Carry-select Adder - Variable-sized Adder

Variable-sized Adder

A 16-bit carry-select adder with variable size can be similarly created. Here we show an adder with block sizes of 2-2-3-4-5. This break-up is ideal when the full-adder delay is equal to the MUX delay, which is unlikely. The total delay is two full adder delays, and four mux delays.We try to make the delay through the two carry chains and the delay of the previous stage carry equal.