about spectre Pnoise analysis~~

spectre pnoise

Hi~
I simulate noise of a fully differential OPA switch cap structure using spectre Pnoise .
I have some problems
First i use PSS and Pnoise analysis , then i want to see input referred noise , and it is impractical small , just about 20nV/Hz (better than IEEE papers so imust some where wrong.......)
my clock 2MHz so i set PSS maxacfreq=240M and Pnoise max sideband =100 , i think it is enough.
i had read some simulation paper , so i think other settlings is correct.
input reffered noise = (output noise)/(Transfer function) is right? i see output noise , input noise,transfer function of Pnoise i think the former statement is right.
and transfer fuction of Pnoise is the same as PAC analysis.
So where i get wrong? How to measure right input referred noise?

Second i also using chopper to eliminate 1/f noise(chopper clock is 1MHz).
The same simulation step like above.
But the ttransfer function is wrong , it very small (minus dB)
So the input refered noise is larger than output noise.
My circuit is correct.
could some body give me some suggestions about it ~~~
thanks~~

I have the same problem (second problem)
Could you solve the second problem?? how is the testbench that you are using?

Thank you