Device and method for variable signal attenuation in wireless communication system

A signal attenuation device built in a stack-up structure in a radio frequency integrated circuit (RFIC), the signal attenuation device comprising:

• a first transmission line positioned in a first layer in the RFIC;
• a second transmission line positioned in a second layer in the RFIC vertically adjacent to the first layer and electromagnetically coupled to the first transmission line;
• and
• a controller,
• wherein the first transmission line comprises a first impedance controller on a first end of the first transmission line,
• wherein the second transmission line comprises a second impedance controller on a first end of the second transmission line, and the first end of the second transmission line is opposite to the first end of the first transmission line,
• wherein the controller is coupled with the first impedance controller and the second impedance controller, and configured to control the first impedance controller and the second impedance controller,
• wherein the signal attenuation device further comprises:
• a first signal port through which current is configured to flow in and out at a second end of the first transmission line which is opposite to the first end of the first transmission line;
• and
• a second port through which current is configured to flow in and out at a second end of the second transmission line which is opposite to the first end of the second transmission line,
• wherein one side of the first impedance controller is grounded and one side of the second impedance controller is grounded,
• wherein each of the first impedance controller and the second impedance controller comprises at least two transistors connected to each other in parallel, respectively,
• wherein the controller is further configured to control an on/off state of each of the at least two transistors of each of the first impedance controller and the second impedance controller, individually, and
• wherein the signal attenuation device is selected by a switch included in the RFIC based on a frequency band.