Ive been reading Sedra/Smith's Micro Electronic Circuits book, and it has a lot of info which I like, however I dont know how much of it is actually practial and useful, for instance it talks about Ebers-Moll equations and models, which I know are useful to understand how transistors work and how the practical equations are derived, but then it talks about stuff like Early voltage and dynamic resistance using Early equations, reverse alpha and beta coefficients, saturation current, etc… and while im solving the drill excercises I wonder if im not just wasting my time on this.
I cant seem to find anything on a transistor datasheet that remotely points to stuff like an Early Voltage parameter, or saturation current, or reverse alpha and similar parameters.
Ive also been reading Boylestad/Nashelsky book which is also great and more practical per se, but it doesnt even mention half of the things present in Sedra/Smith's book, which is why I wanted to go deeper with hopes that it would give me better electronics foundations, which is why im reading Sedra/Smith's book, but even if I understand most of the content of the latter, I fail to see the practical application of most of it…
So, my question is, how useful is to know and learn all these complex stuff? will it improve my design knowledge knowing things like how the doping on the semiconductor, combined with the electron and hole diffusion coefficient and the width of the base interact with the saturation current in the exponential model?
Do people actually use the long Ebers-Moll equations or Early Voltage in real circuit design?
Or do most people just use the simplified and practical equations and leave the other stuff to the phsycisists ?
Best Answer
IMHO it's very useful to know all this stuff, even if you don't use it from day to day, as it deals with the fundamentals of what makes everything else you use IC-wise work.
Whether it will be of "practical use" depends on your field, nowadays especially there is much less discrete design, but if you are designing e.g. a high quality audio amp (I personally work on a lot of all discrete analogue audio gear as well as uCs FPGAs, etc, but I think this probably not so common) or designing analogue ICs, precision test gear, etc then knowing how to work with the above is essential. You generally wouldn't sit down and use all the equations you mention for a design, more recognise the effects of them and know how to compensate (or indeed make use of them)
Knowing the fundamentals gives you grounding you need to make confident design decisions, track down problems and understand why things in practice often look nothing like they do in SPICE.