한국해양대학교

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셀룰러용 포락선 추적 증폭기의 이득 개선 회로 설계에 관한 연구

Title
셀룰러용 포락선 추적 증폭기의 이득 개선 회로 설계에 관한 연구
Alternative Title
A Study on the Design of Improving Gain Circuits for Dynamic Envelope Tracking Amplifier in Cellular Phone
Author(s)
金柱淵著
Publication Year
2001
Publisher
한국해양대학교 대학원
URI
http://kmou.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000002173913
http://repository.kmou.ac.kr/handle/2014.oak/9477
Abstract
The RF power amplifier is required to be linear to maintain signal integrity with limited spectral regrowth in the mobile radio transmitter with digital modulation format. To maintain the linearity of an RF amplifier, a Class-A or Class-AB mode amplifier is typically operated.


In many wireless systems, the power transmitted by the mobile unit is adjusted such that signals arriving at a base station from all portable transmitters are similar in power level. Because of having to accommodate the variable distance between mobile and base units, as well as multipath and shadow fading, the amplifiers operate over a wide dynamic power range extending from a maximum level to 10dB in power back-off.


Envelope tracking(ET) amplifier with variable bias voltage is a certain method for power amplifier application of the third generation cellular phones.


However, the input and output impedance of transistors vary with the changing of the Q-point and power level. Because of the variation of impedance, the gain and efficiency of ET amplifiers decreases a lot and the VSWR and stability become worse. The mismatching of dynamic ET amplifier can't be substantially avoided.


In this thesis, the mismatching of dynamic ET amplifiers is proven to be compensated using a varactor diode.


The gain is experimentally improved by 7㏈ above 15㏈m output power. The efficiency improve about 2.5 times. The DC power consumption ET amplifier of which the impedance is compensated is 37% of bias fixed power amplifier
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전파공학과 > Thesis
Files in This Item:
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