Changing the attenuator to make it a 1x probe

A project log for A 1x, 100 MHz, 35 V common mode diff probe

I needed a differential probe for BLDC motor ESC development and adapted Bud's design for my needs

ChristophChristoph 10/13/2020 at 16:560 Comments

Since the voltages I'm dealing with are not as high as Bud's, I decided that I wanted to modify the input attenuator from 1:250 to 1:25. This had to be done for the resistors and the capacitors.

There was a caveat though: Bud found that the layout introduces some error in the capacitive divider, effectively lowering the capacitance of C1...C4 by 7.5 %. I've taken that into account in my calculations and the result was spot on (pure luck to be honest because I didn't place the smallest cap that was meant for tweaking the result).

I've put the results into a zipped xlsx file that can be found in the project files.