The signal must be able to drive the ADC converter. The frontend ofthe ADC converter usually consisits of a Sample and HoldCircuitry. The incoming signal charges the capacitor at the input ofthe sample and hold circuitry. The incoming signal must havesufficient drive to charge the sample and hold circuitry.
Protecting the ADC input circuitry from overvoltage. If you have amultiplexed input circuitry, one of the signals might be o