Power Integrity and Signal Integrity – EEs Talk Tech Electrical Engineering Podcast #19

Power Integrity and Signal Integrity – EEs Talk Tech Electrical Engineering Podcast #19


hey everybody welcome to another episode
of EE stalk tech as always my name is Mike Hoffman
I’m Daniel Bogdanoff and today we have Kenny Johnson you’ve probably seen Kenny
on our YouTube channel before he came around during scope month gave us a
great little tip about how to use it like a ten thousand dollar active probe
to clean out the charging port of your iPhone that’s still to date my favorite
scope date or scope month video with Kenny – Dr. Kenny and his doctor science
glasses and today we’re gonna talk about power integrity because Kenny is is our
resident power expert so Kenny can you introduce yourself a little bit tell us
about your background yeah sure you know but before I got too far though expert
is a loose term it’s like calling me a giant even though I’m just the tallest
pygmy in the tribe right it’s every relative we’ve had on this podcast says
well you know yeah expert so I’ve come to convince myself that experts never
think they’re experts okay carry on sorry yeah so you know I’ve been working
for this place for like 32 years now and most of that was in R&D and but I’ve taken a
couple of trips over into marketing as poduct line manager and stuff like
that and best part about the job has been through all those years just
visiting with hundreds or maybe a thousand different users out there and
helping them solve their problems and you know my expertise really is more
about like probing and making good measurements and it’s just it’s turned
out the last maybe three or four years when I’ve been working on this stuff
that people have just really been having a hard time with what I call the power
consumer there’s people out there that produce the power and then there’s the
people that use the power the people that produce the power you know they’re
the ones that you know whether like that might be the wind farm or the solar farm
or just a coal-fired power plant all the way up to the plug in the wall and even
from the plug in the wall up to kind of like that you know this silver can that
your AC to DC power supply inside your whatever product you’ve got that’s kind
of the power producer the power consumer guys a guy that’s taken then he’s
worried about the quality and quantity of the power that he’s using and so I
really started kind of get into this like I said I don’t know four or five
years ago or thereabouts and people were sweating
chasing the milliamps in the micro amps and stuff like this around and and so
we’re helping to make those measurements and people kept raising their hand
asking like hey you got something I can look at the ripple of noise on supplies
and I don’t know if as a kid your folks have already the book Horton Hears a Who
or you saw the story you dad but you know at some point it’s like all these
little people are screaming for help and then just one more voice gets on there
and then it finally registers it’s like ah it’s this little dust back that the
protecting and then like no one can hear it except for him because he has nine
years yeah and then there’s like one like teenage kid who’s like I’m not
gonna yeah yeah yeah yeah I’m so and so finally there’s fear such there’s some
threshold of voices where I finally heard us like oh my gosh we need to do
something for these folks and so that’s when we started making like parallel
probes and things like that you know to help out with this power integrity so
it’s um so for the power integrity it’s you know the rough definition is
something almost esoteric sounding like the study of the effectiveness of the
conversion and delivery of DC power from the source to the gates on the IC. I’m
on the edge of my seat right now are you reading out of one of your textbooks
here’s please tell me you wrote one of these wrote the book uh yeah yeah and I
loosely quoted that so I don’t have to actually name my source that’s fine but
really you know folks were just they were freaking out about like hey I need
to measure the ripple of noise on my supplies and we didn’t really have a
good solution for that so then started digging in more and more and found out
how much all this stuff is tied together that what’s happened over the years you
guys all familiar with Moore’s law right that every 18 to 24 months we’re gonna
double the number of gates on an IC sure yeah interesting thing about that I read
it I read a guy’s paper where he says you know if Moore’s law keeps up for
about the next six hundred years we will have a computer that is capable of
simulating every atom in the known universe
ooh Hitchhiker’s Guide to the galaxy style with that article went but anyway
you have a backup right that’s the checkered sky it is so I get the end of
the series too like oh yeah here’s the backup and everything
resumes as if ever oh really again the anyway so with that what happens is you
know we’ve been cramming more and more stuff in there and so you start getting
numb one more gates packed together and
everything and and we start ending up with like thermal hotspots you’re just
just too much power you know you’re gonna you’re gonna fry devices and
everything and so to take care of the power for those hotspots but also to
extend battery life or just you know how many how many kilowatts your thing is
using over here out of the wall is we start dropping voltages and so everybody
starts getting more and more concerned about this ripple and noise on the
supplies and supplying good clean power to everything and so that’s where we all
started in you know it’s um there’s actually when I first got into it I went
out to Amazon and I said okay I need to read a book right and so I started
checking some books and all the books that were published I think there was
two at the time maybe three I mean they literally were just coming out about
