PA and LNA on nrf51822

RE: PA and LNA on nrf51822

Håkon Alseth — Mon, 19 May 2014 07:40:40 GMT

I'm glad to hear that you find the forum useful :-) The VDD_PA pin on the nRF should be connected to the ENABLE pin of the RFPA. This will enable the RFPA to go into a "throughput mode" when disabled, so that the RX signal can go into the radio.

Additional information: The BALUN (or matching network) works both ways. For a transmission, it converts the differential output from the nRF to a single-ended signal. For a reception, it converts the single-ended input into differential signal.

RE: PA and LNA on nrf51822

victor — Fri, 16 May 2014 12:40:35 GMT

Thanks for your awnser, I have one more wuestion, If I use for example www.skyworksinc.com/.../202428A.pdf Which was referenced in your link, then can i still receive data on that nrf51822? Will the received signal go through the PA in the reverse direction?

Thanks for your awnser, this forum is verry good!

RE: PA and LNA on nrf51822

Håkon Alseth — Fri, 16 May 2014 12:32:53 GMT

Hi Victor,

Regarding the usage of LNA, please see this thread: devzone.nordicsemi.com/.../how-can-i-use-pa-to-increase-the-rf-coverage

When it comes to using a RF PA, note that bluetooth sig limits the output power to +10 dBm on bluetooth low energy devices.

The CC2592 includes a differential input which is not tailored towards our nRF-radios, so the performance and spurious emissions will not be optimal (you will most likely fail FCC/CE/ARIB tele-regulatory).

If you are to combine our nRF-chips with a RF PA, then you can choose any 2.4 GHz RF PA that has a single-ended 50 ohm input and output. Logic for tuning the PA on/off can be used via pin "VDD_PA", which goes high around 80 us before a TX-transmission occurs and goes low again when it's finished.

Best regards Håkon