Novel phase difference control technique of fractional-N PLL synthesizers by shifting the LE signals synchronized with a reference signal

This paper proposes a novel phase control technique of microwave signals using a Fractional-N PLL (F-PLL) synthesizer. In the proposed F-PLL synthesizers, a cyclic shift of the control data of the frequency divider (FD) is controllable by the Load Enable (LE) signals. LE is a standard signal implemented with a commercial PLL IC. Therefore, a phase control is possible without using the PLL IC having a dedicated control circuit. Thus, the proposed technique is effective for cost reduction of active phased array antenna (APAA) equipment. The proposed technique was confirmed by measurement with C-Band F-PLL synthesizers. The measured phase difference error from a designed value is ±2° or less.