The present disclosure relates to a capacitor array for an analog-to-digital converter, a successive approximation register analog-to-digital converter and a capacitor array board. The capacitor array includes a control logic generation circuit, a control code logic conversion circuit, a first sub-capacitor array and a second sub-capacitor array configured to form different regions of a high-order bit region and a low-order bit region. In the present disclosure, the capacitances of the second capacitor units are equal, so that the second capacitor units can be sequentially switched. Thus, no matter which bit in the second binary code changes, it will not cause a large number of the second capacitor units to switch together, thereby reducing conversion error. In addition, the capacitor array is divided in regions, which avoids the problem of a large number of parallel branches in case where only the second sub-capacitor array is arranged.
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