In recent years the tremendous progress in personal and wireless communication has pushed the development of RF circuits. At the same time the trend towards the increased integration make the electronic equipment more compact. Today CMOS is the major technology used for the most of the digital and many analog integrated circuits. By reducing the channel length L, channel width 'W', oxide thickness t_ox and power supply V _DD by a scaling factor a and increasing the doping concentration in the channel N_sub by the same factor and have the same electric field in the device. This scaling of MOS transistor makes it attractive for use in radio frequency integrated circuits. The RF circuits includes :

1) Low noise amplifier

2) Mixers

3) Oscillators

4) Phase locked loops

5) Power amplifier.