A Wideband PLL with Adaptive Fast-Locking Current Circuit for Bandwidth
Tracking and Settling Time Reduction
Abstract
This letter presents a 1-3GHz low-power, fast-locking self-biased
phase-locked loop (SPLL) for multiprotocol SerDes applications. The PLL
realizes adaptive bandwidth tracking based on fast-locking current
injection, which accelerates loop acquisition and maintains reduced
settling time across a wide frequency range. Additionally, a start-up
module is adopted to reset the system quickly to an optimal initial
operating frequency. The proposed PLL, fabricated in TSMC 28-nm CMOS
process and occupies a compact 0.028mm2 area. It achieves a roughly
constant settling time of 5 μs over all frequencies and division ratios
range. Compared with the typical SPLL, the measured settling time can be
shortened about 85% large division ratios.