Design Of A PHEMT L-Band Low Noise Amplifier

This paper has mainly introduced the theory of design, circuit simulation, layout and PCB design and debug of the L band Low Noise Amplifier based on pHEMT transistor. Through using the related knowledge, I described the biasing circuit, topology structure of the LNA, matching network and deeply discussed the performance of LNA in different conditions by simulation and testing. It mainly got good performance in request of low noise.In this paper, I firstly analyzed the noise model of two-port network after discussing the model of thermal noise, shot noise and flicker noise. Then I have analyzed the process and noise model of the pHEMT transistor before discussing the related performance such as Noise Figure, S parameter, Stability and Linearity. After designing the two-port biasing circuit and one-port biasing circuit for stability of the gate voltage, I have discussed the stability of Common-Source Stage with Inductive Load and got the DC biasing current from simulation. Then I emphasized on the analysis of balance of Power Matching and Noise Matching, chose the inductive degeneration and discussed its effect to the Noise Figure, S parameter,ldB compression and third-order intercept point, decided the value of electronic component. Considering better Gain, I have designed the Cascode CS Stage with Inductive Degeneration and simulated the performance. After comparing the performance, I decided the design version. Considering the actual component model, I have replaced the ideal component by the muRata component in the ADS simulation for a more real result. After completing the simulation design, I designed the layout of LNA and the PCB, and have deeply discussed the related point when designing the PCB.At last, I used the equipments in the lab, tested and analyzed the circuit on PCB. The test of Noise Figure is accomplished by Y-parameter. Compared with the simulation, I have emphasized on changing the value of inductive degeneration to get the balance of Power Matching and Noise Matching, got and analyzed the performance. Considering the LNA’s sensitivity of varied current biasing, varied voltage biasing and varied temperature, I have done related test and analyzed the result. Finally it got good performance of Noise Figure under the satisfactory result of Gain, Linearity and so on.