A LNA is in fact an amplifier used in a electrical signal path, where signal levels are relatively low. Usually, the LNA is the first element in the chain where the signal is lowest. So, in our case AMP1 is the LNA. As shown in the diagram, the effect of noise figure (NF2) contributed by AMP1 on the output is negligible if G1 and G2 are high, which is usually the case.  However, noise figure (NF1) contributed by the first element AMP1 appears at the output. Hence, a LNA is desired at the location of AMP1. NXP LNA MMICs shown on the upper right hand side are perfect solutions for such applications.