Truth table to Karnaugh map

The starting point for digital circuit design is usually the truth table which gives us the following information:

Under which input condition occurs a certain output condition.

Two variable map

Ex:

Fig. 4-1: Two variable Karnaugh map

The truth table outputs are translated into the Karnaugh map. Each position in the map represents a certain fundamental product.

Three variable map

Ex:

Fig. 4-2: Three variable Karnaugh map

Four variable map

Many digital systems process 4 bit numbers. For this reason, logic circuits are often designed to handle 4 input variables.

Ex:

(see Fig. 4-3)

Fig. 4-3: Four variable Karnaugh map