Novel phase-locked loops with enhanced locking capabilities

In the paper, a novel phase-locked loop (PLL) is introduced. The proposed PLL, denoted by NPLL, is similar to the standard PLL except that it incorporates a nonlinear element and a low pass filter in its loop. The NPLL outperforms the standard PLL: (i) it has a large acquisition range, i.e., it can achieve locking in situations where the standard PLL cannot; (ii) it achieves locking much faster than the PLL. The superior performance of the NPLL is due to the nonlinear element and the low pass filter added to the loop.