Research And Design Of Low Noise Amplifier

With the rapid development of wireless communication technology, low noise amplifiers have become a hot research in recent years which form a critical part of receivers. LNA plays an important role in microwave communications, electronic warfare, radio astronomy, radar systems. It directly affects the performance of the receiver, such as dynamic range, sensitivity, etc.The main function of the LNA is used to amplify useful low signals and decreases the affect of the noises interference, providing useful signals for demodulators as far as possible. The targets of low noise, wide bandwidth, high gain have become hot spots for LNA. The thesis is aimed at the analysis and design of low-noise amplifiers. The main content is introduced below:1. The first one is a narrow-band amplifier which is a key circuit of the three-port module used in 2.4GHz system built by a company, mainly completing the module index distribution of isolator, circulator, LNA, designing the low-noise amplifier circuit according to the design index and testing the sub-circuit, and testing the whole module circuit. The testing results show that the module meets the requirements.2. The second one is a C-band wideband low-noise amplifier which is based on the couplers. The C-band wideband low noise amplifier uses two stages circuit structure. And the first stage is a balanced structure which uses two cascaded couplers(8.36dB)forming the 3dB quadrature coupler, and the second-stage circuit uses Hittite low noise chip with inside matched circuits to improve the overall gain. By optimizing the whole circuit, it meets the design specifications.