Single Channel ADC vs Multichannel ADC

There are no inherent disadvantages to using a multi-channel ADC if you need the additional channels.  Multi-channel ADCs offer the advantage of reduced power consumption per channel, lower cost per channel, and less board real estate.

Using a technique called Dithering, noise can be introduced on the channel (in a specific way) to "spread out" energy that occurs at the harmonic levels.  Hence, using dithering can improve SFDR perforamance while sacrificing SNR performance.

--RJH