- Brent-Kung adder
In electronics, an adder is a combinatorial or sequential logic element which computes the n-bit sum of two n-bit numbers. The Brent-Kung adder is one of the more advanced designs, having a gate level depth of O(log_2(n)).
Adding two n-bit numbers is performed as adding in parallel the lower halves of the addends, the upper halves with input
carry 0, and the upper halves with inputcarry 1, then selecting the appropriate upper half sum based on the outputcarry from the lower half sum. Thus the gate level depth of the n-bit adder is equal to the depth of the half-width adder plus the depth of a mux.
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