EMI Bites: Don’t Let Your Crystal Oscillator Turn Into a Noise Source
Where you place your components isn’t just about convenience—it’s about controlling emissions.
Take the crystal oscillator:
If you place it close to the output and far from the feeding point, the signal can couple into other lines or leak into the power delivery network.
And that’s a fast track to failing EMC tests—both conducted and radiated.
Why this causes problems:
- Long traces between the oscillator and its driver create radiating structures.
- Signals can couple into nearby I/Os like USB, propagating noise off the board.
- The power delivery network can act as a highway for high-frequency interference.
- Poor component placement defeats your decoupling and protection strategy.
Key Insight:
Critical components must be placed close to the pins they support.
How to place components to reduce EMI:
- Place crystal oscillators right next to the MCU or clock input they drive.
- Keep coupling capacitors as close as possible to power pins.
- Place protection components (TVS diodes, filters) right at input/output connectors.
- Minimize trace lengths for signals to avoid unintended antennas.
Hope this helps,
Dario
P.S. Do you want to master EMI Control and PCB Design?
Get all the trainings you need here: https://fresuelectronics.com/trainings
#Electronics #PCBDesign #EMI #EMC #Engineering