The noise components in LDO are basically the
1. Amp Noise
2. Resistor Noise
3. Buffer Noise
4. Pass transistor noise
Now if you see it is a negative feedback system and
hence, the noise added in feed forward path doesn't
change and it adds with the reference. Noise in feedback path is multiplied with the feedback factor.
Hence main noise components are in feed forward
path and hence you try and minimize the noise from
amp, pass device and buffer ..
Regards
Raduga