# How to Design a combinational circuit using a suitable decoder and OR gate

I need to construct a combinational circuit for the below truth table using a decoder and a OR gate. I'm familiar with the normal procedure of drawing combinational circuit diagrams but got confused when I saw "using a decoder" part.

According to the truth table it should be a 4X16 decoder. But How Can I mark the 16 outputs of the decoder with respective to the truth table's sum of production ??? I know how to use OR gate in this question, but implementing the outputs of the decoder is the problem.

• You just don't need to implement the decoder! It's a "building block" avalilable to you ready made. You don't have to syntetize it, just use it. – carloc Jun 17 '17 at 12:08
• Yes I know that it needs to be in Block diagrams. But I don't know how can I implement it – Code Bae Jun 17 '17 at 12:44
• Why do you need to implement it? – user253751 Jan 4 '18 at 11:58