The most important changes in electronic design over the past 25 years?

[blackhead]

Flicking through modern text books for undergraduate students, I find
it startling that little seems to have changed in the way of
electronic design. Can anyone think of obvious examples?

Regards, Larry.

 

[John Devereux]

Flicking through modern text books for undergraduate students, I find
it startling that little seems to have changed in the way of
electronic design. Can anyone think of obvious examples?

Perhaps you need some newer text books?

I guess textbooks teach the "fundamentals", which indeed do not
change. But there have been enormous changes in the *practice* of
electronics.

Obvious ones would be

- the transition to surface mount for most applications.

- ubiquity of cheap, powerful microcontrollers. Meaning more and more
of the functionality of a design is software.

- Complete subsystems now available as single-chip "building blocks",
e.g. A/D convertors that connect direct to transducers, digital
isolators, power supply sequencers.

- low cost or free development tools for microcontrollers. No more $5k
in-circuit emulators or logic analysers.

- easy, online searching and availability of information, samples and
production parts.

Etc etc

 

[John Devereux]

Which textbooks did you look at?

AoE probably

 

[Joerg]

Flicking through modern text books for undergraduate students, I find
it startling that little seems to have changed in the way of
electronic design. Can anyone think of obvious examples?

Regards, Larry.

There have been major changes. In contrast to 25 years ago I nowadays do
almost complete designs on the simulator and then in real life they come
out almost verbatim the same. This was theoretically possible back then
as well, and I did use ECA224 in the late 80's and PSpice in the early
90's, but the available computing horsepower was not even remotely
sufficient. Now it is, and that has changed things fundamentally. At
least for me.

 

[Spehro Pefhany]

AoE probably

<ouch>

 

[Joerg]

Fundamentals don't change, ...

All it takes is one election gone wrong and then they do

... though they seem to not be emphasized
anymore. Observe how many people absolutely tried to deny my loop and
nodal analysis of the "Cute amplifier"... which tells me they were
never actually taught how to do it... and they can't cope with math.
If there's not some software for them to plug into, they can't
"design" or think or withdraw their heads from up their own asses ;-)

25 years? That takes us back to 1988, CMOS was well established for
digital uses, but was just barely beginning for analog applications.
Most analog stuff was still made with bipolar processes.

CD4000 series ICs make nice analog CMOS amps and were available. Same
for the 74C-series but I've never used those on account of their high
prices in Europe back then.

In the mid-90's processes advanced, giving finer feature size and
adding capability to mix both bipolar and CMOS... BiCMOS.

Now, which is why I think I get so much flack with analog analysis, we
have a world that thinks everything can be done with a
microprocessor... just write some code... you don't really need to
know much of any engineering.

It's the same in code. I could do reasonable circuit simulation in 640k
of RAM in the 80's. Now you need a minimum of 1G of RAM and three dozen
concurrently running processes just to be able to write "Hello World".

[...]

 

[John Devereux]

[...]

True enough as far as horsepower goes... today's typical laptop can
outperform a VAX.

Cool, I found a price of $141,000 for the 780 in 1977.

The VAX 11/780 appears to be the standard machine on which all the
"MIPS" benchmarks are based. So a VAX 11/780 is a "1 MIPS" machine.

I have a $4 STM32F4 microcontroller on a $15 eval board on my desk right
now. It is 210 MIPS

 

[Joerg]

By 1977 (36 years ago) I was doing Berkeley Spice on a VAX780. Source
code was in Fortran, for which I rewrote the model for B-E
capacitance... because it was initially incorrect, rising forever in
increasing forward bias. It was corrected in a paper by Gummel. I
probably have a copy around here somewhere.

There was, however, no schematic entry. I drew a paper schematic,
numbered nodes, then created a netlist with a text editor... IIRC "VI"
??

I am not this old but I did write my schematics as text, netlist style,
for PSpice entry. Kept doing that until too many people razzed me about
the fact that nobody else could "see" the circuit that way. "Hey, we've
got Edison electric light in here, you know?".

By 1988 I had my own 80386 plus math co-processor, and MicroSim
PSpice... though it took me years to abandon hand-drawn schematic for
MicroSim Schematics ;-)

Very same setup here, except I opted for the Cyrix math co-processor.
Paid an arm and a leg but that felt like I had installed a
turbo-charger. I still have the two cloth-covered Microsim binders, with
pouches. I also still have the co-processor. Maybe it rises in value
when it gets to be an antique?

[...]

 

[John Devereux]

<ouch>

No insider knowledge, but I suspect Wins problem is that he is trying to
cover the whole field, and it is advancing faster than he is writing...

 

[Adrian Jansen]

Flicking through modern text books for undergraduate students, I find
it startling that little seems to have changed in the way of
electronic design. Can anyone think of obvious examples?

Regards, Larry.

Computer simulations have replaced bench testing.

The design rules are unlikely to change, but the implementation might.

 

[George Herold]

FPGAs and logic simulation

LT Spice; more simulation, less closed-form math

Internet instead of data books

Zillions of complex-function analog chips

Digital photography

Cheap color digital scopes

High-efficiency LEDs

Math programs (Matlab, Octave)

Filter design software

DDS

Delta-Sigma converters

Serious desktop and embedded compute power

Computer based drawings and document libraries, less paper

More purchased blocks, like power converters and signal/RF bricks. That'sa
trend, moving us up the abstraction stack.

Some of them existed 25 years ago, but they weren't as common or affordable as
today.

Undergraduate education should stick to fundamentals, so it wouldn't, or
shouldn't, change much.

