ABSTRACT
This chapter discusses the current state-of-the-art in radio frequency (RF) low noise amplifier (LNA) design. LNA topologies can be classified according to their bandwidth. In a system the input to the LNA can range from the thermal noise level to levels around 0 dBm. Complimentary metal oxide semiconductor (CMOS) LNAs are common in many commercial applications from global positioning system to ultra-wideband systems that do not require extraordinarily low noise figures. The growing consumer market has pushed CMOS technology into sub-0.1 µm feature sizes that allow a large number of very fast transistors to be integrated on to the same die. The advance in transistor speed also benefits the wireless sector, but to a lesser degree since the performance is limited by the physical properties of the material. The shunt-feedback topology provides a relatively easy method of designing broadband LNAs as the input impedance is controlled by resistors.
