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.