Charge-redistribution SAR ADC vs Charge-sharing SAR ADC

Nowadays the majority of SAR ADCs are implemented in charge-redistribution (CR) topology. Charge-sharing (CS) principle turns out to be an alternative approach.

One important distinction between CR and CS SAR architectures is the shape of the current drawn from the reference voltage. The CR SAR interacts with the reference source at each bit decision cycle, the CS SAR draws all the charge required for conversion from VREF in a single cycle and performs the charge processing passively. So CS SAR ADCs ease the requirements of the reference generation circuit.

However, the CS ADC is more susceptible to comparator and noise and offset, because the latter causes non-linearity in the ADC transfer curve. In CR ADCs, comparator offset brings only an offset in the transfer curve.