Analysis of a low noise amplifier with LC-ladder matching and capacitive shunt-shunt feedback

In this paper a new low noise amplifier configuration is proposed to achieve wideband operation. This configuration consists of an LC-ladder filter and a common-emitter stage employing shunt-shunt capacitive feedback to realize wideband matching. Design equations for this configuration are derived, as well as equations for the important performance measures namely noise figure, gain and IIP3. The results of a design for achieving typical low noise amplifier specifications in the ultra-wideband are calculated from these equations and plotted. Without any optimization S
₁₁
of less than -10 dB over the entire frequency band and a minimum noise figure of 2.87 dB are predicted when achieving S
₂₁
of 20 dB. These results indicate that very good performance can be attained through the use of this technique.