The Study And Design Of LNA For GPS Receiver

With the development of wireless communication technology, the high performance and large capability systems are greatly demanded, and the specifications for radio frequency (RF) and communication IC become higher and higher. Therefore, it is valuable to research and design RF transceiver circuit.The low-noise amplifier (LNA) is one of the critical components in the RF receiver. Its main function is the amplification, mixing and filtering for the weak signal from the RF receiver antenna to get the intermediate frequency signal used in the back-end circuits of RE receiver. Low noise amplifier (LNA) is a key component in the front-end of RF receiver. As the first stage of the system, its gain, noise figure (NF) and linearity directly affect the performance of the whole circuits.In this Paper, the component and operation principle of GPS system were introduced firstly, and then the overall architecture of the RF front-end chip was proposed. Then RF device characteristics and some device models of SMIC 0.18μm RF CMOS technology are described in this thesis. The basic design principles of the LNA, including noise, linearity, etc., were introduces, several common basic structures of LNA with their advantages and drawbacks are discussed. The current widely used LNA with source inductor degeneration was analyzed and optimized in detail. According to the practical application and consideration of the mismatch between single-end antenna and differential LNA, a LC balun was designed and integrated with the LNA together.The circuit was design in SMIC 0.18μm RF CMOS technology and stimulated by Cadence Specter RF. The simulation results shown the performance of the circuit with the balun met the requirements. At 1.575GHz, this LNA provides a forward gain of 20.22dB with a noise figure of 1.533dB, while the power consumption is 55.89mW. Also the 1dB compression point is -16.88dBm, IIP3 is -9.33dBm, and the reverse isolation is -37.52dB.The layout of the differential LNA with balun was completed by using the layout tool of Cadence Virtuoso Layout Editor. The die area of the final LNA is 1.70mm×1.365mm.