Short locking time Phase-Locked Loop based on adaptive bandwidth control

This paper presents a new structure of Phase-Locked Loop (PLL) with slope charge pump current, which is depended on the output of the phase and frequency detector. The proposed PLL consists of a conventional charge pump PLL and a slope current control unit. Once the pulse width of the charging current is widening, the slope control unit increases the charge current linearly. It also ensures a better stability, a shorter locking time, and as a result, a low jitter is obtained. Two PLL circuits are simulated under the same conditions: the first one uses the slope current control and locks after less than 2 us with a low rms jitter of 2.05 ps, while the second classical PLL locks after 8 us with high jitter.