Search results for: Analog circuit
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 643

Search results for: Analog circuit

583 Dielectric Recovery Characteristics of High Voltage Gas Circuit Breakers Operating with CO2 Mixture

Authors: Peng Lu, Branimir Radisavljevic, Martin Seeger, Daniel Over, Torsten Votteler, Bernardo Galletti

Abstract:

CO₂-based gas mixtures exhibit huge potential as the interruption medium for replacing SF₆ in high voltage switchgears. In this paper, the recovery characteristics of dielectric strength of CO₂-O₂ mixture in the post arc phase after the current zero are presented. As representative examples, the dielectric recovery curves under conditions of different gas filling pressures and short-circuit current amplitudes are presented. A series of dielectric recovery measurements suggests that the dielectric recovery rate is proportional to the mass flux of the blowing gas, and the dielectric strength recovers faster in the case of lower short circuit currents.

Keywords: CO2 mixture, high voltage circuit breakers, dielectric recovery rate, short-circuit current, mass flux.

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582 Signal Generator Circuit Carrying Information as Embedded Features from Multi-Transducer Signals

Authors: Sheroz Khan, Mustafa Zeki, Shihab Abdel Hameed, AHM Zahirul Alam, Aisha Hassan Abdalla, A. F. Salami, W. A. Lawal

Abstract:

A novel circuit for generating a signal embedded with features about data from three sensors is presented. This suggested circuit is making use of a resistance-to-time converter employing a bridge amplifier, an integrator and a comparator. The second resistive sensor (Rz) is transformed into duty cycle. Another bridge with varying resistor, (Ry) in the feedback of an OP AMP is added in series to change the amplitude of the resulting signal in a proportional relationship while keeping the same frequency and duty cycle representing proportional changes in resistors Rx and Rz already mentioned. The resultant output signal carries three types of information embedded as variations of its frequency, duty cycle and amplitude.

Keywords: Integrator, Comparator, Bridge Circuit, Resistanceto-Time Converter, Conditioning Circuit.

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581 A Digitally Programmable Voltage-mode Multifunction Biquad Filter with Single-Output

Authors: C. Ketviriyakit, W. Kongnun, C. Chanapromma, P. Silapan

Abstract:

This article proposes a voltage-mode multifunction filter using differential voltage current controllable current conveyor transconductance amplifier (DV-CCCCTA). The features of the circuit are that: the quality factor and pole frequency can be tuned independently via the values of capacitors: the circuit description is very simple, consisting of merely 1 DV-CCCCTA, and 2 capacitors. Without any component matching conditions, the proposed circuit is very appropriate to further develop into an integrated circuit. Additionally, each function response can be selected by suitably selecting input signals with digital method. The PSpice simulation results are depicted. The given results agree well with the theoretical anticipation.

Keywords: DV-CCCCTA, Voltage-mode, Multifunction filter

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580 Computer-Aided Teaching of Transformers for Undergraduates

Authors: Rajesh Kumar, Roopali Dogra, Puneet Aggarwal

Abstract:

In the era of technological advancement, use of computer technology has become inevitable. Hence it has become the need of the hour to integrate software methods in engineering curriculum as a part to boost pedagogy techniques. Simulations software is a great help to graduates of disciplines such as electrical engineering. Since electrical engineering deals with high voltages and heavy instruments, extra care must be taken while operating with them. The viable solution would be to have appropriate control. The appropriate control could be well designed if engineers have knowledge of kind of waveforms associated with the system. Though these waveforms can be plotted manually, but it consumes a lot of time. Hence aid of simulation helps to understand steady state of system and resulting in better performance. In this paper computer, aided teaching of transformer is carried out using MATLAB/Simulink. The test carried out on a transformer includes open circuit test and short circuit respectively. The respective parameters of transformer are then calculated using the values obtained from open circuit and short circuit test respectively using Simulink.

Keywords: Computer aided teaching, transformer, open circuit test, short circuit test, Simulink.

