TX power ceilings

Transmit (TX) power performance depends on a combination of radio circuit design, package type, and Printed Circuit Board (PCB) design. A parameter known as TX power ceiling is used to ensure optimal TX power performance.

The TX power ceilings (in dBm) for the nRF70 Series devices assuming an ideal PCB are described in the following table.

Table 1. Default TX power ceilings in dBm
Devicetree parameter name	QFN	CSP
max-pwr-2g-dsss	21	17
max-pwr-2g-mcs0	16	15
max-pwr-2g-mcs7	16	15
max-pwr-5g-low-mcs0	13	13
max-pwr-5g-low-mcs7	13	13
max-pwr-5g-mid-mcs0	13	13
max-pwr-5g-mid-mcs7	13	13
max-pwr-5g-high-mcs0	12	13
max-pwr-5g-high-mcs7	12	13

Note: The values in this table represent the set TX power and not the measured TX power.

For a non-ideal PCB design, where small impedance mismatches exist in the RF path, adjustment of the TX power ceilings might be required. A devicetree overlay file is provided in the nRF Connect SDK for this purpose. The procedure for arriving at these PCB-specific limits, from now on referred to as board ceilings, is described in Procedure and commands for determining TX power ceilings.

The TX power ceiling applied by the firmware for system operation is the smallest of the default TX power ceiling and the board ceiling as specified in the devicetree overlay file. To use the highest possible TX power ceiling, set all board ceilings to a value greater than or equal to the default ceilings.