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| Non ideality in output square wave of a differentiator circuit |
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| bonzer:
Hello everyone! Please help me to understand why does that square wave at the output of differentiator circuit using operational amplifier have that spike at those points of rising edge? The input is a triangular wave with frequency of 30Hz. It's not a simple differentiator, it had a compensation so it derives till like 3kHz than it crosses the output open loop gain of the operational and starts to go down. My opinion is that at those points triangular waves have high frequency components that get cut by the differentiator and therefore can't complete the waveform at the output. What's your thoughts? |
| Benta:
Change your title from "derivator" to "differentiator", then probably more people will react. |
| emece67:
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| bonzer:
Thanks a lot! I think it's exactly my case! |
| rstofer:
I'm on thin ice here... The triangle wave is continuous but its first derivative is not (square wave having a jump discontinuity). Therefore,the triangle wave is not continuously differentialable. So the derivative blows up at the peak (top and bottom) of the triangle wave. Note how the author wants to ignore the peak in this link: https://www.chegg.com/homework-help/questions-and-answers/derivative-triangle-wave-square-wave-illustration-shows-triangle-amplitude-periodt-line-se-q19516514 I'm not sure I would put what your seeing down as the Gibbs Phenomenon because you only see it on one corner of the square wave. The GP affects both ends of both edges. When the square wave changes level, dv/dt approaches infinity. Given infinite harmonic content, dv/dt would approach quite closely. But even with modest harmonic content, the derivative will still be quite high. |
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