Wireless Lan Power Amplifier Design In Cmos Technology

In this thesis, the power amplifier for the RF front-end of WLAN transmitter is studied. According to IEEE802.11a standard, the class-A and class-AB power amplifier are designed mainly by the use of ADS software from Agilent.Firstly, according to the requirements of application background, the class-A power amplifier is designed in two differential stages on the basis of introducing main performance figure and basic working principle for the power amplifier, including DC bias network, amplifier, interstage-matching network, output-matching network and input-matching network. In that design, the cascode inductance is applied in the class-A in order to improve the efficiency. Simulation results are presented as follows. With a supply voltage of 1.8V, working at 5.25GHz, the class-A can acquire a gain of 29.9dB and the quiescent current is 289mA. More over, the Pout,1dB is 19.7dBm and the PAE is about 18.0 percent. The results show that the efficiency of the improved class-A power amplifier has increased and the class-A can be used in 802.11a system.Secondly, the class-AB power amplifier is designed by changing the bias conditions based on the class-A. In that design, the capacitance-compensation technique is proposed in order to improve the linearity of the class-AB. Simulation results are presented as follows. With a supply voltage of 1.8V, working at 5.25GHz, the class-AB can acquire a gain of 23.9dB and the quiescent current is 269mA. More over, the Pout,1dB is 20.6dBm and the PAE is about 23.4 percent. The results show that the linearity of the improved class-AB power amplifier has increased and the class-AB can be used in 802.11a system.Finally, on the basis of introducing the models of main devices in the 0.18μm CMOS technology library form TSMC, the layouts of the class-A and class-AB power amplifier are designed by the use of Cadence software. The work above has certain value for the design of the radio-frequency unit in communication system.