Talk:Brent-Kung adder

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Wrong, this is a conditional sum adder. And the conditional sum adder could be described more precisely like this:

In electronics, an adder is a combinatorial or sequential logic element which computes the n-bit sum of two n-bit numbers.

The conditional sum adder is a combinatorial design similar to the carry select adder. Both split the inputs in blocks and pregenerate sum and carry values for either possible carry input to the block. Once a carry-out value is ready for a block, it is fed into a multiplexer that picks the correct sum and carry-out for the next block.

Unlike the carry select adder, however, the conditional sum adder is a recursive design, in that the number of blocks is exactly 2 (with size and ), and both are also realized as conditional sum adder. This recursion is continued until a small enough block size is reached. Smaller blocks can employ designs such as the ripple-carry adder or carry lookahead adder.