Analog: Integrator, Capacitor Tolerance (publ. 2025-03-27)

I added another integrator today, bringing me up to three integrators. I need four integrators for a particular simulation I am looking at.

I noticed today that the 500 nF capacitors I am using — I put two of them together to get 1 uF — have a 10% tolerance. This seems quite significant as that affects the charging time of the capacitor, and therefore the speed of summing on the integrator, for a given input signal. As far as tolerance, I had been focused on the resistors, using resistors that were 1% or better for input and feedback. But it bothers me that the capacitors could potentially have a difference of 200 nF.

On mouser, I see that Vishay has some 1% tolerance film capacitors that are not very large, but they are rather expensive. Alternatively, I suppose I could order multiple cheap ones and then pick out the most accurate capacitors, though offhand I'm not sure I would come out ahead in the end, as far as total cost.

Copyright

CC BY-SA 4.0 Deed