A beam-forming circuit includes a multi mode power amplifier, a variable gain low noise amplifier, a variable gain phase shifter and a first switch circuit. The multi mode power amplifier amplifies a first RF intermediate signal generated based on a first RF input signal to generate a first RF output signal and performs a first transmission gain adjustment function based on a first control signal in a transmission mode. The variable gain low noise amplifier amplifies a second RF input signal to generate a second RF intermediate signal and performs a first reception gain adjustment function based on a second control signal in a reception mode. The variable gain phase shifter controls a gain and a phase of the first RF input signal at one time to generate the first RF intermediate signal and performs a second transmission gain adjustment function and a transmission phase adjustment function at one time based on a third control signal in the transmission mode, and controls a gain and a phase of the second RF intermediate signal at one time to generate a second RF output signal and performs a second reception gain adjustment function and a reception phase adjustment function at one time based on the third control signal in the reception mode. The first switch circuit receives the first RF input signal in the transmission mode, and outputs the second RF output signal in the reception mode.