The photonic generation of microwaves or millimeter waves using the beat note of two lightwaves is an attractive technique for fiber-wireless communication systems because it enables high-frequency selectivity over the entire radio-frequency region as well as high-speed phase control via electro-optic phase modulators. In this paper, we propose a novel phase control method with small phase drift that uses the polarization dependence of electro-optic phase modulators combined with a feedbackcontrolled birefringent polarization rotator. The high stability and ultrafast phase shift keying operation of an optically generated microwave signal are experimentally demonstrated.