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Article
Realization of Direct Linear Relation Between Control Voltage and Resonance Frequency of the LC Voltage Controlled Oscillator

Author: Azzad B. Saeed
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2018 Volume: 36 Issue: 9 Part (A) Engineering Pages: 966-971
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The main problem of traditional LC ( L represents the inductance, and C represents the Capacitance) Voltage Controlled Oscillators VCOs, is the non-linearity relation between the tuning control voltage and output resonance frequency, which is caused by two following reasons: the first one is the inverse and non-linear relation between the tuning control voltage and produced capacitance of the used varactor diode in the VCO circuit, and the second is the inverse and non-linear relation between the capacitance value of the used varactor diode and the output resonance frequency. In this paper, a proposed circuit has been designed and implemented to solve this problem and realize a direct-linear relation between the tuning control voltage and output resonance frequency for the LC Voltage Controlled Oscillator that utilize the varactor diode as a voltage controlled capacitance. The proposed circuit has been realized using Logarithmic, Inverting, Ant-Logarithmic, and Difference Amplifiers, which they are characterized by their simplicity and low cost. The theoretical and practical results of testing the proposed circuit had been presented using MATLAB software package. The proposed work has been practically tested by 21 measurement points, whereas, it has exhibited stimulant results that supports the successfulness of its design and performance.


Article
New Accurate Wattmeter Based on Logarithmic Amplifiers

Author: Azzad B. Saeed
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2018 Volume: 36 Issue: 11 Part (A) Engineering Pages: 1165-1170
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

Analog Computers can realize most of mathematical equations; theseequations can be solved using difference, adder, logarithmic, anti-logarithmic,integrator, and differentiator amplifiers. The logarithmic and anti-logarithmicamplifiers are the main components of the analog computers, whereas, they canconvert the multiplication and division operations to addition and subtractionones, and they can convert the exponential functions to multiplicationrelationships. These amplifiers depend on the non-linearity of the relationbetween forward current and applied voltage of the diode. All of previous types ofwattmeters, measure the consumed power of a specific load or resistor bymultiplying the difference voltage of that load by the current passes through it(i.e. P=V.I). In this paper, a proposed accurate wattmeter circuit has beendesigned and implemented using logarithmic, anti-logarithmic, non-inverting,and difference amplifiers. The proposed circuit has been utilized for measuringthe consumed power of a resistor that have any resistance value. It differs fromprevious conventional (analog, and digital) wattmeters due to its calculation ofthe consumed power for a given resistor by multiplying the voltage difference(V) across that resistor by itself once time, then the resultant value is divided bythe resistance (R) value of that resistor (i.e. P=V2/R).

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