A brief introduction: I’ve been invited to provide regular perspectives on analog issues, design, components, and more, for Planet Analog, and I've chosen to so via this Analog Angle blog (I’d prefer to call it a “column” rather than a blog, but that’s another story, and for another time).
I am happy to do this, because I have been a part of the analog engineering and editorial world for many years.
We’ve heard the repeated refrains that “everything’s going digital” and “analog is dead/dying.” All I can say is this: “Yes” to that first statement and a loud “Heck, No” to the second one. My sense is that the second theme comes from three groups: newbie engineers who should know better, and will know better soon; software coders who have no need (yet) to know better; and “Wall Street” industry analysts who don’t know better and likely never will.
Here’s the reality of the situation, not as seen by me, but as defined by a “higher authority” — the laws of physics. There’s no avoiding that, in the broad sense, digital is a just subset of analog. Sure, that’s somewhat narcissistic, but that doesn’t mean it isn’t true.
There’s no avoiding this reality. As system clocks increase from the range of several hundred MHz to GHz and higher zones, and as data rates go from hundreds of Mbit/s to tens of Gbit/s, the technical, physical-level issues that presumed digital designers struggle with are primarily analog in nature. We’re talking signal integrity, intersymbol interference, eye patterns, wired/wireless/optical drivers and receivers, switching currents, and EMI/RFI and EMC, just for starters. These formerly modest (or even ignorable) issues now rear their analog heads and make the clean, sanitized world of ones and zeroes into a harsh environment for getting intact, error-free signals from point A to point B.
The implications for high-speed, high-performance digital circuit and system designers are pervasive. It’s not enough to do a good digital design. Any schematic “on paper” is just a start. Issues such as PC board layout, signal grounding, parasitic inductance and capacitance, and adjacent signals all affect the physical implementation of your elegant design.
For those of you who are doing relatively low-speed digital work, don’t get too relaxed: Analog hasn’t forgotten you, either. You still have to worry about current flow, return paths, ground loops, shielding, isolation, IR drop, switching, sources and loads, and timing issues.
As I talk about analog-centric topics in coming weeks and months, the underlying message I have for you is simple: Even if you’re nominally a digital designer, brush up on analog. I don’t mean you have to go back to Maxwell’s equations, but you do have to look at the eternal fundamentals of voltage, current, slewing, noise, power sourcing, grounds, thermal concerns, and temperature coefficients.
That’s where I’ll be going, and I invite you to join me on the journey.