Assuming a design case where an Ultralow Noise Amplifier like AD8331 is used. This amplifier has an input voltage noise of 0.74 nV/√Hz and input current noise of 2.5 pA/√Hz. The amplified signal will be digitized with a 24 bit ADC (Vref=3V) in order to perform an spectral analysis.
I have some questions regarding the selection of a suitable LDO for this application. I need to get 5V from a 15V source.
How would affect the selection of the following LDOs on the overall noise performance of the amplifier?
Example1: Ultra Low Noise LDO: ADM7150 RMS Noise @ 10Hz to 100 kHz (𝛍V rms): 1.6μVRMS
Example2: Low Noise LDO: LT1761 RMS Noise @ 10Hz to 100 kHz (𝛍V rms): 20μVRMS
Example 3 LDO: LM3480 RMS Noise @ 10Hz to 100 kHz (𝛍V rms): 150μVRMS
It makes sense to use an Ultra Low Noise LDO in this application?