This paper proposes an active phased array antenna (APAA) to implement high scalability. The proposed APAA consists of multiple commercial fractional-N PLL (F-PLL) Synthesizers sharing a reference signal. The phase difference control between the antenna elements can be performed independently by clock shift of LE signals to each PLL. Therefore, the phase control by commercial PLL-IC is possible without using PLL-IC having a dedicated control circuit. The proposed system is demonstrated in the C-band, realizing highly accurate phase control and beamforming property.