What is the minimum radio output power for nRF52840 ?

[Roxanne]

Hello,

I am using the nRF840 PDK for testing the radio communication.

During my tests, for TXPOWER=0xD8(at minimum), I found a gap of 7 dBm between the radio output power (value written in TXPOWER register) and the reveived power (RSSI mesured by a spectrum analyser). While the gap is 1 or 2 dBm for all others output power.

Is it ok to find this result ?

Also, I am confusing with the datasheet. It indicates -40dBm for Neg30dBm AND Neg40dBm. In reception, I found -37dBm. So, if my tests are correct, it should be -30dBm. Wich one is correct ?

[run_ar]

Neg40dBm should be -40dBm +/- 4 dB (according to OPS). Neg30dBm is there for legacy support, i.e. -30dBm is the lowest setting on the nRF51 series.