Cascading two LNA stages

[mmarwan]

i have designed 2 seperate LNA circuits, each has its own input and output matching networks, so that each circuit has its own gain and noise figure, and the 2 circuits are matched to a 50 ohm line in the input and output.
But now i want to cascade them, so can i directly do that or i have to make an intermediate matching network (IMN) between the two stages.
And how to design this IMN.
THANKS SO MUCH....

 

[aryajur]

Re: Two stages of LNA !!

Since the output matching network of the 1st circuit needs a 50 ohm load and the input matching network of the second circuit matches it to a 50 ohm source, I think you can simply cascade them. But it would be better if you have just one matching network between the 2 which would match the input of 2nd to the output of 1st, since you may reduce the number of components and the loss and thus a better Noise Figure.