PAE obtained from PSS simulation exceeds 150 % - How come ?

Hi all,

I am simulating just an output stage of a PA using SpectreRF. The transistor drives a port adapter representing an optimum output load.
When I ran PSS and plotted PAE, I noticed that the PAE has no peak (it increases without going down) even input amplitude is 1 Vpeak. Also the PAE exceeds 150 % ! I biased the transistor in class A.

How does this happen ? I also tried to calculate PAE using

PAE = (Pout_rms - Pin_rms)/Pdc * 100%.

From this formula, the PAE has a peak PAE which is at 55 %. Pdc I used is static Pdc (obtained from DC simulation).

I really want to understand how SpectreRF calculate PAE. I tried to read the user's guide, but there is no definition about this.

Please suggest

DYL

Probably there is a bug in Spectre software, or in the model used. Be sure you pointed the software for Pout and Pin to the right ports.
The right formula for PAE is the one you posted.

Hi vfone,

Thank you very much for your reply. Please follow this link to see the discussion on this topic:

The Designer's Guide Community Forum - PAE obtained from PSS simulation exceeds 150 % - How come ?

DYL

The guy who gave the explanation in the link you posted is so confusing that after reading everything I need some time to recover