three four years ago um so it’s been something that is really exploding for a
long time now the truth be told is that people have been doing power integrity
measurements the first reference I ever saw was from some work in like 1930, so people have been like looking at this it’s just that right now it’s
become more and more important because if product functional reliability is
directly proportional to the quality of the power inside that product and so as
we have a lot more functionality in our products you whether that’s your smart
phone or my cool little you know exercise wristband kind of thing there’s
more and more opportunities for things to go south and to fail and so that’s
why there’s this increased focus on this and the and it’s there’s a correlation
then or they’re kind of tied together well you know we’re supplying a voltage
to these things that they’re operating and they’re also consuming current
they’re pulling current through there okay and so you start thinking about
this it’s like wow so that’s sounding vaguely familiar to like Ohm’s law right
and we’re just missing like the the our where’s the R in the whole thing or the impedance yeah yeah exactly exactly and so if you
think about it like a typical product it’s going to have power and ground
planes and you can want the impedance of those things to be pretty low so you’re
not getting some kind of IR drop across the ground plane and so I know it’s a
gross simplification but it’s it’s a pretty easy model to work with is that
the idea coming from some of the the early pioneers this stuff Istvan Novack
or Ray Ridley guys like that they talk about these flat impedance power planes
and the idea is you can kind of take whatever your voltage is you know if
it’s a five volt supply or whatever divided by the the change in current
that you expect you what’s your basically your peak current multiply
that by the tolerance and you end up with like a target impedance for your
power planes yeah and so if you can you know maintain a pretty much a flat and
pedis what happens then is you don’t get a whole lot of noise showing up on your
power splice so if you think about it it goes so you want a flat impedance over
the different current ranges right over over frequency yeah okay yeah yeah and
so you know if you think about it you know remember back to like a circuits
101 is that an inductor is open at high frequency and so we’ve got these these
power planes and really those are just big inductors so at some point their
impedance is going to go up and so when you have things like you’re just writing
data out to memory well there’s some pretty fast transients there they’re
associated with 0 1 0 1 it actually takes some some energy to change that
from a 0 to a 1 and you have to draw some current to do that when you do that
to supply kind of pulls down and sags and anyways so the point is is there’s
uh even though we’re talking about DC is that there is you know high frequency
effects here and so that’s why it’s impedance not resistance to those planes
and so when you look at boards a lot of the times you’ll see like how there’s
always like yeah capacitors all over the place right yeah and the child of the
capacitor you know remember back again that same circuits classic capacitor is
a short at high frequency well kind of pitch it in your head as you start going
from like you know DC on out the impedance of that inductor start going
to creep up well that’s bad we wanted to go back down what do we do hey let’s
slap a capacitor on it because that’s a short that’ll start pulling that
impedance back down but then at some point there’s some inductance associated
with that capacitance and it’s gonna start to go back up again and so you
look at these in these power plane impedances they just look like kind of
like a waves on an ocean it’s just kind of these you know troughs and and peaks
and everything that are the impedance and so that’s what guys are like trying
to design towards whether they know it or not yeah so basically like to Sun
that up when a system requires current it’s basically gonna be a load pulling
current and the supply is gonna dip a little bit mm-hmm and if it’s for
example writing one zero one zero it’s gonna pull and release yeah your current
power supply is going to ripple yep set that’s it exactly and and so
with with a lot of products like maybe the ones that we designed here and
everything you know we’ve got fairly good sized circuit
boards inside our scopes you know many many layers you know robust power planes
robust ground planes things like that but if you think about somebody that’s
doing them some small form-factor product like that maybe some IOT thing
or consumer electronics or even smartphone kind of thing they probably
have room for dedicated power planes and ground planes heck a lot of stuff I take
apart to fix at home only has like it’s only a two sided boards they have like a
power trace and a ground trace yeah well that means that they’re gonna be
fighting that impedance battle pretty quick and so but where most people come
into this is they at least from the what I’ve observed is the majority of people
try to use some intuition and based on past experience to go through and make
the planes kind of as big as possible and and keep distances as short as
possible and that’s why you see the trend of more and more like localized
power regulation you know maybe in the past it used to be you just have one fat
hose that goes to your circuit board supplying the power you just distributed
everywhere well now there’s more or localized regulation so you can keep
those distances shorter the other thing that it does to is it was mind boggling
when I first got into this was for example like a typical solid-state drive
has about twelve supplies in it something like a tablet could have 50
some of our oscilloscopes have a hundred and eighty supplies in it and some
next-generation mobile electronics a hundred to two hundred now it’s not like
