DC blocking cap with nRF52840 and PIFA

[Maxwell1864]

Hello,

Do I have to include a DC blocking capacitor with nRF52840 if I use a PIFA antenna? Can you point me to some documentation (i.e., reference design) that would include capacitance value as well?

Thank you.

[Priyanka]

Hi Fabio,

You can use any antenna matching network for this. But please keep in mind that the nRF needs its own matching network as it is not 50 ohms from the ANT pin and it is also used for filtering the harmonics. Also, the antenna needs it's own matching circuit and for this, a single shunt capacitor can be used, with trace antennas in case you can adjust the length. You can refer any reference diagram for the same, from the hardware files on our website. It would be better to take a look at the dongle hardware reference.

Best Regards,

Priyanka

[Maxwell1864]

Hi Priyanka,

Thank you for your answer. I am using a matching network. Nevertheless, I was more concerned about DC component being shorted to ground by the antenna configuration. I found out that output stage of the radio is transformer coupled so there is no DC component on the ANT ball. Hence I don't need a DC choke.

Thank you.