Showing papers on "Biasing published in 1975"

Photovoltaic effects of metal–chlorophyll‐a–metal sandwich cells

Abstract: The microcrystalline chlorophyll−a film prepared by the method of electrodeposition is shown to have strong photovoltaic effects. The photovoltaic cell (M1‖Chl‖M2) has lamellar arrangement with the Chl−a film sandwiched between two metal electrodes. With dissimilar electrodes of different work functions, φM, the cell usually exhibits a dark rectification behavior. A large forward bias current is seen when the metal with a lower φM is the negative electrode. The rectification is small when the same metal is used as both electrodes. A blocking contact or Schottky barrier is evidently present at the Chl−a‖metal junction particularly fo the metal having a low φM. A p−type semiconduction in Chl−a is implicated. In the photovoltaic mode, cells such as (Al‖Chl‖Hg) and (Al‖Chl‖Au) have an open circuit voltage ranging from 200−500 mV. The power conversion efficiency for these cells is on the order of 10−3% which is among the highest in photovoltaic cells using organic materials. The direction of the photovoltaic c...

Tunnel diode oscillator for 0.001 ppm measurements at low temperatures

Abstract: The results of a systematic study of the design considerations of a low‐temperature tunnel diode oscillator are presented. The calculated circuit performance satisfactorily describes the measured frequency noise and dependence on bias voltage, magnetic field, and temperature. The overall performance allows measurement of changes in the resonant frequency of an LC circuit with a precision of 0.001 ppm. One can thereby detect extremely small changes in a number of material properties such as thermal expansion, surface impedance, and electric and magnetic susceptibilities.

High-frequency amplifiers

Abstract: A comprehensive text/reference introducing the basic techniques of circuit analysis and design as applied to the operation of high frequency amplifiers. Emphasizes the Smith chart, the immittance chart, and scattering parameters. Includes exercises, problems, worked case studies and practical examples. Introduces new procedures for the biasing circuits of bipolar transistors, considering those circuits which use collector feedback with and without a Zener diode in the feedback path and a popular active biasing circuit. Analyzes the oscillatory condition caused by such biasing techniques.

AC biased and resonated liquid crystal display

Abstract: A liquid crystal device biased by an alternating current having a predetermined frequency higher than the dispersion frequency of the liquid crystal material. The liquid crystal device exhibits inherent capacitance across its input terminals which is resonated by an inductor to result in a higher bias current and reduction of image smear of images displayed by such device.

Influence of sputtering parameters on the composition of multicomponent films

Abstract: Multicomponent sputtering is examined using as examples amorphous Gd−Co alloys and related ternary systems Gd−Co−Au and Gd−Co−Mo. Film composition was studied as a function of bias voltage, target voltage, pressure, system geometry and target composition. If the sputtering yield, e, of one constituent is much greater than the yield of the other elements in the system, it is possible to express the film composition as a simple function of the above parameters. For example, in the Gd−Co system eGd ≳ eCo and the Co/Gd ratio in the film is given by (Co/Gd)film = (Co/Gd)target/1 − K (Vb/Vt), where Vb is the effective bias voltage, Vt is the target voltage, and K is a system constant which depends largely on the geometry. The equation involves a number of simplifying assumptions which are only valid in the low bias, low pressure regime. A more complex expression must be used outside of these limits. It has also been shown that there is a simple relationship between sputtering gas incorporation in the film and the effective bias voltage, which provides an independent check on the validity of the sputtering equation.

Electronic circuit using field effect transistor with compensation means

Abstract: A compensation circuit for electronic circuits such as pulse generator circuits which are suitable for MOSICS includes a resistor of high resistance and parallel-connected MOSFETs of the enhancement type and depletion type, respectively. The drain electrodes of the MOSFETs are connected to a power supply through the resistor, and are also connected to the gate electrode of load MOSFET of the depletion type which constitutes a load for a MOSFET of the enhancement type. To the gate of the former enhancement type MOSFET, a controlled bias voltage is applied from the connection point of MOSFETs connected in series between the power supply and ground. By employing the compensation circuit in pulse generator circuits, the instability of the oscillating periods due to changes in the ambient temperature and changes in the supply voltage is compensated. Also, the differences of oscillating periods are decreased among MOSICs.

