Capacitor going to input of op-amp ruining ramp rate

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KC30803

Joined Jan 30, 2024
9
Hi all,
I have this IC which creates a linear voltage ramp proportional to the input voltage based on the capacitor on the output in parallel to ground. I then have to do some analog computation using op amps. When I connect the output of this IC to an op-amp, the ramp is ruined. Is there any way around this? Thank you for your help.

Screenshot 2024-02-16 121135.pngScreenshot 2024-02-16 121116.pngScreenshot 2024-02-16 121909.png
 

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crutschow

Joined Mar 14, 2008
34,428
When I connect the output of this IC to an op-amp, the ramp is ruined. Is there any way around this?
Yes
To start with, learn how capacitors work. :rolleyes:
Then, when you do a simulation, check all the voltages to see if they seem correct.

Here, the op amps have no power, since you have a capacitor in series with the ground pin of each supply, and capacitors cannot conduct DC current.
With no power, the op amp inputs draw current and spoil the ramp.

If you want to show decoupling, the capacitors need be connected from the voltage output to ground. not in series with the supplies.
 
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