PHY is a very common term when it comes to networks , and really even if you have never heard it before, it is something that your network card has, even the one that comes integrated with the motherboard. It is a fairly important component, so in this article we are going to explain what it is, what it is for , and in general everything you have to know about it.
Generally, when talking about PHY it is usually done in conjunction with a network controller, which is of course part of the network card. Today, all network cards have it, and that includes the ones on the motherboards. So, let’s see what it is and what it does.
What is a PHY?
PHY is the abbreviation for ” PHYsical layer “, or “physical layer” in Spanish. It is an electronic circuit generally implemented in an integrated circuit (colloquially known as “cockroach”), and is something indispensable to precisely implement the physical connections of network cards. It is therefore part of the network controller , and serves to connect the link layer (called MAC by Media Control Access) with the physical connection layer, such as the RJ-45 connector of the network card.
A PHY device generally includes an additional encoding layer called PCS (Physical Coding Sublayer) and a Physical Medium Dependent (PDM) layer, which encodes and decodes the data that is transmitted and received.
In summary, PHY is an integrated chip that bridges the network controller and the physical connector of the network card.
Types and examples of use
At the beginning we told you that all network cards have a PHY, but the reality is that this is only so in the case that they have physical connectors (you may think that it would be absurd not to have them, but in professional environments there are network controllers that do not They have PHY because their function is to control other network cards, so yours does not have its own connectors).
Here are some examples and types of those that exist:
- WiFi : The PHY chip consists of radio frequency and mixed signal circuits, called transceivers, and digital baseband circuits that use digital signal processors (DSP) that include, among other things, encryption algorithms and channel codes. It is common for them to be integrated into MAC layers in a SoC.
- 3G / 4G / LTE environments : works the same as in the previous example. Without going any further, all smartphones have a PHY to connect, for example, the signal transmitting and receiving antennas with the terminal’s network card.
- Ethernet : the most common of all, and that we find in PC network cards.
- USB : Believe it or not, many devices also use a PHY for the USB connection, as they provide a bridge between the digital and modulation parts of the interface.
- IrDA: In devices that have infrared communication, they are also necessary to connect the transmitter / receiver to the controller.
- SATA : Some SATA controllers such as those manufactured by VIA use a PHY to communicate the controller with the connectors.
- SDRAM and Flash Memory : As with SATA, some controllers also introduce this element to communicate the physical interface with the controller.