Abstract: Silicon carbide wafers are prepared for semiconductor epitaxial growth by first lapping a silicon carbide wafer derived from a boule, by placing the wafer in a recess of a metal backed template and moving the wafer over and against a rotating plate. Two different diamond slurry mixtures of progressively smaller diamond grit sizes are sequentially used, along with a lubricant, for a predetermined period of time. The lapping operation is followed by a polishing operation which sequentially utilizes two different diamond slurry mixtures of progressively smaller diamond grit sizes, along with three different apertured pads sequentially applied to a rotatable plate, with the pads being of progressively softer composition. In a preferred embodiment the wafers are cleaned and the templates are changed after each new diamond slurry mixture used.

Abstract: A packaging for high-power devices such as Insulated Gate Bipolar Transistors includes a direct bonded copper substrate (DBC), such as beryllium oxide (BeO), soldered directly to a heat generating surface of the high-power device. The direct bonded copper substrate (DBC) is, in turn, soldered directly to a liquid cooled heatsink (HS). The packaging improves the thermal management of the heat generated by the high-power device, and is applicable for use in a switching circuit for a 3-phase electric traction motor (M). The assembly also provides for improved wirebonding design in order to use each high-power device to its fullest.

Abstract: A coil extension of the RF coupling coil, surrounding an electrodeless light bulb containing an inert gas and selected chemical elements, generates a voltage at the distal end thereof which is higher than that which appears across the RF coupling coil proper, and wherein the high voltage from the distal end of the coil extension is returned to the light bulb through a point contact electrode located in relatively close proximity to the low voltage end of the RF coupling coil.

Abstract: A method and apparatus for exciting an electrodeless light bulb containing material including an inert gas and one or more chemical elements which generate a light emitting torus of plasma when excited by an RF signal and which includes two separate excitation coils oriented about the bulb so that the planes of each of the coils are mutually oriented 90.degree. with respect to each other, and wherein each of the coils are driven by respective RF excitation voltages having mutually different frequencies, for example, a difference of 4%, so as to excite the material enclosed within the bulb and cause a stirring action of the fill and effect a pulsating emission of light and rotation of the torus similar to that produced by physical rotation of the bulb itself.

Abstract: A microwave power transistor device (20) is formed with impedance matching circuitry from a single elongated transistor die (70). Each of one or more transistor elements (56) is integrally formed with a blocking DC capacitor (54) on a common substrate of the transistor die. A wire (60 or 92) is connected between accurately positioned capacitor and transistor base connection points (90 and 80) to provide matching inductance for the parasitic base-collector capacitance of the transistor.

Abstract: A method and apparatus for accomplishing a 90.degree. relative phase shift employing a high characteristic impedance outer leg of length .lambda./2 and a low characteristic impedance through leg of length .lambda./4. The high characteristic impedance outer leg is directly connected to the input and the output. The low characteristic impedance through leg is connected to the input and output with first and second diode paths. When the first and second diode paths are in the on state, the low characteristic impedance through leg receives a majority of the input power. Because of the impedance disparity between the high characteristic impedance outer leg and low characteristic impedance through leg, only a small amount of power is routed through the high characteristic impedance outer leg when the first and second diode paths are in the on state and the combined signal phase is not substantially effected.

Abstract: An apparatus and method for discriminating between false images created by multipath and an aircraft of interest in an air traffic control environment by maintaining a three-dimensional database in the area of interest of the air traffic control environment, the three-dimensional database including a position of a radar radiation source, three-dimensional positions, orientations, and sizes of fixed reflectors and three-dimensional positions, orientations, and sizes of non-fixed reflectors; receiving return radar radiation from an unknown object; classifying the unknown object as an aircraft of interest if the return radiation from the unknown object correlates with previous returns; and classifying the unknown object by searching for a plurality of candidate reflectors and if a sum of the distances between the plurality of candidate reflectors is approximately equal to a distance between the unknown object and the radar radiation source, classifying the unknown object as a false image created by multipath.

Abstract: The present invention provides for a low power receiver protector and stepped attenuator for conditioning a received input signal within a microwave receiver front end. The low power receiver protector includes a detector for generating a surge signal in response to the received input signal exceeding a predetermined threshold, a delay line for delaying the received input signal for fixed duration, and a limiter for reducing the voltage of the received input signal in response to the generation of the surge signal. The stepped attenuator includes a plurality of cells each having an attenuation transmission path which includes an attenuator for providing a predetermined amount of attenuation of the received input signal. Each attenuation transmission path, bypass transmission path and delay line comprise a high temperature superconductor to provide minimal loss and reduced size.

Abstract: A method of fabricating ferrite toroids used in ferrite phase shifters. The method employs fabrication techniques found in low temperature cofired ceramics (LTCC) tape technology and involves fabricating long rectangular through-holes, as is required by the toroid design, in layers of green ceramic tape and maintaining the integrity of the through-holes during a firing process wherein ferromagnetic ceramic oxide in the tape is converted to ferrite.

Abstract: A method of growing 4-H polytype silicon carbide crystals in a physical vapor transport system where the surface temperature of the crystal is maintained at less than about 2160.degree. C. and the pressure inside the PVT system is decreased to compensate for the lower growth temperature.

Abstract: A micro-machined vacuum pump is provided which may be utilized with microsensors. The pump in accordance with the present invention is preferably fabricated within a semiconductor substrate and utilizes thermal transpiration to provide compression. The pump has a plurality of flow chambers and a plurality of flow tubes to interconnect the flow chambers. The pump additionally includes means for creating a temperature differential between a first end and a second end of each flow tube to draw the gas therethrough. Drawing the gas through the flow tube increases the pressure within an adjacent flow chamber and induces a pumping action.

