Question

What is Manchester carry chain?

(a) Is a chain of controlled inverter

(b) Variation of a carry-lookahead adder

(c) Variation of a full-adder

(d) Variation of a ripple carry adder

This question was addressed to me in an interview.

Asked question is from 4-Bit Parallel Adder/Subtractor in section Arithmetic Circuits of Digital Circuits

Answer 1

The correct answer is (b) Variation of a carry-lookahead adder

To elaborate: The Manchester carry chain is a variation of the carry-lookahead adder that uses shared logic to lower the transistor count. However, the carry generating logic depends on the logic to generate the carries in the past.