Showing papers by "Hewlett-Packard published in 1975"

Performance of Dual-Gate GaAs MESFET's as Gain-Controlled Low-Noise Amplifiers and High-Speed Modulators

Abstract: This paper describes the microwave performance of GaAs FET's with two 1-mu m Schottky-barrier gates (dual-gate MESFET). At 10 GHz the MESFET, with an inductive second-gate termination, exhibits an 18-dB gain with --26-dB reverse isolation. Variation of the second-gate potential yields a 44-dB gain-modulation range. The minimum noise figure is 4.0 dB with 12-dB associated gain at 10 GHz. Pulse modulation of an RF carrier with a 65-ps fall ad a 100-ps rise time is demonstrated. The dual-gate MESFET with high gain and low noise figure is especially suited for receiver amplifiers with automatic gain control (AGC) as an option. The MESFET is equally attractive for subnanosecond pulsed-amplitude modulation (PAM), phase-shift-keyed (PSK), and frequency-shift-keyed (FSK) carrier modulation.

Apparatus and method for transmitting binary-coded information

Abstract: An apparatus is disclosed for transmitting binary-coded information over a fiber-optic link which provides a link monitor to indicate whether the fiber-optic link is intact and operating. The binary-coded information is translated into a pulse-coded signal which provides a positive pulse for a positive-going transition in the binary signal and a negative pulse for a negative-going transition in the binary signal. In addition, a refresh pulse of the same polarity as the preceding pulse is provided whenever there has been no pulse for a predetermined amount of time.

Tapped-Line Coupled Transmission Lines with Applications to Interdigital and Combline Filters

Abstract: Exact, general, open-wire-line equivalent circuits for tapped-line combline and interdigital arrays are derived using a combination of graph transformations and induction. A significant feature of the equivalent circuits is that they do not require commensurate length sections. The equivalent circuit for tapped-line interdigital arrays is utilzed to develop design equations for tapped-line interdigital filters.

Deep-channel MOS transistor

Abstract: A new type of ion-implanted MOS transistor is described. The transistor functions, for example, as an integrating nondestructively readable photosensor and its technology is fully compatible with the advanced MOS integrated circuits.

InP Schottky-gate field-effect transistors

Abstract: MESFET's with gates 1 µm long were fabricated in LPE layers of InP on Cr-doped InP substrates. The quality of the LPE material is characterized by an electron concentration of 4 × 1015cm-3with a mobility of 2.6 × 104cm2V-1s-1at 77 K for growths from undoped melts. The devices have current gain cutoff frequencies of 20 GHZ or somewhat larger. This value is greater than that of the best analogous GaAs MESFET bya factor of 1.5. A factor of 1.3 is predicted on the basis of a simple theory. The highest power gain cutoff frequency, f max , for the InP device is 33 GHz which is somewhat smaller than that of the best analogous GaAs device. The lowest minimum noise figure at 10 GHz for these first InP devices is 3.9 dB with an associated gain of 4.8 dB. The best result for the GaAs counterpart is 3.2 dB with an associated gain of 7.8 dB. The power gain of the InP device suffers compared to the GaAs device because of degenerative feedback resulting from a large gate-to-drain capacitance and because of a small output resistance. If the magnitudes of these two equivalent circuit elements were the same for MESFET's in the two materials, f max for the InP device would be more than double its present value.

Memory expansion apparatus

Abstract: This invention addresses large memories in a computer through the use of translation tables, associated control circuitry, and an appropriate set of instructions. A portion of the memory address bits from the processor are used to address registers in translation tables. The output of the selected translation table register is appended to the remaining memory address bits (those not used to address the translation table) to form the expanded memory address. Data may be loaded into or read from the memory area selected by one translation table by a program being executed in a memory area selected by another translation table. Also, a user may execute a subroutine in a memory area selected by one translation table and then return to his main program in a memory area selected by another translation table. Memory is seen by the computer as a set of logical pages. Each translation table has a register corresponding to each logical page, starting with the lowest logical page which is called the base page. A fence register is used to partition the logical base page addresses of memory to provide a common area of physical memory accessible by every user. The logical addresses of the base page which address the common area of physical memory are transferred from the computer directly to memory regardless of the translation table base page register contents. Addresses other than those addressing the common area of physical memory are translated through the translation tables. Protection of any memory page from being loaded into or read from is provided through the use of protection bits in the translation tables registers.

Crystal orientation dependence of residual disorder in As-implanted Si

Abstract: MeV 4He+ channeling effect measurements combined with transmission electron microscopy (TEM) and Hall effect measurements were employed to study the orientation dependence of the amount of damage remaining after anneal of 200−keV As−implanted Si. The residual disorder after high−temperature annealing was found to depend upon the crystal orientation. For 〈111〉−oriented Si, anomalously high residual disorder was found in the dose region of 1015/cm2 by both the TEM and channeling measurements. Significantly less disorder was found in 〈100〉− and 〈110〉−oriented Si, the latter exhibiting essentially no residual disorder. The electrical activity of the implanted layer was consistent with the orientation dependence observed.

