uzay1983
Newbie level 6
Distortion Analysis
Hi Guys;
I am designing an LNA that has two stages. operating frequency is 2GHz.
I have a problem with adding the second stage. First stage is common source, and second stage is common source too. It means that I am amplifiying input voltage by cascading the two common source stage.
However, when I connect the second stage, linearity of the LNA is degrading so much.
I am trying the understand the nonlinear behaviour of the second stage.
the linearity of an amplifing stage depends on:
source resistance (or loading effect of the previous stage)
load resistance
biasing
headroom of the transistor
This is really interesting that 1dB input intercept point degrading dramaticly. (Not only IICP but also IIP3 etc.. Are there any reason why is cascading degrading the linearity or can something be wrong?
Hi Guys;
I am designing an LNA that has two stages. operating frequency is 2GHz.
I have a problem with adding the second stage. First stage is common source, and second stage is common source too. It means that I am amplifiying input voltage by cascading the two common source stage.
However, when I connect the second stage, linearity of the LNA is degrading so much.
I am trying the understand the nonlinear behaviour of the second stage.
the linearity of an amplifing stage depends on:
source resistance (or loading effect of the previous stage)
load resistance
biasing
headroom of the transistor
This is really interesting that 1dB input intercept point degrading dramaticly. (Not only IICP but also IIP3 etc.. Are there any reason why is cascading degrading the linearity or can something be wrong?