Question about being a Nurse Practitioner?

Ok so i have been researching a little about how to become a nurse practitioner and i understand what i need to do but i have some questions. I understand that you have to get a BSN and work as a RN for at least 2 years before applying to a NP program which takes 2 years to complete. I remember reading somewhere that in order to become a NP a PHD will be required... is this true? if so, then how long will it take to become a NP after they change the program???