Question

How many AND gates are required to construct a 4 - bit parallel multiplier if four 4-bit parallel binary adders are given?

• A. Sixteen 2 input AND gates
• B. Eight 2 - input AND gates
• C. Four 2 - input AND gates
• D. Two 2 input AND gates

Hint:

When thinking about building combinational circuits like multipliers, it is important to know that AND gates are used for generating the partial products.

Answer 1

The Correct Option is A

A 4-bit parallel multiplier requires AND gates to generate the partial products. For a 4-bit multiplier, each bit of one number is multiplied by each bit of the other number (i.e. \( 4 \times 4 = 16 \) multiplications) using 2-input AND gates. After that, partial products are added up using the given four 4 bit adders. Therefore, a 4-bit parallel multiplier needs 16 two-input AND gates.