Abstract: A phase shifter network which alternates between structurally dual networks is provided. In particular, the phase shifter has a topography which permits the network to be configured as alternatively T or .pi. networks of low pass and high pass delay circuits in accordance with states of a single control signal fed to the phase shifter.

Abstract: A connector for RF packages which provides both RF and DC signals to the package. The connector comprises a silicone block with an embedded RF jumper which connects an RF conductor on the package to an RF feed line. The block also has numerous conductive strips passing through it. These conductive strips connect DC feed lines to DC input pads on the package. The connector is compressed by means of a cover, deforming the elastomer block. The block serves to envornmentally seal the RF and DC inputs from the environmental effects.

Abstract: A BPSK (Binary-Phase-Shift-Keying) modulator having reduced amplitude and phase errors includes two non-ideal N.degree.-bit phase shifters disposed between two 3 dB quadrature couplers to perform out-of-phase combining. When the two phase bits are alternately switched between a reference state and a signal state being N.degree. out of phase with respect to the reference by the cancellation, a 180.degree. binary phase shift keying modulator having reduced amplitude and phase errors relative to the individual phase shifters is provided.

Abstract: A precision voltage reference device having a forward biased and reverse biased silicon junctions arranged as a concentric circular annular monolithic structure is described. Selective hardening of the forward biased junction is provided to adjust carrier lifetime in said junction thereby providing a radiation hardened device. The selective hardening is provided by implanting non-dopant species to induce a predetermined amount of lattice damage at the forward biased junction. This arrangement permits both the forward biased junction and the reverse biased junction to be fabricated on a common substrate.

Abstract: The method of bending relatively thin wall tubing to form a tubular heat exchanger that has relatively tight bends with controlled wrinkles. For example, 1.75-inch outer diameter stainless steel tube may have a wall thickness of 0.035 inches and be bent using a controlled-wrinkle bend die to a 180.degree. bend having a centerline radius of 2.5 inches.

Abstract: A plurality of microwave semiconductor devices is provided by plating a thin heat sink layer on a surface of a wafer of semiconductor material, masking selected portions of the heat sink layer, and plating unmasked portions of the heat sink layer to form a support layer. Substantial portions of the semiconductor material are removed to form a plurality of mesa shaped diodes, at least one semiconductor mesa shaped diode being formed in each region of the semiconductor material disposed on the masked portions of the heat sink layer. Thus each mesa shaped diode, or sets of mesa shaped diodes, has formed on one surface thereof a thin heat sink layer while the mesa shaped diodes are supported by the support layer for subsequent processing. Upper electrodes for the diodes are formed interconnecting the mesa shaped diodes. The individual diodes, or sets thereof, are then separated from the support structure to provide individual single diode, or multiple diode devices.

Abstract: A timing delay circuit includes a first transistor having a control electrode coupled to an input terminal, a reference electrode coupled to a first DC bias terminal and an output electrode coupled to an output terminal of the timing delay circuit. The timing delay circuit further includes a second transistor having a control electrode coupled to the input terminal, a reference electrode coupled to a second DC bias terminal and an output electrode. The timing delay circuit further includes a third transistor having a control electrode coupled to the output electrode of the second transistor, a reference electrode coupled to the second DC bias terminal and an output electrode coupled to the output terminal of the timing delay circuit.

Abstract: A cylindrical multi-port combiner having a graceful degradation characteristic with a high degree of isolation (25 db) between ports and a high combining efficiency (>90.degree.) is disclosed. A radially-spaced inner and outer conductor forms a transmission line operating in a balanced mode. Circumferentially spaced plurality of like transmission lines have inner and outer RF absorbers at the outermost regions of the spaced adjacent inner and outer conductors, respectively. A corresponding end of each transmission line in adapted to be connected to one of a corresponding number of phase-matched RF sources. The other end of each transmission line has its inner and outer conductors connected in parallel, respectively, through stepped impedance-transforming transmission lines to form one connector for connection to an output RF load.

Abstract: A method of patterning a photoresist layer to provide an aperture having retrograde sidewalls is described. Illumination may be through a conical prism arrangement or a conical reflecting mirror and cylindrical mirror arrangement. The method includes the step of directing energy towards a mask which selectively exposes portions of a photoresist layer disposed on the substrate. The energy is directed to the mask at an oblique angle with respect to the normal to the surface of the substrate. The underlying photoresist layer is obliquely sensitized by the obliquely directed illumination. The portions of the layer which are obliquely sensitized are removed leaving behind an aperture having retrograde sidewalls. The retrograde sidewalls are a preferred photoresist profile for easy and reliable lift-off of deposited material from the semiconductor substrate.

Abstract: An electrical jack plug includes an insulating sleeve member disposed over the conductor and ground contact portions of a tip contact member. The sleeve member includes a thin conductive outer sleeve member and an insulating plastic inner sleeve member press fit inside the outer sleeve member. The inner sleeve member has a portion, disposed on the interior thereof, adapted to mate with a complimentary portion of a tip contact member. In assembly, the conductor and ground contacting portions of the tip contact member are surrounded by the insulating inner sleeve member to prevent shorting of such connections. The insulating inner sleeve member has an annular portion extending beyond the conductive outer sleeve member. The inner sleeve member may be comprised of colored plastic to provide a readily visible color coding scheme for interconnections provided by the electrical jack plug.

