Introduction to AND Gate:
Digital logic gates are the building blocks of the digital circuit. Each basic logic gate implements a unique Boolean function and a complex Boolean expression is implemented using the network of basic gates. Three basic logic gates are:
- AND Gate.
- OR Gate.
- NOR Gate.
AND Gate implements the AND Boolean function and similarly OR and NOR Gates implements the OR and NOR functions respectively. Here the discussion will be oriented around the AND Gate only.
AND Gate is one of the basic logic gates that implement the logical conjunction operation. The Boolean expression that represents the logical conjunction and thus represents the functionality of the AND Gate is as shown below:
As shown AND Gate function is represented by the dot. AND Gate operates on minimum two inputs and depending upon the state of each input it delivers the output which is governed by the Boolean AND function. In Boolean algebra each variable can have one of the two values that is ‘0’ or ‘1’. Thus in the Boolean expression of the AND Gate the inputs A and B can assume either ‘0’ or ‘1’ and C which is the output of the AND function of input A and input B also assumes either ‘0’ or ‘1’.
Truth Table of AND Gate:
The relation between the state of the output and that of the input is represented in the form of the table. This table is called the Truth Table. The Truth Table of the AND Gate along with its schematics symbol is shown below:
In order for the output to be HIGH both inputs A and B should be HIGH otherwise the output would be LOW. In terms of Positive Logic ‘1’ is considered to be ‘HIGH’ and ‘0’ is considered as ‘LOW’ and in terms of Negative Logic ‘1’ is considered as ‘LOW’ and ‘0’ is considered to be ‘HIGH’.
AND Gate Circuit:
Now let us understand the circuit that implements the AND Gate. AND Gate can be implemented in a variety of ways depending upon the electronic components required to design the circuit. For example diodes, transistors, resistors and combination of these components can implement the AND Gate. The most popular techniques for designing the AND gates are TTL (Transistor-Transistor Logic) and CMOS (Complementary Metal Oxide Semiconductor Transistor) logics. An example of the circuit implementing the AND Gate is shown in the figure below:
The inputs of the AND Gate are connected to base of the transistors and the output is connected to the emitter. As shown in the figure when both of inputs A and B are HIGH the output is also HIGH. Here transistor acts as the switch when both of the transistors are on the voltage will appear at the emitter. It is important to note here that 5V represents the logic HIGH and 0 V represents the logic LOW.
AND Gate IC Package:
AND gates are available in the IC packages. One of the most popular IC for AND Gate is 7408 which is a Quad-two input AND Gate IC which means that this IC contains 4 independent two input AND Gates. The pinout and connection diagram of the 7408 IC is shown below:
And Gate Symbol:
The AND Gate Symbol with its schematics symbol is shown below:
3 input And Gate cmos :
AND Gates are also available in the cmos IC packages. As mentioned before that CMOS (Complementary Metal Oxide Semiconductor) technologies are used to design AND gate . One of the most popular IC for AND Gate is 7411 triple 3-input AND Gates. The pinout and connection diagram of the 7411 triple 3-input AND IC is shown below and AND gate pin diagram
7411 triple 3-input AND gate cmos
The Truth Table of the 3 input AND Gate along with its schematics symbol is shown :
AND Gate IC NUMBER:
Here is the list of AND GATE ic numbers. AND gate in different ics,different packages CMOS and also TTL
- 7411 3 input AND gate TTL IC
- 4001 which is a QUAD two inputs AND Gate IC
- 7408 Quad 2-input AND gate
- 7421 Dual 4-lnput AND Gate
4 input AND gate truth table
The Truth Table of the 4 input AND Gate along with its schematics symbol is shown below:
- 7421 Dual 4-lnput AND Gate in ttl package 5 voltage ,the symbol of 4-lnput AND Gate is shown above
These basic digital logic gates can be connected in peculiar ways to form other important logic gates. Logic gates formed by the peculiar combination AND, OR and NOT are:
That is all for now I hope this article would be helpful for you in the next article I will come up with OR gate. Stay connected, keep reading and enjoy learning.