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579 Investigation of Constant Transconductance Circuit for Low Power Low-Noise Amplifier

Authors: Wei Yi Lim, M. Annamalai Arasu, M. Kumarasamy Raja, Minkyu Je

Abstract:

In this paper, the design of wide-swing constant transconductance (gm) bias circuit that generates bias voltage for low-noise amplifier (LNA) circuit design by using an off-chip resistor is demonstrated. The overall transconductance (Gm) generated by the constant gm bias circuit is important to maintain the overall gain and noise figure of the LNA circuit. Therefore, investigation is performed to study the variation in Gm with process, temperature and supply voltage (PVT).  Temperature and supply voltage are swept from -10 °C to 85 °C and 1.425 V to 1.575 V respectively, while the process conditions are also varied to the extreme and the gm variation is eventually concluded at between -3 % to 7 %. With the slight variation in the gm value, through simulation, at worst condition of state SS, we are able to attain a conversion gain (S21) variation of -3.10 % and a noise figure (NF) variation of 18.71 %. The whole constant gm circuit draws approximately 100 µA from a 1.5V supply and is designed based on 0.13 µm CMOS process. 

Keywords: Transconductance, LNA, temperature, process.

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578 PSRR Enhanced LDO Regulator Using Noise Sensing Circuit

Authors: Min-ju Kwon, Chae-won Kim, Jeong-yun Seo, Hee-guk Chae, Yong-seo Koo

Abstract:

In this paper, we presented the LDO (low-dropout) regulator which enhanced the PSRR by applying the constant current source generation technique through the BGR (Band Gap Reference) to form the noise sensing circuit. The current source through the BGR has a constant current value even if the applied voltage varies. Then, the noise sensing circuit, which is composed of the current source through the BGR, operated between the error amplifier and the pass transistor gate of the LDO regulator. As a result, the LDO regulator has a PSRR of -68.2 dB at 1k Hz, -45.85 dB at 1 MHz and -45 dB at 10 MHz. the other performance of the proposed LDO was maintained at the same level of the conventional LDO regulator.

Keywords: LDO regulator, noise sensing circuit, current reference, pass transistor.

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577 Investigation of Threshold Voltage Shift in Gamma Irradiated N-Channel and P-Channel MOS Transistors of CD4007

Authors: S. Boorboor, S. A. H. Feghhi, H. Jafari

Abstract:

The ionizing radiations cause different kinds of damages in electronic components. MOSFETs, most common transistors in today’s digital and analog circuits, are severely sensitive to TID damage. In this work, the threshold voltage shift of CD4007 device, which is an integrated circuit including P-channel and N-channel MOS transistors, was investigated for low dose gamma irradiation under different gate bias voltages. We used linear extrapolation method to extract threshold voltage from ID-VG characteristic curve. The results showed that the threshold voltage shift was approximately 27.5 mV/Gy for N-channel and 3.5 mV/Gy for P-channel transistors at the gate bias of |9 V| after irradiation by Co-60 gamma ray source. Although the sensitivity of the devices under test were strongly dependent to biasing condition and transistor type, the threshold voltage shifted linearly versus accumulated dose in all cases. The overall results show that the application of CD4007 as an electronic buffer in a radiation therapy system is limited by TID damage. However, this integrated circuit can be used as a cheap and sensitive radiation dosimeter for accumulated dose measurement in radiation therapy systems.

Keywords: Threshold voltage shift, MOS transistor, linear extrapolation, gamma irradiation.

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576 A New Hardware Implementation of Manchester Line Decoder

Authors: Ibrahim A. Khorwat, Nabil Naas

Abstract:

In this paper, we present a simple circuit for Manchester decoding and without using any complicated or programmable devices. This circuit can decode 90kbps of transmitted encoded data; however, greater than this transmission rate can be decoded if high speed devices were used. We also present a new method for extracting the embedded clock from Manchester data in order to use it for serial-to-parallel conversion. All of our experimental measurements have been done using simulation.

Keywords: High threshold level, level segregation, lowthreshold level, smoothing circuit synchronization..

