An ultra low power frequency synthesizer based on multiphase fractional frequency divider

This paper proposes a 2.4 GHz fractional-N frequency synthesizer based on a multiphase fractional frequency divider with a stepsize of 0.25. A retimer is implemented to remove glitches and improve robustness. The synthesizer fullfills the bluetooth specifications and consumes less than 5.8mW at 1.2V. In contrast to other structures, the proposed concept is simpler, duty cycle free, consumes less power, and operates at higher frequency.