EEVblog Electronics Community Forum
Electronics => PCB/EDA/CAD => Topic started by: bullonwheels on June 19, 2018, 05:27:58 am
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Hi Everyone,
I am having issues with a unit disconnecting its RF BLE link when I take the unit close to a cell phone.
Its a CC2531 IC with keypad on it.
What are the major steps to be considered when laying out the single layer PCB.
Things considered: Added a guard ring across oscillator circuits.
Decoupling caps very very close to IC.
No clock traces near power rails.
Anything else ?
I can share gerbers if needed.
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1. Minimize the loop area of all signals including power. Usually this means using a ground plane.
2. Limit the bandwidth at all inputs and sometimes outputs. Usually this takes the form of RF filtering.
3. Shield sensitive lines and nodes. This might include putting the whole thing into a shielded enclosure and filtering inputs and outputs to keep conducted RF out.
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All of the above, and usually you will need at least a two layer board to stand much chance, your loop areas will just be too big on a single layer design.
Physically smaller components (especially caps!) are better at high frequency, there is much to be said for 0603 or 0402 instead of anything with leads.
Note that by the time you hit 1.9GHz, the parasitic behaviour of components is in play bigtime if you are not careful, and every component looks like an inductor (except inductors that look like capacitors!).
Regards, Dan.
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Consider inserting a SAW filter (step 2 from David)