A tunable impedance network (20, 30, 40, 50) configured for operating in the RF frequency range for impedance matching in an RF signal line, the network (20, 30, 40, 50) comprising: at least one variable impedance bank (24, 34) comprising a plurality of digitally controlled unit cells (23, 33), each having a same nominal impedance value and each connected from a first common terminal to a routing wire (21, 31) in a parallel configuration and arranged, when switched-on, to adjust the impedance of the variable impedance bank (24, 34) by a discrete value; and means configured to generate a plurality of sets of predetermined digital control signals, each set corresponding to a desired impedance; selection means arranged for selecting, based on the desired impedance, a corresponding set of predetermined digital control signals to be supplied to the variable impedance bank (24, 34) to switch-on a corresponding combination of said unit cells (23, 33); and a routing wire section (22, 32) provided between each pair of unit cells (23, 33) in the bank (24, 34), the routing wire section having a predetermined routing impedance which is less than said nominal impedance and which contributes to the actual impedance generated by the variable impedance bank (24, 34); characterised in that each of the sets of predetermined digital control signals is provided for switching-on a combination of unit cells (23, 33) in such a way that the routing impedance contributed by the routing wire section (22, 32) provided between each pair of switched-on unit cells is used to fine-tune the actual impedance generated by the variable impedance bank (24, 34), the routing wire section (22, 32) being designed in such a way that its contribution to the said actual impedance provides for a stepwise variation of the generated actual impedance at a granularity below that of the unit cells. at least one variable impedance bank (24, 34) comprising a plurality of digitally controlled unit cells (23, 33), each having a same nominal impedance value and each connected from a first common terminal to a routing wire (21, 31) in a parallel configuration and arranged, when switched-on, to adjust the impedance of the variable impedance bank (24, 34) by a discrete value; and means configured to generate a plurality of sets of predetermined digital control signals, each set corresponding to a desired impedance; selection means arranged for selecting, based on the desired impedance, a corresponding set of predetermined digital control signals to be supplied to the variable impedance bank (24, 34) to switch-on a corresponding combination of said unit cells (23, 33); and a routing wire section (22, 32) provided between each pair of unit cells (23, 33) in the bank (24, 34), the routing wire section having a predetermined routing impedance which is less than said nominal impedance and which contributes to the actual impedance generated by the variable impedance bank (24, 34); characterised in that each of the sets of predetermined digital control signals is provided for switching-on a combination of unit cells (23, 33) in such a way that the routing impedance contributed by the routing wire section (22, 32) provided between each pair of switched-on unit cells is used to fine-tune the actual impedance generated by the variable impedance bank (24, 34), the routing wire section (22, 32) being designed in such a way that its contribution to the said actual impedance provides for a stepwise variation of the generated actual impedance at a granularity below that of the unit cells.