Microwave Broadband Low Noise Amplifier Design

Microwave broadband low noise amplifier is the important part of the receiver system of radar, electron rivalry, remote measuring and remote control. Broadband matching is very difficult, but we can make it easier with negative feedback and balanced amplifier. So at first we should choose a project, then according to the requirement of the low noise amplifier to choose the transistor, bias and matching.In this paper, we talk about the the development of low noise amplifier, basic theory of broadband low noise amplifier and its design at first. In the forth chapter the series negative feedback and interstage mismatching are presentation, and a low noise amplifier whose operating frequency is 1.5GHz～1.8GHz is developed. In the design and debugging process we found that two different caps with parallel connection may make the amplifier instability. With the analyses of the nonideal cap molding we found that the response curve of two different caps with parallel connection has a saltation whose impedance is infinity and at this pot the amplifier is easy to oscillate. Than some suggestion of the use of cap in amplifier design is presented.In the fifth chapter the shunt negative feedback is presented, and a low noise amplifier whose operating frequency is 0.2GHz～2GHz is developed. This low noise amplifier and the 1.5GHz～1.8GHz low noise amplifier will work well in the environment under -40OC, when the input port and the output port connect with open, short or 50? loads. Both amplifiers achieve leading level in domestic.In the sixth chapter a low noise amplifier whose operating frequency is 6GHz～12GHz is presented. It is a balanced amplifier. In this chapter we discuss the calculation of Lange coupler, the matching of balanced amplifier and the influence of thin film MIC in the design. But for the short of time we just test the Lange coupler and the low noise amplifier, more work such bugging and test need to be down in the future.