Electronic Filter Research Articles

Solar-blind AlxGa1−xN/AlN/SiC photodiodes with a polarization-induced electron filter

Heterogeneous n-III-nitride/i-p silicon carbide (SiC) photodetectors have been demonstrated that enable the tailoring of the spectral response in the solar blind region below 280 nm. The negative polarization induced charge at the aluminum gallium nitride (AlxGa1−xN)/aluminum nitride (AlN) interface in conjunction with the positive polarization charge at the AlN/SiC interface creates a large barrier to carrier transport across the interface that results in the selective collection of electrons photoexcited to the Γ and L valleys of SiC while blocking the transport of electrons generated in the M valley. In addition, the AlxGa1−xN alloys act as transparent windows that enhance the collection of carriers generated by high energy photons in the fully depleted SiC absorption regions. These two factors combine to create a peak external quantum efficiency of 76% at 242 nm, along with a strong suppression of the long-wavelength response from 260 nm to 380 nm.

Main Circuit Parameter Design of Permanent Magnetic Direct-Drive Wind Power Generating System

Design method of main circuit parameter based on theoretical calculation and engineering practice is developed for permanent magnetic direct-drive wind power generating system with dual PWM converter topology. DC bus voltage, DC bus filter capacitor, rating value of power electronic devices and gird-side LCL filter parameters are calculated for an experimental wind power generating system. Hardware platform is built using calculated parameters, and the experimental results show that the design method is viable and expected design goal is achieved.

Efficient band-pass and stop-band filtering by GaAs–Al c Ga1− c As generalized Thue–Morse multibarrier systems

The influence of Al concentration and barrier width on the transmission spectra in GaAs–Al c Ga1− c As heterostructure is studied for two different kinds of the generalized Thue–Morse multibarrier systems (GTMS). These structures provide interesting filter properties with regard to effective band-pass or stop-band (of extremely low width) circuitry. The first kind of GTMS is suitable for application as a band-pass electronic filter, while the second kind as stop-band filter. High Al concentration and large barrier width result in sharp resonances in the transmission spectrum.

Main Circuit Parameters Design in Permanent Magnetic Direct-drive Wind Power Generating System

A novel design method of main circuit parameters based on theoretical calculation and engineering practice is developed for permanent magnetic direct-drive wind power generating system which uses back-to-back PWM converters. DC bus filter capacitor, DC bus voltage, rated voltage and current value of power electronic devices and gird-side LCL filter parameters are calculated for an experimental wind power generating system. A hardware platform is built using devices with calculated parameters, and the experimental results show that the design method is viable and expected design goal can be achieved.

Advances in Novel Diagnostic Endoscopic Imaging Techniques in Inflammatory Bowel Disease

The description and grading of inflammation seen at endoscopic evaluation in inflammatory bowel disease (IBD) are based on conventional white light endoscopy in an era using normal definition endoscopes. The new generation of high-definition endoscopes with electronic filter technology provides an opportunity to visualize mucosal inflammation in more details. The application of these new technologies in IBD is in its infancy, but the added value is beginning to be appreciated. Both the assessment of dysplasia and the assessment of inflammation may gain from use of high-definition endoscopy with filter technology. In addition, the advent of confocal laser endomicroscopy provides an opportunity to explore real-time histology, thus (perhaps) redefining our understanding of pathogenesis and nature of inflammation in IBD. We review the potential of these techniques to transform diagnostic endoscopic assessment of inflammation and dysplasia.

ADJUSTMENT OF ACOUSTIC PROPERTIES BASED ON PROXIMITY DETECTION

One or more acoustic transducers of a device may be adjusted based on automatic detection of device proximity to the user. In a mobile telephone, when the user is using the receiver and holding the telephone against his/her ear, if the telephone detects that the user has moved the telephone further from his/her ear, the telephone will raise the receiver volume. Similarly, if the user is using the speaker, the telephone will adjust the speaker volume as user distance from the telephone changes. In another embodiment the telephone may fade between the receiver and the speaker. Volume is not the only acoustic property that could be adjusted according to user proximity. Frequency response is another property that could be adjusted, such as using appropriate electronic filtering, or by turning on another transducer that is not otherwise being used.

Analog filter diagnosis using the oscillation based method

Oscillation Based Testing (OBT) is an effective and simple solution to the testing problem of continuous time analogue electronic filters. In this paper, diagnosis based on OBT is described for the first time. It will be referred to as OBD. A fault dictionary is created and used to perform diagnosis with artificial neural networks (ANNs) implemented as classifiers. The robustness of the ANN diagnostic concept is also demonstrated by the addition of white noise to the “measured” signals. The implementation of the new concept is demonstrated by testing and diagnosis of a second order notch cell realized with one operational amplifier. Single soft and catastrophic faults are considered in detail and an example of the diagnosis of double soft faults is also given.

