An Ethernet PHY, or Ethernet Physical Layer, is a chip or integrated circuit that implements the hardware send and receive functions of Ethernet frames. It interfaces between the analog domain of Ethernet’s line modulation and the digital domain of link-layer packet signaling.
The Ethernet PHY is responsible for converting digital data into analog signals for transmission over the physical medium, such as copper wires or fiber-optic cables. It also receives analog signals from the physical medium and converts them back into digital data for further processing by the Ethernet MAC (Media Access Control).
The Ethernet PHY usually does not handle MAC addressing, as that is the responsibility of the link layer. Additionally, features like Wake-on-LAN and Boot ROM functionality are typically implemented in the network interface card (NIC), which may have PHY, MAC, and other functionality integrated into one chip or as separate chips.
Ethernet PHYs come in various configurations and speeds, ranging from 10 Mbps to multi-gigabit speeds like 1 Gbps, 10 Gbps, and beyond. They play a crucial role in enabling reliable and efficient communication over Ethernet networks, whether in data centers, enterprise networks, or automotive applications.
It’s important to note that there are different vendors and manufacturers that offer Ethernet PHY solutions, each with their own features, performance characteristics, and compatibility with different Ethernet standards.