The Development Of The L-band Broadband Low-noise Amplifier

Microwave broadband low noise amplifier (LNA) is the key part of receiver system of communications, radar, electronic rivalry, remote measuring and controlling. Noise figure is a crucial index of low noise amplifier, because an amplifier with a low noise index could improve system's sensitivity. The L-band low noise amplifier discussed here is an advanced market research project with very low noise, it works the frequency from 500 MHz to 2000 MHz, thus contain majority channels of communication and wireless systems which used for commercial and armed forces, so it shows a very promising market foreground.The main innovation work is below:1. Based on the majority L-band low noise amplifiers in the market, we decide the indexes with high performance and good rivalrousness.2.Analyze the basic model and high frequency characteristic of resistance, capacitance and inductance of normal factories.3. Decide the L-band LNA's project plan, transistor choose, match and bias circuits design, PCB and housing design, etc. In order to get exact simulation results, the method of electromagnetic field and circuit co-simulation is used.4.The LNAs which discussed in the dissertation adopted Field Effect Transistor (FET) series feedback technique and common PCB and assemble techniques. The circuit applies lumped components primarily. Contrast to adopt chip and ceramic substrates technique, it has the characteristics of low cost, low noise, high performance, easy for adjustment and assemblage etc.5.The self-excitation phenomenon of LNA was analyzed, eliminated and improved during the debugging. Furthermore, the gain flatness was improved by using"open inductance"as a space helix. In addition, it's feasibility was analyzed, simulated and verified during the engineering.6. Three editions of low noise amplifier was designed in one time during the improving. The one with best index and least debugging was chose, thus reducing the period of research and design, as well as the cost.The real result of LNA discussed in the dissertation shows operating current below 160mA, noise figure less than 0.8dB, flatness below±1.4dB and VSWR below 2.0. Thus it has reached international level, and forereached domestic products. The project demand is also achieved.