Difference Between Linear and Nonlinear Circuits

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What is the Difference Between Linear and Nonlinear Circuits

Linear and nonlinear circuits are two different types of electrical systems. In this article, we are going to describe the key difference with comparison and given examples between linear and nonlinear elements and components.

Linear circuits are those which obey the principle of superposition, meaning that the response to a combination of input signals is equal to the sum of responses for each input taken separately.

Nonlinear circuits, on the other hand, do not obey this rule; their output signals can be significantly different from what would be expected from adding together individual contributions from each input signal.

To know more, first of all let’s know what are linear and nonlinear elements and circuits with given examples? Once we know, we will be able to easily differentiate both of them.

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Linear Circuit

A linear circuit is an electric circuit in which circuit parameters (resistance, inductance, capacitance, waveform, frequency etc.) are constant. In other words, a circuit whose parameters are not changed with respect to Current and Voltage is called a Linear Circuit.

Fundamentally, the word “linear” literally means “along with a straight line”. As the name suggests, a linear circuit means linear characteristics in between current and voltage, which means, current flowing through a circuit is directly proportional to the applied Voltage.

If we increase the applied voltage, then the current flowing through the circuit will also increase, and vice versa. If we draw the circuit output characteristic curve in between current and voltage, it will look like a straight line (diagonal) as shown in fig below.

Refer to Ohm’s Law, where we recognize that:

“If the applied voltage increases, then current also increases (where resistance remains the same).”

But this is not always the case. That’s why we use P = V × I instead of V = I × R (in Transformer)

In other words,

In a linear circuit, the output response of the circuit is directly proportional to the input. In other simple words,

In an electric circuit, in which the applied sinusoidal voltage having frequency “f”, the output (current through a component or voltage between two points) of that circuit is also sinusoidal having frequency “f”.

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Examples of Linear Circuits and Linear Elements

• Resistors and resistive circuit based on resistance
• Inductors and inductive circuits
• Capacitors and capacitive circuits

Nonlinear Circuit

A nonlinear circuit is an electric circuit whose parameters are varied with respect to current and voltage. In other words, an electric circuit in which circuit parameters (resistance, inductance, capacitance, waveform, frequency etc.) are not constant, is known as Nonlinear circuits.

If we draw the circuit output characteristic curve in between current and voltage, it will look like a curved or bending line as shown in fig below.

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Examples of Nonlinear Circuits and Elements

• Diode
• Transistor
• Transformer
• Inductor (when the core is saturated)
• Iron Core
• and any circuit composed exclusively of ideal diode.

Solving Linear and Nonlinear Circuits

Solving a nonlinear circuit is a little bit more complex than linear circuits. Linear circuits can be solved with simple techniques and scientific calculators. While solving Nonlinear circuits, a lot of data and information is required.

But nowadays, due to aggressive technological changes and Modernization, we can simulate and analyze, with output curves both linear and nonlinear circuits very easily with the help of circuit simulation tools like PSpice , MATLAB, Multisim etc.

Applications in Modern Electronics