https://devzone.nordicsemi.com/f/nordic-q-a/4731/use-of-rf-front-end-with-gazellHi there I have never used a nRF51822 device but it looks like a good option for a product development. Reliability of the link is a priority so the design will include a PA. I note in previous questions the use of a PA (controlled by VDD_PA) isen-USTelligent Community 13Mon, 08 Dec 2014 08:55:30 GMThttps://devzone.nordicsemi.com/thread/16736?ContentTypeID=1Mon, 08 Dec 2014 08:55:30 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6e6abc4c-1edf-40f8-8e41-76d4d521352eAsbj&#248;rn<p>There are several customers that have used the VDD_PA pin to trigger TX operation on a PA. You can&#39;t load anything from the VDD_PA pin, but you can use it as a trigger.</p> <p>The VDD_PA pin is controlled by the HW itself. So Gazell will control it in the sense that you can control when you want to send data. As soon as Gazell use the tx send command, the chip will enter TX mode and VDD_PA will go high to 1.8 V.</p> <p>VDD_PA will be at 0 V when it is not in TX. So RX and radio off mode, VDD_PA will be 0 V.</p><div style="clear:both;"></div>