--

John Larkin                  Highland Technology Incwww..highlandtechnology.com  jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME  analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators

Excellent,

I want to add the great analog parts now availble for cheap
low noise opamps
0.1% resistors
ceramic caps
(what else do I need?)

George H.

 

[George Herold]

I think John Devereaux fingered the biggest item, which is that
microprocessors are getting faster, cheaper, and smaller.

This, in turn, is driving more and more of the "brains" of systems into
software rather than dedicated analog or digital hardware.  More and more
often, the most sensible way to view a microprocessor in some circuits is
as a very versatile and flexible analog component, that happens to need
some digital massaging to do its job.

This, in turn, means that the analog designer needs to be able (at least)
to understand what software can do, and the software designer needs to be
able to understand what the analog designer wants.

Best, of course, is to be trained and/or facile in both disciplines
(smirk).

Case in point: in 1988 I was working on my Master's thesis, building a
data-link radio receiver (which I found out years later that my thesis
advisor didn't think was going to work).  The original system design
called for the data demodulation to be done on a 4x5 circuit card with
switches and integrators and oscillators forming a couple of PLLs, with
analog signals being sampled at 400Hz by ADCs in the microprocessor that
ran the front panel.

The demodulation ended up being in the microprocessor, which sampled the
audio out of the receiver section at something like 3500Hz and did all of
the PLL-ing and demodulating in digital-land.

Since then arguably by biggest single body of work has been to take
really high performance control loops, and move more and more of the
brains of the loops from analog hardware into software, with overall
gains in compactness, power consumption, thermal stability, and unit-to-
unit variation, not to mention being able to do useful tweaks in the
control laws involving nonlinearities that are easy to implement in code,
but would require fields of piecewise-linear approximations if you even
attempted the task in analog-land.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Softwarehttp://www.wescottdesign.com

Yeah, digital continues to swallow more and more of the world.

George H.

 

[[email protected]]

Xilinx's first, primitive FPGAs came out in 1985, not much better than
using MSI chips. But modern ones have MACs, multiport srams, DRAM
controllers, LVDS, PLLs, SERDES, PCIe, multicore ARMs, all sorts of
goodies, really system on a chip stuff. If you want to do a hardware
divide in VHDL, just do it.

Of course FPGAs grew out of PLDs and FPLAs, which had been around a
decade by then. I used a register with an FPLA in the feedback to
build my own controller in the mid-'70s (it was the "brains" for what
was essentially a DVM).

 

[Tim Williams]

AoE probably

Using AoE2 as an example, the only glaring omissions I recall are:

1. Besides Larkin, who actually uses 68k anymore? Yeah, a few, but
PIC/AVR and ARM pretty much dominate today. (Indeed, the 68k dominated in
its time, but that time has passed. That said, perhaps the PIC/AVR/ARM
market is mature and, by the time most people read the next editions of
these textbooks, will be obsolete!) Few use MSI anymore; CPLDs and FPGAs
are so much easier.

2. High performance parts. GaAs, GaN, PHEMTs, and for power, SiC too.
Even superjunction devices didn't exist at the time.

3. High bandwidth signaling standards; signal integrity. Highly important
today (you can't get too much out of the FPGA from #1 without using up all
your pins, unless you use LVDS or PECL or..), and forms an intersection
between analog and digital which one cannot ignore.

Anecdote regarding #3: at school, I once attended a recruitment
presentation from Plexus. The speaker asked us, "Does anyone know about
signal integrity? If so raise your hand." Out of the about 100 EE
students in the room, I was the only one. Needless to say, signal
integrity is not covered in any undergrad courses.

Tim

 

[brent]

Flicking through modern text books for undergraduate students, I find
it startling that little seems to have changed in the way of
electronic design. Can anyone think of obvious examples?

Regards, Larry.

Printed circuit board fabrication techniques and the software to
design printed circuit boards.

 

[[email protected]]

Embrace, George. Embrace.

Assimilate. You will be...

 

[Archimedes' Lever]

Assimilate. You will be...

Liquid Immersion Lithography.

The move to HDTV and digital broadcasting.

High bandwidth wired connectivity for the masses.

Large form factor fast refresh LCD displays with LED backlighting at a
reasonable price.

And finally... all the Dick Tracy Wrist Radios folks all have now.
just a bit too big for the wrist. And we still call the "phones".

 

[Bill Sloman]

Printed circuit board fabrication techniques and the software to
design printed circuit boards.

We had Racal-Redac software for digitally generating printed circuit
artwork at EMI Central Research back on 1978, which is almost 35 years
ago. It wasn't user friendly, and the draftsmen that drove it needed a
refresher course if they'd been doing something else for more than a
week, but it was a relatively quick way of generating artwork for
digital circuits, if too clunky for analog layouts.

It was probably the Racal-Redac MAXI PCB package which was introduced
around then, but I never actually saw it in operation though - IIRR -
we did check out one of the layouts it produced for us before sending
it out to get turned into a board.

 

[Nico Coesel]

Flicking through modern text books for undergraduate students, I find
it startling that little seems to have changed in the way of
electronic design. Can anyone think of obvious examples?

The biggest change is not needing a huge library with datasheet books
due to internet. Ohm's law won't change for at least another 50 years

 

[George Herold]

Embrace, George.  Embrace.

Grin... do I have any choice?

I went to a local maker-place for electronics night.
I brought my Rigol scope and DMM.
Everyone else there took out their lap tops,
and started tapping keys.

I'm thinking I should bring my soldering iron next time,
I've got a few 'kit' projects I can work on. :^)

George H.