Hi,

trying to simulate a chopper amplifier input referred noise. The use of spectre RF seems appropriate enough.

For the direct plot which option should I choose SSB noise, DSB noise ect. ?  

I am using the following pnoise, pss settings:

pss  pss  fund=100k  harms=3  errpreset=conservative
+    annotate=status
pnoise  (  out  0  )  pnoise  sweeptype=relative  relharmnum=1
+       start=1  stop=50k  log=20  maxsideband=20  iprobe=V2  refsideband=0
+       annotate=status


The direct plot input refered noise does not seems to reduce the flicker noise. have also tried following the chopper opamp with a with a sample and hold and taking the output for pnoise simulation from the sample and hold but this still does not reduce the flicker noise seen on the direct plot when using SSB noise for input refered noise.

I've read Ken Kundert's sc-filters.pdf from www.designers-guide.org/Analysis/  .

Any ideas where I'm going wrong with the simulation setup and direct plot?

Regards,

harmonic

Indeed, with  relharmnum=1 you are observing the noise at the output of the chopper from 100,001 to 150,000 Hz. That is probably not what you want. You should probably not be using a relative sweep.

-Ken