Hi,


just FYI, the cascaded IIP3 equation is a worst case calculation. It only works when the phases of the IM3 and fundamental components line up nicely. This is obviously not the source of your problem however as your simulated IIP3 is worse than what was calculated. I think you need to provide more information. For example, are you sure it isn't a loading issue? Does the curve look well behaved? How did you simulate individual IIP3? In order to be accurate, you need to use the correct source/load impedances for the individual blocks.

You could do an ideal simulation where you cascade the blocks, and then probe the internal node in between the blocks and check the IIP3 of the mixer. For the PA driver, you could inject the input signal at the internal input node while the system is still cascaded.


regards,
Aaron