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a)I want to change my square wave signal from -2.5 to 2.5 volt to 5 volts to 0 volts? actually this will be given to MOSFET driver ir2110.

b) In the first picture, it is my original square wave coming from the Lm393 comparator, but see its ground level is not in zero references, it is below to zero references, that's why I added Capacitor and resistor (100nf,12K ohms), then I get a shape in order of 2.5 v to -2.5 volt. now I need to change my volatge in 5 volts to 0-volt reference.i have not connected my output of Lm393 comparator with hex inverter or MOSFET driver till yet.

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    \$\begingroup\$ Where is the square wave coming from? \$\endgroup\$
    – user253751
    Jun 30, 2020 at 10:30
  • \$\begingroup\$ You want inversion as well yes? \$\endgroup\$
    – Andy aka
    Jun 30, 2020 at 10:35
  • \$\begingroup\$ this square wave is coming from Lm393 comparator \$\endgroup\$
    – Arijeet Roy
    Jun 30, 2020 at 10:42
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    \$\begingroup\$ Please add info to your question about (a) your situation and (b) why you are trying to do this. \$\endgroup\$
    – TonyM
    Jun 30, 2020 at 10:50
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    \$\begingroup\$ You have not - your question says only what you are trying to do, not why or for what. Please add info to your question about (a) your situation and (b) why you are trying to do this. \$\endgroup\$
    – TonyM
    Jun 30, 2020 at 12:28

1 Answer 1

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I believe this whole question is based on the misinterpretation of the oscilloscope screenshot shown first, before adding a capacitor & resistor to the LM393 output.

You said:

I want to change my square wave signal [...] 5 volts to 0 volts

This is what is shown in the first image anyway!

In the first picture, it is my original square wave coming from the Lm393 comparator, but see its ground level is not in zero references, it is below to zero references

Not true.

The waveform is in the lower half of the display, but that does not mean it is negative. The ground reference level for channel 1 is the small "1" shown on the left side of the display. Notice that the whole of the waveform is positive with respect to that level.

oscilloscope screenshot with ground reference marked and simulated with a red line

Above, I have taken the original oscilloscope screenshot image, and circled the ground reference for channel 1 in red. Notice how the whole waveform is positive with respect to that. I have also added a red line which is the imaginary 0 V (ground) level for that image. As you can see, the whole waveform is above that line.

So it seems that you have introduced a new problem by adding your RC circuit, and you do not need that. The original signal is what you wanted, varying between 0 and 5 V approximately, but it was just displayed in an unexpected way so you didn't recognise it.

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  • \$\begingroup\$ Thankyou finally you got my point, I am trying to explain this everyone, sir, you mean to say that in 1st picture I have already generated square wave in 5 volts to 0-volt reference. sir if I provide this signal to the MOSFET driver, did MOSFET driver will work or will it read the signal? \$\endgroup\$
    – Arijeet Roy
    Jun 30, 2020 at 13:30
  • \$\begingroup\$ Sir, only give me this answer to this problem , if I give the signal to this MOSFET driver, and the square wave signal is 5 volt with his own ground level( or you can say it is dc offset) as seen in the oscilloscope, will MOSFET driver be confused which is the original ground level. \$\endgroup\$
    – Arijeet Roy
    Jun 30, 2020 at 13:39
  • \$\begingroup\$ @SamGibsonokay, in simple words I am asking you, In lm393 comparator generates a square wave, my questions are 1)- did the output square wave has any offset? if yes, should I need to remove the offset, else No, can I give to the MOSFET driver, will it work. \$\endgroup\$
    – Arijeet Roy
    Jun 30, 2020 at 13:51
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    \$\begingroup\$ @ArijeetRoy - "you mean to say that in 1st picture I have already generated square wave in 5 volts to 0-volt" Yes. "if I provide this signal to the MOSFET driver [...] will it read the signal?" Yes. With the IR2113 powered from 5 V, the logic level thresholds (shown in the datasheet) mean that 0 V and 5 V will be recognised as logic low and high. "did MOSFET driver will work" I can't answer that. First, that would need a full review of the driver circuit, but that is not what you asked in the question. Second, layout is important and yours isn't built, so I can't predict the future. \$\endgroup\$
    – SamGibson ♦
    Jun 30, 2020 at 14:40
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    \$\begingroup\$ "theoretical my PWM should lie in 5 volts to 0 volts in XY plane" No, that is an abstraction, which you can change with scope settings. "in my oscilloscope , the practical results are not matching with theoretical results" No, you have the wrong expectation of the theoretical result. "in my oscilloscope, the real ground is always at (0,0) coordinates" No, that is not true. The ground reference position can always be moved. "if press auto set [...]" Auto-set is not guaranteed to produce the display you want. Use the scope controls to move the ground reference, if you want that. \$\endgroup\$
    – SamGibson ♦
    Jun 30, 2020 at 15:44

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