Design techniques for successive approximation register analog-to-digital converters

Graduation date: 2012Successive approximation register analog-to-digital converters (SAR ADCs) have been widely used for medium-speed, medium-resolution applications due to their excellent power efficiency and digital compatibility. Recently, SAR ADCs are also penetrating into the applications which have been earlier dominated by delta-sigma ADCs and pipeline ADCs. However, the resolution of SAR ADCs is limited by component mismatch, and their speed is generally slow due to serial operation. In this work, several system innovations and design techniques are investigated for SAR ADCs. First, a semi-synchronous clocking is proposed to optimize the comparator resolving time and DAC settling time in the SAR conversion. Simulations show a 40% speed-up compared with conventional synchronous processing. A self-calibration technique to correct the capacitor mismatch error is also introduced. The proposed calibration algorithm is verified to be insensitive to the non-idealities in the calibration DACs