Expert: Cezar L. Palconet - 3/2/2010

Question
Ihn LNA design shoule one consider Optimium reflection coefficuient conjugate or only the optimum reflection coefrficient for minimum noie design after drwing the noiew figure circles>

Answer
Hi sundararajan


If the wave is travelling on the same medium, reflection coefficient usually follows a symmetrical match, however complex conjugate gain match, which leads to arrive on trading off gain and NF is no easier feat. Careful design consideration can also bring the match required for good return losses closer to the match for better NF.
LNA design typically involves deciding between directly competing performance parameters, choices seldom arrive at  simultaneous improvements, on two or more parameters. Finding the balance in trading off performance variables, becomes the prime consideration, often, simply maximizing a single key parameter, especially in the trade-off between LNA gain and noise figure (NF) as well as linearity and current requirements.

regards.