RF Power Amplifier for nRF51822

[dblasco]

Hello,

I have searched through the questions regarding RF PA recommendations but I think none solved my issue.

I would like the nRF51822 to broadcast at +10dBm, so I want to add a PA. Maybe I am looking for PA's in a bad way, but it has been hard to find something interesting. Finally I found this PA: MGA-665P8-BLK

According to its datasheet, for 2.4GHz it has a gain of 18.42dB and I cannot modify it. Would be a wise idea to program my nRF51822 to emit at -8dBm so the final result is ~10dBm?

In other question I saw a recommendation of this PA: www.skyworksinc.com/.../202428A.pdf This PA has a gain about 33dB and would give me about ~30dBm, so it is more than I need. Am I understanding something wrong?

Thank you!

[Håkon Alseth]

Hi,

The MGA-665P8-BLK PA seems to have a powerdown pin that is active low, while the VDD_PA pin is active high. You would need to add a inverter (transistor) on the signal in order to automatically switch the PA on when the radio is transmitting, and off again when the radio is idle.

The skyworks PA has active high "ENABLE" pin.

Regarding the output power, if the PA has a gain of ~18 dB @ 2.4 GHz, then you must ensure that the input power is approx. -8 dBm to get +10 dBm out of the external RF PA.

Cheers, Håkon