2.Reduction in the S/N ratio
This issue is related to the common-mode input voltage. The maximum input voltage that can be applied to an op-amp decreases as its supply voltage decreases. Therefore, assuming that the amount of noise applied to an op-amp remains constant, the S/N ratio decreases with the supply voltage. However, you do not need to be concerned about the deterioration of the S/N ratio if the input signal level is low and there is no need to reduce the signal amplitude.
If the S/N ratio is unsatisfactory, consider using a low-noise op-amp.
3.Reduction in the slew rate
The predominant factors that determine the slew rate of an op-amp are the parasitic capacitance of its internal signal lines and the amount of current that flows to charge and discharge this parasitic capacitance. As the supply voltage decreases, the internal current tends to decrease. Although op-amps are designed in such a manner that their internal current is not affected by the supply voltage, it still varies slightly with the supply voltage. Therefore, the slew rate tends to decrease with the supply voltage.
If the slew rate is unsatisfactory, consider using an op-amp with a high slew rate.
The following documents also contain related information:
Basics of Operational Amplifiers and Comparators
What is the purpose of using a differential amplifier? (Common-mode rejection ratio: CMRR)
Is there any way to amplify a signal with a voltage close to the power supply level?
What is the common-mode input voltage of an op-amp?
What does rail-to-rail mean?
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