Whats the problem with my two stage opa?

[yihsiu]

help!!! two stage opa

could someone tell me
what 's the problem with my circuit?



vdd: 13 volt vss: -13 volt

i gave vin+ 14volt pulse and sine signal respectively
vin- 13.4 volt


i think the currect output waveform should be from 13 volt to -13 volt

but for my design the output did not swing and the pulse output signal was around 0 to 12 volt
could someone tell me please

thank you very much

 

[noiseless]

Re: help!!! two stage opa

your miller cap feedback should go the the drain of the input transistor, not source.

 

[yihsiu]

Re: help!!! two stage opa

Hi noiseless

i tried but the output still didn't go to swing

 

[sunking]

help!!! two stage opa

make sure the bulk connect of nmos is vss

 

[fantaci]

Re: help!!! two stage opa

it looks that the bottom of the schematic should be ground, not Vdd