Testing and Calibration of SAR ADCs by MCT-Based Bit Weight Extraction

In this paper, a bit weight extraction technique is proposed to test and calibrate the successive approximation register (SAR) analog-to-digital converter (ADC). The proposed technique is based on major carrier transition (MCT) testing, the MCTs are generated through simple capacitor switching and then measured by the embedded comparator and a coarse design-for-test (DfT) digital-to-analog converter (DAC) that couples to the capacitor DAC (CDAC). From the results, the individual bit weights are extracted and the ADC performance can thus be estimated and calibrated. Simulation results show very high test accuracy and linearity improvement can be achieved by the proposed technique.