Comparator common-mode variation effects analysis and its application in SAR ADCs

The effects of comparator input common-mode voltage V
_cm
are analyzed in this paper. The analysis clearly shows a trade-off in the choice of V
_cm
in terms of offset, noise, power and speed. Based on the analysis, an energy efficient SAR ADC switching technique is proposed with less V
_cm
variation and better linearity compared with the widely used monotonic switching technique. Both the simulation results and prototype measured results match with the analysis.