Fig. 2 Proposed switching scheme for 4-bit SAR ADC
Fig. 3 shows the waveform of the proposed DAC scheme for 4-bit switching. The common-mode voltage has minor change in the last conversion which can be tolerable for the comparator. Therefore, the proposed scheme sustains the common-mode voltage nearly constant which provides good CMRR for the comparator while achieving good switching energy efficiency compared to the state-of-the-art methods. In addition, the number of switches required for switching scheme is reduced which does not need complex DAC control logic and signals.