I have a n channel MOSFET controlling a high current LED panel. The FET is driven by a FET driver, which is itself driven by a MCU pin. I am using PWM to control the LED brightness.

I want to double check the PWM with my scope, to ensure the duty cycle is correct. I can check all along the circuit, and I get proper readings from my scope. If I check the outputs from my FET, I get a garbage reading.

This is because, I believe, when the FET is off, the ground clip is disconnected from the ground reference, and it is left floating.

How can I check the FET output with my scope, since whenever the pulse is low, the ground reference is no longer connected?

[![img 1][1]][1]
Scope probe is at 12v, grd clip is at OUT_LED_GND

[![img 2][2]][2]

Scope output


 [1]: https://i.sstatic.net/bqiMY.jpg
 [2]: https://i.sstatic.net/I4Rsf.jpg