Current Transfer Ratio Research Articles

Structural Effects on Electromagnetic Flow Coupler Performance

A prototype electromagnetic flow coupler was tested using 300°C liquid sodium to estimate the effect on performance of generator flow velocity, magnetic flux density, magnetic core length and bus bar length. Its performance was not affected by changes in fluid velocity and magnetic flux density up to 8.3 m/s and 0.51 T, respectively. Besides the experiments, a two-dimensional numerical analysis program based on Ohm's law and the current continuity equation was prepared to estimate the effects of magnetic core length and bus bar construction. The current transferred from the generator to the pump, the current transfer ratio, increased by lengthening the magnetic core being a maximum of 0.706 for a 100 mm core and 0.764 for a 300 mm core. The numerical results showed that the presence of the bus bar in the outer region of the magnetic core gave inferior performance to that in its absence.

Optocoupler based on the avalanche light emission in silicon

The photon emission in silicon light-emitting diodes is very inefficient, due to the indirect bandgap. Moreover the photon energy of 1.1 eV, which equals the bandgap, is outside the visible part of the spectrum and is not sufficient to generate electron-hole pairs in a silicon photodetector. When used in avalanche mode, the emission spectrum covers the visible range and the range where silicon photodetectors show high sensitivity. Therefore, silicon integrated displays and silicon integrated optical devices, such as optocouplers can be realized. When used in an accurate analog optocoupler circuit, the low efficiency of the current transfer ratio of the optocouplers makes the design of the electronic circuit more difficult. However, a circuit of an input stage of an isolated amplifier is given using an optocoupler based on the avalanche light emission in silicon.

New methods of synthesizing transfer functions by applying CCIIs

Abstract Many methods of synthesizing voltage transfer ratios and current transfer ratios have been suggested, but few people have considered transfer immittances which are sometimes important. Simple methods are presented here to synthesize given transfer immittances and current transfer ratios using voltage transfer ratios. The functions used are rational. Similarly, simple methods are proposed to synthesize given voltage transfer ratios and the transfer immittances using current transfer ratios.

Structural Effects on Electromagnetic Flow Coupler Performance.

A prototype electromagnetic flow coupler was tested using 300°C liquid sodium to estimate the effect on performance of generator flow velocity, magnetic flux density, magnetic core length and bus bar length. Its performance was not affected by changes in fluid velocity and magnetic flux density up to 8.3 m/s and 0.51 T, respectively. Besides the experiments, a two-dimensional numerical analysis program based on Ohm's law and the current continuity equation was prepared to estimate the effects of magnetic core length and bus bar construction. The current transferred from the generator to the pump, the current transfer ratio, increased by lengthening the magnetic core being a maximum of 0.706 for a 100 mm core and 0.764 for a 300 mm core. The numerical results showed that the presence of the bus bar in the outer region of the magnetic core gave inferior performance to that in its absence.

Application of superlattice bandpass filters in 10 μm infrared detection

Recently, experimental evidence has revealed that the energy distribution of the dark current in a typical multiple quantum well GaAs infrared detector is extremely broad, in contrast to the narrowly distributed photocurrent. In this letter, we present the current transfer ratio of an infrared hot-electron transistor with a superlattice collector filter. From the current transfer characteristics, we demonstrate that the superlattice is able to collect electrons with specific energy against a broad background. The energy filtering characteristics can be attributed to the underlying band structure of the superlattice. When the filter is applied to infrared radiation detection, the detectivity of the transistor is improved.

Mutual drag of 2D and 3D electron gases in heterostructures

The GaAs AlGaAs semiconductor insulator semiconductor (SIS) structure used for high-performance field effect transistors has also been used in the study of parallel coupled transport between electrons in the FET n + gate (3D) and channel (2D). At temperatures above 50K the predominant coupling involves momentum transfer via Coulomb Mutual Scattering (CMS). At lower temperatures the sign of the coupling reverses and the results may be explained as a CMS mediated thermo-electric effect. The coupling is much stronger for a 2D - 2D EG configuration, where a maximum current to current transfer ratio of 6 × 10 −4 was obtained. Theory developed for this case predicts a temperature dependence of μ 1 μ 2 T where μ 1 and μ 2 are the mobilities in the gate and channel respectively, and an inverse fifth power thickness dependence.

