Disclosed is a phase shifter, which includes a signal generator that generates a first signal and a second signal having a phase orthogonal to a phase of the first signal, and outputs the first signal and the second signal, an operator that generates a first current and a second current, and amplifies the first current and the second current, and a signal converter converting a first digital signal and a second digital signal. The operator includes an input circuit converting the first signal and the second signal, a path selection circuit determining paths of the generated first current and the generated second current, and a cascode circuit buffering the first current and the second current. The operator sums the first current and the second current, controls a vector of the first current and a vector of the second current, and generates a voltage signal through an output load.