Showing papers by "Hewlett-Packard published in 1977"

GaAs MESFET logic with 4-GHz clock rate

Abstract: Monolithic digital ICs with GaAs MESFETs have been built and operated at clock frequencies up to 4.5 GHz. The fabrication process uses selenium-implanted n-channels and a two-level Cr-Pt-Au metallization with 1-/spl mu/m linewidth and 1-/spl mu/m alignment tolerances. NOR gates with 86-ps propagation delay and 40-mW power consumption have been realized. Binary frequency dividers have been designed with master-slave flip-flops operating from dc up to an average maximum frequency of 4 GHz. In addition, more complex circuits have been integrated on single chips. A general-purpose octal counter with input gating and output buffering and an 8-bit multiplexer/serial data generator exhibit stable and reliable operation.

A Compact High-Speed Parallel Multiplication Scheme

Abstract: This paper discusses a compact, fast, parallel multiplication scheme of the generation-reduction type using generalized Dadda-type pseudoadders for reduction and m X m multipliers for generation. The implications of present and future LSI are considered, a partitioning algorithm is presented, and the results obtained for a 24 X 24-bit implementation are discussed.

Acoustic imaging apparatus

Abstract: An array of transducers is provided for transmitting pulses of ultrasonic pressure waves into a body and translating reflections received into corresponding pulses of electrical waves. Phase changing means, which may preferably include heterodyning means, are connected between each transducer and selected taps on one delay line. The taps are just close enough together to provide reasonable overlap of the pulses of electrical waves at the summing point at one end of the delay line. Focussing is attained by adjusting the phases of the waves applied to each tap so that the cycles of carrier wave within the overlapped portion of the pulses at the summing point have reasonable phase coherence.

Method for vapor epitaxial deposition of III/V materials utilizing organometallic compounds and a halogen or halide in a hot wall system

Abstract: A process is provided for the VPE growth of III/V compounds such as Alx Ga1-x As in which the group III elements are transported into the reaction zone in the form of organometallic compounds in the presence of a gaseous halogen or hydrogen halide such as hydrogen chloride (HCl).

Bias dependence of GaAs and InP MESFET parameters

Abstract: A comparative analysis of the bias dependence of critical RF parameters in GaAs and InP metal-semiconductor field-effect transistors (MESFET's) led to the following conclusions. 1) The drain-gate feedback capacitance in GaAs MESFET's is lower than in InP MESFET's, because of a stronger tendency in GaAs to form stationary Gunn domains at the typical drain bias levels employed. 2) The drain-source output resistance in InP MESFET's is lower than in GaAs MESFET's mainly for high drain current units, a fact which is linked to a substrate related softer pinch-off behavior in InP. 3) The current-gain cutoff frequency fT, in the current saturation range of the GaAs MESFET decreases strongly with drain bias as a result of the formation of the stationary Gunn domain. In the InP MESFET, this effect is weaker. At the optimum bias, fT is only 10-20 percent higher in InP MESFET's than in GaAs ones.

High fidelity pressure transducer

Abstract: The capacitive fluid pressure transducers described herein comprise quartz bodies and diaphragms having suitable electrodes deposited thereon to form both sensing and reference capacitors in appropriate configurations for high fidelity measurement of relative blood pressure, said transducers being substantially unaffected by temperature and other environment factors.

Programmable calculator having string variable editing capability

Abstract: A programmable calculator employs modular read-write and read-only memories separately expandable to provide additional program and data storage functions within the calculator oriented toward the environment of the user and two sixteen bit LSI NMOS central processing units. One of the central processing units (LPU) is employed to perform language syntaxing, arithmetic, and general supervision of program execution. The second central processing unit (PPU) is employed for managing input/output operations. Communication between the two central processing units is accomplished by an arrangement through which the two central processing units share a common portion of memory. The calculator also includes a keyboard having a full complement of alphanumeric keys for entering programs and data into the calculator and for otherwise allowing the user to control operation of the calculator. The calculator further includes a CRT that can be operated in either an alphanumeric mode or a graphics mode, two magnetic tape transports that permit the user to store information into and to retrieve information from the user portion of the calculator read-write memory, and an 80-column thermal printer utilizing a print head that includes 560 thermal print resistors arranged in a single horizntal row.

