The Research And Design Of MMIC LNA For RoF Networking Technology

Radio over Fiber (RoF) is a new network technology for the future, it combinesthe low loss, high bandwidth characteristics of optical Fiber communication with theuniversality, flexibility of wireless communication, it is of great significance to solvespectrum tense and improve data transmission rate in the modern mobilecommunication systems. For any RF communication system using RoF networkingtechnology, low noise amplifier (LNA) is one of the essential modules, LNA enlargesthe weak signal from the antenna, and plays a decisive role in determining the noisecoefficient and the sensitivity of receivers.This thesis focuses on the demand of LNA modules in IMT-Advancedcommunication system based on RoF networking technology. Firstly, basic conceptsand theories of RF circuit have been studied, such as S parameters and noise factor aswell as their specific meanings and corresponding requirements to LNA. Then,theories closely related to the LNA circuit design: noise analysis of two-port networkand noise characteristics of FET transistors, are analyzed in detail, pointed out theway to get excellent noise factor in LNA circuits. In addition, several kinds ofcommonly used LNA circuit structures are introduced, and their respective advantagesand disadvantages are analyzed. These work provides essential theories and methodsfor the subsequent MMIC LNA designs work.This thesis emphasis on the development work of two alternative band MMICLNA module of IMT-Advanced communications systems:450-470MHz and2300-2400MHz. In the450-470MHz MMIC LNA, this thesis designed LNAs usingresistive-shunt feedback topology, an effective solution to the noise performancedegradation and integration issues brought by large on-chip inductance. This solutionnot only meets the performance requirements of the project, but also provides amethod for designing monolithic integrated LNA of low frequencies. In the design ofalternative2300-2400MHz MMIC LNA circuits, this paper presents a method ofselecting appropriate input stage transistors based on the optimal noise sourceimpedance theory, and also been proposed is the use of intrinsic transistor gate-draincapacitance Cgdto reduce parasitic resistance in LNA input matching network, thesemethods have a positive significance to improve the noise performance of the LNA.Finally, two of the designed MMIC LNA are taped out and their circuit performances are measured, correctness of the proposed design method has beenproved. Two of the developed MMIC LNA in this work have excellent noiseperformance, meet the LNA performance requirements in communication system ofRoF networking technology, satisfy demand of the aimed project.