What does Linear in electronic mean?

Watch
Mo-Student
Badges: 0
Rep:
?
#1
Report Thread starter 5 years ago
#1
Hi everyone,


In electronics what does linear mean?

What is the most simplest definition of linear? Its a word that has been bugging me for years

Comes as sometimes Linear circuit, or output current is linear etc.

What is the opposite of linear?


Many thanks.
0
reply
Stonebridge
Badges: 13
Rep:
?
#2
Report 5 years ago
#2
(Original post by Mo-Student)
Hi everyone,


In electronics what does linear mean?

What is the most simplest definition of linear? Its a word that has been bugging me for years

Comes as sometimes Linear circuit, or output current is linear etc.

What is the opposite of linear?


Many thanks.
It applies to a system where the output varies continuously as a function of the input.
You could also use the word "analogue" here.

The opposite, then, would be "digital".


In physics, linear has a lot of different applications and shades of meaning.
0
reply
Mo-Student
Badges: 0
Rep:
?
#3
Report Thread starter 5 years ago
#3
(Original post by Stonebridge)
It applies to a system where the output varies continuously as a function of the input.
You could also use the word "analogue" here.

The opposite, then, would be "digital".


In physics, linear has a lot of different applications and shades of meaning.

Thanks so an output which changes continuously for example 2V then 4V, 3V, 5V etc? where as the input stays put with a fixed value of say 10v?

Thank you, you made me finally understand it Image

My physics only the electrical and electronic side only Image
0
reply
Stonebridge
Badges: 13
Rep:
?
#4
Report 5 years ago
#4
(Original post by Mo-Student)
Thanks so an output which changes continuously for example 2V then 4V, 3V, 5V etc? where as the input stays put with a fixed value of say 10v?

Thank you, you made me finally understand it Image

My physics only the electrical and electronic side only Image
No. No.

If the input changes smoothly from say 2V to 4V and the output changes smoothly as a result from 10V to 20V that is "linear". The output = 5 x input. It varies as a function of the input.

If the input was rising smoothly from 2V to 4V and the output suddenly changed from 5V to 20V at some point in between that would not be linear.
0
reply
Mo-Student
Badges: 0
Rep:
?
#5
Report Thread starter 5 years ago
#5
(Original post by Stonebridge)
No. No.

If the input changes smoothly from say 2V to 4V and the output changes smoothly as a result from 10V to 20V that is "linear". The output = 5 x input. It varies as a function of the input.

If the input was rising smoothly from 2V to 4V and the output suddenly changed from 5V to 20V at some point in between that would not be linear.

Ok so as you said the output needs to 5x the input, is this 5x input a must condition for it be considered linear? Can it be 10x input or 2x input etc why 5x is this the rules set which cannot be disputed? Because transformers can step-up the voltage greater than 5x the input.

The other thing is as I can see you said that the output has to be greater than the input. So now say any set-up circuits are the only circuits considered being linear circuits? Or they are the most deserving of being called "linear"?
As for example a set-up transformer circuit for AC Load, or a DC-DC step-up chopper circuits are both types of linear circuits?

Step-down transformer or DC-DC step-down choppers what are they called because they are the completely opposite to the step-up system.


Thanks for your help sir
0
reply
uberteknik
  • Study Helper
Badges: 21
Rep:
?
#6
Report 5 years ago
#6
(Original post by Mo-Student)
Ok so as you said the output needs to 5x the input, is this 5x input a must condition for it be considered linear? Can it be 10x input or 2x input etc why 5x is this the rules set which cannot be disputed? Because transformers can step-up the voltage greater than 5x the input.

The other thing is as I can see you said that the output has to be greater than the input. So now say any set-up circuits are the only circuits considered being linear circuits? Or they are the most deserving of being called "linear"?
As for example a set-up transformer circuit for AC Load, or a DC-DC step-up chopper circuits are both types of linear circuits?

Step-down transformer or DC-DC step-down choppers what are they called because they are the completely opposite to the step-up system.


Thanks for your help sir
Think of linear electronics as a collection of components performing a transfer function which acts to produce and manipulate continuously varying waveforms exclusively in the time-domain. It does not matter what the transfer function is, simply that the function is executed purely in the time domain in an analogue form: be that amplification, logarithmic, exponential, integration, differentiation, chopping, step-up, step down etc.

A digital circuit changes the execution domain of the transfer function from continuous time, to discrete time. i.e. discrete time divisions in which the binary numerical equivalent of the original waveform is created (A/D conversion) and manipulated in binary algebraic computational form before conversion and output to the continuous time domain (D/A conversion) once again.

All semiconductors and components, stand-alone as linear devices. They become part of a digital circuit as soon as the change from continuous time to discrete time is made.

Hence an A/D or D/A convertor will have both analogue and digital sub-functions. These devices are considered part linear and part digital and hence interfacing between the analogue and digital domains.

DC-DC convertors are not considered digital because they are power transfer devices and use waveform chopping as a method of significantly reducing the size of the analogue power transformers which are still needed nonetheless.
0
reply
Stonebridge
Badges: 13
Rep:
?
#7
Report 5 years ago
#7
(Original post by Mo-Student)
Ok so as you said the output needs to 5x the input, is this 5x input a must condition for it be considered linear? Can it be 10x input or 2x input etc why 5x is this the rules set which cannot be disputed? Because transformers can step-up the voltage greater than 5x the input.

The other thing is as I can see you said that the output has to be greater than the input. So now say any set-up circuits are the only circuits considered being linear circuits? Or they are the most deserving of being called "linear"?
As for example a set-up transformer circuit for AC Load, or a DC-DC step-up chopper circuits are both types of linear circuits?

Step-down transformer or DC-DC step-down choppers what are they called because they are the completely opposite to the step-up system.


Thanks for your help sir
5x was just one example of a circuit where the output depends smoothly on the input.
The output can be any continuously varying function.
I didn't say the output "had to be greater than" the input.
The output can be greater or less. It can even be the same.
Also read uberteknik's reply.
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

Should there be a new university admissions system that ditches predicted grades?

No, I think predicted grades should still be used to make offers (738)
33.92%
Yes, I like the idea of applying to uni after I received my grades (PQA) (929)
42.69%
Yes, I like the idea of receiving offers only after I receive my grades (PQO) (413)
18.98%
I think there is a better option than the ones suggested (let us know in the thread!) (96)
4.41%

Watched Threads

View All
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise