These days we think of ourselves as living in the Information Age, an era of unprecedented connectivity and access to information that has been enabled by the Digital Revolution.
The Digital Revolution has relied on a consistent, exponential rise in the density of digital logic gates on silicon (famously doubling every two years, according to Moore’s Law). Most of the media that we use daily have converted from analog to digital formats. Think: phonograph records, analog audio tape, VHS tape, TV signals, still photography, and home movies. Clearly, the world has gone digital, and analog electronics has been left in the dust. Or has it?
Contrary to what you may have heard, all five of the human senses remain analog in nature. For information to be useful it has to be consumed by humans, who tend to have a limited appreciation for raw binary information. Likewise, most of the original sources of information are analog, at least at the level at which we experience them. So, it makes sense that analog electronics is very much needed at the human interface level and always will be.
Moreover, as consumer digital devices proliferate, the need for analog electronics to mediate to the human world guarantees that sensors and amplifiers, displays, and power management electronics will be hitching rides on the rapid growth curve fueled by Moore’s Law.
But it is not just at the human interface that this occurs. It is also at the interface between digital electronics and commonly used electromagnetic storage and transmission media. This is always likely to be true when pushing media to the limits, such as maximizing the density of information on hard drives, or picking up weak signals at the end of a long-distance radio link. Whenever signals need to be conditioned before digitization, analog electronics will be there — at the very least for anti-aliasing purposes — but usually doing considerably more than that.
As one example, consider that today’s multi-gigabit digital SerDes links usually employ continuous time linear equalizers (CTLEs) in the analog domain before they apply digital equalizers. Here is one example (among many) where the fastest digital bits need analog techniques to get along.
So, is analog electronics destined to scrape out a meager existence at the fringes of an increasingly digital world? Not unless we humans are going to allow ourselves to be digitized! Indeed, the trend is rather in the opposite direction, with pervasive computing and ambient intelligence requiring more and better analog sensors to allow smooth and natural interaction with humans and our living environment.
It’s an analog world, after all — don’t bet against it!