Design And Research Of Power Amplifier In Wireless WiFi System

With the rapid growth of mobile communication technology,wireless communication technologies suitable for long and short distance communications have made great progress in the past 30 years,changing people's lives constantly.Being inspired by the rise of mobile phone users and increasing demands for communication data as well as mobile internet,personal mobile communication business,among the various wireless communication technologies,has seen rapid development since 1980 s.Wireless WIFI,as the most typical representative of which,will face great challenges.In this thesis,a power amplifier,which satisfies the 802.11b/g standard,is designed for a wireless WIFI system.The developing background of wireless WIFI system is introduced first.Then follows the analysis of the advantages and challenges of CMOS power amplifiers.The index and different types of power amplifiers are also described as well as the design principle and method in the next chapter.When it comes to impedance matching,the specific principle of transformer and LC matching network are analyzed.Based on TSMC 40 nm technique,a transformer with a turn ratio of 2:3 is then designed and optimized in HFSS.The transformer forms a K value of 0.874 and enhances the efficiency of the power amplifier.Finally,a dynamic gain controlled driving power amplifier and power amplifier are proposed to satisfy the 802.11b/g standard based on TSMC 40 nm technique.Differential cascode structure are adopted in both the designs while the driving power amplifier,controlled by current supply,can be divided into three stages.In dealing with the nonlinearity caused by various MOS capacitance,a PMOS transistor is added.Besides,a RC filtering unit circuit is added to the gate and drain of the self-biased cascode transistor to lower the voltage swing from gate to source,preventing from thermal carrier degradation effect and voltage breakdown.By adjusting the gain of each stage,the overall gain can be tuned to 30.24 dB,35.9dB and 41.58 dB,respectively.The saturated output power is 27.03 dBm and the 1-dB compression point can reach up to 25.02 dBm.