Is bandgap bandwidth large better or small better?

[rom0011]

hi all :

I dont know if bandgap bandwidth is large better or small better.

If bandwidth is larger,i think it has some advantage.

1.better high frequency PSRR

2.fast response

But does it couple more high frequency noise if it has larger bandwidth ?

And I think bandgap does not need large bandwidth.
Because it does not need fast transient response.

Does someone have any idea about this ?

 

[dick_freebird]

You would like to know the noise spectrum on the supply,
and beat that against the PSRR-frequency curve to see
what kind of output noise will result.

A faster bandgap might reject, or pass noise, depending
on its rolloff. Remember that the "forward" frequency
response and the supply-output response are different,
and once the loop begins to fail to null it you are at the mercy
of raw feedthrough.

My preference is to post-filter bandgaps against the reference
ground, rather than depend on a "sporty" amplifier to kill
on-chip noise sources. Pre-regulating with a slow dumb
well-filtered LDO can help too.