A high-speed and ultra-low-voltage divide-by-4/5 counter with dynamic floating input D flip-flop (DFIDFF) is presented in this paper. The proposed DFIDFF and control logic gates are merged to reduce effective capacitance of internal and external nodes, and increase the operating speed of divide-by-4/5 counter. The proposed divide-by-4/5 counter is fabricated in a 0.13-µm CMOS process. The measured maximum operating frequency and power consumption of the counter are 600 MHz and 8.35 µW at a 0.5 V supply voltage. HSPICE simulations demonstrate that the proposed counter (divide-by-4) reduces power-delay product (PDP) by 37%, 71%, and 57% from those of the TGFF counter, Yang's counter [1], and the E-TSPC counter [2], respectively.

A dual-modulus (divide-by-128/129) prescaler has been designed based on 0.25-µm CMOS technology employing new D-flip-flops. The new D-flip-flops are free from glitch problems due to internal charge sharing. Transistor merging technique has been employed to reduce the number of transistors and to secure reliable high-speed operation. At the 2.5-V supply voltage, the prescaler using the proposed dynamic D-flip-flops can operate up to the frequency of 2.95-GHz, and consumes about 10% and about 27% less power than Yuan/Svensson's and Huang's circuits, respectively.