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575 Chua’s Circuit Regulation Using a Nonlinear Adaptive Feedback Technique

Authors: Abolhassan Razminia, Mohammad-Ali Sadrnia

Abstract:

Chua’s circuit is one of the most important electronic devices that are used for Chaos and Bifurcation studies. A central role of secure communication is devoted to it. Since the adaptive control is used vastly in the linear systems control, here we introduce a new trend of application of adaptive method in the chaos controlling field. In this paper, we try to derive a new adaptive control scheme for Chua’s circuit controlling because control of chaos is often very important in practical operations. The novelty of this approach is for sake of its robustness against the external perturbations which is simulated as an additive noise in all measured states and can be generalized to other chaotic systems. Our approach is based on Lyapunov analysis and the adaptation law is considered for the feedback gain. Because of this, we have named it NAFT (Nonlinear Adaptive Feedback Technique). At last, simulations show the capability of the presented technique for Chua’s circuit.

Keywords: Chaos, adaptive control, nonlinear control, Chua's circuit.

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574 Design of SiC Capacitive Pressure Sensor with LC-Based Oscillator Readout Circuit

Authors: Azza M. Anis, M. M. Abutaleb, Hani F. Ragai, M. I. Eladawy

Abstract:

This paper presents the characterization and design of a capacitive pressure sensor with LC-based 0.35 µm CMOS readout circuit. SPICE is employed to evaluate the characteristics of the readout circuit and COMSOL multiphysics structural analysis is used to simulate the behavior of the pressure sensor. The readout circuit converts the capacitance variation of the pressure sensor into the frequency output. Simulation results show that the proposed pressure sensor has output frequency from 2.50 to 2.28 GHz in a pressure range from 0.1 to 2 MPa almost linearly. The sensitivity of the frequency shift with respect to the applied pressure load is 0.11 GHz/MPa.

Keywords: CMOS LC-based oscillator, micro pressure sensor, silicon carbide

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573 High-Resolution 12-Bit Segmented Capacitor DAC in Successive Approximation ADC

Authors: Wee Leong Son, Hasmayadi Abdul Majid, Rohana Musa

Abstract:

This paper study the segmented split capacitor Digital-to-Analog Converter (DAC) implemented in a differentialtype 12-bit Successive Approximation Analog-to-Digital Converter (SA-ADC). The series capacitance split array method employed as it reduced the total area of the capacitors required for high resolution DACs. A 12-bit regular binary array structure requires 2049 unit capacitors (Cs) while the split array needs 127 unit Cs. These results in the reduction of the total capacitance and power consumption of the series split array architectures as to regular binary-weighted structures. The paper will show the 12-bit DAC series split capacitor with 4-bit thermometer coded DAC architectures as well as the simulation and measured results.

Keywords: Successive Approximation Register Analog-to- Digital Converter, SAR ADC, Low voltage ADC.

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572 Solver for a Magnetic Equivalent Circuit and Modeling the Inrush Current of a 3-Phase Transformer

Authors: Markus G. Ortner, Christian Magele, Klaus Krischan

Abstract:

Knowledge about the magnetic quantities in a magnetic circuit is always of great interest. On the one hand, this information is needed for the simulation of a transformer. On the other hand, parameter studies are more reliable, if the magnetic quantities are derived from a well established model. One possibility to model the 3-phase transformer is by using a magnetic equivalent circuit (MEC). Though this is a well known system, it is often not an easy task to set up such a model for a large number of lumped elements which additionally includes the nonlinear characteristic of the magnetic material. Here we show the setup of a solver for a MEC and the results of the calculation in comparison to measurements taken. The equations of the MEC are based on a rearranged system of the nodal analysis. Thus it is possible to achieve a minimum number of equations, and a clear and simple structure. Hence, it is uncomplicated in its handling and it supports the iteration process. Additional helpful tasks are implemented within the solver to enhance the performance. The electric circuit is described by an electric equivalent circuit (EEC). Our results for the 3-phase transformer demonstrate the computational efficiency of the solver, and show the benefit of the application of a MEC.

