تاپیک مرجع مقالات لاتین

[Mehdi.Aref 26780]

A Contribution to the VCO modeling and simulation

Voltage-Controlled Oscillators (VCOs) are at the

heart of many electronic systems such as phase-locked

loops (PLL), radar, and communication systems. The

overall performance of these systems is often limited by the

VCO’s parameters and performance. Optimizing system

performance requires a complete understanding of the

VCO’s characteristics. Most applications require that the

VCO operate at one frequency, and then be quickly

switched to another frequency where it will stay for some

time. The key VCO parameters here are frequency

overshoot, settling time, and post-tuning drift. Depending

on how often a VCO is switched, these parameters will

change. In this paper we describe a model of VCO intended

to be used in system modeling in the PSPICE environment.

Model is especially designed for study of the VCO’s step

response

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[Mehdi.Aref 26780]

A Low-Power, Small Area Quadrature LC-VCO using miniature 3D Solenoid shaped Ind.

A low-power, small area quadrature 5GHz

LC-VCO includes 20GHz oscillator and 1/4 divider has been

fabricated using a miniature 3D solenoid shaped inductor in

90nm CMOS. Owing to a small area and a small magnetic

energy of the 3D inductor, a chip area of 2597μm2 which is

1/10 of the reported smallest LC-VCOs and 2.8mW power

consumption including the divider have been achieved

without degrading a figure of merit (FOM). The phase noise

was -103dBc/Hz (@1MHz offset) and the phase error was

with the chip area as small as that of ring oscillators. This

small area LC-VCO is suitable for low-power, low-cost

wireless transceivers and high speed communication systems

 

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[Mehdi.Aref 26780]

Modeling, Design and Characterization of a New Low-Jitter Analog Dual Tuning LC

This paper describes the modeling, design, and characterization

of a low-jitter 2.4-GHz LC-VCO PLL architecture

realized in a standard 0.12- m CMOS technology. It features

an analog dual control loop for fine and coarse VCO tuning that

allows very low VCO gain (60 MHz/V) for noise rejection while

maintaining a wide tuning range. The coarse input of the VCO

is driven by an analog circuit that adjusts the VCO gain in a

continuous manner. Measurements demonstrate an integrated

jitter of 0.74 ps that is 43% lower compared to results from a

standard PLL topology (STD PLL) with a single control loop.

The PLLs have the same bandwidth and output frequency range

and were built on the same wafer for comparison. The circuit

area of the proposed LC-VCO PLL is 0.7 mm2 and the power

consumption is 32 mW. The area and power consumption of the

proposed LC-VCO PLL are less than 1% larger compared to the

STD PLL

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[Mehdi.Aref 26780]

Algorithm of Digital Image Watermarking Technique Combined with HVS

HVS theory plays important role in the application of digital image watermarking technique. When inserting watermarking, the visual masking feature of HVS could be fully used to design digital watermarking algorithm with good perceived performance. When extracting watermarking from the damaged image, human's visual feature could be combined to recover the damaged image so as to obtain better effect. This article combines with human visual feature to study digital watermarking technique, utilizes watermarking redundant technique to insert watermarking, extracts watermarking in line with the damage situation of watermarking, and combines with visual redundancy feature to achieve a image scrambling algorithm that is easy to recover and a recovery scheme for damaged scrambling image

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[Mehdi.Aref 26780]

Modal Expansion Analysis of Discrete Source Scattering by a Spherically Stratifi

In this paper, an eigenfunction expansion into the standard vecfor spherical wave funcfions is

used to compute the scattering of electromagnetic radiation by a spherically stratified object.

Unlike in most other work on electromagnetic scattering, our incident field is that of an infinitesimal

current elemenf (a point source) and not a plane wave. Its expansion coefficients

are obtained by “matching the far-field”. The coefficients for the scattered fields are then

determined from the boundary conditions at each interface, at the origin and at infinity.

This analysis is employed to determine the radiation properties of a dielectric lens at microwave

frequencies. Each shell is assumed to be homogeneous and isotropic with a given

complex permittivity, permeability and conductivity. The work is extended to include the

scattering of other sources such as horns and microstrip patches which are then used in conjunction

with the lens to form a multiple beam antenna. The calculated quantities are the

antenna gain along with its near- and far-field radiation patterns. These results are compared

to measurements on a 30 cm multiple beam system

 

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[Mehdi.Aref 26780]

FAR-FIELD ANTENNA PATTERNS DETERMINED FROM INFRARED HOLOGRAMS

In this paper, we describe a technique based on optical holography which allows

determination of the amplitude and phase of an unknown antenna on a near-field plane from

amplitude-only measurements. We measure the interference pattern between the fields

radiated by the antenna under test (AUT) and a known reference field. The reference field

is produced by a standard gain horn radiating at an angle to the AUT and positioned so that

the peak of the radiation occurs approximately at the same place as the peak from the AUT.

The fields are detected by a resistive screen which absorbs some of the incident energy and

heats as a function of the electric field intensity distribution. We use an infrared camera to

record the temperature distribution caused by the interference of microwave energy radiated

by the reference and the AUT. Data are processed using an enhanced algorithm based on

conventional holography for recovery of the complex near field . The new algorithm

allows elimination of the spurious images commonly present in optical hologram readouts

using illumination of the hologram with the reference wave

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