I have built a buck converter in constant current mode in the circuit configuration below in order to charge a supercapacitor. A difference amplifier amplifies the voltage across the 20m Ohm resistor and closes the top MOSFET if the current goes below 5.5A and opens the switch once the current reaches 6A. The PWM signal is being applied with an arduino that monitors the voltage from the difference amplifier and is in the place of the signal generator in the image.


The problem is that the PWM signal from the arduino is highly distorted after it is connected to the circuit. I have attached pictures of the PWM before it is connected and after. Any help would be greatly appreciated.

PWM before connected to circuit



PWM when connected to circuit

 

You have obviously posted the wrong circuit, no 20m Ohm resistor, no Arduino, no difference amplifier, in fact barely any relation to your description!

 

You have obviously posted the wrong circuit, no 20m Ohm resistor, no Arduino, no difference amplifier, in fact barely any relation to your description!

No, I believe you are mistaken.

I see you are relatively new. Have you read the Terms of Service? Your posts which I have seen are borderline.

To the point, there is relevance to the included image. As stated, the circuit shown produced an output analogous to the output of the Arduino.

I do agree with what I perceive as your intent. The entire circuit would be valuable.