Pseudomorphic InGaAs base ballistic hot-electron device

We report the first successful incorporation of a pseudomorphic InGaAs base in a ballistic hot-electron device. The device, with a 28-nm-thick In0.15Ga0.85As base, had a collector-base breakdown voltage of 0.55 V and a maximum current transfer ratio of 0.89 at 4.2 K, considerably higher than the 0.75 in a comparable GaAs-base device. Electron energy spectroscopy measurements revealed that at least 30% of the injected electrons traversed the InGaAs base ballistically, causing a strong modulation in the injected currents into the quantized base. The Γ-L valley separation in the strained In0.15Ga0.85As was estimated to be about 410 meV.

Integrable electronically tunable current conveyors

A generalised current conveyor, termed an electronically tunable second-generation current conveyor (ECCII), whose current-transfer ratio can be varied by electronic means, is introduced. A method is proposed for realising ECCII in monolithic integrated form providing both a positive and a negative ECCII in the same circuit. Experimental and simulation results demonstrating the circuit performance are included. Some simple applications which show that their circuit property can be varied by electronic means are also presented.

A bilateral optocirculation circuit with three ports

A bilateral circulation circuit using LED-photodiode optoisolators is proposed. It is revealed theoretically and experimentally that bilateral and circular transmission is achieved by the enhancement of the current transfer ratio through optoelectronic positive feedback loops. Since the feedback loops are dispersed among three ports, it is possible to get circular signals in and out of optional ports. This circuit has stable positive gain and stable coupling efficiency because of optoelectronic feed-forwards. The bilateral frequency responses of gain extend over several hundred kilohertz.

Current-controlled translinear IPIC

A translinear positive impedance converter (IPIC) is described. Its voltage transfer ratio is unity, and its current transfer ratio is controlled by two static currents.

Dc performance of ballistic tunneling hot-electron transfer amplifiers

We present new experimental results of ballistic electron transport through thin n+-GaAs layers. Measurements were done on tunneling hot-electron transfer amplifier devices composed of GaAs and AlGaAs layers. In devices with GaAs active regions (bases) of 300 and 800 Å, collisionless or ballistic transport was observed. By performing hot-electron energy spectroscopy we found that the collected ballistic distributions were similar in shape but differed in magnitude. This suggests the existence of a strong scattering mechanism which randomizes the otherwise ballistic electrons. The maximum differential current transfer ratio α was 0.9 in devices for which about 75% of the injected current traversed the base ballistically. The presence of ballistic transport has also allowed the measurement of the AlGaAs barrier height through observation of the onset of current collection in the devices. Barrier heights higher than those recently reported have been measured. In addition we show the effects of grading the collector barrier. The most noted effect in these cases was a higher transfer ratio.

A current conveyor II realized by Mosfets and its application to switched capacitor filters

AbstractFrom the viewpoint of intergration, a MOSFET configuration is superior to the previous current conveyors (CC) consisting of an operational amplifier and/or bipolar transistorsIn this paper, a current conveyor II (CC II) is composed of an operational amplifier and MOSFETs. It was clarified that the current transfer ratio from X terminal (input) to Z terminal (output) of CC II can be put to variable Ki., not to 1, because the MOSFET is a voltage‐controlled device. As a case of application, a switched capacitor (SC) integrator is realized with our proposed CC II and its transfer characteristic is studied theroretically and experimentally. Then, by applying this SC integrator to a Biquard‐type bandpass switched capacitor filter (SCF), it turned out that the electric capacitor of the SCF can be reduced largely and the SCF integration is superior in this regard.

Inverted base-collector tunnel transistors

Two novel three-terminal devices based on tunneling in quantum well and quantum barrier heterostructures are proposed and analyzed theoretically. In both devices, the relative positions of the base and collector are interchanged from conventional emitter-base-collector sequence. This provides a means for obtaining negligible base currents and large current transfer ratios. In both cases, a base voltage controls the emitter-collector tunneling current by shifting the resonances in a quantum well. Calculations indicate that significant variations in the emitter-collector current-voltage characteristics can be obtained for reasonable base-emitter voltages. We call the two devices a Stark effect transistor and a negative resistance Stark effect transistor, respectively.