there’s a hundred different voltages 1.1 1.1 11.1 – no no there is there’s
redundant voltages in there because what happens is as one if they’re all
connected the same spot as I turn on the display it’s going to yank a bunch of
power out of there there are a bunch of current the supply is going to sag and
it’s gonna sit in fact everything yeah yeah and it’s kind of like when I was in
college we rented a really old house and if I was in the shower and somebody
flush the toilet all the cold water goes down the toilet and I get scorched it’s
like ah right see they put in some flow regulators and all that what these are
doing the same thing so that when somebody turns on the display it doesn’t
like disrupt the you know the mp3 codec or the the memory or something else so
that’s why there is this these multiple copies and then they also try to have
multiple phases so that they’re again even more robust for when they are
interesting when there’s these these demands on these on these voltage
regulators oh it’s so they’re gonna like run three-phase power across the board
and rectify it out at different voltages oh yeah no no I didn’t I didn’t mean it
that way what I meant is like there may be like let’s say there’s a 1.5 volt
supply to something that actually maybe like multiple 1.5 volt DC to DC
converters there and everything there that are sharing the loads so these
regulators attached to the same rail if one gets hit the other one is able to
stabilize it yeah okay yeah make sense and you know so sort of like a you know
two or three of us carrying the load instead of one of us care in the load I
was like that’s gonna be brand new to me as we’re gonna have to pause for a
moment there Wow – those connectors how did I miss
those connectors, the phone now phones converting DC to AC and then rectifier
somewhere else yeah so let’s see where was I going anyway so okay so you’ve got
like all these supplies got a look at it so most people they’re just using kind
of an intuitive approach to this and it’s it’s because a lot of folks don’t
have access to maybe modeling and simulation tools and I know like around
here you know we’ve got some modeling and simulation tools but we’re a large
enough corporation that we’ve got people that are dedicated to support those
tools and be experts on them but you know a lot of people aren’t that
fortunate so they just kind of have to take some rules of thumb and just say
well I’m just gonna make this you know throw down a lot of copper and start
sprinkling a lot over engineering yeah yeah exactly exactly that’s cost and so
that so how do they know if they did a good job or not well you go look at like
the datasheet for the FPGA or the little microcontroller and it’ll tell you on
these critical supplies you know that maximum you know ripple and noise and
fuzz on the power supply is you know plus minus 2% or 5% or whatever it is
and so they want to go measure that to see if they’ve done their job or not and
so that’s where most people jump in and then excuse me after they’ve gone
through that a bit then they start to kind of maybe think a little bit more
about next time when they lay it out maybe they’ll go take a class or maybe
read some of these books but in general it seems like that’s where most people
hang out is they sit there in that in that world kind of measuring it after
the fact I’m not necessarily looking at it and the impedance still made but more
than that in the time domain that stuff it’s interesting no I do have to ask you
brought some show until items for those of us who are listening and not watching
you have a couple it looks like for textbooks and some some printouts here
that you brought in was there just in case we tried to stump you or something
like that well this this is this is so that I can
try to pretend I you know I’m cleverly disguised as a power expert and so this
this is part of the disguise is having a stack of textbooks that’s about eight
inches tall before you start believing Kenny’s claims I think I’ve come to a
conclusion is one that experts are always learning so if you want to be an
expert you have to keep learning but I think
you also might hold the record for most patents in the company is that I don’t
know if that’s an official record do you know how many patents you have so yeah a
lot yeah yeah quick acute story on that so I’m our chief technology officer used
to have the most patents for this particular division this location Jay
Alexander yeah he watches our channels and now he has to watch so Jake
congratulated me a while back I think as my boss had sent an email to some folks
saying you know hey you know Kenny got a patent and so Jay had asked me how many
and I said you know I’ve I I tried I don’t I I try to remain humble on that
I’m not naturally I don’t brag right that’s why I had to bring it up but yeah
and so uh I think the current count is almost 30 and yeah when Jay and I were
having the conversation I think his number was about 25 and I just got
number 26 or 27 and but hey you know I’ve been having turning the crank for a
long time so that’s but there’s guys out there I think at that company like
within keysight that have you know over a hundred TLO guys I’d have to assume oh
yeah technology leadership you know ASIC guys like Mike Byers and some of the
other guests we’ve had yeah so yeah so there’s there’s definitely some some
intellectual giants out there but anyways with the books the reason I
brought the books was because they actually helped me out a lot like I said
when I first got into this I was a probe designer not some kind of like power
engineer and everything so how am I gonna help these guys I had to come up
to speed fast and so I Amazon hit Amazon and was checking out power integrity and
start funding like one book was published then two then three and so I
order them and just kind of read through them and everything and for those that
are listening there’s no point in me kind of holding them all up and
