I have a SMPS buck 3.3V output. I am trying to measure the output voltage at the output capcacitor using Oscilloscope.
I am using a single ended probe with spring ground tip to measure the output voltage.
The oscilloscope ground is connected to the module ground. (The module ground is not the same as board ground)
When I measure the output voltage at the output capacitor (with single ended probe with ground tip) , I find the output voltage to be very noisy.
But when I measure the output voltage using differential probe, I am not able to find the noise?
Can someone tell me where the noise is coming from?
Is this due to different grounds or some common mode current?
Can someone explain me a little clearly with basic terms?