Etching thin film circuits and semiconductor chips

Abstract: A method is provided for etching thin film circuits or semiconductor chips to produce well defined vertically etched walls at rapid etching rates. The substrates to be etched are covered by masks and positioned on a cathode electrode enclosed in a container. Also enclosed in the container is a chemically-reactive gas used as an etchant. According to the method the cathode is negative-biased to ionize the reactive gas and attract the chemically reactive ions toward the cathode. These reactive ions impinge on the substrates in a predominantly vertical direction to produce well defined vertically etched walls.

Synthesi, of Interstage Networks of Prescribed Gain Versus Frequency Slopes

Abstract: Since the achievable gain of transistors typically falls off with increasing frequency, it is necessary to design interstage networks of microwave amplifiers with a complementary characteristic. A method is developed for the direct synthesis of interstage networks of prescribed gain versus frequency slopes. The bandwidth and ripple of these networks can also be precisely specified, and parasitic elements can be incorporated into synthesized networks. Design examples are presented, a complete computer program for the synthesis of interstage matching networks is described, and an octave band microwave amplifier illustrates an application of the interstage design techniques.

Thin film thermal print head

Abstract: The thermal print head disclosed herein comprises resistive heating elements deposited on mesas of glass glaze over an aluminum oxide substrate for more efficient marking of thermally sensitive recording material. After the mesas are formed in the glass glaze by etching, resistive and conductive materials are deposited over the mesas by thin film techniques. Thereafter, the raised heater elements and conductors are delineated chemically, then heat-treated to upwardly adjust the resistance of and to grow a protective oxide over the individual heater elements. Since the resistance value of the heater elements can be controllably increased as a function of the temperature and time of heat treatment, external trimming resistors are eliminated. The protective oxide which forms over the resistors during heat treatment provides better adhesion to wear-resistant materials and an effective barrier to migration of ions from the recording material into the heater elements causing degration of performance and shortened element life.

Growth and properties of VPE GaP for green LEDs

Abstract: The PH3-HCl-Ga-H2 technique for VPE growth of GaP is described. The influence of various growth parameters, including substrate temperature, orientation, and PH3 flow rate on morphology and growth rate are described. For both VPE and LPE nitrogen doping is known to be a major factor in obtaining high green luminescence efficiency. The major emphasis of this paper is an examination of the effect of nitrogen concentration in the range less than 1019 cm−3 (using the Lightowlers correction factor) on the growth process and materials properties, such as defect structure, photoluminescence spectra (at 300 and 77K) and photoluminescence intensity and lifetime. The LED device performance (B/J and efficiency) is used as the final test of material quality. Nitrogen is found to be incorporated far in excess of the solubility limit, and the solid gas distribution coefficient for nitrogen is found to increase rapidly with decreasing temperature below 840°C . The optimum nitrogen concentration for high diode efficacy, photoluminescence intensity, and lifetime is found to be approximately 5 × 1018 cm−3, where diodes fabricated by Zn diffusion into the VPE GaP have efficiencies at a current density of 10 A/cm2 of 0.1%, comparable to the state-of-the-art in the more widely used grown p-n junctions using LPE.

Transcutaneous pH measuring instrument

Abstract: A transcutaneous pH measuring device is provided in which a known volume of fluid is brought into equilibrium with body fluids through a membrane on a portion of skin whose surface layers have been stripped away. The fluid contains a pH sensitive dye. Optical measurements of the transmission characteristics of the fluid are obtained when the fluid is in the optical path. During portions of each operating cycle, the fluid is driven back into the vicinity of the skin to pH equilibrate with body fluids while standardization measurements are obtained using an optical plug of known transmission characteristics in the optical path.

Instantaneous frequency measurement system

Abstract: This invention relates to a system for measuring in real time, by auto-correlation, the period and frequency of a periodic biomedical source signal with random components such as an ultrasound doppler fetal heart beat signal. Before and during delivery of a fetus, the invention enables an obstetrician to continuously monitor and record the heart rate of the fetus in real time.

