Sharif Digital Repository

In this paper, a new method to achieve very small current reference levels on integrated circuits with immunity to temperature variations using peaking current source with MOSFETs operating in subthreshold region is proposed. By adding a source degeneration resistor to the conventional peaking current source architecture, a zero temperature coefficient current can be generated. The proposed low-power circuit operating in the weak inversion region is designed, simulated, and fabricated in a 0.18-μm standard CMOS process. Measurement results verify the circuit operation with about 5% variation over the span of -40° C to +100° C (industrial temperature grade). The supplied current is designed... 

A new architecture for constant-gm rail-to-rail(R-R) input stages is presented that has less than 5% deviation in gm over the entire range of the input common-mode voltage. Furthermore, a new structure for folded cascode amplifier based on the use of a floating current source is presented. Employing these techniques a low-power operational transconductance amplifier(OTA) with 100MHz unity-gain bandwidth, 106dB gain, 60° phase margin, 2.65V swing, and 6.4nVA/√Hz input-referred noise with R-R input common-mode range is realized in a 0.8μm CMOS technology. This amplifier dissipates 10mW from a 3V power supply  

In this paper, a linear piezoelectric stepper (LPS) motor drive using a resonant converter is proposed. The mechanism of operation of the LPS motor is first described. Then, a single-phase equivalent model of the LPS motor is introduced. In addition, design theory of the driving circuit using a current source inverter for the LPS motor is explained in detail. At the end, simulation and experimental results based on the resonant converter are presented and analyzed to verify the validity of the proposed system  

A linear piezoelectric step motor (LPS) driver using current source inverter is proposed in this study. The mechanism of operation of an LPS motor is first described. Then, a single-phase equivalent model of the LPS motor is introduced. A detailed theory of driving circuit design using current source inverter for the LPS motor is explained. At the end the simulation and experimental results are presented and compared  

In this brief, modifications to the peaking current reference with MOS transistors operating in the subthreshold and the strong inversion region has been proposed by means of which very small currents with immunity to temperature variations on a chip can be obtained. Temperature compensation can be done by adding a source degeneration resistor to the conventional peaking current source structure. Design examples are provided for both weak and strong inversion operations with output currents of 1.5 μA and 40 μ A with less than 4% and 10% variation over the span of-40 °C to +100 °C, respectively. A prototype of the circuit operating in the weak and strong inversion region is designed,... 

A matrix converter is a voltage/current source AC/AC frequency converter. In grid-connected operation of a variable-speed permanent magnet synchronous wind power generator, the matrix converter is normally controlled as a voltage source converter. In this control method, the generator-side voltage is synthesized from the grid-side voltage source. However, in the stand-alone mode of operation, the grid-side stiff voltage source is not available, and the input filter of the matrix converter is unstable. In this article, a new control method is presented that controls a permanent magnet synchronous wind generator in a stand-alone mode with a matrix converter as a current source converter. The... 

The current sources in power transformers such as leads and windings are also sources of Eddy current losses. Due to these losses some parts of tank wall are subject to serious local overheating. It affects the safety and reliability of these expensive objects and their power delivery. There are various methods for reduction of these eddy current losses. One of them is the internal shielding of transformer tank wall. In this paper the tank eddy current losses reduction, through its shielding is determined. ©2009 IEEE  

Electrical Impedance Tomography (EIT), is one of the medical imaging technologies. It can also be used in industrial process monitoring. In this method, the image of the electrical conductivity distribution of the inner part of a conductive subject can be reconstructed. The image reconstruction process is done by injecting an accurate current into the boundary of a conductive subject (e.g. body), measuring the voltages around the boundary and transmitting them to a computer, and processing on acquired data with a software (e.g., MATLAB). The images are obtained from the peripheral data by using an algorithm. Precise EIT instrumentation plays an important role in the final images quality. In... 

LLC resonant converter has been used widely as dc-dc converter for achieving constant dc voltage. In this paper, an LLC resonant converter, by adding an inductance to its conventional topology and considering the rectifying stage stray inductances, is proposed for an adjustable wide range regulated current source (20-200 A dc) for using as ion implanter's filament power supply. The additional inductor increases output current adjustment range and efficiency, especially at light loads. Transformer's leakage inductances and rectifying stage stray inductances have been considered. Because of these inductances, the rectifier stage always works in continuous conduction mode, and its conduction... 

The leads with heavy current passing through the covering plates, and the winding in a transformer, are sources of eddy current losses. Due to this loss some regions of tank wall are subject to serious local overheating. It affects the safety and reliability of this expensive object and power delivery. In this paper these eddy current losses are calculated through a new formulation by application of Finite Element Method, using FEMLAB software. These results are compared with measurement results and the computational results of two other methods: the Turowski method and a method based on application of EDMAG software. © 2008 Australasian Universities Power Engineering Conference (AUPEC'08)  

This paper presents a phase-noise reduction technique for voltage-controlled oscillators (VCOs) using a harmonic tuned (HT) LC tank. The phase-noise suppression is achieved through almost rectangular-shaped VCO oscillating signal which effectively maximizes oscillating signal slope at zero crossing points resulting in-phase-noise degradation. In addition, by shortening down converted noise power around oscillating signal second harmonic, more phase-noise suppression has been achieved. A comprehensive analysis for frequency and amplitude deviations as high as 20% for third harmonic and its effect on output phase-noise suppression has been discussed. In the followings, a comprehensive analysis...