everything but there’s uh there’s at least three or four great resources out
there if you just go hit Amazon and type in power integrity is there is there one
in particular that you choose like you guys recommend
it’s not an official endorsement yeah yeah yeah you know a female if you don’t
have much time to read at all there’s a book by dr. Eric Bogatin and his
original book called a signal long-lost cousin yeah he originally wrote a book
called signal integrity and it then he did an update to it that was called
signal integrity and power integrity simplified okay and so it’s the second
edition of his book and so there’s about two or three chapters in there and it’s
a pretty good overview I think he’s got another edition out now that’s got even
more content but if you just want to start there it gives you some great
ideas about like why should I even care you know what happens I mean as long as
it’s there we’re good and so he tells you why you should care some steps to
take some measurements to make and it’s that’s a good basic one to start with
and you know something that I wanted to share just this this quick experience
was you know as we were going around and starting to talk to people about some of
that techniques and things that we had for for measuring the ripple of noise on
the supplies I remember talking to some of the first users they were in the lab
that they called their Sippy lab so this is a very large you know like fortune no
integrity integrity exactly and like sippy cups the anyways and so that’s the
thing is they’re they’re so tightly related is that power integrity will
affect your signal integrity fire integrity also affects your EMI and your
EMC but it was so these guys and a lot of the more of up like progressive or in
the forefront companies everything have these SIPI labs or things so when in
there and I was talking to the manager of the power integrity part and you know were
showing him how to make some measurements and he’s like wow that’s
great results that’s better than I could get before and everything and he says
you know what I wish there was a button I could push that would tell me is it
worth improving the design anymore because he says you know like his
engineers we can always like tweak it and try to improve
is it worth it you know what am I going to get from this and everything and so I
think there’s without getting into endorsing particular products there are
some more tools out there now be analysis applications or even some of
these textbooks that can kind of help you understand then what you can get
because get this there’s multiple papers that say power supply induced jitter is
the single biggest source of data jitter in a digital system interesting and I’ve
got that color yeah I’ve got a couple of cool little IOT development kits you
know so if I was like I want to make my little fishtank monitor for at home or
whatever was I I take these and I can without even trying they start stumbling
and dropping bits which would be basically okay that’s either gonna
affect my battery life because you know I didn’t I didn’t you know my error
checking says okay some of the data again send me the data again send me the
data again or maybe it’s actually things freeze up and so that power supply
adduced jitter is really kind of the thing that people are looking at and so
there’s some some papers out okay we’ve got some but basically if you go check
that out if you clean up your supplies you’re gonna get a lot more a lot more
margin in that domain so to clean up a supply is it like a bypass capacitor
thing you have to go through or what’s what does that look like wire brush soft
bristled toothbrush yeah the majority of time that’s really what it is is it like
when remember when I was talking about that that flat and Peeta’s profile well
let’s say you’ve got some some noise that’s showing up in your system that’s
we instruct people like after you’ve looked at the power supply in the time
domain good thing to do is go look at it in the frequency domain throw up an FFT
and then you’ll start seeing some spikes in there at the various frequencies and
that’s usually a good way to kind of get a fingerprint or you know tell some DNA
for like who’s committing the crime you like okay I see a 100 MHz megahertz spike
or whatever and so they sudden you know okay so that’s starting to bleed through
now I need to do something to try to suppress that hundred megahertz noise
for my supply and if you know the frequency you can work backwards into
the impedance that you need to hell exactly exactly so if you were to go
look at that impedance profile you’re probably see that your impedance is
starting to pick up around that 100 megahertz it’s like okay let’s go pick a
cap that’s gonna knock that down about there and go plop that down and
everything and that’s that’s kind of at the easiest that’s what most people do
okay and and you want to put that if I remember right I was just reading about
learning more about this you want to put it like right by your load yeah you
don’t want to put it out by your power like that’s a source of your power rail
you want to put it right where the chip is going to need it or whatever your load
is yeah you know it seems like there’s some general rules in the universe that
apply to just about everything and like closer to closer to the device is always
better whether you’re like putting down the bypass caps or like we’re always
telling people like if you’re making a measurement or you’re gonna go measure
the signal well you want to measure it at the receiver right see what the
receivers in and because that’s going to tell you a lot more so those general
ideas of like closer to the the device that’s being powered or closer took the
device that you’re concerned about and so yeah you go through those they’re you
know there’s one thing that so I think before you get in the white band gap
yeah it’s been like 24 minutes no sorry I told you it goes quick so we might