Method of driving a matrix type liquid crystal display device

Abstract: A method of line-by-line scanning liquid crystal dots at the intersections of signal and scanning lines arranged in a matrix form, a signal including a selective voltage enough to excite the liquid crystal dot into illumination and a bias voltage for averaging a cross talk voltage is applied to the signal line. The duration time or pulse width of the selective voltage may be varied in accordance with a desired tone level, so that a display with tone can be achieved while the cross talk voltage is averaged.

A linear self-biased magnetoresistive head

Abstract: Evaluation of the distortion resulting from imperfect biasing of a magnetoresistive (MR) read head shows that it is unacceptable in wide band recording systems. A general solution to the problem is presented which involves differentially sensed elements. A practical implementation and performance of a shielded head is discussed. Analytical techniques are shown for designing current-biased MR heads, which allow predictions of performance closely matching experimental results.

Multiplication mode bistable field effect transistor and memory utilizing same

Abstract: A novel solid state device which exhibits two-terminal negative resistance characteristics. The negative resistance characteristic may be readily shaped by external bias control, providing a wide range of oscillatory or bistable properties. The negative resistance characteristic is obtained by a novel means of device operation exploiting an electron hole pair multiplication effect which is enhanced by high substrate doping in conjunction with appropriate biasing of the junctions within the device. The device exhibits a bias voltage controlled small signal negative resistance region, i.e., the device has a unique feature, a negative slope over an adjustable portion of its V-I characteristic. Bistable action is obtained with a single device. In the first stable state ("off") of the device, power dissipation is zero. In the second stable state ("on") of the device, power dissipation is adjustable to less than one micro-watt. One embodiment of the device is a novel and unobvious modification of a known N channel FET structure. The device may be readily fabricated by using large scale integration techniques well known in present day FET technology. The novel solid state device has utility in at least the following applications: (1) high density non-refresh memory; (2) gated latch (as three terminal device); (3) astable, monostable and bistable devices; (4) level detector, and (5) small signal (linear) oscillatory circuit.

Magnetoresistive sandwich including sensor electrically parallel with electrical shunt and magnetic biasing layers

Abstract: MAGNETORESISTIVE SANDWICH INCLUDING SENSOR ELECTRICALLY PARALLEL WITH ELECTRICAL SHUNT AND MAGNETIC BIASING LAYERS Abstract of the Disclosure A magnetoresistive Permalloy* film is deposited upon a sub-strate and coated with a separating layer composed of titanium or a similar high resistivity, conductive material. A soft bi-asing layer of a material such as Permalloy* or a hard biasing material such as cobalt chromium is deposited upon the separt-ing layer to complete a sandwich. All layers are coextensive in outline because their outlines are formed by a single etching step.

Multi-layer semiconductor photovoltaic device

Abstract: A semiconductor photovoltaic device is comprised of 2n layers of alternating p-type and n-type material having respective PN junctions between adjacent layers, wherein n is an integer greater than 1 Each layer has a thickness which is less than the diffusion length of a minority carrier therein The PN junctions are excited by light which is incident on the device to thereby cause majority carriers to be accumulated in the respective layers so as to forward bias all of the PN junctions As a result of this forward biasing, minority carriers are injected across a first PN junction fr0m one layer into an adjacent layer and then traverse the next PN junction into the next succeeding layer The photovoltaic device thus is adapted to supply a voltage and a current to a load

Active bias circuit for operating push-pull amplifiers in class A mode

Abstract: A transistor audio amplifier of the Class AB complementary symmetry type is biased with a new bias circuit to keep both transistors on during all normal signal conditions. The bias circuit includes a pair of series connected V BE Multipliers with an interconnection between the two multipliers receiving signal feedback from the amplifier output such that the Multipliers can bias both complementary transistors on for all normal signal operating conditions.

Permanent magnet films for biasing of magnetoresistive transducers

Abstract: The design and material requirements are presented for a permanent magnet biased magnetoresistive (MR) stripe for high resolution MR recording transducers. Preparation details of three alternative biasing films (Fe 3 O 4 the preferred choice) as well as implementation and-testing of experimental transducers are described.

