Abstract: One aspect of the invention is directed to on-chip high-frequency, low-jitter clock circuits including long Josephson junction (LJJ) oscillators usable as clock sources. LJJ oscillators embodying the invention may be formed using either “linear” or “annular” long Josephson junctions. This invention enables the generation and distribution of a stable high-frequency on-chip single flux quantum (SFQ) clock. The on-chip clock circuit may include a clock selector circuit and a clock distribution scheme and may be integrated with RSFQ circuits and/or with a wideband analog-to-digital converter (ADC) comparator. The invention also includes a new fluxon “sender” circuit suitable for synchronizing the LJJ oscillator with another oscillator, either on-chip or external to the chip. The new sender circuit may also enable the realization of a novel phase-locked loop (PLL) circuit.

Abstract: A magnetic flux-enhanced control line for a superconducting flux flow transistor (SFFT). The SFFT includes a pair of superconducting electrodes which provide a voltage output, a region of weakened superconductor connecting the electrodes and a control line. The region of weakened superconductor carries a current I.sub.body and the control line carries a current I.sub.Control. The control line further has a portion thereof proximate the weakened region for providing a localized magnetic field through the weakened region as a function of I.sub.Control. The magnetic flux through the weakened region induces vortices therein which have a resistance r.sub.o. The proximate portion of the control line forms a tortuous current path whereby the magnetic flux through the weakened region is increased for increasing r.sub.o so that the output voltage of the transistor is increased without increasing I.sub.Control.

Abstract: The present invention relates to a superconductive electromagnetic wave mixer comprising a local-oscillator section and a receiving section, said receiving section serving as a section at which an electromagnetic wave from the local-oscillator section and an externally originating electromagnetic wave are combined. The local-oscillator section and said receiving section are each formed by at least one Josephson junction employing at least one oxide superconductor.

Abstract: A low-noise oscillator includes a resonator constituted by a coil, a capacitor and a sustaining coil which are made of superconductivity material and maintained at a low temperature below the critical temperature; a linear amplifier which always operates in its linear zone; and a load.The amplitude of oscillation is stabilized when it has attained a threshold value such that the superconducting material constituting the coil of the resonator becomes progressively resistive under the action of the magnetic field produced by this coil. The coil then dissipates part of the energy injected into the resonator. Since the high-frequency noise of the oscillator is essentially determined by the low-frequency noise of its nonlinear element, the use of superconducting material at low temperature in order to constitute the nonlinear element makes it possible to obtain an oscillator having very low noise.

Abstract: Microwave oscillators and amplifiers which utilize a superconducting slow-wave circuit. The slow circuit is made from materials which exhibit superconductivity at relatively high critical temperatures. The slow wave circuit is integral with the device's vacuum housing. Coolant exterior to the vacuum housing maintains the circuit in the superconducting state. The slow-wave circuit, which protrudes into the vacuum housing provides modulation of an electron beam which traverses the interior of the vacuum housing. Output power is ultimately extracted from the slow wave circuit.