Question

The carry propagation delay in 4-bit full-adder circuits ___________

(a) Is cumulative for each stage and limits the speed at which arithmetic operations are performed

(b) Is normally not a consideration because the delays are usually in the nanosecond range

(c) Decreases in direct ratio to the total number of full-adder stages

(d) Increases in direct ratio to the total number of full-adder stages but is not a factor in limiting the speed of arithmetic operations

I have been asked this question in exam.

I want to ask this question from 4-Bit Parallel Adder/Subtractor topic in section Arithmetic Circuits of Digital Circuits

Answer 1

Right answer is (a) Is cumulative for each stage and limits the speed at which arithmetic operations are performed

The explanation is: A full adder is a digital circuit with 3 inputs and two outputs SUM and CARRY. The carry propagation delay in 4-bit full-adder circuits is cumulative for each stage and limits the speed at which arithmetic operations are performed.