue signal fed to a fine ADC for generation of additional significant bits. This also requires a high-gain broadband linear amplifier, which is not generally available within superconductor technology. In a preferred embodiment, a distributed digital fluxon amplifier is presented, which also integrates the functions of integration, filtering, and flux subtraction. A subranging ADC design provides two ADCs connected with the fluxon amplifier and subtractor circuitry that would provide a dynamic range extension by about 30-35 dB.

Abstract: A superconducting circuit is disclosed for fast digital readout of on-chip diagnostics in an array of devices in an integrated circuit. The digital readout comprises a digital RSFQ multiplexer to select the readout channel. This permits a large number of devices to be tested with a minimum of input and output lines. The devices may comprise digital devices (such as elementary RSFQ cells), or analog devices (such as inductors, resistors, or Josephson junctions) with a SQUID quantizer to generate a digital signal. The diagnostic array and the digital multiplexer are preferably configured to operate as part of the same integrated circuit at cryogenic temperatures.

Abstract: A system and method for receiving a signal, comprising an input adapted to receive a radio frequency signal having a strong interferer; a signal generator, adapted to produce a representation of the interferer as an analog signal generated based on an oversampled digital representation thereof; and a component adapted to cancel the strong interferer from radio frequency signal based on the generated analog signal to produce a modified radio frequency signal substantially absent the interferer. The system typically has a nonlinear component that either saturates or produces distortion from the strong interferer, which is thereby reduced. The system preferably employs high speed circuits which digitize and process radio frequency signals without analog mixers.

Abstract: An improved microfabrication technique for Josephson junctions in superconducting integrated circuits, based on the use of a double-layer lithographic mask for partial anodization of the side-walls and base electrode of the junctions. The top layer of the mask is a resist material, and the bottom layer is a dielectric material chosen so to maximize adhesion between the resist and the underlying superconducting layer, be etch-compatible with the underlying superconducting layer, and be insoluble in the resist and anodization processing chemistries. The superconductor is preferably niobium, under a silicon dioxide layer, with a conventional photoresist or electron-beam resist as the top layer. This combination results in a substantial increase in the fabrication yield of high-density superconducting integrated circuits, increase in junction uniformity and reduction in defect density. A dry etch more compatible with microlithography may be employed.

Abstract: A radio frequency receiver subject to a large in-band interferor employs active cancellation with coarse and at least one fine cancellation signal, each with a respective radio frequency combiner, in order to increase the effective dynamic range of the receiver for weak signals of interest. One or both can be digitally synthesized. This is particularly applicable for co-site interference, whereby the interfering transmit signal is directly accessible. A similar system and method may also be applied to external interferors such as those produced by deliberate or unintentional jamming signals, or by strong multipath signals. An adaptive algorithm may be used for dynamic delay and gain matching. In a preferred embodiment, a hybrid technology hybrid temperature system incorporates both superconducting and semiconducting components to achieve enhanced broadband performance.

Abstract: A cryogenic optoelectronic data link, comprising a sending module operating at a cryogenic temperature less than 100 K. An ultrasensitive electro-optic modulator, sensitive to input voltages of less than 10 mV, may include at least one optically active layer of graphene, which may be part of a microscale resonator, which in turn may be integrated with an optical waveguide or an optical fiber. The optoelectronic data link enables optical output of weak electrical signals from superconducting or other cryogenic electronic devices in either digital or analog form. The modulator may be integrated on the same chip as the cryogenic electrical devices. A plurality of cryogenic electrical devices may generate a plurality of electrical signals, each coupled to its own modulator. The plurality of modulators may be resonant at different frequencies, and coupled to a common optical output line to transmit a combined wavelength-division-multiplexed (WDM) optical signal.

Abstract: A system and method for receiving a radio frequency signal, comprising a device for digitizing, without prior alteration of frequency, an analog radio frequency representation of each of a plurality of radio frequency signals to produce a respective plurality of digital radio frequency signals having a respective associated radio frequency digital clock, the plurality of digital radio frequency signals having a sufficiently high respective associated clock rate to preserve an information content of an information communication present in the analog radio frequency representation; a switch matrix adapted to concurrently switch the plurality of digital radio frequency signals and associated digital radio frequency clock to ones of a plurality of digital signal processors; and a control adapted to selectively automatically control the concurrent switching of a plurality of digital signals and associated digital clock to the respective plurality of digital signal processors; wherein the digital signal processors

Abstract: A fluid control assembly is connected between a cold gas container intended to be operated at deep cryogenic temperatures (e.g., 4K) and a gas reservoir for controlling the flow of fluid between the container and the reservoir. The fluid control assembly may be a passive valve assembly or an electrically controlled valve assembly which controls fluid flow between the reservoir and the container as a function of temperature and/or pressure differentials. The fluid control assembly enables the container to be rapidly cooled by restricting the amount of fluid flow from the reservoir into the container when the container is subjected to thermal cycling within a limited temperature range (e.g., 4K to 11K). The fluid control assembly together with the gas reservoir and the container form a thermal damper which is suited for use in a cryocooling system for producing the cryogenic temperatures (e.g., 4K) to operate superconducting devices which may need to be thermally cycled to remove trapped flux.