Showing papers by "Agilent Technologies published in 1990"

Quadrature measurement and calibration of a vector modulator

Abstract: Method and apparatus for calibration of a vector modulator of electrical communication signals that produces an output composed of the vector sum of two modulated signals that are phase shifted relative to one another. The two output component signals are first calibrated to produce zero quadrature angle error, then compensated for carrier leakage and balanced to provide equal output amplitudes for equal data input amplitudes. Iteration of these calibrations is not necessary. The already-adjusted parameters remain calibrated as subsequent adjustments of other parameters are made.

MOCVD system for forming superconducting thin films

Abstract: A system for MOCVD fabrication of superconducting oxide thin films provides a feed tube having a narrow slot along its length with a uniform mixture of powdered precursor materials packed inside the tube. The mixture composition is such that the resulting film has the desired stoichiometry. The tube moves downward at a controlled rate past a bank of heating lamps surrounded by a heat reflector. At each position of the tube this structure heats a localized section of the precursor material, with a sharp temperature gradient at the boundary of the section so that the heating is confined to this section. The precursor material in the heated section is substantially completely vaporized, with negligible decomposition and nonvolatile residue formation, and the vaporization rate is governed by the downward velocity of the tube. The vaporized material escapes through the longitudinal slot, and is swept by a carrier gas into a reaction zone. Oxygen is mixed with the gas stream, and the reaction products are deposited as a thin film on the substrate. A modification of this system includes coils adjacent to the reaction zone, connected to an rf generator. These coils produce a plasma in the reagent gas mixture that enhances the chemical reaction.

Guard ring structure with graded be implantation

Abstract: An avalanche photodiode having a beryllium guard ring. The beryllium is implanted at a dosage of at least 5×1014 per cm2 and subsequently annealed to provide a guard ring profile with a p+core and a superlinearly graded tail. The doping profile of the guard ring immediately adjacent the core is superlogarithmic.

Method and apparatus for synchronously distribution digital signals in high speed systems

Abstract: Method and apparatus for ensuring synchronism among modules of a distributed digital system (DDS) to a master clock signal is disclosed. The master clock signal is distributed at a frequency f c /N, and circuitry associated with each module multiplies the distributed master clock signal by N to provide a desired sync frequency f c to each module.

Tractor and trailer combination air cushioned vehicle

Abstract: Two wheels of different modes are provided which add guidance capabilities to air cushioned vehicles. A tractor utilizes the wheel of the first mode, a wheel mounted upright upon a hollow tubular hub, being a half-torus. A trailer utilizes the wheel of the second mode, a wheel mounted upright upon a sphere which is cut off at the base to allow for ample platform clearance. Both vehicles are air cushioned, enabling them to hover above a support surface. Steering is affected by directing the tractor vehicle with the aid of a novel curved gear series on the inside rim of the wheel of the first mode. Twisting action upon the rim and wheel resulting from stress created between the steering sprocket and a drive sprocket, being synchronized when normal by a timing belt. The steering sprocket is effected by operator control and encounters the curved portions of the special gear teeth, thereby causing the tractor to turn. The wheels of both modes can be tilted by the operator's actions. Pressure differences in opposite chambers formed between the hub structures of the wheels and the outer shells at the sides of both wheels occur as fluid pressure is released from valves situated at the sides of both wheels in greater proportion on one side or the other.