Internal USB 2.0 Achieves USB 3.0 Speeds

The new specification for Embedded USB 2.0, known as eUSB 2.0 V2, significantly enhances the data transfer rates of embedded USB 2.0 controllers, enabling speeds of up to 4.8 Gbit/s. This advancement is particularly beneficial for devices like notebook webcams.

Initially introduced around 16 years ago, the USB 3.0 specification revolutionized data transfer by increasing the maximum speed from 480 Mbit/s (USB 2.0 Highspeed) to 5 Gbit/s (SuperSpeed, now referred to as USB 3.2 Gen 1). However, this shift required new cables, connectors, and ports due to USB 3.0's use of additional pairs of wires to transmit differential signals, similar to how PCI Express operates.

Unlike its predecessor, the eUSB 2.0 V2 specification simplifies the process by utilizing the existing two signal paths, D+ and D-, associated with older USB technologies. Despite this simplification, eUSB 2.0 V2 is capable of transmitting much higher volumes of data, scaling integer multiples of 480 Mbit/s all the way to 4.8 Gbit/s.

Importantly, eUSB 2.0 V2 does not involve external cables, connectors, or hubs, allowing only one retimer chip within the signal path and an internal connector, which is not standardized.

The eUSB2V2 1.0 specification was released in August 2024, building upon the earlier Embedded USB 2.0 (eUSB2) framework. Notably, the new standard reduces the signal voltage on the D+/D- lines from 3.3 volts to between 0.36 and 0.8 volts, facilitating easier integration of eUSB2V2 controllers into chips with smaller fabrication processes, where lower voltage tolerance is crucial.

This specification primarily targets the cost-effective internal connection of built-in webcams in laptops and similar devices. As high-resolution video signals have become more prevalent, the traditional 480 Mbit/s bandwidth is increasingly inadequate. Furthermore, standardized transmission methods for higher data rates, such as USB 3.x or MIPI CSI-2, demand additional signal paths.

Moreover, many chips already require at least one USB 2.0 controller, thus integrating an eUSB2V2 controller can streamline development compared to alternative interfaces. Chip design tool providers, including Cadence, have already made eUSB2V2 available as an Intellectual Property Core (IP-Core) for use in chip development.