Glitch-free single-phase D-FFs for dual-modulus prescaler

This work proposes some glitch-free, general purpose, and fast D-type flip-flop (D-FF) circuits. A prescaler and a voltage-controlled oscillator (VCO) are the main blocks that determine the operating speed for phase-locked loop (PLL). The prescaler and VCO must be optimized for high speed to increase the speed of PLL. The prescaler includes the D-FF. Therefore, this work proposes a dynamic technique for free charge sharing at high-speed and low-power consumption. A 128/129 dual-modulus prescaler using the proposed D-FF shows a maximum operating frequency of 2.7 GHz at a power consumption of 14.32mW given a 3.3 V power supply. Various conventional D-FF glitch-free characteristics are also compared to show the superior quality of the proposed D-FFs herein.