Keywords: Inrush current, magnetic equivalent circuit, nonlinear behavior, transformer.

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571 Frequency-Variation Based Method for Parameter Estimation of Transistor Amplifier

Authors: Akash Rathee, Harish Parthasarathy

Abstract:

In this paper, a frequency-variation based method has been proposed for transistor parameter estimation in a commonemitter transistor amplifier circuit. We design an algorithm to estimate the transistor parameters, based on noisy measurements of the output voltage when the input voltage is a sine wave of variable frequency and constant amplitude. The common emitter amplifier circuit has been modelled using the transistor Ebers-Moll equations and the perturbation technique has been used for separating the linear and nonlinear parts of the Ebers-Moll equations. This model of the amplifier has been used to determine the amplitude of the output sinusoid as a function of the frequency and the parameter vector. Then, applying the proposed method to the frequency components, the transistor parameters have been estimated. As compared to the conventional time-domain least squares method, the proposed method requires much less data storage and it results in more accurate parameter estimation, as it exploits the information in the time and frequency domain, simultaneously. The proposed method can be utilized for parameter estimation of an analog device in its operating range of frequencies, as it uses data collected from different frequencies output signals for parameter estimation.

Keywords: Perturbation Technique, Parameter estimation, frequency-variation based method.

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570 Variable-Relation Criterion for Analysis of the Memristor

Authors: Qingjiang Li, Hui Xu, Haijun Liu, Xiaobo Tian

Abstract:

To judge whether the memristor can be interpreted as the fourth fundamental circuit element, we propose a variable-relation criterion of fundamental circuit elements. According to the criterion, we investigate the nature of three fundamental circuit elements and the memristor. From the perspective of variables relation, the memristor builds a direct relation between the voltage across it and the current through it, instead of a direct relation between the magnetic flux and the charge. Thus, it is better to characterize the memristor and the resistor as two special cases of the same fundamental circuit element, which is the memristive system in Chua-s new framework. Finally, the definition of memristor is refined according to the difference between the magnetic flux and the flux linkage.

Keywords: Memristor, Fundamental, Variable-Relation Criterion, Memristive system

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569 An Efficient VLSI Design Approach to Reduce Static Power using Variable Body Biasing

Authors: Md. Asif Jahangir Chowdhury, Md. Shahriar Rizwan, M. S. Islam

Abstract:

In CMOS integrated circuit design there is a trade-off between static power consumption and technology scaling. Recently, the power density has increased due to combination of higher clock speeds, greater functional integration, and smaller process geometries. As a result static power consumption is becoming more dominant. This is a challenge for the circuit designers. However, the designers do have a few methods which they can use to reduce this static power consumption. But all of these methods have some drawbacks. In order to achieve lower static power consumption, one has to sacrifice design area and circuit performance. In this paper, we propose a new method to reduce static power in the CMOS VLSI circuit using Variable Body Biasing technique without being penalized in area requirement and circuit performance.

Keywords: variable body biasing, state saving technique, stack effect, dual V-th, static power reduction.

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568 Two Active Elements Based All-Pass Section Suited for Current-Mode Cascading

Authors: J. Mohan, S. Maheshwari

Abstract:

A new circuit topology realizing a first-order currentmode all-pass filter is proposed using two dual-output second generation current conveyor and two passive components. The circuit possesses low-input and high-output impedance, which makes it ideal for current-mode systems. The proposed circuit is verified through PSPICE simulation results.

Keywords: active filter, all-pass filter, current-mode, current conveyor.

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567 A Novel Optimized JTAG Interface Circuit Design

Authors: Chenguang Guo, Lei Chen, Yanlong Zhang

Abstract:

This paper describes a novel optimized JTAG interface circuit between a JTAG controller and target IC. Being able to access JTAG using only one or two pins, this circuit does not change the original boundary scanning test frequency of target IC. Compared with the traditional JTAG interface which based on IEEE std. 1149.1, this reduced pin technology is more applicability in pin limited devices, and it is easier to control the scale of target IC for the designer.

