Understanding the XOR Gate from NAND Gates In Logic Gates Design.


Artificial Neural Network For Nor Logic Gate With 2-Bit Binary Input

The XOR (Exclusive OR) gate can be constructed using NAND gates. To create an XOR gate from NAND gates, you need to combine multiple NAND gates in a specific configuration. Here’s the logical representation and a step-by-step explanation:

XOR Gate Truth Table:

Input AInput BOutput
000
011
101
110

Creating an XOR Gate from NAND Gates:

You can use four NAND gates to construct an XOR gate. Follow these steps:

  1. NAND1:
  • Connect Input A and Input B to the inputs of NAND1.
  • The output of NAND1 is the logical AND of A and B, which will be 1 only when both A and B are 0.
  1. NAND2:
  • Connect Input A to the input of NAND2.
  • Connect the output of NAND1 to the second input of NAND2.
  • The output of NAND2 is the NOT (inversion) of A AND B. It will be 1 when A AND B are 0.
  1. NAND3:
  • Connect Input B to the input of NAND3.
  • Connect the output of NAND1 to the second input of NAND3.
  • The output of NAND3 is the NOT (inversion) of A AND B. It will be 1 when A AND B are 0, similar to NAND2.
  1. NAND4:
  • Connect the outputs of NAND2 and NAND3 to the inputs of NAND4.
  • The output of NAND4 is the logical OR of the inverted inputs from NAND2 and NAND3. It results in 1 when either NAND2 or NAND3 has a 1 output.

The output of NAND4 represents the XOR operation between A and B. It will be 1 when either A is 1 or B is 1, but not both.

So, by combining these NAND gates in this specific way, you can create an XOR gate.

Traditionally, binary logic gates serve as the building blocks of digital circuits, playing a pivotal role in the world of digital electronics.

They are responsible for performing logical operations on binary inputs, taking in one or more binary inputs and producing a single binary output based on specific logical rules. The most common types of logic gates include AND gates, OR gates, and NOT gates. These gates are represented by standard symbols, have defined functions, and function using truth tables.

The AND gate is a fundamental logic gate that has two or more inputs and produces an output of 1 only if all of its inputs are 1. It is represented by the symbol “&”. For example, if input A is 1 and input B is 1, the output will be 1. However, if any of the inputs are 0, the output will be 0. The truth table for an AND gate is as follows:

ABOutput
000
010
100
111

The OR gate, represented by the symbol “∨”, is another basic logic gate that produces an output of 1 if any of its inputs are 1. It only produces an output of 0 if all of its inputs are 0. Its truth table is as follows:

ABOutput
000
011
101
111

The third basic logic gate is the NOT gate, which has only one input and produces an output that is the opposite of the input. It is represented by the symbol “¬”. For example, if the input is 1, the output will be 0, and vice versa. The truth table for a NOT gate is as follows:

InputOutput
01
10

These basic logic gates form the foundation upon which more complex logic functions can be built. One versatile gate that can be used to construct various logic gates is the NAND gate. NAND stands for “NOT AND”, which means that a NAND gate produces the opposite of what an AND gate produces. It has two or more inputs and produces an output of 0 only if all of its inputs are 1. If any of the inputs are 0, the output will be 1. The symbol for a NAND gate is an AND gate followed by a circle, indicating the negation. Its truth table is as follows:

ABOutput
001
011
101
110

NAND gates have the interesting property that they can be utilized to construct all the other basic gates, including the AND gate, OR gate, and NOT gate. This is known as “universal logic” because NAND gates can be used to build any other logic gate.

To construct an AND gate using NAND gates, we can simply take two inputs and pass them through a NAND gate, and then pass the output of the NAND gate back into another NAND gate. The inputs to the first NAND gate act as inputs to the AND gate, and the output of the second NAND gate becomes the output of the AND gate. The truth table for this construction is as follows:

ABOutput
000
010
100
111

Using a similar approach, we can construct an OR gate using NAND gates by taking two inputs, passing them through NAND gates, and then passing the outputs of the NAND gates into another NAND gate. The inputs to the first NAND gates act as inputs to the OR gate, and the output of the final NAND gate becomes the output of the OR gate. The truth table for this construction is as follows:

ABOutput
000
011
101
111

Similarly, we can construct a NOT gate using a NAND gate by connecting both inputs of the NAND gate together. This creates a situation where both inputs of the NAND gate are always the same, meaning the output will be the opposite. The truth table for this construction is as follows:

InputOutput
01
10

NAND gates are not only used to construct basic gates, but also find application in various digital systems. For example, they are commonly used in multiplexers, which are devices that can select one of many inputs and pass it through to the output based on control signals. NAND gates are also utilized in decoders, which convert coded inputs into individual outputs, and in processors where they perform calculations and logic operations.

Understanding logic gates, including their construction from NAND gates, is crucial for professionals in the electronics field. It enables them to design and troubleshoot digital circuits and comprehend the fundamental principles of digital systems. Logic gates play a significant role in the development of various electronic devices, making them a vital component in the world of digital electronics.

Eddie Mcfarren

Eddie Is no stranger to technical writing after spending years in Networking, IT Infrastructure management, and online content marketing. He is an avid researcher, Software and apps dev tester who spends hours solving problems behind the scenes. Get in touch with him via social media and you can email him via contact@gawkygeek.com

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