Green-emitting diodes in vapor phase epitaxial GaP

Abstract: Green light-emitting diodes (LEDs) have been fabricated by Zn diffusion into vapor phase epitaxial (VPE) GaP grown by the PH3HClGaH2 technique with nitrogen doping achieved by adding NH3 to the gas stream. The diffusion was carried out at 900°C using a totally vaporizing source of Zn and P in a closed ampoule. The junction depth, surface concentration and diode performance are reported as a function of Zn pressure during diffusion. The diode properties, such as capacitance-voltage and current- and flux-voltage characteristics, were investigated. The slope of the log I vs V plot was found to be ∼ 1 2 kT at low voltages. This component of the diode current was found to be nonradiative and to be purely a surface leakage current which disappears for diodes with large perimeter-to-area ratios. In these diodes with long lifetimes and low ND − NA, the effect of conductivity modulation was observed in the diode characteristics. The optimum conditions for high efficiency LEDs were found to be ND P A cm −1 and dislocation density

Non-linearity in constant current electron capture detection

Abstract: Constant current electron capture detection in gas chromatography has increased the range and improved the stability of electron capture detector analysis. Systematic non-linearities of response have been seen for some compounds. Various electronic phenomena have been investigated and found not to be the cause. Two kinetic mechanisms have been developed theoretically. One of these, involving the fraction of sample that is ionized in the detector, is found to be consistent with the experimental data.

Birefringent polarization prism with a large angular aperture

Abstract: An apparatus for polarizing natural light incident on a polarizer with an intermediate layer of one birefringent or biaxial material mounted between a pair of prism substrates of a second birefringent or biaxial material with a liquid or other index matching medium between the prism substrates and the intermediate layer to provide optical coupling between the three above-mentioned constituent parts of the prism. The materials of the prism substrates and of the intermediate layer being selected to be substantially transparent and to have orthogonal indices of refraction (n o and n e for birefringent materials and any two of n a , n b and n c for biaxial materials) which are considerably different for each individual material over the spectral region of the desired polarization. Further, the material of the intermediate layer is selected such that its greatest index of refraction curve is substantially equal to the lowest index of refraction curve of the material of the prism substrates over the spectral region of the desired polarization, and the optic axes of these materials are oriented in the assembled prism so that one constituent electric field component of the incident light experiences these matched indices of refraction. In addition, the liquid or other index matching medium is selected to have an index of refraction which is also substantially equal to the two matched indices of the prism materials. The single intermediate layer may be replaced with a sandwich of a plurality of intermediate layers. The composition of the plurality of intermediate layers alternates between the first and second birefringent or biaxial material with the outer layers being constructed from the second birefringent or biaxial material. In addition, the liquid or other index matching medium is used between each of this plurality of intermediate layers to provide optical coupling between each layer and the prism substrates. This prism configuration with a single or plurality of intermediate layers and the technique for choosing the prism materials provides the large angular aperture and, with the proper choice of materials, is operable substantially over the infrared, visible and ultraviolet spectrums.

High pressure pump with metering

Abstract: A pumping system is provided in which a low pressure metering pump injects fluid charges into a high pressure pump which in turn operates into a high pressure load. The high pressure pump is designed to always present a low pressure at its input on its intake stroke. This insures that the metering pump will always operate into a low pressure regardless of the load, and will therefore be enabled to always accurately meter charges into the high pressure pump. In various embodiments, the high pressure pump and/or the low pressure pump include spring elements for providing well defined pumping pressures. In some embodiments, an oil reservoir and diaphragm provide a well defined pressure against which the metering pump can operate.

Performance of dual-gate GaAs MESFETs as gain-controlled low-noise amplifiers and high-speed modulators

Abstract: A dual-gate GaAs MESFET with maximum gain of 18 dB at 10 GHz and minimum noise figure of 4 dB with 12 dB associated gain will be described. Variation of second gate potential has been found to yield gain modulation with a 44 dB dynamic range and 70 ps risetime.

Modular printed circuit board mountable push-button switch with tactile feedback

Abstract: A push-button switch mechanism suitable for use with printed circuit boards is disclosed comprising a body that has a slidable plunger for actuating a cantilevered contact attached to the body A button is attached to the plunger and when the button is depressed, the plunger deflects the cantilevered contact toward conductors on a printed circuit board to which the body is attached A leaf spring in the body holds the plunger in an up or extended position and returns the plunger to this position after the button has been depressed When the button is depressed the leaf spring is compressed along its longest axis and buckles, thereby providing tactile feedback The switch may be provided with a light which is connected to the printed circuit board and is located in a cavity in the plunger Illumination from the light may be seen through a translucent portion in the button

Analysis of arsenic range distributions in silicon

Abstract: MeV4He ion backscattering and differential sheet resistivity measurements were made on As implants into silicon at room temperature. Analysis of backscattering measurements yields the projected rangeR p and projected standard deviation ΔR p . Over the energy range of 50 to 250 keV, the values ofR p are found to agree well with LSS theoretical predictions; however, values of ΔR p are systematically higher than theoretical calculations. Backscattering and differential sheet resistivity measurements on samples annealed at 950°C are in general agreement and indicate diffusional broadening of the profile.

