10.8 A multi-standard 2G/3G/4G Cellular modem supporting carrier aggregation in 28nm CMOS

Mobile networks today are divided into multiple radio access technologies (RATs) scattered over a variety of frequencies and functionality depending on the network region. The scattered networks require that the digital baseband for mobile user equipment handle multiple RATs, multiple bands, as well as seamlessly transition between these. In 3GPP release 10 [1] the problem with scattered frequency bands has been addressed by the possibility to aggregate spectrum from two separated carriers to create a wider aggregated total bandwidth. Which carriers to combine depends on the spectrum available to the specific operator.