Factors for selection of the ADC;
1) Sampling rate.
Higher sampling rates mean that the continuous waveform of the
analog signal can be closely approximation. When multiplexer is
used the rate of ADC divided by the number of channels that are
processed through the multiplexer.
2) Conversion time.
The maximum possible sampling rate of ADC is limited by the
ADC conversion time. Is the time interval between the
application of the incoming signal and encoding of it. It is
depends on;
•Number of bits (n) used to define the converted digital value
(as n increase the conversion time is increased and the
resolution is improved).
•Type of conversion procedure used by the ADC.