Patents Assigned to AT&T Bell Labs
  • Patent number: 4901121
    Abstract: A method for producing, without etching, a perforated layer of epitaxial metal silicide, especially CoSi.sub.2, on a single crystal Si substrate, with epitaxial Si overlying the silicide layer. The layer thickness, and the number and size of the openings in the layer are such as to make the structure suitable as an electronic device, in particular, as a permeable base transistor. The number and/or size of the openings is a function of processing parameters such as the substrate orientation, the annealing temperature of the film, or the Co/Si ratio of the deposited material. A device comprising a perforated silicide layer is also disclosed.
    Type: Grant
    Filed: April 18, 1988
    Date of Patent: February 13, 1990
    Assignee: American Telephone & Telegraph Co., AT&T Bell Labs.
    Inventors: John M. Gibson, John C. Hensel, Anthony F. Levi, Raymond T. Tung
  • Patent number: 4879519
    Abstract: A distortion compensation circuit for power amplifier producing a prescribed distortion component receives an input signal having at least one carrier therein in a prescribed frequency range. The input signal is applied to a first circuit path having an amplifier that produces an amplified signal with the prescribed distortion component and to a second circuit path that delays the input signal without distortion. The output signals of the first and second circuit paths are combined in a first combiner to form a signal representative of the prescribed distortion component. A second combiner forms a signal having an amplified input signal component and inverted phase prescribed distortion component responsive to the output of the first combiner and the output the first circuit path.
    Type: Grant
    Filed: October 31, 1988
    Date of Patent: November 7, 1989
    Assignee: American Telephone and Telegraph Company, AT&T Bell Labs
    Inventor: Robert E. Myer
  • Patent number: 4810325
    Abstract: Epitaxial layers are grown from a body of molten material which includes flux and layer constituent components; included in the flux are lead oxide and a small amount of boron trioxide. As compared with prior-art processing in the absence of boron trioxide, enhanced yield is realized as believed to be due to reduced adhesion of solidifying material entrained upon withdrawal of a substrate after growth. The method is particularly useful in the manufacture of magnetic domain devices designed to operate at extreme temperatures, as well as in the manufacture of magneto-optic devices such as, e.g., switches, modulators, and isolators.
    Type: Grant
    Filed: June 15, 1987
    Date of Patent: March 7, 1989
    Assignee: American Telephone and Telegraph Company, AT&T Bell Labs
    Inventor: Steven J. Licht
  • Patent number: 4803540
    Abstract: A lead frame for mounting a semiconductor chip in an integrated circuit package incorporates a deformation absorbing member as an integral part of the paddle support arm so that the initial, desired physical and electrical characteristics are unaltered after a forming operation such as paddle downsetting.
    Type: Grant
    Filed: November 24, 1986
    Date of Patent: February 7, 1989
    Assignee: American Telephone and Telegraph Co., AT&T Bell Labs
    Inventors: Harold W. Moyer, Harry R. Scholz
  • Patent number: 4797386
    Abstract: Separation between a magnetized member and a Type II superconducting member inherently manifestets stability in separation distance, in lateral direction and in attitude. Uses include levitation of fixed and moveable members as well as superconducting bearings.
    Type: Grant
    Filed: April 22, 1987
    Date of Patent: January 10, 1989
    Assignee: American Telephone and Telegraph Company, AT&T Bell Labs
    Inventors: Ernst M. Gyorgy, Frances Hellman, David W. Johnson, Jr.
  • Patent number: 4791628
    Abstract: A demultiplexer for demultiplexing a multiplexed input data signal into M output channels using M sequencer means clocked from an overlapping M phase system clock. The system clock operates at a frequency equal to the input data signal rate divided by M. Each sequencer means is clocked by a unique combination of the M phase system clock signals to select one data channel from the multiplexed input data signal. Since all sequencer means circuits are synchronized to the system clock, no variable delay lines are needed to align the timing between the circuit stages. A time delay latch is provided where needed in each sequencer means to enable all channels to output data concurrently. The demultiplexer includes a real-time data-framing capability to assure that the input data is correctly mapped to the proper output channels.