Improved Particle Swarm Optimization (PSO) for Performance Optimization of Electronic Filter Circuit Designs

This article discusses and analyzes particle swarm optimization (PSO) approach in the design and performance optimization of a 4th-order Sallen Key high pass filter. Three types of particle swarm features are studied: basic PSO, PSO with regrouped particles (PSO-RP) and PSO with diversity embedded regrouped particles (PSO-DRP). PSO-RP and PSO-DRP are proposed to solve the stagnation problem of basic PSO. Based on the developed PSO approaches, LTspice is employed as the circuit simulator for the performance investigation of the designed filter. In this paper, 12 design parameters of the Sallen Key high pass filter are optimized to satisfy the required constraints and specifications on gain, cut-off frequency, and pass band ripples. Overall results show that PSO with diversity embedded regrouped particles improve the conventional search of basic PSO and has managed to achieve the design objectives.

Design of multichannel electronic wave filters with each channel energy and bandwidth adjustable independently

We propose a simple method to design multichannel electron wave filters based on graphene superlattices with one-dimensional periodic potentials, which can choose not only the peak energy of each channel but also the bandwidth independently. This method is described by two samples for the design of two-channel, three-channel filters. Additional defects are introduced symmetrically into the superlattices, then modes are generated, which overlap with the channels that need to tune. These defects make the bandwidth of a certain channel increased without location shifted, while the other channels almost keep constant. The corresponding electronic devices may benefit from this method.

Spintronic mechanics of a magnetic nanoshuttle

We investigate theoretically the prospects for using a magnetic nanoelectromechanical single-electron tunneling (NEM-SET) device as an electronic spin filter. We find that strong magnetic exchange forces on the net spin of the mobile central dot of the NEM-SET structure lead to spin-dependent mechanical displacements ("spin polarons"), which give rise to vastly different tunnelling probabilities for electrons of different spin. The resulting spin polarization of the current can be controlled by bias and gate voltages and be very close to 100% at voltages and temperatures below a characteristic correlation energy set by the sum of the polaronic and Coulomb blockade energies.

A General Strategy to Superstructured Networks and Nested Self-Similar Networks of Bismuth Compounds

We have reported the synthesis of superstructured nanonetworks of BiOCl and nested nanonetworks of Bi(2)S(3) in a series of lattice-directed topotactic transformations [C. F. Guo et al. J. Am. Chem. Soc. 2011, 138, 8211-8215]. Here we extend the transformations to a much broader system including ordered nanowall networks of BiOCl, BiOBr, Bi(2)O(2)CO(3), β-Bi(2)O(3), and Bi(2)S(3), as well as nested self-similar networks of Bi(2)S(3) and amorphous BiO(x). We suggest even more superstructured networks and nested self-similar networks of bismuth compounds with a lattice parameter of ~2(n/2) × 3.9 Å (n = 0, 1, 2, 3, 4), might also be obtained. The superstructured networks and nested networks are novel architectures that may find applications in electronic devices, sensors, filters, and photocatalysts.

Tunable Optoelectronic Oscillator Incorporating a High-Q Spectrum-Sliced Photonic Microwave Transversal Filter

A tunable optoelectronic oscillator implemented employing a high-Q-factor spectrum-sliced photonic microwave transversal filter without using any electronic microwave filters is proposed and experimentally demonstrated for the first time to our knowledge. The high-Q-factor photonic microwave transversal filter is implemented using a sliced broadband optical source and a dispersive element, to perform frequency-tunable microwave frequency selection. The central frequency of the microwave filter is a function of the wavelength spacing of the sliced optical source and the chromatic dispersion of the dispersive element. Therefore, the oscillation frequency can be tuned by changing either the channel spacing of the sliced broadband optical source or the chromatic dispersion of the dispersive element. A proof-of-concept experiment is performed. An optoelectronic oscillator with a tunable frequency range of 9.7 GHz is achieved. The generated microwave signal exhibited a good phase noise performance with a phase noise of -120 dBc/Hz at an offset of 10 kHz.

Horizontal-parallax-only Optical Scanning Holography with an Electronic Low-pass Filter

We propose a novel technique that records the horizontal-parallax-only (HPO) hologram of a real object using optical scanning holography (OSH). The proposing HPO-OSH is composed of a conventional OSH and an electronics low pass filter. When we scan an object along vertical direction before horizontal direction, the electronic low pass filter filters the vertical fringes with preserving horizontal fringes and gives an HPO hologram. To the best of our knowledge, this is the first time to record the HPO hologram using OSH without either truncation of the scanning beam or digital post processing.

Electronic Energy Band and Transport Properties in Monolayer Graphene with Periodically Modulated Magnetic Vector Potential and Electrostatic Potential

We investigated the electronic energy band and transport features of graphene superlattice with periodically modulated magnetic vector potential and electrostatic potential. It is found that both parallel magnetic vector potential and electrostatic potential can decisively shift Dirac point in a different way, which may be an efficient way to achieve electron or hole filter. We also find that applying modulated parallel and anti-parallel magnetic vector potential to the electrons can efficiently change electronic states between pass and stop states, which can be useful in designing electron or hole switches and lead to large magneto-resistance.

