Design And Electromagnetic Pulse Protection Research Of Receiver Front-End LNA

With the growing trend towards military combat in electromagnetic pulse weapon known as"the second atomic bomb", living space of RF microwave receiver intended for application in wireless telecommunication, radar, information surveillance system has encountered great threats. Under such circumstance, as the important unit of RF receiver front end, low noise amplifier (LNA) plays a critical role in the whole system while its function performance influences the whole system operation and its capability performance directly works on key parameters such as sensitivity, dynamic range, etc. Consequently, the research on electromagnetic pulse protection applied in RF receiver front-end LNA represents a significant part in improving the anti-electromagnetic damaging ability of information-based equipments and ensuring the equipment reliability in complicated electromagnetic environment during the warfare.This paper mainly focuses on the following points:1. According to the capability requirements, this paper designs a S-band LNA intended for application in RF receiver front end and performs its amplifier circuit simulation with ADS software. The simulation results show that the new LNA solves the low-end stability problem of amplifier. Meanwhile, this paper accomplishes the modeling and co-simulation with Momentum for amplifier PCB circuit .The testing results further validates the ADS simulation results.2. Taking the characteristic of RF receiver front-end LNA into account, this paper adopts a scheme by using PIN diode amplitude-limited circuit combined with power detection controlling circuit to satisfy the electromagnetic pulse protection requirement. The amplitude-limited circuit with PIN diode possesses the capacity of confining the pulse signal amplitude with the maximum Instantaneous peak power (2000W) to 10mW below. Afterwards, the controlling circuit of power detection further limits the amplitude with precision of 1dB.3. Experiments including S-band continuous wave injection with high power have proved the validity and reliability of circuit design for electromagnetic pulse protection.4. According to GJB151A-97 named"electromagnetic emission and susceptibility requirements for military equipments and subsystem", we perform testing program of RS105,irradiation sensitivity of transient electromagnetic field . The results show that when the receiving antennas is exerted by high power electromagnetic pulse with peak field higher than 50kV/m, rising time less than 10ns and falling time longer than 75ns, the designed circuits of electromagnetic pulse protection can prevent the damage of LNA circuits.The design thoughts and experiment methods have established a basis for further study of engineering and serialization for electromagnetic pulse protection circuits.