Wisconsin Alumni Research Foundation

Honeywell G.m.b.h.

Alliant Techsystems Inc.

James B Beyer

Jon S Martens

Gert K Hohenwarter

James E Nordman

Vladimir Sokolov

Stanley E Swirhun

Steven Deibele

James B Summers

Joseph W Byrne

Robert L Cravens

Donald N Bosch

A superconducting active device has dual control inputs and is constructed such that the output of the device is effectively a linear mix of the two input signals. The device is formed of a film of superconducting material on a substrate and has two main conduction channels, each of which includes a weak link region. A first control line extends adjacent to the weak link region in the first channel and a second control line extends adjacent to the weak link region in the second channel. The current flowing from the first channel flows through an internal control line which is also adjacent to the weak link region of the second channel. The weak link regions comprise small links of superconductor, separated by voids, through which the current flows in each channel. Current passed through the control lines causes magnetic flux vortices which propagate across the weak link regions and control the resistance of these regions. The output of the device taken across the input to the main channels and the output of the second main channel and the internal control line will constitute essentially a linear mix of the two input signals imposed on the two control lines. The device is especially suited to microwave applications since it has very low input capacitance, and is well suited to being formed of high temperature superconducting materials since all of the structures may be formed coplanar with one another on a substrate.

Dual control active superconductive devices

A voltage controlled oscillator (VCO 10) is disclosed in a 'ring' configuration using two FETs. Two isolated voltage control terminals provide increased tuning bandwidth. The design uses an active feedback topology resulting in greater device size for higher output power and circuit Q.

Voltage controlled oscillator

A highly directive, broadband, bidirectional distributed amplifier has a series of FETs connected between input and output lines which have their effective transconductances scaled in accordance with binomial coefficients along the distributed amplifier to maximize the directivity of the amplifier. Directivities on the order of -25 to -35 dB are obtained over as much as an octave in frequency. The effective binomial scaling may be achieved by insertion of appropriately sized capacitors in the gate lines of each of the FETs. The minimization bandwidth may be shifted to lower frequencies by incorporating passive impedances between the active devices in both the gate and drain lines. These impedances preferably comprise T-section inserts composed of serially connected lumped inductors and a capacitance from the junction between the inductors to ground. The distributed amplifier is bidirectional so that it can be excited from either port on the gate line with high directivity exhibited at each respective port on the drain line.

Highly directive, broadband, bidirectional distributed amplifier

Active superconducting devices are formed of thin films of superconductor which include a main conduction channel which has an active weak link region. The weak link region is composed of an array of links of thin film superconductor spaced from one another by voids and selected in size and thickness such that magnetic flux can propagate across the weak link region when it is superconducting. Magnetic flux applied to the weak link region will propagate across the array of links causing localized loss of superconductivity in the links and changing the effective resistance across the links. The magnetic flux can be applied from a control line formed of a superconducting film deposited coplanar with the main conduction channel and weak link region on a substrate. The devices can be formed of any type to superconductor but are particularly well suited to the high temperature superconductors since the devices can be entirely formed from coplanar films with no overlying regions. The devices can be utilized for a variety of electrical components, including switching circuits, amplifiers, oscillators and modulators, and are well suited to microwave frequency applications.

Active superconducting devices formed of thin films

A distributed amplifier has a plurality of amplifying sections which are connected between input and output lines comprising artificial transmission line sections. Input line attenuation compens

Distributed amplifier with attenuation compensation

A monolithic microwave integrated circuit broadband mixer in which the distributed amplifier concept is used to develop a broadband mixer circuit.

Monolithic microwave integrated circuit broadband mixer

A parallel type modulator is disclosed which utilizes a pair of bi-phase modulators (10), each of which are capable of independent phase and amplitude modulation. In each bi-phase modulator, a carrier frequency signal is split by a power splitter (20) into two signals 180.degree. apart in phase which are passed through directional couplers (30 and 31) and a pair of PIN diodes (35 and 36) to a summing junction (37). A bias source circuit (42) delivers biasing current to the coupled outputs of the directional couplers (30, 31) and through the PIN diodes (35, 36) to the summing junction (37); this current is returned to ground through a bias return circuit (44) which conducts the DC or low frequency biasing signal but allows the carrier frequency output signal to be passed through to the output of each bi-phase modulator. Reduction of the bias current to one diode below null levels at which the intermediate signals cancel will cause a carrier frequency signal to appear at the summing junction which will be in phase with the signal passed through the other diode. A continuous variation of the bias current through one of the diodes at a level below the null current level will result in amplitude modulation of the output signal at the summing junction. The PIN diodes are always operated in their conducting regions so that large parasitic reactances at microwave frequencies are avoided. A parallel modulator can be formed of a pair of the bi-phase modulators provided with carrier frequency signals in quadrature, and with the outputs of each bi-phase modulator being summed to yield an output signal at the carrier frequency which can have an arbitrary phase angle and continuous modulation of amplitude.

Growing community of inventors

Madison, WI, United States of America

James B Beyer