Is Matching the LNA Input for GOPT Always Worth the Effort?

In receiver applications, optimizing for the very best in LNA noise figure (NF) performance is a logical step for ensuring that the radio can obtain the ultimate in receiver sensitivity. To that end, designers often embark on a quest to find that perfect LNA match which yields the lowest possible NF. One must be careful, however, to assess all of the tradeoffs involved with seeking such perfection; in many situations, the better approach involves making very slight sacrifices in NF performance in exchange for matching simplicity. Understanding these tradeoffs begins with thorough assessment of an LNA’s simulated noise circles.