Abstract: A high electron mobility transistor includes a pair of charge screen layers disposed over a first one of active and charge donor layers of the high electron mobility transistor. The pair of screen layers are patterned to provide a double recessed channel. A first charge screen layer disposed adjacent to the charge donor layer is etched to provide a recess having a first length between source and drain electrodes, whereas a second charge screen layer disposed over the first aforementioned charge screen layer, as well as, a portion of the aforementioned first charge screen layer are etched to provide a second, substantially longer length between source and drain electrodes. The gate electrode is provided in the first aforementioned recess in Schottky barrier contact with the charge donor layer.

Abstract: A subscriber line interface circuit that provides regulated current to telephone subscribers in an improved manner reducing the amount of power required to operate while maintaining a constant current source. The current to the telephone subscribers flows through a switching transistor, an inductive storage element, sensing resistors and a transformer. The desired operating characteristic is obtained by cycling the switching transistor. The switching transistor is cycled on at a preset interval causing the telephone subscriber current to flow from the switching transistor. The switching transistor is cycled off in response to an increase in the telephone subscriber current as sensed by the sensing resistors thereby causing the current to flow from the inductive storage element.

Abstract: A water filter system for use in refrigerators having water dispenser and/or icemaker features. The filter system includes a commercially available filter cartridge which removes common water contaminants. A shut off valve temporarily stops the flow of water to the filter to permit replacement of the cartridge. The filter is disposed within the refrigerator for easy access and may be further disposed in a recess in one of the refrigerator walls or the refrigerator door to avoid reducing the useable food storage volume. The shut off valve may be closed by activating a conveniently located switch, by opening the refrigerator door, by opening a cover over the recess, or alternatively may be normally closed and opened only in response to activation of the icemaker or water dispenser features.

Abstract: Surface compression layers are provided over aluminum oxynitride by coating a base of said material with a glass frit having a thermal expansion coefficient lower than that of the material, and firing the frit to glass the glass frit after firing the base and coating are allowed to cool thus placing the coating in compression.

Abstract: Apparatus for simulating a complex system includes controller means having a sequence of instructions executed by the controller means for providing digital signals representative of a selected state and location of at least one of a plurality of indicators devices, in accordance with a software model of a system being simulated, and for receiving digital signals representative of an occurence and value of rotational motion, for receiving digital signals corresponding to an occurence of making and breaking of a signal path, and for processing said receive signals in accordance with a predetermined sequence of instructions corresponding to the model of the system simulated by the apparatus. The apparatus further includes a mock-up of the system being simulated, including a control panel corresponding substantially to the actual system having disposed thereon switches, indicator lights, and rotational motion devices, such as joy sticks, potentiometers, track balls, and the like.

Abstract: A low cost simulator for training electronic warfare operators to recognize signatures of various emitters. The simulator consists of a card which can be plugged into an IBM PC or compatible computer. Through the computer, various characteristics of one, or a plurality of emitters are entered. The simulator, using an existing digital signal processing (DSP) chip generates a replica of a signal received by a radar system receiver from one, or a plurality of emitters.

Abstract: A sensitivity velocity control program in a surveillance radar for distinguishing wanted moving targets from unwanted moving targets by processing radar target return data and having prestored evaluation criteria for accepting/rejecting the moving targets. The radar target return signals are processed to determine their true radial velocity and apparent radar cross section. The program evaluates these measurements based on a look-up table of preselected acceptable levels of minimum true radial velocity for each apparent radar cross section. The program declares a target acceptable when its radial velocity matches or exceeds the preselected minimum radial velocity for that radar cross section stored in a computer memory. The acceptance criteria relates to the type of target (aircraft, missile, bird, etc.) being accepted or rejected. In general, the criteria accepts large targets having low to high radial velocities.

Abstract: A telephone interface circuit for use in a digital loop carrier system. A transformer for coupling analog information and a switch responsive to a hook condition signal is provided. The hook condition signal provides an indication of the "on/off hook" condition of a corresponding telephone subscriber. The switch provides a closed circuit condition to "sink" a DC current when the corresponding telephone subscriber is "off hook" and an open circuit condition when the corresponding subscriber is "on hook". The telephone interface circuit further includes a capacitor serially coupled with the primary winding of the transformer, to prevent DC current from passing through the primary winding of the transformer. A combination telephone interface circuit that can be adapted for use as a remote terminal interface circuit or as a central office terminal interface circuit is also included. The combination interface circuit includes first and second circuit paths disposed in parallel with each other.

Abstract: A frequency multiplier is shown to include either a frequency doubler or a frequency tripler coupled to an amplifier with a temperature compensation circuit and a feed forward gain control loop. With such an arrangement, a frequency multiplier is provided wherein variations of an output signal of the frequency multiplier are minimized due to changing characteristics of the frequency multiplier caused by ambient temperature variation or from a varying input signal level.