    Type: Grant
    Filed: October 16, 1987
    Date of Patent: December 13, 1988
    Assignee: American Telephone and Telegraph Company, AT&T Bell Labs
    Inventor: Robert G. Swartz
  • Patent number: 4787698
    Abstract: A biconic connector (40) includes two plugs (44-44) each of which terminates a single fiber optical cable (55) and each of which includes a truncated conically shaped end portion (50). The connector also includes an alignment sleeve having back-to-back conically shaped cavities each of which is adapted to receive an end portion of a plug. In order to minimize loss through the connection, it becomes important for the centroid of the cross-sectional area of a light beam in the end face of the plug to be coincident with the axis of revolution of the conically shaped surface of plug. This is accomplished by holding the plug in a fixture such that its end portion is exposed and the fixture adapted to be turned about an axis of rotation. Images of a light beam launched into the optical fiber are acquired in a plane through the end face of the plug.
    Type: Grant
    Filed: November 27, 1985
    Date of Patent: November 29, 1988
    Assignees: American Telephone and Telegraph Co., AT&T Bell Labs, AT&T Technologies, Inc.
    Inventors: Robert P. Lyons, John M. Palmquist, Susan S. Sachs, Ralph A. Treder, Jr., Thomas L. Williford, Jr.
  • Patent number: 4785345
    Abstract: An integrated transformer structure is disclosed. In one embodiment, the primary transformer winding is formed using dielectrically isolated (DI) technology so as to isolate high voltages applied to the transformer primary from other components in the substrate. Alternatively, conventional junction isolated technology may be used, where physical separation between the integrated transformer and other components may be provided. In accordance with the present invention, the primary winding comprises a planar spiral formed with a low-resistivity material and incorporated with the substrate. An insulating layer is then formed over the primary winding. A planar spiral configuration is also used to form the secondary winding, where the secondary may be formed of a deposited metal and is formed on top of the insulating layer so as to be directly above the primary winding. The result is an effective air-core transformer structure capable of isolating thousands of volts.
    Type: Grant
    Filed: May 8, 1986
    Date of Patent: November 15, 1988
    Assignee: American Telephone and Telegraph Co., AT&T Bell Labs.
    Inventors: Spencer A. Rawls, Luke J. Turgeon
  • Patent number: 4765706
    Abstract: Low-loss coupling between a local feed connection or node, and a multi-mode optical fiber bus is provided by reflective insertion of a relatively small number of modes into the bus fiber. Essentially all input power available at the node is thus inserted into the bus, while but a small portion of power is extracted from the bus.
    Type: Grant
    Filed: July 29, 1986
    Date of Patent: August 23, 1988
    Assignee: American Telephone and Telegraph Co., AT&T Bell Labs.
    Inventors: Enrique A. J. Marcatili, Thomas H. Wood
  • Patent number: 4719591
    Abstract: A network comprising analog amplifiers with a resistive interconnection matrix that connects each amplifier output to the input of all other amplifiers. The connections embodied in the matrix are achieved with conductances whose values are computed in accordance with the set of decomposition functions for which the solution is sought. In addition to the specified connectivity implemented. Further included is a second matrix that connects externally applied voltages to the amplifier inputs via resistors whose values are also computed in accordance with the set of decomposition functions for which the solution is sought. Still further and in accordance with another aspect of the invention, means are included for varying the amplifier gains from an initial low value to an ultimately high value in the process of arriving at a solution to an applied problem.
