Questions About Selecting a Shunt Resistor

[pololo]

I'm attempting to perform power analysis on my target, which operates at 3.3 volts. The average current while running is around 140mA without the resistor.

With a 5V power source, I utilized a 10Ohm resistor as a shunt resistor. The shunt resistor was connected between 5V and the target VCC pin, and the voltage difference between VCC PIN and GND was measured. (The decoupling caps have been taken out.) The oscilloscope, on the other hand, did not provide a suitable power consumption line.

Is something wrong with my setup? Is there any advice on selecting a shunt resistor?

I’ve read some articles like https://www.apogeeweb.net/electron/what ... istor.html, but I still have no idea.

Thank you so much for your assistance!

[redpitaya]

Try using a 50 Ohm shunt resistor. You might get better results because the output filter of the Red Pitaya is set for a 50-Ohm load.
https://content.redpitaya.com/blog/usi ... e-analyser