Capacitive Analysis of Twisted Nematic Liquid Crystal Displays

Abstract: Magnetocapacitive null (MCN) and capacitance versus voltage (C-V) measurements are valuable tools for analyzing electro-optical properties of twisted bematic LCDs. the C-V technique is particularly useful when resulrs are presented in the form of reduced capacitance CR(V) = [C(V) - C]/(C∥ - C1) = sin2α, where αe(V) is an effective molecular tilt. Thus, the effective voltage induced distortion of the LC is determined by monitoring CR-V.

Plotter with automatic pen-changer

Abstract: An X-Y plotter is provided having an automatic pen changer comprising a pen repository, a memory for storing data identifying a pen selected by a user, a plot head for automatically fetching pens from and depositing pens into the repository, a processing means having a routine stored in a read-only-memory for providing head-movement coordinates, and a control means for moving the head to said coordinates, the pen-changing action (fetching and depositing) being performed solely by movement of the head to said coordinates. Deposited pens are automatically capped to prevent drying-out, fetched pens are automatically uncapped prior to use.

Further experimental data on stress and thermal gradient compensated crystals

Abstract: Recent interest in a quartz-crystal cut, which is compensated for stress effects and thermal gradient effects on its frequency characteristics, has required further experimental confirmation of its suitability for high-precision frequency standards Presented in this note are experimental data on the performance of 51 units fabricated in the vicinity of (yxwl) 2193°/3393° along with mode spectra plots and temperature-performance data for a typical quartz resonator

Logic state analyzer

Abstract: Clock signals, data words and qualifier signals are received via monitor probes during a data acquisition mode, selected data words being stored in a memory in response to the clock and qualifier signals. The stored data words may then be displayed in a tabular or a map format on a cathode ray tube screen. Data words may be acquired randomly, i.e., in a free-running sampling mode, or acquired selectively by using pattern recognition and delay trigger circuits. Using the tabular display format, data words are displayed as ones and zeroes. Using the map display format, each data word thus acquired is displayed on the CRT screen as a dot during a subsequent display mode. The position of each dot on the CRT screen uniquely identifies its address or state value. The most significant bits determine the vertical position on the CRT screen and the least significant bits determine the horizontal position of the dot. The intensity of the dot indicates the relative frequency of occurrence of that logic state. A trace between dots is utilized as a vector to indicate the sequence in which the data words are acquired, the brightened or intensified end of the vector indicating the direction. The vectors are non-linear so that when logic flow occurs in opposite directions between logic states, the vectors will not overlap and obscure useful information. A cursor is provided to select a map area to be displayed in an expanded map mode, wherein a portion of the map may be displayed on a larger scale. Also, a comparator mode is provided to allow comparison of acquired input data with that stored in an auxiliary memory.

Optical bar code reader

Abstract: An optical bar code reader is provided employing a dual focusing system in which a source of light is focused by a first lens to a small area of the bar code, which reflects the light back through a second lens to a detector. In preferred embodiments of the invention the source and detector are solid state semiconductors mounted on the same substrate, while the focusing lenses are integrally molded as part of a single lens support. Spherical aberration is minimized by utilizing aspheric lenses.

Exploring a Stack Architecture

Abstract: Computer architects design a high-performance system out of the same components that the rest of us would use to build a common one. They do it through an understanding of how the system will actually be programmed. Such was the insight which led to the development of stack-based computers.

Venting method for a chromatograph oven

Abstract: An oven for a chromatograph is shown in which intake and exhaust ports are both located on the opposite side of the fan from the columns, and in such manner that ambient air entering through the intake port merges with hot air from the oven before reaching the columns.

The Effect of Solid-State Reactions Upon Solder Lap Shear Strength

Abstract: The effect of solid-state reactions between gold plating and the eutectic solders 88Au:12Ge, 80Au:20Sn, 90SN:10Au, and 85Pb: 15Au and the off eutectic solder 60SN:36Pb:4Ag upon the solder lap shear strength has been investigated at four aging temperatures ranging from 75 to 150°C. Failure analysis of the lap shear samples has shown that Au-Ge and Au-Sn solders failed cohesively whereas Sn-Au, Pb-Au, and Sn-Pb-Ag solders failed adhesively. Scanning electron micrographs and microprobe analysis of gold-solder metallographic sampies aged at 125°C revealed the presence of AuSn, AuSn 2 , AuSn 4 , and voids at the plating-solder interface of Sn-Au solder. AuSn 2 and AuSn 4 intermetallic compounds were detected at the interface of SnPb-Ag solder, and AuPb 2 was detected at the interface of Pb-Au solder. The zeta phase of the Au-Sn binary system was detected at the plating-solder interface of the Au-Sn solder. The plating-solder interface of the Au-Ge solder was devoid of any intermediate phases or intermetallic compounds. The results of the lap shear measurements have shown that all five solders can be expected to exhibit adequate strength for microelectronic purposes for >105h at a sustained temperature of <100°C when the mating materials have similar coefficients of thermal expansion. However, with dissimilar thermal expansion coefficients, the SnAu and Sn-Pb-Ag solders both failed catastrophically within 103h at 100°C