Abstract: A common transmit module of a programmable digital radio has a digital submodule which receives a bit stream and produces a modulated IF signal, and an analog submodule which receives the modulated IF signal and converts the modulated IF signal to a frequency corresponding to a specific type of radio function. The digital submodule includes (a) a sequential/parallel instruction set processor for signal processing and control, (b) a reconfigurable format unit, and (c) a modulator which receives the output signals of the reconfigurable format unit and produces the modulated oscillation signal.

Abstract: A digital submodule is included in a software programmable common receive module for receiving IF signals and producing a serial bit stream. The digital submodule is programmable based on a selected application of a plurality of radio applications and, if present, a selected function of a plurality of functions of the selected radio application. The digital submodule may include an analog to digital converter for converting IF signals received from an analog submodule into digital signals. The digital signals are supplied to a programmable signal processing unit which is configured, according to the selected radio application and, if present, the selected function, to perform control functions, processing and analysis of the digital signals and generate output signals. The output signals are then formatted by a formatting unit producing formatted digital signals. The formatted digital signals are then supplied to a system bus.

Abstract: A cavity pattern for a laminated structure such as a substrate for integrated circuitry is formed in a sheet of unfired low temperature cofired ceramic (LTCC) material also known as "green" tape. One sheet at a time is placed in a flexible ram forming die including a resilient rubber pressure pad and a template including the pattern to be formed in the sheet. A pair of outer pressure plates hold the pressure pad and template in place. When a sheet of unfired LTCC material is placed between the pressure pad and template and pressurization is applied to the outer plates, extrusion of the rubber material through the template causes the tape to be sheared off at the edges of the holes in the template, thus effectively cutting the required pattern in the sheet. Following pressurization, the sheet now with the pattern cut therein is removed from the die and the residual tape cut-outs are subsequently removed from the template by a vacuum.

Abstract: A radar electronic scan apparatus 10 employs an array of transmit/receive phase-shift modules 14 with a plurality of ferrite phase-shift subarrays 16. Each ferrite phase-shift subarray has a pair of phase-shift ferrite substrates 32A and 32B mounted on a support with each substrate having four phase taps for connection to radiators of the electronic scan apparatus.

Abstract: A top-via etch technique for forming dielectric membranes for thin film devices, the dielectric membrane being deposited on the upper planar surface of the substrate. After the thin film device is formed on the dielectric membrane, a photoresist etch mask is deposited on the entire upper planar surface of the substrate, including the thin film structure. Vias are formed through the dielectric membrane and the protective photoresist etch mask to expose the upper planar surface of the substrate along opposite first and second ends of the thin film device. The upper planar surface of the substrate is isotropically etched using a reactive ion etching technique for example, to form air gaps beneath the dielectric membrane. The etching process may be carried out in etch segments of predetermined intervals, each followed by a cool down period of a prescribed interval.

Abstract: A method and apparatus for generating a low phase noise RF signal where the output from a low phase-noise stabilized local oscillator operating at relatively high frequencies in the GHz range is combined in a power combiner with a digital data stream generated by a digital waveform generator and which is representative of one or more analog signals in a predetermined frequency spectrum of relatively lower RF frequencies in the MHz range. The combined signal is applied to a Josephson junction array whose output consists of a data stream including pulses of precise constant amplitude and which is then fed to a bandpass filter circuit having a predetermined bandpass. The filter extracts the lower frequency analog signal but now consisting of a signal having low phase-noise.

Abstract: A die attach procedure for SiC uses the scrubbing technique to bond a SiC die to a package. A first layer is formed on the SiC die. This first layer, preferably of nickel, bonds to the SiC die. A second layer, preferably amorphous silicon, is then formed on the first layer. The second layer bonds to the first layer, and forms a eutectic with the material, usually gold, plating the package when the SiC die is scrubbed onto the package.

Abstract: An electrodeless light bulb assembly having a standard light bulb base located at one end of an extruded cylindrical heat sink including a set of elongated fins extending radially outward from an annular inner body portion. An electrodeless light bulb, excitation coil, and transparent cover for the bulb are located at the other end of the heat sink. A solid state electrodeless lamp driver circuit is thermally coupled to the heat sink and is located in a hollow inner space region formed by the inner body portion. The annular inner body portion also includes at least one but preferably a plurality of boiler/condenser heat pipes located around its periphery for thermally coupling the heat from excitation coil and the driver to the fins where heat is transferred to the air via natural convection. The excitation coil can be formed from a length of conventional electrical conductor or it can be formed from a length of heat pipe connected at one end to the driver and at the other end to the heat sink.

Abstract: The microwave field intensity of a cell type atomic clock is stabilized through time division feedback control of the power of the microwave signal implemented by a microcontroller. The depth of the microwave dip is calculated from differences in measurements of the optical signal when the microwave signal is dithered around the atomic transition frequency of the active medium, and measurements taken when the optical signal is dithered around the optical wavelength of the active medium while the microwave signal is adjusted to produce no microwave absorption, either by reducing the microwave power to zero or by detuning it from the atomic transition frequency of the active medium. RF synthesizers suitable for regulating microwave power include a synthesizer using a step recovery diode for frequency multiplication and having the power to a driver amplifier or the bias applied to the diode regulated. A digital synthesizer can also be used to generate a regulated microwave signal.