4733

4452

كارشناسي ارشد

الكترونيك

اصفهان: دانشگاه صنعتي اصفهان، دانشكده برق و كامپيوتر

1388

نه،95،[II]ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

رسول امير فتاحي، امير برجي

رسول دهقاني

88/8/13

1395/08/25

مهندسي برق و كامپيوتر

ID4452

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Improving the efficiency of class F RF power amplifier using defected ground structure Seiied Majid Mohamadi m mohamadi@ec iut ac ir Date of Submission April 20 2009 Department of Electrical and computer engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisors Rasoul Amirfattahi Fattahi@cc iut ac ir Amir Borji aborji@cc iut ac irAbstract Due to high demand for more compact and longer lasting wireless devices increasing theefficiency of power amplifiers has received considerable attention High efficiency greatly increasesthe useful battery life since the device consumes less DC power for the same level of output power The efficiency of a class F power amplifier is investigated in this thesis It has a higher efficiency thanthe linear class A power amplifier The class F power amplifiers do not operate in linear regime sincethe active device is used as a switch Efficiency is enhanced through proper shaping of the current andvoltage waveforms at the output of transistor by harmonic filtering The voltage and current are shapedto a square and half sinusoidal waveforms respectively Ideally an infinite amount of harmonicterminations is required to create the desired waveforms However these waveforms can be adequatelyapproximated by keeping only five harmonics Theoretically harmonic terminations must behave asopen circuit at odd frequencies and short circuit at even frequencies High quality lumped elements atvery high frequencies are expensive thus it is desirable to design the harmonic filter using printedcircuit technology Furthermore in order to decrease the size of printed circuits and yet to maintain high qualityfactor Defected Ground Structures DGS have been introduced in recent years These structuresdisturb the return path of the current by creating an aperture in the ground plane of microstrip line sotransmission line parameters such as line capacitance and inductance are changed which can be used tocontrol undesirable harmonics In this thesis at first characteristics of class F power amplifiers are presented then DefectedGround Structure is introduced and will be used as output harmonic picking filter A class AB amplifieris designed and simulated A lumped element filter is then used to pick the 3rd and 5th at the output andit is shown that the power added efficiency is increased Simulations are performed using Agilent sAdvanced Design System ADS To control main frequency term first and third harmonics properDefected Ground Structure has been design Later the above harmonic picking filter is implementedusing a DGS structure and the results are compared to those of the lumped element design It is shownthat introducing the DGS design has marinated the PAE and gain while reducing the size andeliminating the need for expensive lumped elements so it can be resulted that Defected GroundStructure is an appropriate replacement for lumped element filters in class F power amplifier Key words Class F power Amplifier Power Added Efficiency Defected GroundStructure

رسول امير فتاحي، امير برجي

رسول دهقاني