What is the output of the operational amplifier with the input given?

Thread Starter

Wise Solomon

Joined Apr 24, 2019
3
I am trying to draw out the output of the operational amplifier with the input given below
1.PNG
The first thing I did was calculating the gradient of the slope to give me the slew rate
SR = (change in voltage)/ (change in time) = 0.2/1u = 200kV/sec
This is all I managed to find out.
What is my next step?
What are the expected results?
Thanks, any help and guidance are welcomed
 

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Thread Starter

Wise Solomon

Joined Apr 24, 2019
3
No schematic was given, no op amp was specified, so I assume any opamp will do the job? Yup, its some theoretical question for fun. My "own-paced" homework haha
 

OBW0549

Joined Mar 2, 2015
2,986
No schematic was given, no op amp was specified,
Without that information, your question is unanswerable.

so I assume any opamp will do the job?
WHAT job???? You haven't described any "job," just asked what the response of the op amp will be to the input you gave-- a completely nonsensical question, given the lack of a specific application circuit w/ schematic diagram. With the information given, the best anybody could do is say "the op amp will probably do something."

Yup, its some theoretical question for fun. My "own-paced" homework haha
You need to change your "pace" or you won't learn a darned thing.
 

WBahn

Joined Mar 31, 2012
24,698
I am trying to draw out the output of the operational amplifier with the input given below
View attachment 175745
The first thing I did was calculating the gradient of the slope to give me the slew rate
SR = (change in voltage)/ (change in time) = 0.2/1u = 200kV/sec
This is all I managed to find out.
What is my next step?
What are the expected results?
Thanks, any help and guidance are welcomed
What operational amplifier? What circuit it is in?
 

WBahn

Joined Mar 31, 2012
24,698
No schematic was given, no op amp was specified, so I assume any opamp will do the job? Yup, its some theoretical question for fun. My "own-paced" homework haha
This is like someone asking what will be the response of the car be if the accelerator is pressed from idle to the floor in 100 ms, held there for ten seconds, and then eased off back to idle over 100 ms. Then, when asked what car and what kind of road responding that they assumed any car and any road will give the same result.
 

crutschow

Joined Mar 14, 2008
23,358
An op amp by itself, is a very high-gain differential input amplifier.
Without additional circuitry its only practical use is as a comparator.
For that condition, the op amp output would be a square-wave for your input.

Suggest you do some "own-paced" homework on op amps.
 
Last edited:

MrAl

Joined Jun 17, 2014
6,494
I am trying to draw out the output of the operational amplifier with the input given below
View attachment 175745
The first thing I did was calculating the gradient of the slope to give me the slew rate
SR = (change in voltage)/ (change in time) = 0.2/1u = 200kV/sec
This is all I managed to find out.
What is my next step?
What are the expected results?
Thanks, any help and guidance are welcomed
Hi,

Your next step is to select an op amp and a circuit.
A typical op amp is the LM358, and a typical circuit is an inverting or non inverting amplifier with gain of 1.
However, depending on the choice of op amp, the slew rate of the op amp itself will have to mix with the slope of your input wave at the beginning and end. This might lead to a quadratic (a*t^2) looking wave at the start and end, with some flatness in between.
If you choose to use a low pass filter circuit with the op amp then you will get a smoother output.

So pick an op amp and circuit you'd like to see work with that input and we can go from there.

EDIT: Changed "cubic" to "quadratic" above. During the input slopes the slew rate of the op amp will create a quadratic waveshape either rising or falling.
 
Last edited:

Thread Starter

Wise Solomon

Joined Apr 24, 2019
3
Hi all, thanks for the response, yup, its true that it lacks on information and also lacking in learning speed. I'm sorry guys n girls. Anyway, what are the possible ways to delay the input time as shown in diagram above? Thanks
 

WBahn

Joined Mar 31, 2012
24,698
Hi all, thanks for the response, yup, its true that it lacks on information and also lacking in learning speed. I'm sorry guys n girls. Anyway, what are the possible ways to delay the input time as shown in diagram above? Thanks
Apply the input at a later time???...

You really need to be more specific in the questions you are asking.
 

atferrari

Joined Jan 6, 2004
3,456
As I learnt (by posting possible solutions to untold problems that I only knew) it would be better you explain what do you need to implement or solve.
 

MrAl

Joined Jun 17, 2014
6,494
Hi all, thanks for the response, yup, its true that it lacks on information and also lacking in learning speed. I'm sorry guys n girls. Anyway, what are the possible ways to delay the input time as shown in diagram above? Thanks
Hi,

Yes, cut it in half and give half to each input :)
(from King Solomon)

You dont show any diagram. Are you referring to the original diagram?
 
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