Design and analysis of low noise amplifier using active feedback for boundary layer radar

The design of low noise amplifier (LNA) at 915MHz for boundary layer radar application is presented in this paper. An active feedback with neutralization capacitance is adopted for the design to boost the gain of the LNA. The excellent optimum tradeoff between noise figure (NF) and gain is achieved by using source degenerated inductor and input and output T-network LC tuning circuit. Source degenerated inductor is useful in achieving stability over a wide range of frequencies. To obtain optimum performance of LNA, low loss and low cost dielectric substrate RT/duroid RO4003C is used. The simulated results of LNA show that the circuit is having a noise figure of 0.233 dB which is very close to the minimum noise figure of the circuit with a gain of 21 dB. The isolation loss is less than -27 dB and the input and output return losses are less than -10 dB. LNA consumes a total power of 180 mW from 3 volts supply.