Self-biased trinary input circuit for MOSFET integrated circuit

Abstract: A trinary input circit for an MOSFET integrated circuit includes a biasing stage formed by using a standard inverter, whose output is connected to its input so as to establish a particular bias voltage level when the input to the trinary input circuit is left floating. The output of the biasing stage is applied to the inputs of a second inverter stage having a higher beta ratio than the bias stage and to the input of a third inverter stage having a lower beta ratio. The bias stage when left open circuited will seek a quiescent voltage which is above the switching threshold of the second stage and below the switching threshold of the third stage. Thus, as a result of the relative beta ratios of the three stages when the input to the bias stage is left open, the bias stage will seek a particular voltage level such that the high beta ratio stage produces a logic 0 output and the low beta ratio stage produces a logic 1 output. When a voltage greater than a certain value which is defined as a logic 1 is applied to the input, thus overriding the biasing stage, both the second and third inverter stages produce logic 0 outputs and, when a voltage less than a certain value which is defined as a logic 0 is applied to the input, to override the biasing stage, both inverters produce a logic 1. Three logic input conditions are therefore defined by two signals for use within the integrated circuit chip.

On the direct currents through interface states in metal-semiconductor contacts

Abstract: The direct currents through interface states in metal-semiconductor majority-carrier contacts are calculated analytically. A transition is observed with forward bias voltage from metal-controlled to semiconductor-controlled occupancy of the interface states. Calculations for the Au- n -type silicon system indicate that interface state currents are comparable with band currents for densities ≳ 10 11 cm −2 eV −1 (oxide thickness 15 A) or 10 13 cm −2 eV −1 (10 A).

Magnetic recording reproducing system

Abstract: This invention provides a magnetic recording reproducing system which is able to obtain an optimum recording bias current for various magnetic tapes different in characteristic. The system is designed so that a reference frequency signal of a predetermined level is recorded on a magnetic tape while applying a continuously variable recording bias by use of a triangular waveform or a sawtooth waveform, whose voltage varies linearly, and means is provided to rectify and smooth the reproduced reference signal and to compare a peak value output thereof with an output obtained by suitably attenuating the peak value output and an output obtained through a peak value memory circuit so that the time when the levels of both signals coincide may be detected to stop an increase of the recording bias current, the value of which serving as the optimum recording bias current.

Apparatus for measuring the beam current of charged particle beam

Abstract: In an ion implantation apparatus, a structure for measuring the beam current at the target wherein a Faraday Cage is formed by walls adjacent to and electrically insulated from the target in combination with the target, means for biasing the target at a negative potential, means for biasing the walls at ground potential and means for measuring the target current and the wall current and for combining the two to provide an accurate beam current measurement.

The potential and electric field at the metallurgical boundary of an abrupt p-n semiconductor junction

Abstract: Analytical equations are presented that rigorously establish the electrostatic potential and electric field at the metallurgical transition point of an abrupt p-n semiconductor junction. From these equations, the classical depletion-layer approximation is shown to be rigorously correct only when (N A = N D ), although this solution remains adequate for engineering purposes if 1.0 ≤ N A / N D ≤ 10.0, approximately. It is also shown that mechanisms of operation take place within an asymmetrical abrupt junction (N A ≥ N D ) that cannot be deduced from the depletion-layer aproximation. For example, the asymmetrical junction is shown to contain an electrostatic potential and an electric field at its metallurgical transition point that are essentially constant throughout a wide range of reverse biasing voltage. These characteristics imply that the total electrostatic charge within its p-type and n-type space charge layers remain essentially constant, and that its p-type space-charge layer is of constant width, despite the application of a reverse biasing voltage. These heretofore unreported mechanisms of operation arise from a layer of mobile charge carriers residing at the low-doped side of the metallurgical transition between n-type and p-type semiconductor material.

Electrophotographic exposure and development system

Abstract: Imaging means are provided to radiate a light image of an original document onto a photoconductive drum to produce an electrostatic image. A developing electrode is disposed adjacent to the drum and voltage source means apply a biasing voltage to the developing electrode. Sensing means sense the electrostatic potential of a background area of the electrostatic image and control the voltage source means in accordance therewith. Limiting means limit the biasing voltage to one of a first upper limit or a higher second upper limit. In order to improve the reproduction of low contrast documents, the exposure intensity is reduced to a value at which the difference in brightness of the light and dark areas of the document will produce a maximum difference in electrostatic potential on the drum. For normal documents, the biasing voltage is limited to the first upper limit. For low contrast, low density documents, the biasing voltage is limited to the second upper limit to prevent darkening of the light areas of the copy. For documents having low contrast and large dark areas, the biasing voltage is limited to the first upper limit so that the dark areas will be reproduced with high density.