Calculator having merged key codes

Abstract: A hand-held, programmable, electronic calculator is capable of performing a larger number of functions than the number of keys on its keyboard and has one or more prefix keys to allow one function key to initiate more than one function. Each key generates a unique key code when it is depressed, and the calculator may be programmed by storing a series of the key codes in a memory. Memory space can be saved by generating unique merged codes to represent the combination of a prefix key and a function key, and storing this single merged code rather than the two key codes.

Gallium arsenide spawns speed

Abstract: Monolithic digital circuits employing `MESFET' devices promise multigigabit and higher data rates. The basic operation of MESFET is described.

Fiber optic connector

Abstract: The retainer sleeve of a three piece ferrule suitable for very small diameter optical fibers has an outside diameter threaded portion at the closed end so that, after the ferrule and optical fiber have been assembled, an outer sleeve, having a correspondingly threaded inside diameter, can be used to adjust the optical fiber end to be positioned flush with the end face of the ferrule during assembly. The design of the outside threaded sleeve for retaining the connector of two fibers to be connected is improved by inserting a shim sleeve of molded, pliable material having a "D"-shaped inside diameter to apply force to the outside diameter of the ferrules when inserted therein for reliable, concentric snug-fit.

Low parasitic capacitance and resistance beamlead semiconductor component and method of manufacture

Abstract: A beamlead semiconductor component and a method for manufacturing the semiconductor device with low parasitic capacitance and electrical resistance is provided. The beamlead component includes a thick layer of glass forming one end of the component directly beneath one of the beamleads and extending up to the edge of the active device on the beamlead surface of the component. On the opposite side of the active device from the glass layer is a metalized cavity that provides the electrical contact for a second beamlead with the semiconductor substrate. From the other surface, the non-beamlead surface, of the component another metalized cavity adjacent to the active region of the component and the metalized cavity on the beamlead surface has been etched. The cavity in the other surface of the component exposes a portion of the deepest surface of the metalization in the cavity on the beamlead surface to make electrical contact between the two metalizations. These interconnected cavities thus provide an electrical via between the two surfaces of the component. The use of the thick layer of glass beneath the one beamlead provides a considerable reduction in the parasitic capacitance between this beamlead and various layers of the substrate to which it is not connected. The metalized cavity in the other surface of the component substrate and the via reduces the resistance of the device by thinning the substrate beneath the active region and limiting the length of longest current path through the semiconductor material to a single thickness of that material.

Frequency counter and method

Abstract: An averaging frequency counter for determining the frequency of recurrence of input signals has an event counter for counting a number of the input signals, a gate counter for counting a number of time intervals during which the input signals are counted, and a time interval measurement circuit for measuring the cumulative duration of the time intervals. A systematic error associated with the measurement of the duration of each time interval is determined during an application of a calibrated frequency to the averaging frequency counter by dividing a calculated total time error by the number of time intervals. The systematic error is subsequently used to correct a measurement of an unknown frequency during an application of the unknown frequency to the averaging frequency counter by subtracting a product of the number of the time intervals and the systematic error from the cumulative duration.

Open-loop electric drive with corrective controller

Abstract: A controller minimizes periodic torque or force perturbations in an inductor-type synchronous motor drive by supplying current waveforms to each motor phase that contain a fundamental frequency component and selected harmonic components. The harmonic components in the phase currents heterodyne with the periodic permanent magnet flux fundamental frequency to create periodic torques or forces which subtract from the unwanted torques or forces perturbing the moving portion of the motor. The controller, which includes an interpolator, a memory, and a converter, provides for smooth incremental movement of a member such as a plot head, at substantially constant velocity, by applying selected continuous periodic waveform signals as phase currents to the windings of inductor-type synchronous motors.

