Research And Design Of Broadband Low-Noise Amplifiers For The Purpose Of Electronic Reconnaissance

The main task of electronic reconnaissance is to reconnoiter the signals of radar, missile guidance and other electronic equipment that are used by the enemies. The modem electronic reconnaissance system integrates the technology of communication reconnaissance, radar detection and satellite reconnaissance, relies on the sharing of broadband radio frequency front end to complete the receiving. Thus, broadband low noise amplifier becomes a key module for a radio frequency front end. This paper analyzes matching technology for broadband amplifiers, researches the circuit structure of broadband amplifiers and designs a broadband low noise amplifier that connects three frequency bands:0.5-4GHz, 4-12GHz,12-18GHz.Firstly, both negative feedback structure of paralleled resistances and broadband matching technology are applied in designing the broadband low noise amplifier in the broadband of 0.5 to 4GHz. The test result shows that the amplifier gain is greater than 28dB, and noise factor is lower than 2.2dB. However, there is a certain degree of deterioration in input and output reflection coefficient at high frequency section. Our design generally meets the performance requirements.Then, in the second structure, balanced circuit, negative feedback structure of paralleled resistances along with an oval grooved quadrature coupler are designed to approach a broadband low noise amplifier for 4 to 12GHz. According to the simulation results, the amplifier gain is greater than 20dB, and noise factor is lower than 2.8dB, both input and output reflection coefficient are lower than-20dB. Test results differ partially from the simulation results, which will be discussed later in this paper.Last but not least, we use balanced circuit, and substrate integrated waveguide quadrature coupler to design a broadband low noise amplifier for the bandwidth from 12 to 18GHz. The simulation result shows that the amplifier gain is greater than 27.8dB, Gain flatness is lower than 2.7dB, and noise factor is lower than 2.3dB, both input and output reflection coefficient are lower than-12.9dB.