have a whole nother podcast on wide bandgap semiconductors that’s cool power I think that’d
be pretty cool too you know there’s like going to tease it like gallium arsenide
universe witching I just throw this out real quick this is from the US
Department of Energy hands looking at this just a little while ago and they’ll
actually pay for guys like you and me to go back and get a degree in Power
Engineering and the reason is is because these wide bandgap semiconductors
gallium nitride silicon carbide if for example we were to just go through and
change the existing motor controllers out there for like pumps and things like
that we could save enough electricity for a million homes it’s because there’s
so much more efficient if we change how many homes are in the u.s. home sizes
like do two ish cup could be a couple hundred million populations what all the
homes if we went through and changed just like
existing like you know that your wall warts and the
motor controllers and stuff like that it’s it it’s about maybe five six
percent of the homes in the u.s. right just just from changing those out
anyways it’s it’s the wave of the future for power power electric perfect so
we’re gonna talk about that next episode real quick on the census data there was
just really interesting research study out this is totally unrelated but I have
to share because it’s so cool um so you know like Facebook advertising says oh I
can reach this many people in this age gap if you look at what the social media
sites say they can reach from advertising standpoint and what the US
Census the data says Facebook is claiming and these other you know
advertising tech companies are claiming to reach like forty percent more people
than the US says actually exists in the country I believe that this well I don’t
want to draw okay I probably believe Facebook over it’s gotta be somewhere in
the middle because I’m not gonna go there anyway yeah so at the end of every
podcast episode we like to ask our guests a stupid question
so I think I know what your question is but go for it no okay well I can ask it
for you because this is what you’d come up with okay what is your favorite power
real voltage and why I didn’t think of that Wow I’d have to say three point three
okay I love the symmetry of that number number but I remember with three point
three was the small stuff you know everything was five volts when I first
started working and as like oh you’re working with the small stuff three point
three but it’s just the symmetry of that three point three yeah that’s that’s the
favorite it’s nice did you have a question too I do okay so
I like five volts because a USB good so we’ve been talking a lot about power
integrity and so it sounds like that’s getting a lot of attention
what other part of electronics designs do you feel like deserves more integrity doesn’t have enough integrity yeah who
doesn’t have enough in no I yeah Tony who’s Native security
what do you think lots of competing guys yeah you know unfortunately I uh
my wife’s car got broken into yesterday and her purse got stolen we had to
freeze all the credit cards and so that brings a certain it’s probably good to
do anyway after what happened a few weeks ago well that’s that’s what I’m
saying so actually the blessing in disguise errs were getting new credit
cards issued across the board and I thought about that last night trying to
make a lemonade out of lemons is going wall Hey okay so somebody hijacked all
my stuff from that one credit bureau some that information is bogus now you
know where where people are starting right now that the other thing with
integrity is just counting the milliamps that go everywhere you know that people
are trying to save power whether it’s to be green 2 save the planet or be green 2
save some green and so that’s the other phase of this that where I think we’re
starting to see a take off is just how many coulombs and I scooping up and
throw it away and everything how much how much current am I using it’s being
distributed cleanly but is it being used effectively yeah yeah yeah yeah exactly
so you know whether we’re whether we’re trying to save the planet or you know I
did a thing like about 10 years ago got an infrared camera and for work well
what’s the first thing you do well he’ll you take that take a selfie yeah gotta
go check stuff out right it’s like no the kids and and you know so checking
out the dog and it’s like whoa he’s well insulated only his nose glows in his
ears or something like that then we’re like doing handprints on the wall as I
moved around the house the number of things that were glowing that I thought
were off you know go down to the basement wow look at the treadmill oh
look at the you know the the the the the furnace you know the thermostat and just
how much of that is wasted and so whether that’s whether you’re green for
that or just being green 2 save the utility bill is that I think that’s the
that’s the other Porsche is just using it more efficiently soft power switches
are cheaper I think that’s what it comes down to yeah yeah we all of our favorite
youtubers very very very very fond of actual physical power switches yes yes
we do yeah they shout out Dave dance yeah an
electric boom actually did a great video with the thermal camera he ran around it
pretty nice so you can go check that out all right so we are officially out of
time so thanks for tuning in make sure you subscribe to the podcast give us a
five star rating please we that really helps us keep doing what we’re doing you
can also see this podcast and its entirety and get the RSS feed and all
that type of stuff if you do custom feeds on EES talk tech comm EE stack
tech comm i’m daniel bogdanoff mike coffman and patent heavy Kenny Johnson
is with us and we’ll have him back next time to talk about wide wide bandgap
semiconductor powers power or something I don’t know we’ll figure it out next
episode thanks for watching see you next time Cheers adios guys
you you

