problems in designing Injection-Locked Frequency Dividers

Hi friends:
I need some help in designing IJFD.
My design is based on a 5-stages delay cells ring oscillator. and the inject frequency is around 3GHz.
Is there anyone can tell me how to control the modulus of the circuit, becuase everytime when I tried to get a modulo-8 design it came out with modulo-2, and I don't know how to improve it.

Thanks.