Hierarchical Fail Bit Counting Circuit In Memory Device

Apparatuses and techniques for counting 0 or 1 bits in a set of bits using both serial and parallel processes. The counting process includes a hierarchy in which the count from different parallel processes at one level in the hierarchy are passed to a smaller number of different parallel processes at a lower level in the hierarchy. A final count is obtained by an accumulator below the lowest level of the hierarchy. The position and configuration of the circuits can be set to equalize a number of circuits which process the different bits, so that a maximum delay relative to the accumulator is equalized.