High-speed digital design: Innovation at full-throttle

The onset of the 21st century has showcased the advances in semiconductor technology, which consequently had a notable effect on what can be done in a single IC. Transistor gate lengths as small as 22nm have made possible ICs with performance at ultra-high speeds and remarkable transistor densities.

At the turn of the 21st century the upper limit on transistor count of an IC was 200 million transistors with data speeds as high as 2.5Gb/s over a single data path. As of the present, ICs are commonly made with more than a billion transistors with data rates as high as 28Gb/s over a single data path.

These advances in IC technology have made possible products that could only have been imagined a few years ago. In addition to all of the products that have been in use for many years, two very diverse new product categories have developed around these advances.

These are the ultra-dense cell phones and tablets that have crept into every aspect of our lives and, driven by these same devices, the ultra high performance routers, switches and servers that provide all of the Internet services they require.

The first of these has driven component packages to lead pitches as small as 0.4mm or 16mils with components on both sides of the PCB substrate. This has given rise to build up PCBs and laser drilled blind vias as small as 0.1mm or 4mils. This technology had driven laminate manufacturers to develop ultrathin laminates and prepregs that have glass weaves that are uniformly spread out to improve the quality of the laser drilled blind vias.

The effect of these changes is not apparent when one looks at the size of the cell phones and tablets as the external packages remain relatively the same. What these changes have done is make it possible to put entire systems, such as GPS, in the same package with the phone as well as allow the user to surf the web and watch real time TV and movies on these same devices. On top of all this high quality cameras are included that allow the user to easily take movies and still photos. This is remarkable innovation made possible by improvements in IC technology.

The second of these has driven the performance of routers, switches and servers used in the cloud to unprecedented highs in a very short time period.

A terabit router in 2007. It is only 1U high, weighs 10kg and consumes 700W.

More recently, the capacity of the 1U router has increased to 2.5Tb/s in the same size package with 32 each 40Gb/s ports across the front panel.

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