Revisiting the impedance matching for CS-LNA

Abstract

This article reconsiders the impedance matching problem for common source CMOS LNA (CS-LNA) and proposes several improved equivalent models that take into account both Cgd capacitance and the type of load, resistive or inductive, normally not considered by the classical approach. These newly developed models might offer valuable insights about the input impedance, amplifier stability and quality of impedance matching, all these being of great interest in LNA design. The simulation results show good agreement, in terms of frequency response, between the proposed models and transistor based CS-LNA. Hence, it would justify further consideration of Cgd when designing the matching network while taking into account the load, as well. The analysis covered the frequency range 0.1–7 GHz.