An integrated circuit has a first circuit portion on a first level and a second circuit portion on a second level different from the first level. The first circuit portion includes a first cell having a first voltage value at a first node and a second voltage value at a second node. The second circuit portion includes a second cell coupled with the first cell, the second cell being selectively controllable to supply a voltage to the first cell based on an instruction to supply the voltage. The instruction to supply the voltage is based on a determined mismatch between the first voltage value and the second voltage value being greater than a predetermined threshold value.