Keywords: Boundary scan, JTAG interface, Test frequency, Reduced pin

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566 A Study on ESD Protection Circuit Applying Silicon Controlled Rectifier-Based Stack Technology with High Holding Voltage

Authors: Hee-Guk Chae, Bo-Bae Song, Kyoung-Il Do, Jeong-Yun Seo, Yong-Seo Koo

Abstract:

In this study, an improved Electrostatic Discharge (ESD) protection circuit with low trigger voltage and high holding voltage is proposed. ESD has become a serious problem in the semiconductor process because the semiconductor density has become very high these days. Therefore, much research has been done to prevent ESD. The proposed circuit is a stacked structure of the new unit structure combined by the Zener Triggering (SCR ZTSCR) and the High Holding Voltage SCR (HHVSCR). The simulation results show that the proposed circuit has low trigger voltage and high holding voltage. And the stack technology is applied to adjust the various operating voltage. As the results, the holding voltage is 7.7 V for 2-stack and 10.7 V for 3-stack.

Keywords: ESD, SCR, latch-up, power clamp, holding voltage.

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565 A New Digital Transceiver Circuit for Asynchronous Communication

Authors: Aakash Subramanian, Vansh Pal Singh Makh, Abhijit Mitra

Abstract:

A new digital transceiver circuit for asynchronous frame detection is proposed where both the transmitter and receiver contain all digital components, thereby avoiding possible use of conventional devices like monostable multivibrators with unstable external components such as resistances and capacitances. The proposed receiver circuit, in particular, uses a combinational logic block yielding an output which changes its state as soon as the start bit of a new frame is detected. This, in turn, helps in generating an efficient receiver sampling clock. A data latching circuit is also used in the receiver to latch the recovered data bits in any new frame. The proposed receiver structure is also extended from 4- bit information to any general n data bits within a frame with a common expression for the output of the combinational logic block. Performance of the proposed hardware design is evaluated in terms of time delay, reliability and robustness in comparison with the standard schemes using monostable multivibrators. It is observed from hardware implementation that the proposed circuit achieves almost 33 percent speed up over any conventional circuit.

Keywords: Asynchronous Communication, Digital Detector, Combinational logic output, Sampling clock generator, Hardwareimplementation.

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564 Temperature Sensor IC Design for Intracranial Monitoring Device

Authors: Wai Pan Chan, Minkyu Je

Abstract:

A precision CMOS chopping amplifier is adopted in this work to improve a CMOS temperature sensor high sensitive enough for intracranial temperature monitoring. An amplified temperature sensitivity of 18.8 ± 3*0.2 mV/oC is attained over the temperature range from 20 oC to 80 oC from a given 10 samples of the same wafer. The analog frontend design outputs the temperature dependent and the temperature independent signals which can be directly interfaced to a 10 bit ADC to accomplish an accurate temperature instrumentation system.

Keywords: Chopping, analog frontend, CMOS temperature sensor, traumatic brain injury (TBI), intracranial temperature monitoring.

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563 Measurement Fractional Order Sallen-Key Filters

Authors: Ahmed Soltan, Ahmed G. Radwan, Ahmed M. Soliman

Abstract:

This work aims to generalize the integer order Sallen-Key filters into the fractional-order domain. The analysis in the case of two different fractional-order elements introduced where the general transfer function becomes four terms which is unusual in the conventional case. In addition, the effect of the transfer function parameters on the filter poles and hence the stability is introduced and closed forms for the filter critical frequencies are driven. Finally, different examples for the fractional order Sallen-Key filter design are presented with circuit simulations using ADS where a great matching between the numerical and simulation results is obtained.

Keywords: Analog Filter, Low-Pass Filter, Fractance, Sallen-Key, Stability.

