Design Of Low Noise Amplifier Based On WLAN 802.11b

With the development of the WLAN (Wireless Local Area Networks) in recent decades, demand of single chip RF transceiver goes up in and out of China. Superheterodyne receiver which has excellent sensitivity and selectivity has been in communication domain. The main process of designing RFIC block is SiGe.However,the problems in application of WLAN are caused by cost and integration of RFIC block.The higher integration and low power dissipation have made the CMOS process and direct-conversion receivers attract people's attention.According to the requirement of the WLAN802.11b,This paper used direct-conversion architecture with two conversions,planning for reqirements of the RF blocks.With the principle of improving integration,lowering power dissipation,lowering cost and having some surplus,this paper has designed the components LNA and low noise mixer based on Chartered 0.18μm RF CMOS process.The transceiver RF front-end uses the 1.8V vlotage supply.In the design of the RF front-end, the effect of the low dissipation must be considered since the low power supply limits the voltage swing of the circuit nodes and may affect the DC operation point, power gain and linearity of the RF front-end. The improved, suitable biased RF circuits are proposed to keep the excellent performance of the RF front-end even with low power supply.This paper introduces two matching design techniques by analyzing the noise of MOSFET, and applies this match technique in LNA and mixer with low dissipation,and the two blocks are both based on Chartered 0.18μm CMOS process. As a result, very low noise figures become possible at very low power consumption levels.Moreover,the linearity of LNA had been improved with changing the architecture of the LNA,while minimizing the degradation of gain and noise figure. The differential LNA has been designed based on the JAZZ 0.35um BICMOS process.So, the characteristic and layout of the differential LNA have been summed up.The merged LNA and mixer have good performance in low power using the PCSINM technique, the Double direct-conversion receiver which using the merged LNA and mixer can lower cost and have abroad application in communication.