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What Makes USB 3.0 Faster Than USB 2.0?

It goes without saying that USB 3.0 includes numerous improvements in signaling technology:

New separate cabling is used for ultra-high speed signals. But this simply allows the use of new signaling technology while maintaining backward compatibility.

Dedicated transmit and receive cables allow full duplex instead of half duplex. That's fair enough, but the headline speeds only apply in one direction anyway.

More advanced clock recovery coding techniques. Fine, but the headline speed is the raw bandwidth before coding overhead is taken into account.

USB 3.0

USB 3.0

Various other signal improvements have been adopted and reused from the PCI Express standard, such as asynchronous transfers. However, as with the points above, these improvements are at best intended to make better use of the header bandwidth to transfer data, not to explain why the header bandwidth itself is 10 times that of USB 2.0.

So what exactly is the technology that allows USB 3.0 to achieve a headline speed of 5Gbps compared to USB 2.0's 480Mbps?

The answer is that it has absolutely nothing to do with the cable or signal used. Rather, it is simply an advancement in silicon technology in the integrated circuits that implement and utilize USB. In the decade since the USB 2.0 and USB 3.0 standards were designed, silicon technology has made huge strides, driven by the market's desire for ever-faster CPUs.

It's worth adding that silicon processing speeds have since caught up to the limits of copper technology, at least as we currently understand the physics. 10Gbps for USB 3.1 is about as fast as you get for a serial interface, so USB C-Cable and USB 3.2 are parallel interfaces, not serial.

One of the paths forward is optical fiber, which can be much faster than that and reasonably cost effective over short distances. One reason to stick with copper is the benefit of achieving power transmission in the same cable. However, 5k screens have pushed the boundaries of what can be achieved with USB C, just like external flash drive technology.

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