Low-noise Amplifier Intends To Electromagnetic Interference Effects

Low-noise amplifier (LNA), which lies in the front of communications receiving system, is a typical'front door'attacking target in high power microwave (HPM). So it is very important to study pulse effects of the LNA. The paper's purpose is to study microwave pulse effect mechanism and experiment, to understand its effects on the LNA, providing HPM protection technologies for the front-end of communications.First, details of the background, significance and researching situation are introduced in this paper. The theoretical analysis and key technologies of the LNA are also interpreted. After that a circuit model for LNA is proposed and simulated, then processing and testing are done, indicating that the LNA sample's performance is to meet requirements, followed by the analysis of weak electromagnetic pulse and reason causing failure. This model is used for simulation such as microwave power, pulse-width and so on.A dynamic injection method effects system is established, compared with the simulation result, the experimental study of injection method is done. At the end, the circuit simulation data and injected experimental results are compared and analyzed. Some effect statistics trends such as microwave power and pulse-width are summarized. Simulation results are in accord with experimental data, indicating that the SPICE simulations are powerful in HPM effects researches. Simulation and experimental studies have shown that the gain suppress time has a saturation when the pulse width is about 150ns-250ns. But the suppression time does not increase apparently when the pulse width is above this value.Microwave pulse effect mechanism of the LNA is discussed and qualitative physical explanation is also given. The line of the effects research and the pulse effect mechanism of transistor are briefly discussed.