A Thesis for the Degree of Master Design of 2~2.5 GHz Variable Gain LNA and 2.4 GHz Low Power Folded RF Front- End

Currently, there are two demands in RF front-end design such as multi-standard application and low power consumption. However, it is difficult to satisfy these demands simultaneously. Therefore, two design techniques are explained in this paper, respectively. In this paper, two RF circuits, a variable gain LNA and low power folded RF frontend, are designed. At first, a variable gain LNA (VG-LNA) is designed to achieve a flexible gain control of LNA. The proposed VG-LNA is implemented in TSMC 0.18 um CMOS process. This is composed of two stage amplifier, and its gain is controlled by the shunt feedback loop made up of a gain control transistor (GCT) and a coupling capacitor in second stage. The channel resistance of GCT in the shunt feedback loop