13 thoughts on “Power Integrity and Signal Integrity – EEs Talk Tech Electrical Engineering Podcast #19

  1. I got sucked into power electronics unexpectedly a a number of years ago. I had NO idea how deep the rabbit hole would go until I looked closer, then closer, and again closer. I kept discovering that more and more problems on the digital side of the systems could be traced back to power issues. I quickly learned that capacitors are not going to fix everything. Measurements are uniquely challenging, PCB layout is not trivial, etc.

    On top of power integrity demands going up, the demand for the size and cost to go down creates a brutal challenge. Polyphase converters are excellent, glad to hear the topic brought up here. They use a distributed clock to synchronize the switching as various phases which shrinks the solutions size, reduces noise, and provides an opportunity for redundancy if needed.

    Good talk…..thanks.

  2. Very interesting discussion on power integrity and how to limit power surges and ripple.150 mini power supplies sounds crazy.Soft power switches could be a topic in itself. General lack of simulation and modeling tools will have quality ramifications but we also have to balance the budget and cut the cloth to measure. Security issues are another major discussion hotspot. Roll on next video !

  3. Please make one about FPGAs! From history, to current trends, to the future of them, and also how they compare to other alternatives, etc. I'm sure there is a lot that could be talked about. Also maybe it could be interesting if you allowed us before a podcast is recorded to suggest some ideas on stuff we would like to be discussed…

  4. Fantastic topics! As a repair guy, the lightbulb just went on when you folks started discussing power induced jitter. Wow! Been working a problem on a device and now I can't wait to go try something at the repair bench tomorrow to see if my issue goes away.

  5. Excellent talk. A great review AND I learned a coupla things. Thank you! But why do you guys need the headphones???? 🙂

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