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In this paper, a systematic review of phase-locked loop (PLL)-based closed-loop control methods for interleaved discontinuous conduction mode/continuous conduction mode (DCM/CCM) boundary boost power factor correction (PFC) converters is presented. A detailed analysis of the stability of the PLL with instant averaging filter is performed and verified by simulation. The stability of the PLL with instant averaging filter and with RC filter is compared by simulation. Based on the simulation results, it is concluded that the PLL-based closed-loop methods always provide stable operation, unlike the open-loop control methods, where the only method that results in stable operation is the slave synchronization to the turn- on instant of the master with current-mode control. It is also shown that the dynamic response of the PLL-based closed-loop methods with master-slave approach and democratic approach is almost identical. Experimental results obtained on a 300-W, universal input, 400-V output, interleaved DCM/CCM boundary boost PFC prototype circuit with a dedicated controller IC utilizing a democratic, PLL-based closed-loop method are also provided.