Abstract: The crystallographic plane-dependent, amphoteric nature of Si-doped AlGaAs is used to provide a low threshold semiconductor laser. An active layer of AlGaAs is sandwiched between an injection layer and a current confining layer of AlGaAs. The injection layer is doped to be n-type conductivity. The confining layer is amphoterically doped with Si to be n-type in a (100) plane and p-type in a (111)A plane. The resulting p-n junctions, heterostructure, and geometry provide the current and the optical confinement for the semiconductor laser.

Abstract: This invention relates to a space vehicle 10 in which solar radiation is utilized to generate thrust by virtue of a solar thermal propulsion unit 12. The propulsion unit comprises basically reaction engines 14 including a DeLaval nozzle 22, heating chamber 26, solar window 28 and inflatable paraboloid solar collector 34.

Abstract: A wide band, feedforward, power amplifier circuit has greater stability when quadrature hybrid devices are used to match the output impedance of the power amplifier with the load.

Abstract: An AC to DC converter that utilizes a split capacitor, half bridge, DC to DC converter compensates for unequal voltages across each member of a split capacitor bank. A voltage balance control circuit senses any differences in voltages across the member capacitors and generates an error correcting signal for modifying steering signals to an inverter that is used to convert a DC signal from the half bridge DC to DC converter to a high frequency pulse width modulated AC signal by alternately placing each member of the split capacitor bank and consequently their stored energy across the output terminals of the inverter. The error signal causes the steering signals to connect the member capacitor with the larger sensed voltage across the output terminals for a relatively larger period of time than the capacitor with the lesser sensed voltage.

Abstract: A feedback network for a linear amplifier provides for sampling the input signal and removing the modulation from the input signal while maintaining a 180.degree. phase relationship with the input which is essentially the process of converting it into a square wave. The output signal is also sampled and the envelope separated from the sampled output signal and used to drive a modulator which modulates the square wave. This modulated square wave is then mixed with the input signal prior to amplification. In addition, automatic gain control is provided by a level comparator that compares the output signal with the input signal and the results of the comparison is used to attenuate or to control the level of the modulated square wave.

Abstract: A magnetic field sensor is illustrated which in one useful application comprised two orthogonally positioned coils each having its own electronics and each wound on separate small strips of core material and positioned in a gimballed fixture for use as an electronic compass. The sensing coils in each sensor sense only the components of magnetic field in that plane with one output being representative of the field along the axis of one of the coils and the other being representative of the field along the axis of the other coil. A secondary winding cooperating with each of these coils provides an output signal which is operated upon to remove any DC components and provide a signal indicative in waveshape of the flux in the core. Opposite polarity peak detectors are then used to determine the relative peak voltages with respect to ground for the purpose of determining the DC component which had been removed. The DC component is indicative of any external fields affecting the flux levels in the core material.

Abstract: The invention is directed to continuous (gapless) propagation structures for use with magnetic bubble domain devices. The gapless structures are arranged so that magnetic bubbles will propagate therealong without a significant change in size or diameter of the bubble. In addition, the structures are configured so that the bubbles will propagate in a preferred direction without ambiguity.