Abstract: The present invention provides an electronic device having superior qualities. The electronic device includes an active region located over a substrate and an undoped layer located over the active region. The electronic device further includes a doped upper cladding layer located over the undoped layer, wherein a diffusion barrier region including aluminum is located between the undoped layer and the doped upper cladding layer. In an exemplary embodiment of the invention, the diffusion barrier region is a diffusion barrier layer or a number of diffusion barrier layers located between a plurality of the undoped layers.

Abstract: The present invention provides an optoelectronic device and a method of manufacture therefor, that prevents dopant diffusion and controls the dopant concentration therein. The optoelectronic device includes an active region formed over a substrate, and an interface barrier layer and barrier layer located over the active region. The optoelectronic device further includes an upper cladding layer located over the interface barrier layer and the barrier layer. In an exemplary embodiment of the invention, the interface barrier layer is an indium phosphide interface barrier layer and the barrier layer is an indium gallium arsenide phosphide barrier layer.

Abstract: The present invention provides an electronic device having superior qualities. The electronic device includes an active region located over a substrate and an undoped layer located over the active region, the undoped layer having a barrier region including aluminum located thereover. The electronic device further includes a doped upper cladding layer located over the barrier region. In an exemplary embodiment of the invention, the barrier region is a barrier layer or a number of barrier layers located between a plurality of the undoped layers.

Abstract: A source of an input supply voltage is coupled via a current limiting resistor to a load. A diode has a first terminal that is coupled to a junction terminal between the resistor and the load. A second terminal of the diode is coupled to an output of a regulated power supply where a regulated supply voltage is developed. The diode clamps a second output supply voltage developed at the first terminal of the diode to the regulated supply voltage. When the power in the load exceeds a predetermined value, the diode ceases conducting. In this way, the conductor that couples the second output supply voltage to the load need not meet the strict 15 watt node spacing requirements.

Abstract: A focus supply circuit, comprising: a power source for generating a high voltage for energizing a cathode ray tube, including a transformer having a high voltage winding with at least one intermediate output tap; and, a focus screen assembly, having a resistive chain with an input terminal coupled for receiving the high voltage, a focus output terminal for energizing a focus electrode of the cathode ray tube and at least one intermediate input tap between the input terminal and the focus output terminal, coupled to the at least one intermediate tap of the high voltage winding by an independent conduction path. An effective bias current for the cathode ray tube flows in the resistive chain. The voltages at the intermediate taps correspond to one another within a tolerance. The conductive path presents sufficiently low impedance to substantially inhibit variation of the high voltage due to variation of leakage current from the focus electrode.

Abstract: A screen grid voltage or a focus voltage for a cathode ray tube is controlled via a digital-to-analog converter. The voltage variation range of the screen grid or focus voltage that can be obtained for the entire variation range of an output signal of the digital-to-analog converter is not significantly larger than that required for the type of cathode ray tube that is utilized.

Abstract: In a horizontal deflection circuit output stage, a retrace pulse voltage is developed in a primary winding of a flyback transformer and transformer-coupled to a secondary winding and rectified for developing a high voltage. A portion of the transformer-coupled rectified voltage is combined in a voltage divider with a second rectified voltage. The second rectified voltage is produced in a peak rectifier from the retrace pulse voltage in the primary winding in a manner that bypasses the secondary winding. A screen grid voltage is developed at a terminal of the voltage divider. A change in beam current loading produces variations in opposite sense in the combined rectified voltages in a manner to regulate the screen grid voltage.

Abstract: A first resonant retrace circuit is operable for generating a first voltage signal and a second resonant retrace circuit coupled to the first resonant retrace circuit is operable for generating a second voltage signal summed with the first voltage signal. An auxiliary winding of a flyback transformer in the first resonant retrace circuit generates a first feedback pulse signal representative of the first voltage signal. A regulator senses the summed first and second voltage signals and generates a second feedback pulse signal representative of the summed first and second voltage signals. The second resonant retrace means is responsive to the regulator. A resistive summing junction combines the first and second feedback pulse signals to generate a composite feedback pulse signal. A voltage level is generated indicative of the energy in the composite feedback pulse signal.

Abstract: A method for semiconductor device fabrication that uses a mixture of SiCl.sub.4, CF.sub.4, O.sub.2, and He to selectively etch GaAs with respect to AlGaAs. Etch selectivities greater than 300:1 are obtained.

Abstract: An apparatus for cutting an article into sheets includes an upper jaw pivotally mounted to a lower jaw. The lower jaw includes three coplanar cutting edges, and the upper jaw includes three cutting edges which cooperate with those of the lower jaw. Longitudinal cutting edges of the upper jaw are curved along their lengths, and the end element of the upper jaw is slanted with respect to the end element of the lower jaw. The apparatus may be attached to existing mounting points of a backhoe.

Abstract: Retrace pulses are integrated by an R-C network to produce a ramp signal. The resistive member of the R-C network is bypassed by a diode to provide rapid retrace at the conclusion of the ramp portion of the integrated signal. A voltage divider at the output of the integrator adjusts the DC level of the ramp signal without affecting the constant of integration of the R-C network.

