An attenuator includes a T-type two terminal pair network including first and second terminals, first, second and third circuits, wherein the first terminal receives an input signal to be attenuated, wherein the first circuit is connected between the first and second terminals, wherein the second circuit is connected between the first circuit and the second terminal and is connected to the first circuit via a node, wherein the third circuit is connected to the node, and a capacitor connected to the node, wherein the capacitance value of the capacitor is variable.