Patent attributes
A tunable fractional phase locked loop (PLL) (hereinafter “tunable PLL”) is described herein and includes a controller configured to tune the tunable PLL to a range of frequencies corresponding to a frequency of the input clock signal. The tunable PLL includes a phase detector configured to receive an input clock signal and a feedback signal, a voltage controller oscillator (VCO) configured to receive the error signal from said phase detector and in response thereto to generate a VCO clock signal, a controller configured to generate a dithered division ratio having an average value corresponding to a ratio of a number of edges of the VCO clock signal generated in a cycle of the input clock signal, and a feedback module configured to generates a feedback signal to tune the PLL such that the PLL operates in the range of input frequencies of the input clock signal.