IEEE Solid-State Circuits Magazine - Summer 2016 - 21

pulse turned out to be long enough
for the entire circuit to function, but
it could have just as easily failed and
is definitely not good design practice.) I
was even happier when it worked well
enough that Sandra began using it
for her experiments.
After this success, I was given great
latitude in specifying new hardware
to build. Over the next three years, I
spent every summer and January break
working at NBS. I ended up building a large number of instruments,
from systems that would automatically control ac bridges to electronics
to precisely control the pressure in
an experimental cell. Looking back
at these projects, most could be done
today with a Arduino class microcontroller and a little external hardware,
but those devices wouldn't exist for
another decade or two.
Eventually, I noticed a pattern
repeating with the different projects I
would propose and build. Since I was
so confident in my ability, when I proposed/started any project, it didn't
occur to me that it might not work. I
just thought about how great it would
be when it worked. Generally, somewhere between the design and implement phase of the project, I realize
the mess I am in and start to worry.
As I am now worried about failing, it
can take me some time to start the
actual implementation. But as I wait, I
think of all the people I convinced to let
me build this project. Because not building it would definitely be a failure, I
have to build it. So I push through the
implementation, often in a panic near
the end, as I have thought about many
design issues I overlooked in the original design that might cause the system to fail. Now things speed up as I
want to finish the implementation to
see how bad the situation is.
By the time I start debugging, I
have many places to check if things
don't work, since I have a list of things
I might have done wrong; I've generally come up with a plan to incrementally bring the system up to deal with
potential issues. I know where to look
for problems if they occur, and the
system works after some debugging,

For my 14th birthday, I got a kit that allowed
me to build 50 different electronic circuits,
which included a number of different AM radios.
which restores my faith in my ability
to make things and the cycle repeats
itself. You would think that these confidence oscillations would dampen
over time, but they don't seem to. I'm
just thankful that while I am underdamped, I never went unstable.
In addition to all the digital controllers/filters I built, NBS is where my
interest in mixed signal design started. Given all the precision measurements that were needed, our lab used
a large number of lock-in amplifiers,
which are phase-synchronous detectors to measure small ac signals (to
nV). The units in the lab were built by
Princeton Applied Research and were
pretty expensive. This bothered me
since I grew up in a house where my
mom taught me the value of money.
I thought I could build a lock-in amp
that was about ten-times cheaper than
the ones that they were buying and
have roughly the same performance
by using some of the new op-amp and
CMOS switches that were available.
While, again, many people were skeptical that my design would have good
performance, one of my mentors, Bob
Hocken, loved this idea and encouraged me to do the design. After the first
prototype was a great success (built
using the wiring pencil in Figure 6), we
created a printed circuit board layout
for the design. By the time I left NBS,
they were used all over the bureau.
In retrospect, I couldn't have had
a better job. I was in a supportive
environment, with lots of opportunities to learn new things. I got to take
apart (or at least read the manuals)
for the equipment that they had and
then create new equipment that they
needed. Plus they had a great parts
store, which allowed me to feed my
habit. It felt like they paid me to play.

MIT
Like my job at NBS, my start at MIT
was a little rough but ended up great.

I remember being in a panic after
taking a few tests that I thought were
very hard. In some cases, the tests
were just extremely hard, and in others, my confidence backfired: I creatively misinterpreted the questions,
making them much more "interesting." Rather than asking the teacher
what was going on, which is what I tell
my students to do, I just thought it
was a trick question that I could figure
it out. Oops. I quickly appreciated MIT
making all its freshman-year classes
pass or fail.
During that year, I took my first
class in linear circuits. While for
most of my fellow students, it was
one of the boring classes you needed
to take to be an electrical engineer,
for me, it was like unlocking a door
to this magic kingdom. The difference wasn't that I was a nerd (which
I clearly was) but rather all the time I
had spent the previous summer reading EE trade-rags. This was another
one of those fortunate coincidences.
During that time, I saw all these figures about how to build kinds of filters and amplifiers, but I had no idea
how they worked. I did use some of
them for my projects that summer,
but it was purely a cookbook solution
as I copied the circuit exactly.
While all the other students were
groaning about having to analyze resistors, capacitors, and inductors circuits,
I finally understood the principles that
governed all the circuits that I had seen
and could deconstruct their operation.
I knew this understanding was the key
information I needed to optimize the
circuits for my applications next time I
would be at NBS. It was fabulous. This
experience shaped one of my principles for teaching: just-in-time learning.
I believe that students are more likely
to learn a concept if they have already
seen the problem area where it can be
applied and tried to solve it the "hard"
way. I guess, in teaching, sometimes it

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Table of Contents for the Digital Edition of IEEE Solid-State Circuits Magazine - Summer 2016