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andrewsdai
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Last seen: 6 months 3 weeks ago
Joined: 2015-09-21 00:18
AN-B-027 and matching

I was wondering how the antenna matching works. In the DA14531 datasheet, there is a 1.8pF/3.3nH/1.8pF pi network right at the RF pin.  Is this required to get the pin to 50 ohms?

The reason I'm asking is that the AN-B-027 app note has matching as well.  Are both matching networks required (the pi network from the datasheet plus the matching network in the app note), or is the datasheet's pi network a placeholder, and can be replaced by the matching in AN-B-027?

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PM_Dialog
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Last seen: 2 days 9 hours ago
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Joined: 2018-02-08 11:03
Hi andrewsdai,

Hi andrewsdai,

The Pi Filter is needed to remove the out of band emission. Also, the extra Pi Filter for the RF circuit is needed to avoid Spurious Emissions Reduction. For more information on the antenna filters, see application note Designing Printed Antennas for Bluetooth Smart.

https://www.dialog-semiconductor.com/sites/default/files/an-b-027_designing_printed_antennas_for_bluetooth_low_energy_2v3.pdf

Th AN-B-027 application note provides guidelines for designing printed antennas, so you can use it as a reference. What kind of antenna you are interested in your design? Any of the matching network described in the application note.

You can also find the DXF files as well - AN-B-027: Designing Printed Antennas: DXF files.

Thanks, PM_Dialog