Microwave Octave-Band GaAs FET Amplifiers

Abstract: The design of microwave broadband amplifiers using the 1mu-gate GaAs field-effect transistors covering the 4-8 GHz and 7-14 GHz octave bands is presented. The broadband matching networks of these amplifiers consist of lumped and/or distributed circuit elements. Using analytical and computer-aided optimization techniques, a typical octave-band amplifier has been designed with a nominal power gain of 8 dB with a maximum deviation of /spl plusmn/0.07dB covering the 7-14 GHZ band based on the measured scattering parameters of a 1mu GaAs FET chip. For a packaged 1mu GaAs FET, a 4-8 GHZ band amplifier has been designed with a gain of 7.2 dB /spl plusmn/ 0.2 dB.

Cartridge latching mechanism

Abstract: A cartridge latching mechanism is provided in which a few simple elements function to position and latch a tape cartridge into a housing containing driving elements for the tape cartridge and magnetic heads for reading and writing on the tape. Manual insertion of the cartridge rotates the latching mechanism about a pivot point whereupon a spring force engages to create a torque which positively engages the cartridge and latches it into position. Depression of an eject button disengages the latching mechanism and rotates it in an opposite direction, whereupon the same spring generates an oppositely directed torque to positively eject the cartridge.

General purpose calculator having selective data storage, data conversion and time-keeping capabilities

Abstract: A battery powered hand-held calculator is disclosed which includes a built-in metric to U.S. conversion function for converting units from one system to the other; a degrees-minutes-seconds conversion function for converting angles or units of time from degrees-minutes-seconds to the decimal system and conversely.

Noise burst source for transfer function testing

Abstract: A method and apparatus for accurately measuring the transfer function of a linear system or the linear part of a non-linear system. This is accomplished by using a spectrum estimation technique which utilizes a "transient random" stimulus consisting of a short burst of random signals applied to a system under test for a period of time that is shorter than the time used to measure a single spectrum. Thus the measurement period includes the time for the "transient random" burst and for the response of the system to substantially decya to zero. The spectrum measured over this period is used to form a first estimate of the transfer function. Other "transient random" stimuli, uncorrelated with the prior records, are then generated and the above procedure is repeated to achieve an average value for the transfer function estimate of the desired accuracy. Through the use of several "transient random" stimuli, leakage and distortion in the measurement are minimized, thus greatly improving the accuracy of the estimation technique in measuring the transfer function of the system under test.

Pulse code modulation recording and/or reproducing system

Abstract: A system for high-density data recording at low tape speeds receives a unipolar signal representing encoded digital data and transforms it to a bipolar signal having a constant pulse width. The low-frequency response required of the system is minimized because the power spectrum of the signal is altered through a time domain transformation. The narrow bandwidth enables the use of very low tape speeds at high bit packing densities. Tape speeds of 15/32 ips or less at densities about 20 thousand (k) bits per inch (BPI) are possible. The spectrum of the transformed code has no direct current (DC) component which eliminates the need for a base line compensator in the reproducing portion of the system.

Group delay measurement apparatus and method

Abstract: A network analyzer which compares a reference signal supplied to a device under test with an output signal from the device under test is used to measure the group delay caused by the device under test. The reference signal is produced by a swept frequency signal generator. During the sweep of the signal generator the difference between the instantaneous frequencies of the reference signal and the output signal from the device under test is determined as is the rate of change of the frequency of the reference signal. The instantaneous frequency difference is divided by the rate of change of the reference frequency to produce an instantaneous indication of the group delay produced by the device under test.

Instrumentation: Insight into interfacing: Thorough and unambiguous understanding of interface systems demands sound design concepts and a precise descriptive language

Abstract: An interface system definition, one optimized for the interconnection of programmable bench instruments, must contain many vital communication capabilities if it is to interconnect independently manufactured products at reasonable costs. It must also maintain a high level of compatibility, and a high degree of flexibility. The purpose of this article is to discuss not only the definition of the interface itself, but also the manner in which it is organized and the method by which it satisfies the user's needs.

Apparatus and method for measuring the frequency of a sweeping signal

Abstract: A swept frequency measuring system is provided with an electronic counter for measuring the frequency of the sweeping signal from a sweeping signal generator, at a predetermined point in the sweep indicated by a marker. Upon the occurrence of a marker, the counter starts counting the frequency of the signal while the sweeping signal generator continues to sweep. After a predetermined interval, the counter stops counting for a second predetermined interval and, then, during a third predetermined interval counts down from the count made during the first interval. The resultant count remaining in the counter is an indication of the frequency of the sweeping signal at the marker, and this count is displayed in a digital display.