Aging phenomena in a low‐temperature glass–ceramic capacitance thermometer

Abstract: On plunging a glass–ceramic capacitance thermometer into liquid helium or nitrogen, the capacitance decays slightly for about 30 min before stabilizing. This aging effect at 4.2 K corresponds to a drift of about 15 mK at 1 kHz measuring frequency. The effects of several parameters on this aging are investigated: encapsulation, lead‐wire material, measuring frequency and voltage, bias voltage, voltage application, and dip temperature. The aging appears to be due to a slow component of relaxation of the glass matrix surrounding the precipitated SrTiO3 microcrystals. Aging effects occur whenever the glass matrix is spatially perturbed, either by thermal expansion (above 77 K), or by electrostrictive coupling to the microcrystals following a voltage pulse, or by warming or cooling across the 65 K transition temperature. An application of the Devonshire phenomenological theory of polar dielectrics satisfactorily explains the salient features of the aging effect based on this delayed relaxation component.

Thermal input to substrate during deposition by hollow-cathode discharge

Abstract: Ag and Cr have been evaporated by a low−voltage, high−current electron beam from a HCD gun and deposited on a negatively biased substrate. The flux of Ag ions which strike the substrate was detected separately from Ag atoms, gas atoms, and ions of argon, as reported elsewhere. In the present study, calorimetric measurement of heat dissipated at the negatively biased receiving plane (substrate) shows that the major contribution to heat input comes from energetic neutrals rather than from metal ions; the contribution is, for example, 48% and 23%, respectively, of the total heat dissipated. The bias voltage, argon pressure, electron−beam voltage, beam current, and Ag deposition rate are −200 V, 0.75 mTorr, 45 V, 55 A, and 0.8 μ/min, respectively. Thick films of Cr deposited on steel sheets are evaluated as functions of substrate temperature and negative−bias voltage.

Coherent effects in series arrays of proximity effect superconducting bridges

Abstract: Planar series arrays of up to 500 proximity effect superconducting bridges have been fabricated with sufficient uniformity to respond coherently to incident radiation (10-20,000MHz) without separate biasing. By varying the geometry, resistance for the arrays can range from .1-50Ω. Despite this high total impedance, low frequency coherent response to external radiation is limited only by single bridge voltage noise. Low frequency (30-500MHz) coherent internal voltage oscillations of current biased arrays have been detected and confirm that the oscillating voltage signal grows linearly in bridge number while the voltage noise increases only as the square root. An array of n elements responds to incident high frequency radiation in first approximation as though it were a simple Josephson junction but quantized in units of n(h/2e). Coincident operation to high frequency depends strongly on small ( \leq 1\mu ) bridge separation. High resistance, coincident operation, and exponential dependence of critical current on temperature make these arrays good candidates for voltage standards, coherent and bolometric radiation detectors, and cryogenic rf sources.

Cascode FM tuner for a radio receiver

Abstract: An FM tuner having an improved automatic frequency control circuit and designed for use in an AM-FM receiver is described. The tuner employs a mixer transistor and an oscillator transistor connected in circuit so that they form a single series path across the bias source. This feature permits one to control conduction in both transistors by control of one and thus simplifies both biasing and mode conversion. Preferably, the transistor bias source and the source of AFC control potential are consolidated to save decoupling components. When the base of the mixer transistor is connected to the source through a low d.c. impedance, the AFC potential is transferred (less the mixer junction drop) to the collector of the oscillator transistor, where it provides sensitive automatic frequency control action. The circuit design uses a minimum of components.

Power switching control circuit with enhanced turn-off drive

Abstract: A transformer-coupled power switching device control arrangement utilizes an active feedback energy source connected to the primary of the coupling transformer to enhance the turn-off drive to the power switching device. The active feedback energy source produces an output directly dependent upon the magnitude of the power switching device output current and independent of the duration of said output current. When the output current drops to zero, the active feedback source is disabled, and a bias network is connected to the transformer primary. The bias network maintains a reverse voltage at the control electrode of the power switching device and establishes a bias current through the primary suitable for resetting the transformer core flux.

