Design Of A PHEMT Low Noise Amplifier In General Navigation Receiver

With the rapid development of wireless communication, Global Navigation Satellite System (GNSS) has been one of the fastest growing information industries in the world. GNSS can provide positioning, navigation and timing service in the characteristics of all-weather, all-space, continuity and real-time using. It plays an important role in the military area and has huge social economic value. During the past decade, GNSS has become the focus of development of technology among some leading countries. As an important part of the GNSS, Navigation receiver system is a key factor, its performance directly affect the entire the GNSS work.In this thesis, a radio frequency (RF) front-end low noise amplifier (LNA) in a general navigation receiver system is designed and discussed in great detail. Firstly, two kinds of semiconductor process used in current RF front-end LNA are compared based on the navigation receiver RF front-end application background, and several existing commercial GNSS RF front-end LNA chips are compared. Secondly, based on the theoretical analysis of noise model, a few main performance parameters of the LNA are introduce in detail, including the Noise Figure (NF), S parameter and Linearity etc.Then, the performances of several basic LNA topologies are analyzed in a great detail. According to requirements of the navigation receiver system and interference analysis, a two-stage and containing SAW filter LNA based on 0.25μm pHEMT process is designed, including the cascode common source stage with inductive degeneration, the bias circuit with temperature compensation, and the common source stage with inductive degeneration. At the same time, the total LNA is optimized for the parameter, including NF, Gain and Linearity etc respectively. The total topology design can provide low noise figure and high gain while suppressing the interference signal.Finally, the substrate of the total LNA is presented and debugging optimization is finished. According to the actual measured results, the total LNA can reach above 30dB linear gain, NF can be as low as 0.7dB, input third order intercept point is-10dBm, input return loss keeps lower than-lOdB from 15$8Hz～1620MHz. Band rejection attains -35dBc in average to entire band, and the current consumption keeps 10mA.The measured results demonstrate that the total LNA can meet the requirements for navigation receiver system, and some parameters of the total LNA over existing commercial GNSS RF front-end LNA products.