There is an issue concerning minimum output power.If you look at High Performance RF Transceiver for Narrowband Systems. (Rev. B) ,
on page 12 it says that minimum output power can be set to -40 dBm within coarse step size range. What is a coarse step size range?
In CC112x Low-Power High Performance Sub-1 GHz RF Transceivers User’s Guide, on page 35 a formula for output power calculation is given.
According to the formula (output power = (PA_POWER_RAMP+1)/2) -18, where 3 ≤ PA_POWER_RAMP ≤ 64 it is impossible to get -40dBm output power.
For receiver sensitivity measurements I would require transmitter output power to be as low as possible, so I am wondering is there a way to lower it down to 40 dBm?