Westinghouse Electric Corporation

Northrop Grumman Systems Corporation

United States of America as Represented by the Secretary of the Air Force

Kenneth J Petrosky

Robert Miles Young

Harry Buhay

Narsingh Bahadur Singh

Marvin H White

Andre E Berghmans

Brian Paul Wagner

David A Kahler

David J Knuteson

John A Ostop

Thomas J Knight

Ty Richard McNutt

Sean R McLaughlin

Prosenjit Rai-Choudhury

Jerry W Hedrick

George M Bates

James H Wilson

John A Costello

Paul A Potyraj

Richard R Papania

Billy F Brown

Gene A Madia

The disclosure relates to a high purity 2H-SiC composition and methods for making same. The embodiments represented herein apply to both thin film and bulk growth of 2H-SiC. According to one embodiment, the disclosure relates to doping an underlying substrate or support layer with one or more surfactants to nucleate and grow high purity 2H-SiC. In another embodiment, the disclosure relates to a method for preparing 2H-SiC compositions by nucleating 2H-SiC on another SiC polytype using one or more surfactants. The surfactants can include AlN, Te, Sb and similar compositions. These nucleate SiC into disc form which changes to hexagonal 2H-SiC material.

Method and apparatus for growing high purity 2H-silicon carbide

A Class C bipolar transistor amplifier including circuit means having a non-linear, high-current, low-knee voltage transfer characteristic in series with the emitter RF choke of a common base bipolar transistor, which increases the emitter bias voltage, and in turn forces the amplifier deeper into Class C operation during overdrive, effectively limiting the output power. In one embodiment, a low ohmic resistor and a MOSFET device are connected in series with the emitter RF choke of a common base bipolar transistor Class C amplifier. An active feedback control loop implemented with conventional operational amplifier (OP AMP) circuitry controls the MOSFET device so as to operate in the knee region of its current-voltage characteristic during power overdrive. In a second embodiment, a single non-linear circuit element such as a constant current diode having a high-current, low-knee voltage transfer characteristic is connected in series with the emitter RF choke. The constant current diode consists of a depletion mode MOSFET or JFET having the gate directly connected to the drain.

Power saturation control of class C bipolar amplifiers

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.

Microwave power transistor having matched impedance with integrated DC

A heat dissipating module and package for power microwave transistors and method of making same that includes a substrate having a thick copper layer bonded to a ceramic core which is thereto subjected to high processing temperatures.

Thick film copper metallization for microwave power transistor packages

A method for fabricating microwave power transistor elements onto a semiconductor body. An oxidizable barrier material is applied onto the wafer that both acts as a barrier to prevent diffusion between the contact metal of the transistor and the silicon and also acts as a ballast resistor. A contact metal layer is then deposited onto the barrier material at selected locations and the excess barrier material is removed. Barrier material is left between the contact metal and the silicon and at the selected ballast resistor locations. The ballast resistors may then be trimmed, increasing the value of the resistors, by oxidizing a thin surface layer of the exposed barrier material at the ballast resistor locations.

Method of making and trimming ballast resistors and barrier metal in

Apparatus which provides both range and bearing information between a transponder and a transponder interrogator. The interrogator transmits an acoustic interrogating pulse which is received by the transponder and in response thereto transmits back a first signal of a certain frequency f1. Two spaced apart hydrophones on the transponder provide their respective output signals to a phase meter, the output signal of which is indicative of the direction, that is, bearing, from which the interrogating pulse impinged. The phase meter output is converted to a corresponding time delay after which a second signal of a frequency f2 is transmitted. A counter in the interrogator starts counting upon transmission of the interrogating pulse and stops upon reception of the first signal of frequency f1. A second counter of the interrogator starts its count when the first counter turns off and terminates its count when the second signal f2 is received. The count in the first counter is converted to a corresponding range display and the count in the second counter is converted to a corresponding bearing display.

Apparatus for determining range and bearing

D.C. reconstruction of sampled CCD output signals is achieved by subtracting the output current pulses of two CCDs (or subtracting parallel outputs of the same CCD) with a differencing circuit containing two biasing current mirrors, a current sink device and an output capacitor. The two current mirrors are used with each biasing the output of a complementary CCD to positive and acting to mirror the CCD output current. A third current mirror converts the output of one of the CCDs into a current sink. An output capacitor performs subtracting by converting all outputs to voltage and combining the positive biased output of one CCD with the current said output of the second CCD.

Bi-directional current differencer for complementary charge coupled

Apparatus for forming one or more sonar beams in response to acoustic energy received by a transducer array. To minimize volume utilization, a plurality of CCD's are formed on an integrated circuit chip with the CCD's being of progressively smaller length. Half of the CCD array is folded over to match the other half so that each CCD has an opposing CCD with both CCD's propagating a signal toward a common output diode. By providing one integrated circuit chip for each desired beam with appropriately different clocking frequencies multiple beams may be formed, and with the provision of a variable clocking frequency, one or more beams may be steered. Transversal filter operations may also be performed by the apparatus.

CCD Signal processor

Magnetometer instrumentation which processes the signals from an array of magnetometer assemblies wherein the need for multiple sets of motor driven resistors to change the gain of the signal processing channels is eliminated by the provision of an arrangement which utilizes multiplying digital-to-analog converters that are directly commandable by digital signals.

Magnetometer instrumentation with digitally controlled range changing

An acoustic multi-tone code signal is transmitted through a water environment to a receiver unit which includes a multi-tone code decoder. If the signal-to-noise ratio of the input signal is above a certain threshold, only then will the coded signal be passed on to the decoder which will provide an output control signal in accordance with the particular code.

Growing community of inventors

Glen Burnie, MD, United States of America

Kenneth J Petrosky