here all
here i am designing current reuse lna in cadence and i got s11 = -24 db and s22 = 26db but s12 = s21 = -44 db
what parameter should i change to get proper output at 2.4 Ghz at 0.18um technology
I'd start with whatever fixes your scattering parameters. S22 should not be larger than 0dB, and one of S12 or S21 should be larger than 0 dB if amplification is occurring.
input and output return loss (S11 and S22) tells you how much energy reflected back from the load. so it has to be as low as possible and surely < 0dB as planar metamaterials said. typical value wil be < -12dB.
S21 is you LNA gain. it has to be higher and typically can vary from 8dB to higher depending upon device used.
S12 is isolation/reverse gain. you want it to be as low as possible.
something really wrong with your simulation. i cant suggest anything yet since the results doesnt make sense!
now S11 and S22 is fine. S12 and S21 still doesnt make sense. since your S11 and S22 is good, your S12 and S21 suppose to be good! check your simulation setup and make sure you are doing the right thing.
Actually in schematic resisitor not connected properly and after proper connection i found following result
s11=-25.86db
s12=-62.90db
s21=-19.97db
s22=-28.021db
NF = -2.9176db
is this result are ok
To stop guessing, please post a picture of your simulation setup. A negative noise figure would be great and should make a patent of your circuit . Seriously, post a pic. Because you have no amplifier but an attenuator.