High-voltage GaAs diodes with subnanosecond gate voltage recovery

High-voltage GaAs switching diodes with subnanosecond characteristic times of reverse current decay on switching from forward to reverse bias were studied. The diode structures studied had impurity concentration profiles in the base region close to those of the charge-storage diodes and operated in the regimes corresponding to those employed in silicon-based high-voltage fast-recovery drift diodes. The application prospects of the proposed GaAs diodes are demonstrated, for example, in the devices generating pulses with a front width of several hundred picoseconds, a current of several hundred amperes, and a voltage of a several kiloelectronvolts at a frequency of up to several hundred kilohertz.     

Cryogenic liquid level monitor using a frequency to voltage converter

A simple cryogenic liquid level monitor based on a frequency-to-voltage converter is described. The monitor is simple to construct and its design obviates the need for special techniques to eliminate the effects of stray capacitance. It has excellent linearity, high sensitivity, and uses a simple two-terminal capacitance probe.     

Dynamic voltage restorer based on a four-leg voltage source converter

Analysis and control of a dynamic voltage restorer are described. The voltage restorer is based on a four-leg voltage source converter. The three-phase input variables are resolved into the positive, negative and zero-sequence components using a weighted, recursive, least-squares estimator. Identical controllers have been used for each sequence component. A laboratory model of the restorer has been constructed and its performance has been tested by simulation and experiments.     

Dc-to-Dc converter using inductive-energy storage for voltage transformation and regulation

A nondissipatively regulated dc-to-dc converter that operates very efficiently at high frequencies is presented. The circuit is characterized by a small number of power handling components, many of which perform multiple duties. Only one power transistor is used, and the characteristics of the main power handling magnetic element of the circuit are such that this element is not only able to provide voltage transformation but also to perform certain filtering functions which in conventional converters normally require a separate filter inductor. Two different methods of nondissipative closed-loop regulation are presented-one involving control of the duty cycle of the power switch, and the other involving magnetic-amplifier control of the average output current. Certain design considerations are presented, and a test circuit is described.     

A method of obtaining the radiation modulation function in an optoelectronic digital angle converter using a radon transform

A method of obtaining the radiation modulation function in the optical channel of practical optoelectronic digital angle converters using the apparatus of analytical geometry together with a local radial Radon transform is considered. The majority of the instrumental errors that arise when manufacturing and assembling the optomechanical unit are taken into account. The method can be extended to a wide class of optical coding devices and has practical applications.     

Fabrication of high breakdown voltage silicon Schottky barrier diodes using various edge termination structures

In this work, the design and fabrication of Au/n-Si Schottky barrier diodes (SBDs) with various edge termination schemes, including a reduced-surface-field-type lateral super-junction, a polycrystalline silicon (poly-Si) floating ring, and a p⁺-poly-Si guard ring, are presented. Experimental results show that the reverse leakage current of the proposed SBDs was reduced and the breakdown voltage increased with an increase of the poly-Si width of the guard ring.It was found that the device and fabrication technology developed in the present study is applicable to the realization of SBDs with a high breakdown voltage (≥ 160 V), a low reverse current density (≤ 5.6 μA/cm²), a low forward voltage drop (≤ 5.6 V @ 1 A/cm²), and an adjustable Schottky barrier height of 0.764 to 0.784 eV.     

Toward a free-space parallel optoelectronic computer: a 300-MHz optoelectronic counter using holographic interconnects

We built and tested one of the key components of a free-space holographically interconnected stored-program optoelectronic computer: a counter. The counter is constructed with 1-ns-latency optoelectronic NOR gates and is interconnected with holographic optical elements. Two synchronization methods were also demonstrated: the gate-and-strobe method and the time-of-flight method. These counters represent prototypical optoelectronic finite-state controllers. They were developed to demonstrate the feasibility of providing optoelectronic controllers for optoelectronic processors.     

Analysis of the structural parameters of an a-Si : H n+-i-n+ structure by numerical simulations

In this study, we discuss measurements of the J–V characteristics of an a-Si : H n⁺-i-n⁺ structure, and the results of numerical simulation using the AMPS-1D simulation program. Application of the AMPS simulation model to the sample structures considered allows us to determine the structural properties of the a-Si : H n⁺-i-n⁺ structure. The one-dimensional simulation program was examined in n⁺-i-n⁺ structures with different qualities and thicknesses of the i-layer. We find that the n⁺/i interface is more abrupt for a device with a high density of states (DOS), resulting in high values of the activation energy (E _act). In contrast, thin samples of good quality (low DOS) give low values of E _act. Analysis by numerical modeling confirms the experimental results.     

