Is there a way to estimate/measure power supply noise frequency? or measuring it with an oscilloscope is the only way?
For example, the processor in the board I am looking at has an external 24MHz crystal, on-chip 400MHz PLL driving CPU clock, 480 mbps USB bus, extenal memory interface running at 133mhz, SPI bus running at 25MHz and several GPIOs. I would like to know the possible digital power supply noise frequencies for this board.
or is it greatly dependent on switching of internal gates, bypass capacitors and board layout and hence cannot be estimated with mere clock frequencies.
Thanks in advance. mjnk