Regulated high voltage ac power supply with regulated d.c. bias current

Abstract: A circuit for concurrently producing regulated high voltage a.c. current and bias d.c. current on one output line, where all regulation is accomplished in low voltge circuits, power supply being particularly useful as the power source for copier and duplicator corotrons. The basic wave shape is a rectangular wave which is amplified and regulated for application as the a.c. input to a corotron. The corotron itself is used as the rectifier for the d.c. bias current, with this current being variable in either the positive or negative direction by varying the symmetry of the a.c. rectangular wave. Since the part of the wave which has the shorter duration must have the higher amplitude, and current in the corotron increases with voltage, a feedback loop which controls the rectangular wave duty cycle will regulate the d.c. bias current as well.

Sputter gas pressure and dc substrate bias effects on thick rf‐diode sputtered films of Ti oxycarbides

Abstract: Films 1–10 μ thick have been prepared by rf‐diode sputtering from targets of TiO0.5C0.5, TiO0.25C0.75, TiC, and TiN. These films were deposited on commercial, cobalt‐bound, cemented, complex‐carbide cutting‐tool inserts. The inserts were sputter etched immediately prior to sputter coating. This etch was found to be essential for obtaining good bonding. The sputtered films were prepared under various conditions of argon gas pressure ranging from 3 to 56 μ and substrate bias from 0 to −200 V dc. The sputtered materials exhibited similar microstructures under the same deposition conditions. In general, it was found that higher pressures and less negative biasing gave a ’’cauliflower’’ structure. Reducing the pressure and increasing the negative substrate bias produced more columnar films with less porosity but at a reduced deposition rate for constant power input. X‐ray diffraction analysis and Auger spectroscopic analysis of the TiO0.5C0.5 target and a sputter deposited film showed only a slight reduction i...

MOSFET circuitry with automatic voltage control

Abstract: An automatic voltage regulating system for an integrated circuit having a plurality of enhancement mode metal oxide semiconductor field effect transistors on a common semiconductor crystal, the regulation system including a group of series connected metal oxide semiconductor field effect transistors on the same crystal, wherein the combined threshold voltage of such regulating transistors forms a reference to control the bias voltage for the remaining transistors.

Fluid cooled commutated electric motor

Abstract: A commutated electric motor, which motor is cooled by the fluid which it pumps. The motor has a molded end cover construction, the material being the bearing material, and providing for guiding of the brushes. Torsion springs are utilized as the sole biasing means and current carrying members for the brushes. Also, the fluid is pumped along a closed channel structure and directed against the brushes to increase endurance.

Current-voltage characteristics of silicon metallic-silicide interfaces

Abstract: The general quantum and electronic theory of the metal-semiconductor contacts, proposed in previous works, is applied to silicon-metallic silicide interfaces in order to calculate their current-voltage characteristics. The analysis takes into account the actual potential profile due both to the semiconductor depletion layer and to the electric dipole created, around the metal-semiconductor interface (MSI), by the quantum mechanical tunneling of the metal free electrons into the semiconductor and by the metal conduction band bending. The current across the MSI, ascribed to the thermionic assisted tunneling, is calculated by taking into account the anisotropy of the effective masses, the many valley-structure of the semiconductor energy bands and the quantum mechanical reflection and tunneling through the energy barrier by means of the generalized transmission probability of Kemble. The results shown by the analysis, which excludes explicity the image-force lowering of the energy barrier height, are the reduction of the height and width of the barrier itself and (hence) the increase of its “transparency” to the thermionic current produced by the increase of the reverse bias voltage and/or of the semiconductor impurity concentration. The effects of such properties of the energy barrier on the current-voltage characteristics of the MSI are the absence of a true reverse saturation current, an ideality factor n greater than 1 and a value of the energy barrier height, deduced from the forward current-voltage characteristics, lower than that true and than that obtained from the measured of the junction capacitance vs the bias voltage. The analysis, applied to interfaces between n -type silicon and the metallic silicides RhSi, ZrSi 2 , PtSi and Pd 2 Si, yields numerical values which agree well with the experimental ones obtained by several authors on the same contacts which, when it is necessary to eliminate field-enhancement at the electrode periphery and leakage currents, incorporate a guard ring. Effectively such a guard ring and the absence of intervening layers of oxide and of other contaminants in the silicon-metal silicide contacts allow one to acquire experimental data more easy to interpret quantitatively than those relative to other contact types.