FEDEVEL
Platform forum

Nspace , 11-17-2025, 07:55 PM

Hi, I have some questions about the design of the power supply lesson of this course: why is the project using a RC low-pass filter before the analog power supply instead of a LC filter and why was a cutoff frequency of 361 Hz chosen for this filter?
The choice of a RC filter seems counterintuitive to me because as the instructor himself notes in the video these should only be used when the noise requirements are not that stringent, and the filter in question is in the power supply for the analog stage, which should be the part of the circuit which is most sensitive to noise.
I also couldn't explain why the cutoff frequency was chosen: it's in the middle of the frequency band that the project is targeting (20-20k Hz). Why isn't it lower than 20 Hz (to filter out all noise in the audio band) or higher than 20 kHz (to make sure that the analog parts can respond to transients quickly)?