NRF21540 RF port matched to 50ohms

RE: NRF21540 RF port matched to 50ohms

JONATHAN LL — Fri, 23 Jul 2021 08:01:39 GMT

[quote user="rolandash"]One thing i would like to make sure before i finished up the schematic is if the L1/C2 in 21540 ref-circuit used for matching 21540 or matching antenna?[/quote]

The components are both for 50ohm matching (fundamental frequency) and filtering (harmonic frequencies)

Regards,
Jonathan

RE: NRF21540 RF port matched to 50ohms

rolandash — Fri, 23 Jul 2021 06:52:13 GMT

Jonathan LL

thank you. I will do that.

One thing i would like to make sure before i finished up the schematic is if the L1/C2 in 21540 ref-circuit used for matching 21540 or matching antenna? It looks like it is intended to matching 21540, as there is another shunt capacitor C3 can be used to tunning the antenna. But since 21540 is already 50ohm matched so i am bit confused, should C3 alone is enough here?

RE: NRF21540 RF port matched to 50ohms

JONATHAN LL — Thu, 22 Jul 2021 11:45:03 GMT

Hi,

The nrf52833 and other nrf52 series chips needs matching components to be 50 Ohms, but also to filter harmonics as this is a equally importen factor.

Here is a example of how it is normally done, if you where to include the nrf21540(including the components form the reference circuitry) then that would be after the C3 and L1 component in the picture above.

It is still recommended to include the series inductor and shunt capacitor for the ANT ports.

If you have a specific inquiry then i do recommend that you make a new ticket and ask for a HW review and information on specifics of you design.

Regards,
Jonathan