Interfacing PA with nRF51822

[Sreekanth]

Hello,

I would like to know whether the below PA can be interfaced with nRF51822? For our application we need to increase the power of the BT. so I have selected the below PA from skyworks,

1. SE2431L- can this be used to increase the range.
2. SKY66108- can this be directly connected to nRF51822 as this has a balun inside the FEM.

Thanks, Sreekanth

[Håkon Alseth]

Hi,

PA's have been widely discussed in several threads, for instance this one: devzone.nordicsemi.com/.../

Your second option will most likely not work, as the nRF51 matching network has two jobs:

1. Differential to single-ended impedance conversion
2. Heavy filtering.

Having a BALUN that does both of these jobs sufficiently is hard to achieve, and I would recommend that you use our reference layout with either discrete or integrated BALUN option, then connect this to an external single-ended 50 ohm input/output RF PA, such as your first option. You can use the "VDD_PA" pin to control the external RF PA.

Note: The bluetooth core spec for LE devices limits you to sending max. +10 dBm EIRP. This means that you will only gain 6 dB link budget compared to running the nRF51 with +4 dBm output.

Cheers, Håkon