Data is received that has been transmitted via a combination of radio frequency signals using carrier aggregation, each radio frequency signal occupying a respective radio frequency band, the bands being arranged in two groups separated in frequency by a first frequency region, the first of the two groups occupying a wider frequency region than the second group. Embodiments provide a method and apparatus for downcoverting the radio frequency signals using quadrature mixing to give inphase and quadrature components, and the inphase and quadrature components are filtered using a first bandpass filter bandwidth to give first bandpass filtered inphase and quadrature components and filtered using a second bandpass filter bandwidth, different from the first bandpass filter bandwidth, to give second bandpass filtered inphase and quadrature components.