Abstract
In the recent ten years, the rapid growth of wireless portable communication products has led to numerous developments. There are two high speed data rate wireless local area network (WLAN) communication systems which are the IEEE802.11a and HIPERLAN. They are operated in the 5-GHz frequency band (5.15-5.35/5.47-5.725 GHz). In order to achieve the high integrated density and low cost, the radio frequency (RF) front-end has caught the attention in standard CMOS technology. A CMOS RF receiver needs a high performance low noise amplifier (LNA) and we set the center frequency at 5.2GHz, in this thesis. The LNAs designed in this thesis, used a RF/Mixed Mode 0.18μm CMOS process technology. The simulation tool is ADS 1.5 of Aligent. Firstly, we provide the equations of single stage cascode LNA voltage gain with and without body effect. We found that the gain is higher and noise figure is lower without body effect. Secondly, assume at the same power consumption, in the cascode circuit with body effect, at 1.8V supply voltage, the noise figure is 2.3dB, power gain is 12.506 dB, and IIP3=1dBm; the noise figure is 1.939dB, power gain is 16.061dB, but the IIP3=-9.7dBm. In addition, we propose some other cascode LNA topologies to improve the body effect and enhance the performances. A lower noise cascode LNA which has NF=1.989dB, S21=15.206dB, and IIP3=-3dBm; an ultra low power dissipation LNA which has just 4.914mW, and NF=2.443dB, S21=15.167dB; and a low supply voltage cascode LNA which has just only 1V, and NF=2.079dB, S21=15.030dB.