In telecommunications, a multi-band device is a communication device that supports multiple radio frequency bands. All devices which have more than one channel use multiple frequencies; a band however is a group of frequencies containing many channels. Mobile carriers use multiple bands, internationally, to communicate with their telecommunications infrastructure. Multiple bands in mobile devices support roaming between different regions where different standards are used for mobile telephone services. Where the bands are widely separated in frequency, parallel transmit and receive signal path circuits must be provided, which may impact the manufacturing cost of multi-band devices due to increased circuit complexity.