A device includes a comparator to provide an indication of a difference between Vp on a first terminal coupled to a top plate of each of a first group of differential capacitors, and Vn on a second terminal coupled to a top plate of each of a second group of differential capacitors. The device includes a control circuit coupled to the comparator. The control circuit is to receive a first indication of a difference between Vp and Vn; responsive to the first indication, cause a first driver to provide a reference voltage to bottom plates of one of the first and second groups, and cause a second driver to provide a ground voltage to bottom plates of the other of the first and second groups; receive a second indication of a difference between Vp and Vn; and provide a digital value responsive to the first indication and the second indication.