A variable attenuator operable in a frequency band from at least 10 GHz is disclosed. The variable attenuator includes an input port; an output port; a first transmission line connecting the input port with the output port; an attenuating unit provided between the first transmission line and the ground; and a second transmission line. The attenuating unit includes at least one transistor with two current terminals coupled with the first transmission line and ground, respectively. The second transmission line is coupled between the two current terminals of the transistor. The second transmission line is operable as an inductor in the frequency band. A feature of the variable attenuator is that the transistor and the second transmission line cause a resonance frequency within the frequency band by a capacitor between the two current terminals and the inductance of the second transmission line.