I find the concerned frequency of output noise of bandgap is usually 0.1~10Hz and that of LDO is usually 100~100kHz.
(1)I think it should be different according to application, but I find that in most datasheets it is specified as above, why?
(2)how to test the output noise?connect the output pin directly to the spectrum analyzer and integrate it? But I find the spectrum analyzer in our lab has very low precision in such low frequency, is there other method to measure the noise?