A dual-slope phase frequency detector and charge pump architecture to achieve fast locking of phased-locked loop

A dual-slope frequency detector and charge pump architecture to achieve fast locking of phased-locked loops is proposed and analyzed. The proposed topology is based on two tuning loops: a fine-tuning loop and a coarse-tuning loop. A course-tuning loop is used for fast convergence, and a fine-tuning loop is used to complete fine adjustments. The proposed PLL circuit is designed based on the TSMC 0.35 μm 1P4M CMOS process with a 3.3V supply voltage. HSPICE simulation shows that the lock time of the proposed PLL can be reduced over 82% in comparison to the conventional PLL. An experimental chip was implemented and measured. The measurements results show that the propose PLL has fast locking properties.