4134

3904

كارشناسي ارشد

الكترونيك

اصفهان : داتشگاه صنعتي اصفهان : دانشكده برق و كامپيوتر

1387

نه ، 120 ، [II] ص . : مصور ، جدول ، نمودار

ص . ع . به : فارسي و انگليسي

سعيد صدري ،حسين فرزانه فرد

رضا مطهري

20/7/1378

مهندسي برق و كامپيوتر

ID3904

به فارسي و انگليسي : قابل رويت در نسخه ديجيتال

AbstractNowadays solid state radio transmitters SSRT are as common as tube transmitters SSRTs are even superior to tube transmitters in some applications because of specialspecifications like lower noise lower DC voltage supply and easier maintenance andrepairing requirements One of the significant parts of radio transmitters is RF poweramplifier There are several parameters in RF power amplifiers which depending on theapplication contribute more to the amplifier performance One of these parameters isamplifier bandwidth Providing wider bandwidth in solid state transmitters is veryimportant since it improves the received data resolution Two important applications ofVHF wideband radars are search radars and synthetic aperture radars employed torecognize unknown targets The purpose of this work is to design a power amplifier with at least 200Watts outputpower over frequency range from 100MHz to 300MHz After a comprehensive literaturereview on different classes of RF power amplifiers and their structures and alsoinvestigating several transistor technologies the Push Pull AB class as the structure andVDMOS as the transistor element are selected Since one of the most important parts of anamplifier is its matching network various matching networks are studied and transformerstructure is selected for this purpose Such a structure produces the possibility of widebandwidth in matching network Another problem solved is compensation of transistorgain slope over frequency spectrum Through several various methods lossy compensationtogether with VSWR control technique is added to overcome the above mentioneddifficulty By this technique the minimum output power of 200watts with less than 1 5dBripple over the frequency band is obtained To determine the circuit performance of the amplifier design Harmonic Balance simulation with nonlinear model of the transistor is incorporated Harmonic Balancesimulation provides the possibility of verifying bias circuit effect on matching network andamplifier output power Such analysis makes the simulation results more reliable At lastthe amplifier is verified for large signal and small signal stability to ensure that no spuriousoscillation is accrued in the amplifier

سعيد صدري ،حسين فرزانه فرد

رضا مطهري