Heterodyne phase lock system

Abstract: A heterodyne phase lock system is disclosed having a plurality of oscillator circuits, a similar plurality of heterodyne (mixer-filter) circuits representing an input circuit, and a similar plurality of heterodyne circuits representing a control circuit, at least one of the oscillator circuits being a voltage controlled oscillator (VCO) circuit. The heterodyne circuits of the input circuit are cascaded, i.e., linked each to the other, successively, and the heterodyne circuits of the control circuit are likewise cascaded. Each oscillator is linked to a pair of heterodyne circuits, i.e., to one heterodyne circuit in the input circuit and to one heterodyne circuit in the control circuit, and applies a common output signal to said pair of heterodyne circuits. The control circuit includes a phase lock circuit, and is responsive to an applied reference signal for adjusting the output of the VCO and correcting for or substantially cancelling frequency drift, residual FM, and phase noise introduced into the system by the oscillators. This manner of linking oscillators to both heterodyne input and control circuits in a system so as to be able to correct, by adjusting a single oscillator, for frequency drift, residual FM, and phase noise from all of the oscillators in the system, is applicable to receiver and generator type systems alike. The system also includes an offset oscillator for tuning the system.

Adjustable fiber optic connector

Abstract: The retainer sleeve of a ferrule suitable for very small diameter optical fibers is coupled to a connector barrel so that, after the ferrule and optical fiber have been assembled, the position of the optical fiber end with the coupling surface of the ferrule may be adjusted The connector barrel also includes means for securely locking the adjusted position of the optical fiber in the ferrule

Diffraction limited CW optically pumped lasers

Abstract: The far infrared spectral characteristics of inductive metal mesh dielectric hybrid mirrors were investigated. From experimental and theoretical studies, the mirrors were found to exhibit etalon effects due to the finite Si substrate thickness and to have two separate diffraction conditions. With grid spacing g and substrate index of refraction n , for n^{-1} the mirrors diffract in transmission while for g/\lambda > 1 the mirrors diffract both in transmission and reflection. Using both inductive and capacitive mesh mirrors, EH 11 outputs have been obtained at the milliwatt level in the range 70 μm to 1.2 mm. Powers in excess of 10 mW were obtained from CH 3 OH at 96 and 118 μm, HCOOH at 393 μm, CH 3 I at 447 μm, and CH 3 F at 496μm.

Stable fiber optic scintillative x-ray screen and method of production

Abstract: An X-ray intensifying screen pair comprising a thin screen and a fiber optic thick screen is disclosed, together with a method for producing the fiber optic thick screen, which method includes the steps of evaporation and vacuum deposition. The thin screen comprises a gadolinium oxysulphide rare earth scintillator capable of providing good image resolution, and the fiber optic thick screen comprises a thallium doped cesium iodide scintillator that is capable of high speed (i.e., good X-ray photon-stopping and photon-conversion) operation, that is stable under ambient conditions, and that requires low patient dosage.

Smoothing a raster display

Abstract: Image forming means are described in which the discontinuities usually occurring in a raster scan display presentation of a waveform are smoothed by varying the width of the path pattern

Microprogrammable control processor for a minicomputer or the like

Abstract: A minicomputer comprises a microprogrammable central processing unit wherein micro-instruction execution speed is optimized through the use of variable micro-instruction timing logic and by grouping micro-instruction according to execution time. Furthermore, data paths are arranged so that micro-routines that implement more complex operations, i.e., memory reference instructions, follow the fastest route possible. When micro-instructions requiring longer data paths are programmed, the computer dynamically varies the length of the microcycle to be a function of both the type of micro-instruction to be executed and the state of the minicomputer when the micro-instruction is to be executed. A microprogrammable processor port is provided to allow coupling of external hardware, e.g., I/O devices, other processors, etc., directly to the microprogrammed control processor. This capability is in addition to the standard input/output system of the minicomputer, thereby providing an alternate interface path for devices requiring very fast transfer rates. These devices interfaced through the microprogrammable processor port are directly coupled to the internal data busses of the minicomputer and addressed under direct microprogram control as if they were internal processor registers. Block transfers of data are provided via this microprogrammable port to allow transfers of large blocks of data without dependence on the I/O system timing of the minicomputer. A remote program load feature is provided whereby an I/O device or data communications interface can initiate a bootstrap operation in a remote computer, i.e., the computer can be halted, a preselected ROM loader program is transfer into memory, all input/output instructions in the loader are automatically configured to the proper select code of the I/O device, and the computer is restarted at the proper loader program starting address.

Dual slope integration circuit

Abstract: A circuit for performing dual slope integration to provide a digital measurement of an input voltage of either positive or negative polarity employs a single source of reference potential in combination with a switchable resistive network as a source of reference current.