This Peripheral Component Interconnect Express (PCIe) x4 PHY is compliant with PCIe 4.0 Base Specification with support of PIPE 4.4 interface spec. Lower power consumption is achieved due to support of additional PLL control, reference clock control, and embedded power gating control. Also, since a fore mentioned low power mode setting is configurable, the PHY is widely applicable for various scenarios under different consideration of power consumption.