Bilateral optoisolator amplifier with multiple feedback loops

A bilateral amplifier using photodiode-type optoisolators is proposed. It has sufficient gain for use in telecommunication equipment, achieved by enhancement of the current transfer ratio through multiple optical feedback loops. It is clear from experimental and theoretical results that the positive gain increases with the feedback multi-factor n, and that a gain of 20 dB can be obtained for n = 6.

A floating NIC without constraint and its application

A floating negative immittance converter (NIC) with two current conveyors (CC) and without any passive parameters has been presented. The nonequality in the current transfer ratios of the current conveyors has been shown to be compensated for by the addition of a single resistor. An application of the NIC to realize a lossless floating inductor has also been demonstrated. An approximate practical realization scheme of the NIC is appended with results.

Modified current mirror with a ‘voltage-following’ capability

A negative current mirror suitable for monolithic IC fabrication is described. It is unusual in that it is a ‘voltage-following’ circuit in which the input-output offset voltage is small and only weakly dependent on operating conditions. A base-current compensation scheme enables the circuit to exhibit a current transfer ratio comparable with that of the ‘Wilson’ current mirror.

The diffusion of hot electrons across a semiconductor base

A theoretical description of the diffusion of electrons injected at energies much greater than optical or inter-valley phonon energies into a semiconductor and their collection over a semiconductor-semiconductor barrier is given. Energy loss is assumed to be solely by collisions with high frequency phonons via the deformation-potential interaction, and specific solutions of the Boltzmann equation are obtained for a delta-function injection and parabolic bands. Application of the theory to silicon gives useful current-transfer ratio base widths of 150 Å and less, and the effect of quantum-mechanical reflection is found to be relatively unimportant. The results for the current-transfer ratios are dependent on non-parabolicity in the conduction band of silicon, and a model for the latter is described. An effective attenuation length of 360 Å is predicted for silicon. The distribution function for hot electrons should reflect the variation of density-of-states in the conduction band.

Highly Photo-Sensitive Diodes (SnO2 and In2O3–Si) and Their Applications

When a transparent SnO2 and In2O3 layer was used to make heterojunctions with Si, highly sensitive photo-diodes for weak visible light were obtained. Optical and electrical characteristics of these diodes have been investigated for to a photo-coupler and an electronic spectroscope. Connecting these diodes to a photo-coupler combined with a light-emitting diode, an improved current transfer ratio (CTR) of the photo-coupler compared to those of commercially available ones was achieved. In the application to the spectroscope, a photo-diode array was installed in place of the dry plate of the spectroscope, and a spectrum of the light source was obtained instantaneously on a cathode-ray tube using an IC multiplexer.

Linear signal transmission with optocouplers

Until now, optocouplers have not been considered very suitable for linear, isolating circuits, owing to their nonlinearity in the current transfer ratio. In this paper, a circuit for linear signal transmission consisting of a pair of optocouplers in a feedback arrangement is analyzed. The nonlinearity of the optocouplers is practically eliminated by using coupler pairs with good tracking in their transfer function. This paper analyzes the distortion and gain of such a circuit as a function of linearity tracking, modulation index, and LED-DC-bias level. Measurements reported in this paper show that with a linearity tracking of only 10 percent, stringent distortion requirements such as for analog signal transmission in telephony can be fulfilled. The circuit achieves a distortion of 0.5 percent based on a 10 percent linearity tracking at a modulation index of 0.2 and the temperature stability of the gain is -0.09 percent//spl deg/C.

Negative current-mirror using n – p – n transistors

The interconnection of an operational amplifier and an n–p–n transistor array facilitates the design of a negative-current mirror that avoids the use of p–n–p devices. For an input current in the range 1 μA–1 mA, current transfer ratios that differ from unity by less than 0.3% are achievable. The incremental output resistance is inversely related to the operating current, and exceeds 10 Mω at 1 mA.