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562 Design and Implementation of 4 Bit Multiplier Using Fault Tolerant Hybrid Full Adder

Authors: C. Kalamani, V. Abishek Karthick, S. Anitha, K. Kavin Kumar

Abstract:

The fault tolerant system plays a crucial role in the critical applications which are being used in the present scenario. A fault may change the functionality of circuits. Aim of this paper is to design multiplier using fault tolerant hybrid full adder. Fault tolerant hybrid full adder is designed to check and repair any fault in the circuit using self-checking circuit and the self-repairing circuit. Further, the use of conventional logic circuits may result in more area, delay as well as power consumption. In order to reduce these parameters of the circuit, GDI (Gate Diffusion Input) techniques with less number of transistors are used compared to conventional full adder circuit. This reduces the area, delay and power consumption. The proposed method solves the major problems occurring in the most crucial and critical applications.

Keywords: Gate diffusion input, hybrid full adder, self-checking, fault tolerant.

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561 High Dynamic Range Resampling for Software Radio

Authors: Arthur David Snider, Laiq Azam

Abstract:

The classic problem of recovering arbitrary values of a band-limited signal from its samples has an added complication in software radio applications; namely, the resampling calculations inevitably fold aliases of the analog signal back into the original bandwidth. The phenomenon is quantified by the spur-free dynamic range. We demonstrate how a novel application of the Remez (Parks- McClellan) algorithm permits optimal signal recovery and SFDR, far surpassing state-of-the-art resamplers.

Keywords: Sampling methods, Signal sampling, Digital radio, Digital-analog conversion.

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560 Design of 900 MHz High Gain SiGe Power Amplifier with Linearity Improved Bias Circuit

Authors: Guiheng Zhang, Wei Zhang, Jun Fu, Yudong Wang

Abstract:

A 900 MHz three-stage SiGe power amplifier (PA) with high power gain is presented in this paper. Volterra Series is applied to analyze nonlinearity sources of SiGe HBT device model clearly. Meanwhile, the influence of operating current to IMD3 is discussed. Then a β-helper current mirror bias circuit is applied to improve linearity, since the β-helper current mirror bias circuit can offer stable base biasing voltage. Meanwhile, it can also work as predistortion circuit when biasing voltages of three bias circuits are fine-tuned, by this way, the power gain and operating current of PA are optimized for best linearity. The three power stages which fabricated by 0.18 μm SiGe technology are bonded to the printed circuit board (PCB) to obtain impedances by Load-Pull system, then matching networks are done for best linearity with discrete passive components on PCB. The final measured three-stage PA exhibits 21.1 dBm of output power at 1 dB compression point (OP1dB) with power added efficiency (PAE) of 20.6% and 33 dB power gain under 3.3 V power supply voltage.

Keywords: High gain power amplifier, linearization bias circuit, SiGe HBT model, Volterra Series.

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559 Transient Voltage Distribution on the Single Phase Transmission Line under Short Circuit Fault Effect

Authors: A. Kojah, A. Nacaroğlu

Abstract:

Single phase transmission lines are used to transfer data or energy between two users. Transient conditions such as switching operations and short circuit faults cause the generation of the fluctuation on the waveform to be transmitted. Spatial voltage distribution on the single phase transmission line may change owing to the position and duration of the short circuit fault in the system. In this paper, the state space representation of the single phase transmission line for short circuit fault and for various types of terminations is given. Since the transmission line is modeled in time domain using distributed parametric elements, the mathematical representation of the event is given in state space (time domain) differential equation form. It also makes easy to solve the problem because of the time and space dependent characteristics of the voltage variations on the distributed parametrically modeled transmission line.

Keywords: Energy transmission, transient effects, transmission line, transient voltage, RLC short circuit, single phase.

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558 Bridgeless Boost Power Factor Correction Rectifier with Hold-Up Time Extension Circuit

Authors: Chih-Chiang Hua, Yi-Hsiung Fang, Yuan-Jhen Siao

Abstract:

A bridgeless boost (BLB) power factor correction (PFC) rectifier with hold-up time extension circuit is proposed in this paper. A full bridge rectifier is widely used in the front end of the ac/dc converter. Since the shortcomings of the full bridge rectifier, the bridgeless rectifier is developed. A BLB rectifier topology is utilized with the hold-up time extension circuit. Unlike the traditional hold-up time extension circuit, the proposed extension scheme uses fewer active switches to achieve a longer hold-up time. Simulation results are presented to verify the converter performance.

