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  2. Adder–subtractor - Wikipedia

    en.wikipedia.org/wiki/Addersubtractor

    A 4-bit ripple-carry addersubtractor based on a 4-bit adder that performs two's complement on A when D = 1 to yield S = B − A. Having an n-bit adder for A and B, then S = A + B. Then, assume the numbers are in two's complement. Then to perform B − A, two's complement theory says to invert each bit of A with a NOT gate then add one.

  3. Adder (electronics) - Wikipedia

    en.wikipedia.org/wiki/Adder_(electronics)

    4-bit adder with logical block diagram shown Decimal 4-digit ripple carry adder. FA = full adder, HA = half adder. It is possible to create a logical circuit using multiple full adders to add N-bit numbers. Each full adder inputs a , which is the of the previous adder.

  4. Carry-lookahead adder - Wikipedia

    en.wikipedia.org/wiki/Carry-lookahead_adder

    The carry-lookahead 4-bit adder can also be used in a higher-level circuit by having each CLA logic circuit produce a propagate and generate signal to a higher-level CLA logic circuit. The group propagate and group generate for a 4-bit CLA are:

  5. Carry-skip adder - Wikipedia

    en.wikipedia.org/wiki/Carry-skip_adder

    Breaking this down into more specific terms, in order to build a 4-bit carry-bypass adder, 6 full adders would be needed. The input buses would be a 4-bit A and a 4-bit B, with a carry-in (CIN) signal. The output would be a 4-bit bus X and a carry-out signal (COUT). The first two full adders would add the first two bits together.

  6. Carry-select adder - Wikipedia

    en.wikipedia.org/wiki/Carry-select_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 is the special type of Variable-sized carry select adder, called as square root carry select adder. [2] This break-up is ideal when the full-adder delay is equal to the MUX delay, which is unlikely.

  7. Subtractor - Wikipedia

    en.wikipedia.org/wiki/Subtractor

    The full subtractor is a combinational circuit which is used to perform subtraction of three input bits: the minuend , subtrahend , and borrow in . The full subtractor generates two output bits: the difference D {\displaystyle D} and borrow out B out {\displaystyle B_{\text{out}}} .

  8. Kogge–Stone adder - Wikipedia

    en.wikipedia.org/wiki/Kogge–Stone_adder

    An example of a 4-bit Kogge–Stone adder is shown in the diagram. Each vertical stage produces a "propagate" and a "generate" bit, as shown. The culminating generate bits (the carries) are produced in the last stage (vertically), and these bits are XOR'd with the initial propagate after the input (the red boxes) to produce the sum bits. E.g., the first (least-significant) sum bit is ...

  9. Brent–Kung adder - Wikipedia

    en.wikipedia.org/wiki/Brent–Kung_adder

    The Brent–Kung adder is a parallel prefix adder (PPA) form of carry-lookahead adder (CLA). Proposed by Richard Peirce Brent and Hsiang Te Kung in 1982 it introduced higher regularity to the adder structure and has less wiring congestion leading to better performance and less necessary chip area to implement compared to the Kogge–Stone adder (KSA).