AND Gate – Logic Gates Tutorial
An AND gate is a logic gate where the output goes HIGH (or “1”) only if all its inputs are HIGH. So if the inputs A AND B are HIGH, the output Q will also be HIGH.
The logic or Boolean expression for an AND gate is 
which means that:
If A and B are true, then Q is true
Truth Table
AND gates can have more than two inputs. But no matter how many inputs it has, it will only give out a HIGH or logic “1” if all its inputs are HIGH. As soon as one of the inputs goes LOW, the output goes LOW too.
2-input AND Gate Truth Table
| Input A | Input B | Output Q |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
3-input AND Gate Truth Table
| Input A | Input B | Input C | Output Q |
|---|---|---|---|
| 0 | 0 | 0 | 0 |
| 0 | 0 | 1 | 0 |
| 0 | 1 | 0 | 0 |
| 0 | 1 | 1 | 0 |
| 1 | 0 | 0 | 0 |
| 1 | 0 | 1 | 0 |
| 1 | 1 | 0 | 0 |
| 1 | 1 | 1 | 1 |
IC Alternatives with AND Gates
If you want to experiment and build circuits with AND gates, you’ll find them in both the 4000 IC series and the 7400 IC series:
- 4081: Four 2-input AND gates
- 4073: Three 3-input AND gates
- 74HC08: Four 2-input AND gates (HC is the family, can also be LS/HCT/…)
- 74HC09: Four 2-input AND gates (HC is the family, can also be LS/HCT/…)
- 74HC11: Three 3-input AND gates (HC is the family, can also be LS/HCT/…)
These should all be available as hobbyist-friendly through-hole chips. Just make sure you buy the DIP package version.
Example Circuit: Testing the AND gate
Below is a circuit that you can build to demonstrate how an AND gate works.
Normally, both inputs to the AND gate are LOW because of the pull-down resistors. When you push any of the push buttons, you’ll make the input pin HIGH.
The Light-Emitting Diode (LED) on the output shows the result. A lit LED represents a HIGH output. An unlit LED represents a LOW output. As you’ll see, the LED will only turn on if you push both buttons at the same time.
Next Step in the Logic Gates Tutorial
Check out the other articles in this logic gates tutorial:
NOT Gate/Inverter
AND Gate – (You are here)
NAND Gate
OR Gate
NOR Gate
XOR Gate
XNOR Gate