    Type: Grant
    Filed: November 7, 1985
    Date of Patent: January 12, 1988
    Assignees: American Telephone and Telegraph Company, AT&T Bell Labs., Calif. Institute of Technology
    Inventors: John J. Hopfield, David W. Tank
  • Patent number: 4712077
    Abstract: A phase-lock loop includes a tristate phase detector, a filter and a voltage-controlled oscillator connected in a loop for regenerating clock signals in response to a sequence of data signals applied to the input terminal of the tristate phase detector and the loop. The tristate phase detector opens its output lead whenever a zero is applied to the input terminal of the loop. A resistor is interposed between the tristate phase detector and the loop filter to clamp excursions of a control signal, causing the filter to produce a consistent tuning control signal and forcing the voltage-controlled oscillator to oscillate at a frequency within a preselected frequency range independent of the ones density in the digital sequence applied to the input terminal of the loop.
    Type: Grant
    Filed: December 22, 1986
    Date of Patent: December 8, 1987
    Assignee: American Telephone and Telegraph Company, AT&T Bell Labs
    Inventors: Henry G. Ansell, Jeffrey H. Saunders
  • Patent number: 4706240
    Abstract: A switching system having a control network for establishment of a path and a data switching network responsive to the path determined by the control network for switching data between a plurality of input ports to a plurality of output ports. The control network is a self-routing network that is fabricated utilizing electronic devices; whereas, the data switching network is fabricated using photonic devices. The electronic network is of the butterfly architecture and the photonic network is of the cross-bar architecture. A translation circuit is utilized to convert the path determined through the self-routing butterfly control network for use in determining the path through the photonic cross-bar network.
    Type: Grant
    Filed: November 29, 1985
    Date of Patent: November 10, 1987
    Assignee: American Telephone and Telegraph Co., AT&T Bell Labs
    Inventor: William A. Payne, III
  • Patent number: 4698804
    Abstract: A digital transmission system includes a plurality of stations sharing a common transmission line. Variable length messages, set off by flags, are exchanged between pairs of stations. While a message is being received, the downstream portion of the transmission line is segmented to permit simultaneous use by another station pair. If a message is received from an upstream station while a message is being transmitted downstream, an abort message flag terminates the transmitted message abruptly to permit flowthrough of the received message. When any station is not in use or out of order, it is bypassed to permit use of the transmission line by the rest of the stations.
    Type: Grant
    Filed: January 22, 1985
    Date of Patent: October 6, 1987
    Assignee: Telephone and Telegraph Company, AT&T Bell Labs
    Inventors: Christopher Flores, Bhaskarpillai Gopinath
  • Patent number: 4689125
    Abstract: A process is described for making semiconductor lasers with cleaved facets for end mirrors. The process involves electrochemically photoetching slots with deep, narrow cross-sections in a wafer and applying stress to cleave the wafer in the desired place. Extremely short and reproducible semiconductor lasers can be made by this procedure (less than 50 or even 25 .mu.m) which yields extremely useful semiconductor lasers particularly for communication applications. Also, the procedure requires a minimum of skill to produce excellent quality cleaved semiconductor lasers (including short-length lasers) with high yields.
    Type: Grant
    Filed: May 28, 1986
    Date of Patent: August 25, 1987
    Assignee: American Telephone & Telegraph Co., AT&T Bell Labs
    Inventors: Charles A. Burrus, Jr., Paul A. Kohl, Tien P. Lee, Frederick W. Ostermayer, Jr.
  • Patent number: 4688160
    Abstract: A single ended forward converter periodically resets the transformer core to prevent saturation and returns magnetizing energy to the energy source, requiring only the addition of one resonating capacitor to the converter circuit.The transformer is reset and the energy recovered into the input voltage source by resonant commutation of the magnetizing current between the magnetizing inductance and a resonating capacitor. A resonant current path is completed during a nonconducting interval of the power transistor switch through a resonating capacitor, shunting the output rectifying diode connected to the secondary winding, and the flyback diode of the output filter to permit transfer of the transformer's magnetizing energy to the input energy source. This magnetizing energy transfer from core to capacitor to input energy source has a resonant quasi-sine waveform and utilizes the resonant properties of the network to enable its flow back into the input voltage source.
