I recently found this op amp exercise and solved it using superposition .The result was UA

I first need to draw U1 and U2 and then based on UA draw the output result.Stuck doing this and now way to figure it out if I'm doing this right so I came here for some needed help

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This is my attempt to just plot U1 and U2 without then trying to plot the output UA.

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Asking for some advice if my approach of graphing this is right. U1 seems to be right I'm just not sure about U2

  • 4
    \$\begingroup\$ I'm voting to close this question as off-topic because it is a generic question about graphing software, not specific to electronic design. \$\endgroup\$ Jan 14, 2020 at 20:24
  • \$\begingroup\$ @Elliot Alderso, I have edited the question. Would really appreciate some advice \$\endgroup\$
    – E199504
    Jan 14, 2020 at 20:51
  • \$\begingroup\$ I think you have U1 and U2 exchanged in your graph. Also you can see that U1 should hit 2V at 20us, and thus 1V at 10us \$\endgroup\$
    – jonathanjo
    Jan 14, 2020 at 21:11
  • \$\begingroup\$ @jonathanjo, yes U1 and U2 are exchanged. Can you please give an answer on how would you go on graphing this. I want o understand the concept . Would appreciate it a lot \$\endgroup\$
    – E199504
    Jan 15, 2020 at 9:23
  • \$\begingroup\$ @be1995 see answer given below \$\endgroup\$
    – jonathanjo
    Jan 15, 2020 at 12:57

1 Answer 1


I can tell you nothing about what these functions mean with regard to op-amps, but the following should help you get the graphs you're after.

You go about this by first understanding the notation:

U1 is a linear function on t, Û1 is essentially a scalar constant to adjust the amplitude, and T1 is a scalar to adjust the slope. The function is defined over a T1 wide period centred on t=0, ie, from -T1/2 to +T1/2.

U2 is a sinusoidal function on t, expressed as a cosine so it is also centred on t=0, so expressed as cosine. Û2 scales the amplitude to 2V. f2 is the frequency: 2π is the constant to convert cycles to radians.

UA is simply a linear combination of those two functions.

The two easiest ways to graph this are use either a graphing program/website or a spreadsheet.

Graphing Website

You might find the graphing site https://www.geobra.org/graphing helpful. I use it for quick graphs of this kind. There are plenty of graphing packages and sites available.

First I folded up the constants and multiplied everything by 1,000,000 just for convenience, giving T1=20 and f2 as 0.1. Then you create the three functions by typing them in to the box on the left (by the three coloured dots). You might have to read the manual to see how to type in the functions, but it's easier than it looks. The program then just draws the graphs for you. If you click on the graph lines or coloured dots you can see various values on the graph (eg points of inflection).

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Having noticed that we go from -10μs to +10μs, we construct a table in a spreadsheet with a least a hundred rows, which will give us a detailed enough graph. I pick 0.1μs just for convenience, which means we will have 201 rows. Then you make a column for t and each function; then you make a graph of it. The scatter plot function expects each row to have the horizontal coordinate and several vertical, just what's needed. You adjust scales and grids until it's easy to read.

enter image description here

  • \$\begingroup\$ thank you very much that helped me a lot. Is there a way you can graph this. It is slightly different and I don't know how to implement it in the geora website link. Would mean a lot \$\endgroup\$
    – E199504
    Jan 17, 2020 at 18:39
  • \$\begingroup\$ can you please help me on how to plot the value from the link on the comment above. would mean a lot \$\endgroup\$
    – E199504
    Jan 18, 2020 at 21:09
  • \$\begingroup\$ Please help me with this, I have created a new question . I would mean so much to m Link to quetion here \$\endgroup\$
    – E199504
    Jan 19, 2020 at 17:14

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