Energy-Efficient and Area-Saving Asymmetric Capacitor Switching Scheme for SAR ADCs

An asymmetric architecture and energy-efficient capacitor switching scheme for successive approximation register (SAR) analog-to-digital converters (ADC) are proposed. The novel architecture achieves 81.25% reduction in capacitor area over the convention SAR. With the third reference voltage VCM and split-MSB switching procedure, the proposed switching scheme achieves 99.01% less switching energy over the convention SAR. Besides the significant energy saving, this asymmetric capacitor architecture also obtains a good performance in nonlinearity simulation. Based on the Matlab simulation for capacitor mismatch, the maximum differential nonlinearity and maximum integral nonlinearity of the proposed scheme are 0.166LSB and 0.122LSB, respectively.