LogicRoo / Combinational Gates / Parallel Adder - Truth Table, Boolean Expression & CMOS Circuit | Logicroo

n Full Adders

Parallel Adder - Truth Table, Boolean Expression & CMOS Circuit | Logicroo

Learn the Parallel Adder with interactive circuit diagrams, truth tables, Boolean expressions, ripple-carry operation, CMOS implementation, timing diagrams, and digital logic examples.

Parallel Adder

n Full Adders

Adds two 4-bit numbers (A₃A₂A₁A₀ and B₃B₂B₁B₀) plus an initial carry-in by chaining four full adders — the Carry-out of each stage feeds the Carry-in of the next.

A (3→0)

B (3→0)

Cin

Sum

0000

Cout

A (dec)

B (dec)

Sum (dec)

Stage i: Sum_i = A_i ⊕ B_i ⊕ C_i (XOR) · C_i+1 = (A_i · B_i) + (C_i · (A_i ⊕ B_i)) (OR + AND)
Result = A + B + Cin, carried through FA0 → FA1 → FA2 → FA3

Sample truth table (Cin = 0)
A	B	Sum	Cout