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KEYSIGHT OSCILLOSCOPE GLOSSARY

What are Logic Gates?

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Logic gates are electronic devices most commonly used in digital electronics and computer science. They act as a building block for complex integrated circuits that process data, information, and commands. Logic gates take two or more electrical inputs and produce an output signal based on the logic of their design.

Think of them like a switch in your home that turns on the light when you flip it. The switch can only be in one of two states – on or off. Logic gates are like these switches, but they take multiple inputs and produce an output based on a combination of the inputs.You would commonly find them in digital devices such as computers, calculators and even modern cars.

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What Are the Seven Basic Logic Gates?

The seven common logic gates are AND, OR, NOT, NAND, NOR, XOR and XNOR. Each has its unique purpose and performs a specific function when combined with other gates.

 

Gate typeFunction

AND gate

Produces an output of 1 only when both inputs are 1.

OR gate

Produces an output of 1 if at least one of the inputs is 1.

NOT gate

Produces an output that is the opposite of its input. If the input is 1, the output is 0, and vice versa.

NAND gate

Produces the opposite of an AND gate output. It produces an output of 0 only when both inputs are 1 and 1 otherwise.

NOR gate

Produces the opposite of an OR gate output. It produces an output of 1 only when both inputs are 0 and 0 otherwise.

XOR gate

Produces an output of 1 if the inputs are different and 0 if they are the same.

XNOR gate

Produces the opposite of an XOR gate output. It produces an output of 0 if the inputs are different and 1 if they are the same.

 

 

What Is a Truth Table?

A truth table is a chart that shows the output of a logic gate for all possible combinations of inputs. It is used to show the relationship between inputs and outputs and can help to understand how the gates work together in electronic circuits.
For example, if we want to know what output an AND gate will produce when both inputs are 0 and 1, we can look at the truth table for an AND gate. We will see that the output is 0 when both inputs are 0 and 1 when it has one 0 input and one 1 input.

InputOutput
ABQ
000
100
010
101

  Example of an AND gate truth table

The seven basic gates are essential components in digital electronics as they provide the foundation for understanding how circuits work. By combining these gates in different ways, complex logic circuits are created and used to process data, information and commands.
Truth tables are also important for understanding how the gates work together. Understanding logic gates is essential for anyone wanting to pursue a technology or digital electronics career, as they provide the basis of knowledge needed to create complex systems.

Key Takeaway
Logic gates are the fundamental building blocks of digital circuits. They are electronic circuits that operate on one or more inputs to produce an output signal that is either a logical "1" or "0". Examples of logic gates include AND, OR, NOT, NAND, NOR, and XOR gates.

What Is Boolean Algebra?

Boolean algebra is a type of mathematics used to analyze and minimize digital circuits. It involves using logic gates and truth tables to reduce a circuit or equation into its simplest form. 

Boolean algebra is a branch of algebra that deals with binary inputs and logical operations. It is a system of mathematical logic that uses binary values (0 and 1) to represent logical statements and their relationships. The values 0 and 1 represent false and true, respectively.
The boolean function identifies redundancies in circuits, simplifies equations, and creates new logic functions. It’s vital for anyone wanting to understand how digital circuits are built and maintained.
Logic gates, truth tables, and boolean algebra are all essential components of digital electronics and computer science. They provide the foundation for understanding how complex circuits work, and their combined use allows you to create powerful systems that can process data, information, and commands.
 

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What Is the Composition of Logic Gates?

Logic gates are composed of transistors, diodes, resistors and capacitors.

  • Transistors control the flow of current in a gate circuit
  • Diodes act as voltage-controlled switches
  • Resistors and capacitors store and transfer electrical energy within a circuit

For example, imagine the flow of electricity in a logic gate. When you apply a voltage to the input of the gate, transistors control the current flow from one point to another. Diodes allow current to flow in one direction but not the other, and resistors and capacitors store or transfer energy within the circuit.
These components work together to create the desired output from the gate. We can design and build more complex digital circuits by understanding how these components work together.
 

What Is Logic Gate Emulation in Oscilloscopes?

Gate emulation is the process of using an oscilloscope to simulate a logic gate circuit. This is done to debug, troubleshoot and test logic gates.

When using an oscilloscope for this purpose, you need to configure the scope by setting up various parameters such as voltage range and time base. You can then observe the output from the logic gate on the oscilloscope’s display.

Observing the display allows you to analyze the circuit for errors and watch how it behaves under different conditions. This helps you understand how logic gates work and will enable you to spot any issues before they become a problem. Gate emulation also allows you to create more complex circuits, eliminating the need to physically build and test each circuit stage.

What Is a Three-State Logic Gate?

A three-state logic gate is a type of logic gate that has an additional output called a ‘high impedance’ state. This additional state allows you to control the output by one or more inputs.

You typically use three-state logic gates in memory circuits, allowing the data stored in each memory cell to be read and written. The three states are logic 0, logic 1 and high impedance.

The advantage of using a three-state logic gate is that it allows for greater control over the output of a circuit. This type of gate can design complex circuits with fewer components than if individual gates were used in each stage.

For example, a circuit that requires eight AND gates to be wired together can instead use a single three-state logic gate. The advantage of this is that it reduces the number of components and connections required to build the circuit, meaning it is smaller and uses less power.
 

What Are the Limitations of Logic Gates?

Although logic gates are essential components of digital circuits, they have a few limitations.

  1.  The first is the limited number of inputs and outputs a gate can handle. More complex systems require additional logic gates to control their operation.
  2.  Another limitation is that logic gates rely on binary signals (ones and zeros). This means they are unsuitable for processing analog signals, and an analog-to-digital converter is required to convert them into a form the gates can understand.
  3.  Finally, logic gates cannot always handle high-frequency signals. Depending on their design, some gates may be unable to pass high frequencies or will produce incorrect outputs in response to them.
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We offer a wide range of high-quality, premium refurbished oscilloscopes backed by a 1-year warranty. You can be confident you are choosing a quality oscilloscope supported by a trusted manufacturer.
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