This paper presents a CMOS 2:1 differential parametric frequency divider (PFD) design with an output frequency of 2.4 GHz and an input voltage range of 450-890 mV at 4.8 GHz. The topology is suitable for integration into RF Systems-on-a-Chip (SoCs), and has been constructed for sub-6 GHz applications. A design and optimization methodology for this on-chip PFD is also described in this paper. The simulation results show a performance improvement of the proposed differential PFD compared to a single-ended PFD designed for the same output frequency in the same 65nm CMOS technology.