Abstract: A compensating coil for a scanning electron beam display, such as a color television tube, reduces undesirable deflection of the electron beams due to ambient magnetic fields, in particular the geomagnetic field. The coil has a winding disposed to encircle the tube neck, perpendicular to the Z axis. A degaussing coil is positioned on the tube envelope to provide for demagnetizing metal structures within the envelope. In order to provide more complete degaussing, the supply current to the compensating coil is interrupted during the degaussing operation. In order to prevent a charge from accumulating on the compensating coil, one terminal is coupled through a resistor to a source of reference potential.

Abstract: An accessory track apparatus have a track disposed at a peripheral region of a top plate supporting a piece of equipment such as a personal computer. One or more accessory holders are inserted into the track by way of an octagonal anchor plate on the holders, which anchor plate allows insertion and removal of the holders at corners of the track. A space or cavity between the top support plate and track allows for 360.degree. routing of electrical wiring of up to several feet in length.

Abstract: A voltage at a control grid of a cathode ray tube is generated at a blanking level to provide beam current blanking when horizontal deflection loss occurs. The control grid voltage at the blanking level is developed in a capacitor prior to an instant in which the horizontal deflection loss occurs. When the capacitor voltage is applied to the control grid to provide the blanking level, the capacitor is discharged slowly. To maintain the capacitor charged, prior to such instant when horizontal deflection is lost, the capacitor voltage is not applied to the control grid as long as the horizontal deflection is normal, regardless of whether vertical deflection loss occurs. Either horizontal deflection loss or vertical deflection loss will disable a video driver stage that controls the cathode of the cathode ray tube for providing additional beam current blanking capability.

Abstract: A parabolic voltage generating circuit includes an arrangement for generating a sawtooth vertical deflection current that flows in a vertical deflection winding, in a DC blocking capacitor and in a deflection current sampling resistor. An emitter electrode of a transistor is coupled between the deflection winding and the capacitor. A base electrode of the transistor is coupled between the capacitor and the resistance. A collector current of the transistor varies in a vertical rate parabolic manner and has a DC average value that is determined by a DC average value of a voltage that is developed in the capacitor. The collector current is applied to an East-West raster distortion correction circuit for modulating an amplitude of a horizontal deflection current.

Abstract: An SCR switch of a switch mode power supply is coupled between an unregulated supply voltage and a filter capacitor. A regulator oscillator generates trigger pulses for controlling a switching operation of the SCR switch of the power supply to produce an output supply voltage that energizes a deflection circuit. The regulator oscillator produces trigger pulses that are applied to the SCR switch during both power-up and power-off operation. A resistor coupled between the unregulated supply voltage and the filter capacitor maintains the filter capacitor charged during power-off operation to prevent the trigger pulses from causing the latching operation in the SCR switch throughout the power-off operation. In this way, an audible parasitic vibration sound is not being generated by the power supply during the power-off operation.

Abstract: A switch regulator includes a controllable SCR switch that is coupled in series with a filter inductor and a horizontal deflection generator, and the series combination is coupled across a source of unregulated direct voltage for providing a path for an increasing current flow in the inductor during a portion of a trace interval in which the switch is closed. Horizontal rate signals are coupled from the deflection generator to the switch via a first winding for controlling the opening of the switch. A catch diode is coupled to the filter inductor to form a path for a decreasing current flow in the first inductor during at least a portion of a retrace interval. The first winding is coupled in series with a second inductor to form an arrangement that is coupled between the unregulated voltage and the SCR switch. A current in the second inductor maintains the switch conductive during a portion of retrace that varies in accordance with a beam current for improving regulation of an ultor voltage.

Abstract: In a deflection circuit that operates in any scan frequency selected from a plurality of frequencies, the supply voltage that is DC-coupled to a first terminal of a trace capacitor is increased when the scan frequency increases. The deflection circuit includes a diode modulator that is controlled by a modulation voltage having an AC component voltage that varies at a vertical rate. The increase in the supply voltage causes an increase in a DC component voltage of the modulation voltage that is coupled to a second terminal of the trace capacitor such that the voltage in the trace capacitor increases in the same proportion as the supply voltage. The proportional increase in the trace capacitor voltage maintains the raster width unchanged when the scan frequency increases.

Abstract: A video display apparatus includes a regulated transformer power supply that provides power to an external load device, such as a computer, via one winding on the power supply transformer. Operation of the video display apparatus without the external circuit attached may cause degradation of the other transformer winding load circuits due to insufficient transformer power transfer as a result of decreased external power supply loading. A diode is connected from the external load supply to another load circuit to supply power to the other load circuit when the external device is not attached. When the external device is attached, the diode is reverse biased and does not conduct.

Abstract: Photoelectrochemical etching of gallium arsenide in highly alkaline aqueous solution yields optically smooth etched surfaces suitable for many optical devices. Higher optical quality is obtained for lower irradiation energy provided sufficient energy is available to produce holes in the valence band.