thanks dick_freebird.
this is the only time i have tried to design startup circuit for bandgap. i understand
that it is important so that bandgap operates in a desired stable point. i have read
different forums here regarding how to test if startup circuit is working or not but i
get more confused.
regarding fluctuations, i am referring to the voltage output of my bandgap before it
settles to vref=1.17v. previous simulation, it took me about 500ms. right now,i got
this output on transient sim:
but i dont understand. i just followed instructions i have read in forums here. i ramp
vdd from 0 at different time.
when i checked my .lis file (by the way, i am using hspice)..all devices in my bandgap
are cutoff in time<7us. i am not sure if i have checked my startup circuit correctly,
if it is working or not.
without startup circuit and with fixed vdd=3.3v, my bandgap is working. when i ramp vdd
from 0, all devices are cutoff (bandgap and startup circuit). when i ramp vdd from 0
and when i add 7us after .op command,i.e., .op 7us, it shows in the .lis file that devices
are in saturation(except some devices of startup circuit). what does it means?i need to
make sure my startup circuit is working. please help.
thank you.