Gigabit Ethernet on Category-5 cable is the high speed Ethernet LAN for twisted pair copper medium [1]. Each Gigabit Ethernet consists of multiple receive and transmit channels. The timing recovery system that controls the clock between receive and transmit channels requires a multi-phase high speed PLL. This paper reviews the different methods in generating high speed multi-phase PLLs, including the classical analog interpolating method, the "feedback phase selection" method, and the digital multiplexing and clock dividing method.