Error analysis of a symmetrical converter R-2R with a voltage source

Conclusions The error of a symmetrical converter R-2R is greater than that of an unsymmetrical converter.To reduce converter error owing to a nonideal switch it is required that the digit resistors have a positive error and the weight resistors negative error. Then the factor leads to a reduction of the node voltages and an increase in the transfer coefficient. The resulting error will be positive.Nonideal switching transistors result in negative error.Translated from Izmeritel'naya Tekhnika, No. 3, pp. 52–53, March, 1971.     

Optoelectronic measurement of voltage pulse repetition frequency bypicosecond laser diodes

Based on the indirect electro-optic sampling technique, we have designed and tested an optoelectronic frequency meter by using a picosecond gain-switched laser diode. It is the first step towards the construction of a sampler frequency meter for the nondestructive characterization of ultrafast electronic signals     

Evaluation of low-frequency AC-DC difference of coaxially mountedthermal voltage converter

The paper describes results of measurements of AC-DC transfer difference of a coaxially mounted, thermal voltage converter. Results of experiments, conducted in the 1 kHz to 1 MHz frequency range, are compared with results of simulations, using a simplified model of the converter. AC-DC transfer difference contributions, originating in the input connector and elements of the coaxial enclosure, are presented     

The effect of the molecular structure on the optoelectronic properties of a fluorophore for use in organic light-emitting diodes

A novel yellow light-emitting material, (2Z)-3-[4,4"-bis(dimethylamino)-1,1':4',1"-terphenyl-2'-yl]-2-phenylacrylonitrile (BDAT-P), having the modified molecular structure from red fluorescent compound, (2Z, 2'Z)-3,3'-[4,4"-bis(dimethylamino)-1,1':4',1"-terphenyl-2',5'-diyl]bis(2-phenylacry-lonitrile) (ABCV-P), was synthesized in order to study the effect of the molecular structure on the optoelectronic properties of a light-emitting material. UV-visible absorption and photoluminescence (PL) emission peaks measured in various solvent systems were summarized in Table I. In the respective solvent system, the bathochromic shift of PL emission peak relative to the peak of UV-visible absorption was much larger for ABCV-P with two electron donor-acceptor pairs than for BDAT-P with one electron donor-acceptor pair. EL emission peaks of devices using BDAT-P and ABCV-P as the host emitters measured to be 573 and 613 nm, respectively. Commission Internationale de l'Eclairage (CIExy) coordinate of device using BDAT-P was measured to be (0.4855, 0.5021) at 7 V, which was correspond to the yellow color.     

反激变换器输出纹波电压分析与测量

针对反激变换器输出纹波电压比较大的缺点,分别分析了连续电流模式(CCM)、断续电流模式(DCM)的能量传输过程,并通过能量传输过程中反激变压器次级线圈电流和输出电容电压之间的关系,从根本上得出了反激变换器纹波产生的机理;对于纹波测量,总结出了三种正确的测量方法,并介绍了各种测量法的相关测量装置及相应注意事项,简述了EIAJ-RC9002A测量标准。实验测量表明,采用同轴电缆法测量纹波电压正确可行。     

Analysis and design of a single-phase AC/DC step-down converter for universal input voltage

This work presents a single-phase AC/DC step-down converter, which is composed of two power stages, buck-boost converter and buck converter. The front stage is used for a power-factor-correction (PFC) circuit and is operated in discontinuous conduction mode (DCM) by using the pulse-width modulation (PWM) technique to achieve almost unity power factor and low total harmonic distortion of input current (THD_i). The rear stage is also operated in DCM to achieve voltage step-down and low DC-link voltage. The proposed converter can be applied for universal input voltage (85-265 V) and wide output power range. Also, the steady-state analysis of voltage gain and boundary operating condition are presented. Moreover, the selections of inductors, capacitors and input filter are depicted. Finally, a hardware circuit with simple control logic is implemented to illustrate the theoretical analysis.     

Multilayer light emitting diodes using a PPV based copolymer

We have investigated the electrical and optical properties of poly((2,5-(dimethoxy) p-phenylene vinylene)-p-phenylene vinylene) (PDMeOPV/PPV) copolymer used as an emitting layer in light emitting diodes. With p-phenylene vinylene (PPV) used as a hole transport layer and polyphenylquinoxaline (PPQ) as an electron transport layer, the emission intensity of the devices has substantially increased without alteration of the transport property. The different conduction mechanisms in the diodes were examined and discussed in terms of the energy band diagrams of the polymer layers. A balance of the injected charge carriers confined in the copolymer could explain the enhancement of the performance of the multilayer diodes.