A dual-modulus prescaler divides the input signal by one of the moduli according to the control signal. In this paper, a new fast dualmodulus prescaler is proposed. The proposed prescaler has a ratioed-NOR structure different from a conventional ratioed-NAND structure. The proposed one can operate at a higher speed by using parallely connected NMOS transistors instead of using series-connected ones. HSPICE simulation results using 0.65µm two-poly two-metal CMOS process parameters show that the maximum operating frequency of the proposed dual-modulus prescaler is 2.8GHz with power consumption of 40.7mW at 5V supply voltage at 25ºC. The proposed dual-modulus prescaler can be utilized for the frequency-synthesis in communication systems.