High-Order Lowpass Filters Using DVCC Elements

Special cells using a differential voltage current conveyor are presented. The use of these cells for high-order lowpass filter design is described. The filters can be designed to operate in different modes

New families of voltage-mode and current-mode filter circuits.

In some previous papers, feed forward configurations of realizing second order all pass transfer functions with complex poles by adding some configurations to a first order circuit are discussed. In this dissertation, the above idea extended to realize some other basic second order complex pole filter transfer functions. A new corollary for circuit conversion is proposed and proved. This corollary is useful for converting op amp based voltage-mode circuits to their CCII based equivalent circuits, as are other existing theorems. But the new corollary is useful for converting circuits that cannot be converted by other theorems

Fractional-Order Asymptotical Phase Shifter With Flat Magnitude Response

This work deals with design of fractional-order asymptotical phase shifter having constant magnitude response within almost three decades (100 Hz – 100 kHz) and frequency dependent phase difference going from 0 to 45 degrees. PSpice simulations employing macromodels of off-the-shelf active parts brought the results suitable for brief analysis of the complete solution of our phase shifter in both frequency and time domain. Magnitude flatness with only ±0.3 dB variation and maximal phase error in the middle of operational bandwidth 3.7 degrees prove very good performance of designed circuit

Conservative Chaos Generators with CCII+ Based on Mathematical Model of Nonlinear Oscillator

In this detailed paper, several novel oscillator\'s configurations which consist only of five positive second generation current conveyors (CCII+) are presented and experimentally verified. Each network is able to generate the conservative chaotic attractors with the certain degree of the structural stability. It represents a class of the autonomous deterministic dynamical systems with two-segment piecewise linear (PWL) vector fields suitable also for the theoretical analysis. Route to chaos can be traced and observed by a simple change of the external dc voltage. Advantages and other possible improvements are briefly discussed in the text

Designing of a variable frequency standalone impedance analyzer for in vitro biological applications

Maximum biological samples have some electrical property, which gave us a new dimension in the field of biomedical engineering. Now-a-days measurement of impedance by applying an electrical voltage/current, has a broader application for analyzing different biological samples. Most of the devices used for the measurement of bio-impedance are bulky and much costlier. This approach will help us to design a portable, standalone, multi frequency (10Hz – 10kHz) bio-impedance monitoring device with acceptable accuracy and resolution for in-vitro studies of biological cells and tissue

Sensor based real-time mechatronic control of computer integrated manufacturing

Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2008Industrial competition is characterised by increasing globalisation of markets, coupled wit

Automation of garment assembly processes

Robotic automation in apparel manufacturing is reviewed and investigated. Gripper design for separation and de-stacking of batch cut fabric components is identified as an important factor in implementing such automation and a study of existing gripper mechanisms is presented. New de-stacking gripper designs and processes are described together with experimental results. Single fabric component handling, alignment and registration techniques are investigated. Some of these techniques are integrated within a demonstrator robotic garment assembly cell automating the common edge binding process. Performance results are reported

Unique massflow estimation technique for horizontal conveyor belts

Bibliography: leaves 185-187.Massflows on conveyor belts need to be measured in various process streams in mineral extraction processes to ensure good plant management. Conventional weightometers are, however, too expensive to allow a widespread installation in these processes. This study investigates more economic means to measure the massflow on horizontal conveyor belts. A deterioration of accuracy resulting from an instrument using this technique is expected, but the advantages of being able to instrument entire plants is very attractive. The study uses a model a whereby the kinetic energy of the belt system is determined during a perturbation to the system. From this the massflow can be determined

