Wide-band CMOS cascode low-noise amplifier design based on source degeneration topology

A design methodology for a wide-band CMOS low noise amplifier (LNA) with source degeneration is presented. By allowing an arbitrary source degeneration and employing a general input matching network, the proposed wide-band CMOS LNA can be shown for any choice of transistor width to achieve the minimum noise figure at all frequencies of interest. The transistor width simply affects the gain of the LNA at the cost of power dissipation. These results apply uniquely to CMOS LNAs, as they are derived from a quasi-static MOSFET model. To validate these design concepts, a wide-band LNA was realized in 0.25-mu m CMOS technology. The measured noise figure ranges from 2.7 to 3.7 dB, over 3.2-4.8 GHz with power consumption of 20 mW. A close agreement with the theoretical results is observed.