The field of EMC is a highly specialized niche within the field of electrical engineering. Anything that uses electrical power, either AC or DC, was designed by an engineer. When I ask how designers classify themselves they generally respond as being an analog, digital, EMC engineer or something else, basically their job title in the company. In reality, there is no such title as analog, digital, digital microwave or microwave engineer….we are all in reality electrical engineers, nothing more or less. The word digital is technically an invalid description on what components do or what engineers call themselves. The word digital comes from the word digit and digitus (Latin for finger) used for discrete counting [Wikipedia]. A digital engineer is thus in reality, “An infinitely fast AC slew rate signal engineer”.
Since putting all these words as a large sentence on a business card is too long, we shorten it to digital. Draw a sine wave and then make the edge rate transitions really fast, with a finite period of time for both rising and falling edges. The sine wave now appears visually as a digital pulse. Since there must be a finite period for a waveform to go from 0V to voltage potential, we can never have a true digital signal as digital, by definition, is an instantaneously change of logic state which does not exist within our world based on physics (on or off). Therefore we have in reality an analog signal or propagating wave as expressed by Maxwell in his equations and the research of many other pioneers that preceded him.
If the word digital is thus an invalid term in electrical engineering, then there is no such thing as a digital component. The input and output of every device is in reality an op-amp, which is an analog device. Therefore,it is common for analog engineers to not think in the digital domain since semiconductor manufacturers call their devices a digital component.
It is critical for us, as engineers, to understand both the time and frequency domain as it relates to component operation and signal propagation. Electromagnetic fields propagate in the frequency domain (analog) but are implemented on printed circuit boards, chosen by so-called digital components which are again very fast analog devices, thus the confusion exist on what we call ourselves with regard to the field of electrical engineering.
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