DIGITAL DESIGN
In the strictest sense of the word, there’s no longer such a thing as “Digital Design.” Perhaps there never really was.
Except at low speeds (and there are fewer and fewer devices running at low speeds any more), in the strictest sense of the word, there’s no longer such a thing as “Digital Design.” Perhaps there never really was.
What does exist (thanks to mathematicians who were willing to replace a few integral symbols with uppercase sigma “summation” symbols to see what would happen) is a large set of very powerful mathematical tools to describe what we can do when we’ve properly quantized and discretized the world. And thanks to folks like Shannon and Nyquist, we even have highly workable definitions of what constitutes proper quantization and discretization.
The power of digital circuits is that often with them, we’re no longer acting directly on signals with a choice of physical components, we’re instead acting on abstract concepts. Abstract concepts don’t wear out. They don’t break. They don’t start to hiss and pop over time because dirt and dust settled into them.
Beyond that, with digital representations of signals, we can create things that would otherwise be impossible to realize using conventional components. Things such as “finite impulse response” filters or “brick wall” filters cannot be made with actual electronic components. But they can be described by mathematics. So when one is needed, we can convert analog signals to mathematical representations of it, perform the filter action, and return the result to the “real world” via digital-to-analog conversion.
Additionally, most modern control systems are digital. A handful of feedback loops remain analog due to the reaction times required of them. But digital systems, being software programmable (and therefore far more flexible), are much more common.
And many processors are now specialized to implement the fast multiply-add functions required of digital signal processing. But beyond DSP, there are quite a few other places in the digital world where being able to multiply and accumulate a sum quickly is of tremendous value.
At Focus Embedded we can:
Operate in both continuous and discrete time domains. Our understanding of signal processing starts with mathematics. The fact that the number crunching may be digital is an implementation detail. The fundamental underpinnings of it all are in the math.
Recognize where information is lost when crossing from analog (s-plane) to digital (z-plane) domains. Similarly we can spot where false information can be generated going from one domain to the other. Fourier Theory describes what's real and what's a false image that may show up where you least expect it.
Implement control systems (analog or digital) and do the continuous or discrete-time analyses required in determining their responsiveness and stability using techniques such as Root Locus of Evans and Routh-Hurwitz Matrices.
Find suitable tradeoffs between stability, responsiveness, risetime, damping, bandwidth, etc. More of any is not always better. Better is better, and we don't lose track of what problem we're actually solving.
Determine where it makes sense to implement digital logic in discrete components, a microcontroller, or programmable logic (FPGA and CPLD).
Still do all the basic things you’d expect of digital designers, such as timing analysis and careful design and routing of printed circuit boards for impedance control and line-length matching to assure signal integrity in those places where it’s critical. Because at their most fundamental level, in the real world digital signals are really analog signals in the end.