| ??? 06/01/05 01:09 Read: times |
#94166 - PCB Design Guidelines For Reduced EMI Responding to: ???'s previous message |
PCB Design Guidelines For Reduced EMI.pdf
... The third noise source is the oscillator circuit, where the oscillator swings rail to rail. In addition to the fundamental frequency, harmonics are introduced on the output side because the output buffer is digital, which squares the sine wave... ... If proper separation is maintained between the crystal and its tank circuits from other components and traces on the PCB, and the loop areas are kept small, there should be no problems with this noise source. But it has been shown that if ICs or passive components, such as the main VBatt series inductor, are placed close to the crystal, harmonics of the crystal can couple and propagate... ... Other more difficult loops are actually ambient field loops. For example, the crystal itself radiates energy that can be coupled into a wire running nearby. Then, the wire contains noise that tries to get back to the crystal loop. That may involve a very long and convoluted path, which serves as another antenna for noise from the crystal... ... Most EMI-related crosstalk problems center around the crystal, when the victim is located too close. No unrelated components should be closer than 1 inch to the crystal... ... Routing near the crystal, and the crystal and tank circuit itself, should be checked... |
| Topic | Author | Date |
| EMV QUESTION | 01/01/70 00:00 | |
| You Can do... | 01/01/70 00:00 | |
| Of course | 01/01/70 00:00 | |
| More for clamping than for grounding.. | 01/01/70 00:00 | |
| Extra capacitance? | 01/01/70 00:00 | |
| PCB Design Guidelines For Reduced EMI | 01/01/70 00:00 | |
| Perspective | 01/01/70 00:00 | |
| thanx for thanx// | 01/01/70 00:00 | |
| Moreover | 01/01/70 00:00 | |
Best xtal PCB I know | 01/01/70 00:00 |