Circuitry comprising: a first radio path comprising a first filter configured for a first radio access technology (RAT) system; a second radio path comprising a second filter configured for a second radio access technology (RAT) system different to the first RAT system; means for obtaining a first indicator, dependent on the first RAT system, wherein the first indicator is one of a predetermined number of states; means for obtaining a second indicator, dependent on the second RAT system wherein the second indicator is one of a predetermined number of states; and means for using a combination of the states of the first indicator and the second indicator to control characteristics of at least the first filter.