Why my op-amp differentiator output waveform not perfect

Thread Starter

Harvey Wang

Joined Mar 16, 2018
1
Hi all,
I created a op-amp differentiator by myself using LM741 and capacitor with100nf resistor with 10k ohms. However, when I input Ramp signal, my output waveform is like this(graph below). I don’t know why, how can I fix it?6183F38A-06EF-4B16-9708-251FEE300BF9.png
 

MrChips

Joined Oct 2, 2009
19,918
Are we to assume that trace C1 is the input signal and trace C2 is the output of your differentiator?

What is the make and model of your oscilloscope?
What are you using as oscilloscope probes?
 

DickCappels

Joined Aug 21, 2008
6,087
Yep, the LM741 is probably having trouble slewing at the end of each slope.

Also notice that your triangle waveform is nonlinear for the first
approximately 50 us of each slope.
 

crutschow

Joined Mar 14, 2008
24,077
Simulation shows that about 250Ω in series with the input capacitor slows down the slew rate so there's no overshoot or ringing (if it's a standard op amp RC differentiator), even with the lowly old 741.
 
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