Question

What are carry generate combinations?

(a) If all the input are same then a carry is generated

(b) If all of the output are independent of the inputs

(c) If all of the input are dependent on the output

(d) If all of the output are dependent on the input

This question was posed to me in semester exam.

I'm obligated to ask this question of Fast Adder & Serial Adder in section Arithmetic Circuits of Digital Circuits

Answer 1

Right answer is (b) If all of the output are independent of the inputs

The explanation is: If the input is either 0, 0, 0 or 0, 0, 1 then the output will be 0 (i.e. independent of input) and if the input is either 1, 1, 0 or 1, 1, 1 then the output is 1 (i.e independent of input). Such situation is known as carry generate combinations.