Side-dependent electron escape from graphene- and graphane-like SiC layers

The structural and electronic properties of SiC-based two-dimensional (2D) crystals are studied by means of density functional theory and many-body perturbation theory. Such properties cannot simply be interpolated between graphene and silicene. The replacement of half of the C atoms by Si atoms opens a large direct electronic gap and destroys the Dirac cones. Hydrogenation further opens the gap and significantly reduces the electron affinity to 0.1 or 1.8 eV in dependence on the carbon or silicon termination of the 2D crystal surface, thus showing a unique direction dependent ionization potential. This suggests the use of 2D-SiC:H as electron or hole filter.

Determination of Sugar Content in Sugar Solutions using Interdigital Capacitor Sensor

A novel low-cost electronic tongue system for sugar content determination in sugar solutions is proposed. The system consists of a sine wave generator, a resistor, and an interdigital capacitor sensor forming a first-order electronic high-pass filter circuit. The interdigital capacitor sensor has the planar interdigital structure and the consecutive fingers are connected to positive and negative electrodes. The system has been assembled and the experiments were conducted. The experimental results show that the proposed system has a great potential to determine the sugar content in sugar solutions. It also provides an opportunity for the development of a microcontroller-based low-cost sensing system as an electronic tongue system.

Nanofibers: Effective Generation by Electrospinning and Their Applications

Electrospinning is the most versatile technology in use today, for the generation of polymer nanoscale fibers. The nano materials generated using this technology have a large surface area and are highly porous making it very useful in many applications in diverse fields such as energy storage, healthcare, biotechnology, environmental engineering, defense and security. The production of the fibers and the morphology can be easily controlled by modifications to the processing parameters. The relatively high production rate and simplicity of the setup makes electrospinning highly attractive. This review summarizes the effect of various processing parameters on the effective generation of nanofibers. By simple modifications to the electric field inside the electrospinning chamber the fiber collection can be easily controlled. In addition, the various applications of electrospun fibers in electronic devices, environmental sensors and filters, energy storage, and in biomedicine such as in tissue engineering, drug delivery and enzyme encapsulation are examined and the current research in each field is also explored in this review.

Solving medical problems with BioMEMS.

A routine laboratory exercise for an undergraduate electrical engineering student is to build a simple electronic filter circuit and determine its frequency and transient response. During the exercise, the student exposes the circuit to a range of electrical signals and captures the voltage and current characteristics. The relationship between what the circuit is exposed to and how it responds allows for developing a transfer function that provides insight into how the circuit operates.

Investigation of Shielding Effectiveness Caused by Incident Plane Wave on Conductive Enclosure in UHF Band

Electromagnetic compatibility is achieved by reducing the interference below the level that disrupts the proper operation of the electronic system or subsystem. This compatibility is generally accomplished by means of electronic filters, and component or equipment shielding. Shielding an electromagnetic field is a complex and sometimes formidable task. The reasons are many, since the effectiveness of any strategy or technique aimed at the reduction of the electromagnetic field levels in a prescribed region depends largely upon the source (s) characteristics, the shield topology, and materials. In this paper, the effect of an incident plane wave with linear polarization on aluminum shield in UHF frequency is investigated, then, the type of shield material is changed and shielding effectiveness caused by it is investigated. Also, the linear polarization of incident wave is converted to circular polarization and shielding effectiveness variation is obtained in this stage. Slots and apertures are very important parameters to determine suitable shielding effectiveness. In following paper, slot is placed on shield, and its shielding effectiveness is evaluated. The effects of slot width variation, slot length variation and slot displacement, on shielding effectiveness are investigated. Finally, the effect of different aperture structure is evaluated and shielding factor is obtained in any stage. The whole of simulations in this paper, are done with CADFEKO.

Bacterial riboswitches

This wikipedia entry provides an extensive description of natural and engineered riboswitches. Most known riboswitches have been found in bacteria. This webpage provides a link to an electronic thesis file describing a riboswitch that responds to the herbicide atrazine. This web article discusses synthetic riboswitches. These are tools that researchers can use to control bacterial metabolism. The development of synthetic riboswitches requires the ability to screen aptamers for the ability to bind molecules of interest. The use of the method to develop a riboswitch for the natural product theophylline is described. This page contains an extensive list of references related to ribozymes and riboswitches. On and off riboswitches were deployed in tandem to produce regulation that mimics an electronic band-pass filter. This web article describes modeling for the effective design of synthetic riboswitches. This page provides a good overview of riboswitches and has useful graphics. This blog page provides a discussion of a paper and a good overview of riboswitches. This page contains an extensive list of references on mostly natural riboswitches. This page contains a patent on riboswitches. As described, riboswitches can be used to make biosensors, engineer metabolism and carry out gene therapy. A ribozyme has been explored to block bacterial resistance to beta-lactam antibiotics. This Facebook page describes ribozymes that recognize purine nucleotides. There are links to Protein Databank files to these ribozymes. This database allows one to screen sequences for potential function as ribozymes. This description of bacterial riboswitches is from the Microbe blog. Links to additional information are provided. This page provides a link to a thesis describing novel functions of riboswitches. With widespread genome sequencing, more types of riboswitches are being identified in bacteria. This link is to a lecture on riboswitches.