Hello guys,

I have been busy with a problem for couple of days. I will be more than grateful if you help me with this.

I am new in RF design and I am trying to simulate a simple LNA with ADS. My problem is, I do not want to match my LNA's output to 50ohm because, it is in the chip and it will be connected to mixer.

My question is, when I put terminal at the output of LNA what should be the Z of terminal. Without output terminal I am not able to observe noise and some other parameters. I can just plot S11  >:(

best,

Ata

Yes i tried. The problem is, I want to use mixer after lna, therefore my next stage will be the gate of transistor. I found rf nmos transistor input impedance at 1Ghz and it is like a+bj. But problem is, here a equals 600 ohm which again requires matching. I cant understand why they say inside chip we dont need matching. In high frequencies like 1GHz input impedance drops from 1 meg to 600 !!!! Im totally confused.

I am confised about something. In courses and books, they match input but they say because its inside chip, we dont need output matching ! However when i check output impedance ( input impedance of mixer) in 1GHz, real part is 600 ohm, which effects our design highly !