    Type: Grant
    Filed: December 19, 1985
    Date of Patent: August 18, 1987
    Assignee: American Telephone and Telegraph Co., AT&T Bell Labs
    Inventor: Simon Fraidlin
  • Patent number: 4682284
    Abstract: A memory subcontroller (203) of a computer (100) includes a queue (301) for storing read and write requests issued by memory using units (101-103) to a memory (104), apparatus (303, 304) for executing requests on the memory, and a circuit (302) for administering the queue. When the queue is empty and the executing apparatus is ready to receive a request for execution, a request incoming from a using unit bypasses the queue: it is received by the executing apparatus directly and is not stored in the queue. Otherwise, the queue administration circuit stores the request in the queue and then awaits results of validity checks on the stored request. If the request is found to be invalid, generally the administration circuit discards the request from the queue by freeing the queue location (210) or locations that store the invalid request to store the next received request. The invalid request is then overwritten by the next received request.
    Type: Grant
    Filed: December 6, 1984
    Date of Patent: July 21, 1987
    Assignee: American Telephone & Telegraph Co., AT&T Bell Lab.
    Inventor: Eldred P. Schrofer
  • Patent number: 4680810
    Abstract: The novel technique for stabilizing an electronic device, e.g., a semiconductor laser, is disclosed. The technique can advantageously be used to stabilize the bias current of such a laser at or near the lasing threshold of the device. A preferred application of thus stabilized lasers is in optical communication systems. The inventive technique comprises determination of a derivative of a variable characteristic of the device operation, e.g., the voltage across a laser, with respect to a parameter, e.g., the laser bias current. The derivative is determined by a novel method. For the particular case of laser bias stabilization, the method comprises injecting one or more nonsinusoidal ac current components into the laser, and phase-sensitivity detecting the voltage changes at the ac frequencies. The method can, in principle, be used to determine derivatives of arbitrarily high order.
    Type: Grant
    Filed: June 28, 1985
    Date of Patent: July 14, 1987
    Assignee: American Telephone and Telegraph Company, AT&T Bell Labs
    Inventor: Robert G. Swartz
  • Patent number: 4672518
    Abstract: A switching converter in which current mode voltage regulation is implemented includes circuitry to add ramp compensation to the sensed current signal at light load and reduce or disable this ramp signal compensation at heavy load. This load dependent ramp signal improves the stability of operation of the converter and maintains its inherent current limit performance over a wide range of loading. An alternative connection allows for disabling the current sense signal and hence, transforming the current mode to voltage mode control under light load.
    Type: Grant
    Filed: July 30, 1986
    Date of Patent: June 9, 1987
    Assignee: American Telephone and Telegraph Co., AT&T Bell Labs
    Inventor: James H. Murdock
  • Patent number: 4668927
    Abstract: A multi-positional mercury switch (1, 2) for use with miniature relays. The mercury switch apparatus has mercury wettable magnetic contact structures (11, 12, 13, 21, 22) supported in a sealed envelope member (10, 20) supporting the magnetic contact structures with free ends thereof positioned to engage or disengage each other in response to a magnetic field generated by current appearing in a coil (410) externally surrounding the envelope member. A mercury wettable member (3, 15, 23, 24) having a porous construction for holding mercury is mounted on ones of the magnetic contact structures within the sealed envelope member for wetting the magnetic contact structures.
    Type: Grant
    Filed: March 6, 1986
    Date of Patent: May 26, 1987
    Assignee: American Telephone & Telegraph Co., AT&T Bell Labs
    Inventor: James E. Bennett
  • Patent number: RE32516
    Abstract: The loop switching system of this invention overcomes the problems of prior art loop switching systems by providing dynamic rearrangeability of loop switching systems. In particular, the subject loop switching system is comprised of a number of port circuits or nodes serially connected together to form one or more loops. The interconnection of these various ports into one or more loops is implemented on a dynamic basis by means of a central switching matrix.
    Type: Grant
    Filed: July 1, 1985
    Date of Patent: October 6, 1987
    Assignee: American Telephone & Telegraph Co., AT&T Bell Labs
    Inventor: Richard F. Cantwell, Jr.