Wideband CMOS Low Noise Amplifier Design Based On Source Degeneration Topology

A design methodology for wideband CMOS low noise amplifier (LNA) with source degeneration is presented. By allowing an arbitrary source degeneration and employing a general input matching network, the minimum noise figure of the proposed wideband CMOS LNA can be made independent of the transistor width by properly choosing the source degeneration reactance. This result shows that the proposed topology is effective as a wideband LNA, since the same transistor can be used 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 LNA, as they are derived from a quasi-static MOSFET model. To validate these design concepts, a wideband LNA was realized in 0.25μm CMOS technology. The measured noise figure ranges from 2.7-3.7dB over 3.2-4.8GHz with power consumption of 20mW. A close agreement with the theoretical results is observed. Submitted to Trans. Circuits and Systems I