Power Amplifier and Low Noise Amplifier control configuration (PA/LNA)

The SoftDevice can be configured by the application to toggle GPIO pins before and after radio transmission and before and after radio reception to control a Power Amplifier and/or a Low Noise Amplifier (PA/LNA).

The PA/LNA control functionality is provided by the SoftDevice protocol stack implementation and must be enabled by the application before it can be used.
Important: In order to be used along with proprietary radio protocols that make use of the Timeslot API, the PA/LNA control functionality needs to be implemented as part of the proprietary radio protocol stack.
Figure 1. Example of timings when PA/LNA control is enabled. The PA pin is configured active high, and the LNA pin is configured active low

The PA and the LNA are controlled by one GPIO pin each, which are activated, respectively, during radio transmission and radio reception. The pins can be configured to be active low or active high. The SoftDevice will guarantee that the pins will be set to active 5±2 us before the EVENTS_READY signal on the RADIO using a GPIOTE connected with a PPI channel to a timer. The selected time difference allows for a sufficient ramp up time for the amplifiers, while it avoids activating them too early during the radio start up procedure (which results in amplifying carrier noise etc.). The pins are restored to inactive state using a PPI connected to the EVENTS_DISABLED event on the RADIO. See nRF52832 Product Specification for more details on the nRF52 RADIO notification signals.