All grid-connected power converters require a device/algorithm for the synchronization with the utility grid. Among different synchronization techniques that have been proposed in recent years, the phase-locked loop (PLL) is probably the most popular one. The PLL, however, in its standard structure, has a limited filtering capability. A simple yet effective idea to deal with this problem is including additional filters in the PLL structure. In this paper, an adaptive filtering technique for including into the PLL structure is suggested. A systematic design approach for tuning the PLL control parameters is then presented. The effectiveness of the proposed PLL is finally verified through a comparative performance analysis with the state-of-the-art PLLs.