2-input OR gate using 2:1 mux

2-input OR gate using 2x1 mux: Figure 5 below shows the truth table for a 2-input OR gate. If we observe carefully, OUT equals B when A is '0'. Similarly, OUT is '1' (or A), when A is '1'. So, we can make a 2:1 mux act like a 2-input OR gate, if we connect D0 pin to B and D1 pin to A, with select connected to A.

Figure 5: Truth table of 2-input OR gate

Figure 6 below shows the implementation of 2-input OR gate using a 2:1 multilpexer:

Figure 6: Implementation of 2-input OR gate using 2:1 mux

Also read:

• NOT gate using 2:1 mux
• 2-input XOR gate using 2:1 mux
• 2-input NOR gate using 2:1 mux
• 2-input XNOR gate using 2:1 mux
• 2-input NAND gate using 2:1 mux
• 2-input AND gate using 2:1 mux

2-input XNOR gate using 2:1 mux

2-input XNOR gate using 2x1 mux: Figure 1 below shows the truth table of a 2-input XNOR gate. If we observe carefully, OUT equals B' when A is '0' and equals B when A is '1'. So, a 2-input XNOR gate can be implemented from a 2x1 mux, if we connect SEL pin to A, D0 to B' and D1 to B.

Figure 1: Truth table of 2-input XNOR gate

The implementation of 2-input XOR gate using a 2x1 mux is as shown in figure 2.

Figure 2: Implementation of 2-input XNOR gate using 2x1 mux

Similarly, we can observe the output for different values of B and follow the same steps to obtain the XNOR gate implementation.