Keywords: Bridgeless boost, boost converter, power factor correction, hold-up time.

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557 A Processor with Dynamically Reconfigurable Circuit for Floating-Point Arithmetic

Authors: Yukinari Minagi , Akinori Kanasugi

Abstract:

This paper describes about dynamic reconfiguration to miniaturize arithmetic circuits in general-purpose processor. Dynamic reconfiguration is a technique to realize required functions by changing hardware construction during operation. The proposed arithmetic circuit performs floating-point arithmetic which is frequently used in science and technology. The data format is floating-point based on IEEE754. The proposed circuit is designed using VHDL, and verified the correct operation by simulations and experiments.

Keywords: dynamic reconfiguration, floating-point arithmetic, double precision, FPGA

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556 Calibration of Time-Skew Error in a M-Channel Time-Interleaved Analog-to-Digital Converter

Authors: Yu-Sheng Lee, Qi An

Abstract:

Offset mismatch, gain mismatch, and time-skew error between time-interleaved channels limit the performance of time-interleaved analog-to-digital converters (TIADC). This paper focused on the time-skew error. A new technique for calibrating time-skew error in M-channels TIADC is described, and simulation results are also presented.

Keywords: Calibration, time-skew error, time-interleavedanalog-to-digital converters.

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555 Molecular Dynamics and Circular Dichroism Studies on Aurein 1.2 and Retro Analog

Authors: Safyeh Soufian, Hoosein Naderi-Manesh, Abdoali Alizadeh, Mohammad Nabi Sarbolouki

Abstract:

Aurein 1.2 is a 13-residue amphipathic peptide with antibacterial and anticancer activity. Aurein1.2 and its retro analog were synthesized to study the activity of the peptides in relation to their structure. The antibacterial test result showed the retro-analog is inactive. The secondary structural analysis by CD spectra indicated that both of the peptides at TFE/Water adopt alpha-helical conformation. MD simulation was performed on aurein 1.2 and retro-analog in water and TFE in order to analyse the factors that are involved in the activity difference between retro and the native peptide. The simulation results are discussed and validated in the light of experimental data from the CD experiment. Both of the peptides showed a relatively similar pattern for their hydrophobicity, hydrophilicity, solvent accessible surfaces, and solvent accessible hydrophobic surfaces. However, they showed different in directions of dipole moment of peptides. Also, Our results further indicate that the reversion of the amino acid sequence affects flexibility .The data also showed that factors causing structural rigidity may decrease the activity. Consequently, our finding suggests that in the case of sequence-reversed peptide strategy, one has to pay attention to the role of amino acid sequence order in making flexibility and role of dipole moment direction in peptide activity. KeywordsAntimicrobial peptides, retro, molecular dynamic, circular dichroism.

Keywords: Antimicrobial peptides, retro, molecular dynamic, circular dichroism.

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554 Design and Simulation of Low Noise Amplifier Circuit for 5 GHz to 6 GHz

Authors: Hossein Sahoolizadeh, Alishir Moradi Kordalivand, Zargham Heidari

Abstract:

In first stage of each microwave receiver there is Low Noise Amplifier (LNA) circuit, and this stage has important rule in quality factor of the receiver. The design of a LNA in Radio Frequency (RF) circuit requires the trade-off many importance characteristics such as gain, Noise Figure (NF), stability, power consumption and complexity. This situation Forces desingners to make choices in the desing of RF circuits. In this paper the aim is to design and simulate a single stage LNA circuit with high gain and low noise using MESFET for frequency range of 5 GHz to 6 GHz. The desing simulation process is down using Advance Design System (ADS). A single stage LNA has successfully designed with 15.83 dB forward gain and 1.26 dB noise figure in frequency of 5.3 GHz. Also the designed LNA should be working stably In a frequency range of 5 GHz to 6 GHz.

Keywords: Advance Design System, Low Noise Amplifier, Radio Frequency, Noise Figure.

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