Rx I/Q Output Common-Mode voltage can be changed or adjusted using bits D11:D10 in register 15.
These baseband outputs (RXBBI+, RXBBI-, RXBBQ+, and RXBBQ-) are differential low impedance buffered outputs. The outputs are designed for direct connection (DC-coupled) to the inphase (I) and quadrature (Q) ADC (analog to digital converter) inputs of the baseband IC/section.