Design And Implementation Of Microwave Broadband Low Noise Amplifier

In today’s information society, ubiquitous communication networks exist around us like the air, and have become the indispensable important part of modern life. In an age of booming communications technology, broadband/UWB technology stands out for its advantages of large capacity and high rate. Low-noise amplifier is the key part of broadband communications system, LNA is located in the front of the receiver, its performance directly determines the receiver sensitivity and the noise figure of whole system, therefore, the study of broadband/ultra-wideband low noise amplifier is important for the research of broadband communication system technology.The main content of this thesis is to design and implement microwave broadband/ultra-wideband low noise amplifier. The thesis first describes and analyzes the theory and design methods of wideband low-noise microwave amplifiers, theoretical part involves the transmission line theory, noise analysis of two-port networks and noise characteristics of transistors, and in the design method, the thesis mainly focuses on transistors’ selection method based on the optical noise source impedance match theory, the broadband impedance matching techniques utilizing the negative feedback effect of transistors’ parasitic gate-drain capacitors, the theory and the design method together provide support for the following wideband low-noise microwave amplifiers’ design. Chapter 3 in this thesis design a 3.1-10.6GHz low noise amplifier for Ultra-wide band(UWB) communication systems, the LNA is designed based on Win commercial 0.15um pHEMT process, when designing the LNA, the aforementioned wide band impedance matching techniques utilizing the negative feedback effect of transistor’s intrinsic gate-drain capacitor are made full use of. The designed 3.1-10.6GHz LNA has a simulated performance of gain bigger than 15dB and noise figure less than 1.8dB and good input/output impedance match. Chapter 4 in this thesis designs a 50MHz-1.8GHz ultra wideband LNA for ISM multiband communication system, the LNA used discrete ATF commercial transistors and was fabricated on a PCB board, when designing the LNA, an improved Kukielka circuit structure was utilized. The measurement results show that the designed LNA has a gain bigger than 26dB and noise figure less than 1.4dB and good input-output impedance match, which not only reached performance specifications, but also verify correctness of the design idea and method.This thesis designed two microwave wideband LNAs for UWB communication and ISM multiband communication system. When designing the two LNAs, some novel ideas and design methods were applied, the designed process itself as well as the result should provide some useful reference for other microwave wideband LNA design.