A first phase shift circuit amplifies, when a first signal, a second signal having a phase difference of 90 degrees from the first signal, a third signal having a phase difference of 180 degrees from the first signal, and a fourth signal having a phase difference of 270 degrees from the first signal are output from a 90-degree distributor that distributes an input signal, each of any three signals from among the first signal to the fourth signal. A second phase shift circuit amplifies each of any two signals of any three signals and one signal that is not amplified by the first phase shift circuit from among the first signal to the fourth signal. One or more phase shift circuits of the first phase shift circuit and the second phase shift circuit each include a compensation circuit that compensates for a phase error of the synthesized signal.