Well this is just a general question about switch mode power supplies, but i have recently built a buck converter, and read that it is very important where in the circuit you place your probes, to measure output ripple and noise.
As output capacitance i have a electrolytic cap, and a small 100n ceramic. When i measure directly above the ceramic capacitor, i can clearly see the ideal/textbook output ripple, with a small amount of high frequency ringing, which measures to about 50mVpp. But when i move my probes to measure above my resistive load, the output noise amplifies to around 200-300mVpp.
How come? I dont understand where this noise is coming from, when closer to the circuit im measuring way less noise? Is it radiated noise picked up from the inductor coil? Or am i missing something