Another one is an uniform-sized carry-select adder. It has O(sqrt(n)) delay considering MUX delay &lt;&lt; full adder delay IIRC.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Carry-select_adder" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Carry-select_adder</a>