A mobile communication device is provided, comprising: a first radio configured to process a first signal in a first frequency band, and a second radio configured to process a second signal in a second frequency band, wherein the first frequency band and the second frequency band are overlapping at least in part; and an antenna-plexer circuit, coupled to the first radio and the second radio, and comprising at least one shared antenna to send the first signal and the second signal, and the antenna-plexer circuit further comprising a combining circuit coupling the first radio and the second radio with the shared antenna, wherein the combining circuit comprises at least one bulk acoustic wave filter configured as a band rejection filter having an attenuation slope having an amount of at least about 0.15 dB/MHz at the cut-off frequency.