A 2-MS/s, 11.22 ENOB, Extended Input Range SAR ADC With Improved DNL and Offset Calculation

A 12-bit successive approximation register analog-to-digital converter (ADC) with extended input range is presented. Employing an input sampling scaling technique, the presented ADC can digitize the signals with an input range of $3.2\,\,V_{\mathrm {pp-d}}$ ( $\pm 1.33~V_{\text {REF}}$ ). The circuit also includes a comparator offset compensation technique that results in a residual offset of less than 0.5 LSB. The chip has been designed and implemented in a 0.13- $\mu \text{m}$ CMOS process and demonstrates the state-of-the-art performance, featuring an SNDR of 69.3 dB and the SFDR of 79 dB without requiring any calibration. Total power consumption of the ADC is 0.9 mW, with a measured differential non-linearity of 1.2/−1.0 LSB and INL of 2.3/−2.2 LSB.