Variable attenuator and mobile communication apparatus

摘要

A variable attenuator is provided with a comb line formed of first and second lines electromagnetically coupled at a coupling degree of M, and diodes connected to the first and second lines constituting the comb line. One end of the first line is grounded through a capacitor and also connected to an input terminal through a capacitor. A diode is connected between the ground and the other end of the first line such that its anode is connected to the other end of the first line. The node connecting the other end of the first line and the anode of the diode is connected to a control terminal through a resistor. One end of the second line is grounded through a capacitor and also connected to an output terminal through a capacitor. Another diode is connected between the ground and the other end of the second line such that its anode is connected to the other end of the second line. The node connecting the other end of the second line and the anode of the diode is connected to a control terminal through a resistor.