High gain and bandwidth current-mode amplifiers : study and implementation

Doutoramento em Engenharia ElectrotécnicaEsta tese aborda o problema do projecto de amplificadores com grandes produtos de ganho por largura de banda. A aplicação final considerada consistiu no projecto de amplificadores adequados à recepção de sinais ópticos em sistemas de transmissão ópticos usando o espaço livre. Neste tipo de sistemas as maiores limitações de ganho e largura de banda surgem nos circuitos de entrada. O uso de detectores ópticos com grande área fotosensível é uma necessidade comum neste tipo de sistemas. Estes detectores apresentam grandes capacidades intrínsecas, o que em conjunto com a impedância de entrada apresentada pelo amplificador estabelece sérias restrições no produto do ganho pela largura de banda. As técnicas mais tradicionais para combater este problema recorrem ao uso de amplificadores com retroacção baseados em configurações de transimpedância. Estes amplificadores apresentam baixas impedâncias de entrada devido à acção da retroacção. Contudo, os amplificadores de transimpedância também apresentam uma relação directa entre o ganho e a impedância de entrada. Logo, diminuir a impedância de entrada implica diminuir o ganho. Esta tese propõe duas técnicas novas para combater os problemas referidos. A primeira técnica tem por base uma propriedade fundamental dos amplificadores com retroacção. Em geral, todos os circuitos electrónicos têm tempos de atraso associados, os amplificadores com retroacção não são uma excepção a esta regra. Os tempos de atraso são em geral reconhecidos como elementos instabilizadores neste tipos da amplificadores. Contudo, se usados judiciosamente, este tempos de atraso podem ser explorados como uma forma da aumentar a largura de banda em amplificadores com retroacção. Com base nestas ideias, esta tese apresenta o conceito geral de reatroacção com atraso, como um método de optimização de largura de banda em amplificadores com retroacção. O segundo método baseia-se na destruição da dualidade entre ganho e impedância de entrada existente nos amplificadores de transimpedância. O conceito de adaptação activa em modo de corrente é neste sentido uma forma adequada para separar o detector óptico da entrada do amplificador. De acordo com este conceito, emprega-se um elemento de adaptação em modo de corrente para isolar o detector óptico da entrada do amplificador. Desta forma as tradicionais limitações de ganho e largura de banda podem ser tratadas em separado. Esta tese defende o uso destas técnicas no desenho de amplificadores de transimpedância para sistemas de recepção de sinais ópticos em espaço livre.This thesis addresses the problem of achieving high gain-bandwidth products in amplifiers. The adopted framework consisted on the design of a free-space optical (FSO) front end amplifier able to amplify very small optical signals over large frequency bandwidths. The major gain-bandwidth limitations in FSO front end amplifiers arise due to the input circuitry. Usually, it is necessary to have large area optical detectors in order to maximize signal reception. These detectors have large intrinsic capacitances, which together with the amplifier input impedance poses a severe restriction on the gain-bandwidth product. Traditional techniques to combat this gain-bandwidth limitation resort to feedback amplifiers consisting on transimpedance configurations. These amplifiers have small input impedances due to the feedback action. Nevertheless, transimpedance amplifiers have a direct relation between gain and input impedance. Thus reducing the input impedance usually implies reducing the gain. This thesis advances two new methods suitable to combat the above mentioned problems. The first method is based on a fundamental property of feedback amplifiers. In general, all electronic circuits have associated time delays, and feedback amplifiers are not an exception to this rule. Time delays in feedback amplifiers have been recognized as destabilizing elements. Nevertheless, when used with appropriate care, these delays can be exploited as bandwidth enhancement elements. Based on these ideas, this thesis presents the general concept of delayed feedback, as a bandwidth optimization method suitable for feedback amplifiers. The second method is based on the idea of destroying the impedance-gain duality in transimpedance amplifiers. The concept of active current matching is in this sense a suitable method to detach the optical detector from the transimpedance amplifier input. According to this concept, a current matching device (CMD) is used to convey the signal current sensed by the optical detector, to the amplifier’s input. Using this concept the traditional gainbandwidth limitations can be treated in a separate fashion. This thesis advocates the usage of these techniques for the design of transimpedance amplifiers suited for FSO receiving systems