What is a Non-Linear Device? Example & Advantages

Supercapacitor - Non linear Devices

Electrical / Electronic device

Electrical or electronic elements are separated into two types based on the characteristics of the current flow when voltage is applied across them:

  • Linear Element 
  • Nonlinear Element 

Linear Element 

  • When the applied voltage across linear elements varies, the current flow through them also changes linearly.
  • Example- Resistor, Inductor & Capacitor

Characteristics of Linear element

The voltage-current graph of linear element is shown below.

Characteristics of Linear element

Non-Linear Element

Non-linear elements are those through which the applied voltage changes without linearly affecting the current flowing through them. The voltage-current graph of the non-linear element is often exponential rather than a straight line like the linear element. This exponential line shows that the relationship between an increase in current and an increase in applied voltage is not linear or homogeneous. 

Non-Linear Devices

Non-linearity can be understood from the response between the input power (or voltage) and the output power. The response shows the output for a given input is non-linear. 

Characteristics of Nonlinear Devices

Characteristics of Nonlinear Devices

Examples of Non-Linear Devices

The best example of a non-linear device is a diode, PN Junction. All semiconductor devices, including BJT and FET, can be regarded as examples of non-linear devices. 

Properties of Non-Linear Devices

  1. Non-linear components typically do not adhere to Ohm’s Law.
  2. The voltage current relationship is non-linear.
  3. Although the voltage current graph is not always a straight line, it may of exponential form. 
  4. It’s possible that the current flow through the non-linear parts is not constant.

Where do the non-linear devices are used?

  • Controlling the flow of current through a non-linear device is its primary purpose. Because of this, the majority of the linear components are controlled by current. 
  • Anyhow, non-linear elements are utilized in applications for frequency control, rectification, current source, and current control.

Difference between Linear and Non-Linear Elements

Linear ElementsNon-Linear Elements
The linear element’s current flow is uniformThe non-linear element’s current flow is not uniform
Only linear elements adhere to Ohm’s Law; Non-linear elements does not obey Ohm’s law
A linear element’s primary function is to oppose the current flow, energy storing, or energy conversionA non-linear element’s primary role is to manage the flow of current via diverse situation
Voltage-current relationship is linearVoltage-current relationship is not linear
Example- Resistor, Inductor and CapacitorExample- Diode, BJT & FET

Some of the Non-Linear Devices and circuits

Surge Protection Circuit

  • Surge protectors often combine non-linear components like MOVs and BBD’s (bidirectional break-over diodes) with inductors, capacitors, and other non-linear components. The world of electronic components has seen the emergence of electrical double-layer capacitors, sometimes known as supercapacitors or ultra-capacitors.
  • For the same volume as an electrolytic or film capacitor, these typically have a million times higher capacitance. However, their DC voltage ratings, which are in the range of (2-4) V, are incredibly low. Super-capacitors capacity to withstand brief transient surges of high voltage. Due to their exceptionally low ESR and high capacitance, SCs can withstand transient surges of high voltage for brief periods of time without overcharging in contrast to other capacitor types (electrolytic and ceramic). 
Super capacitor

MOV & Transient Voltage Suppression 

  • In a Surge Protection Device, the Metal oxide varsitors (MOV) and transient voltage suppressors (TVS) are very important devices. They are a bidirectional breakover diodes which is also anon-linear devices.
MOV & Transient Voltage Suppression 

Amplifier

  • Amplifier which is an active device are non-linear. The transfer characteristic at small-signal levels is constant with drive level and it is also same as the device’s small-signal gain. 
  • The power gain of the amplifier decreases and is considered to enter gain compression at increasing power levels. 
  • When the output power reaches a certain level, no more power can be produced at the output even when the input is driven even harder. 
Amplifier

Mixer

  • To convert one frequency to another, a mixer is utilized. As a passive device, there is no DC power delivered to it.
  • It is also a non-linear device
  • It has constant conversion loss for low signals but at high signals, the response will compress and eventually saturate.
Mixer

Multiplier 

The multiplier exhibits non-linear behavior. When it comes to the manner in which power is transferred, a frequency multiplier has a striking resemblance neither to an amplifier nor to a mixer nor to a limiter. The power that is output by a multiplier typically follows what is known as a “square-law” curve. This indicates that the output power is inversely proportional to the power that is supplied, which is measured in watts squared.

Function Generator 

  • AD-538 and AD-639 are non-linear devices application  
  • AD-538 which is used as function generators and type AD-639 are used as trigonometric function generators for nonlinear devices. 
  • When working with these devices, it is essential to keep in mind that certain digital approaches, such as direct digital synthesis (DDS), continue to have restrictions when applied to frequencies higher than a few megahertz.
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