Good one, Mel!
This page will help
guide your career path in the field of microwave engineering. What
technologies should you stay away from if you want to avoid precipitated
upon by a future pink-slip blizzard?
Without a single doubt, this page covers a topic that will NEVER
be covered in any trade journal, IEEE paper or government solicitation.
What can we say, we're there for you!
Career Figure of Merit
If you are looking for career enhancement, stick to the principal that cost reduction is just as important as performance improvement when you are developing technologies. We define the following Figure of Merit:
Career FOM=(Improvement in Performance) x (Relative Cost)
You can express this in decibels: using the example of RF CMOS, you might achieve 1/10 the price but at 1/10 performance, and your career will advance 0 dB. But if you were to perfect gallium nitride on silicon and process it on 8 inch wafers, the performance might degrade 1 dB compared to SiC but the cost will drop substantially and you may well achieve a 3 dB career FOM.
After we review
these dead or dying technologies, your homework assignment is as
follows: practice in front of a mirror repeating the response that
is needed during meetings when a particular career-killing topic
comes up... instead of just saying "no way Jose", just
say "good one!" but try to minimize the smirk. Then if
you are called on the carpet later by Mayor McCheese, you can play
your comments either way, either "good" in the sense that
Michael Jackson used the word "bad", or good as in, "not
altogether crazy". Remember never to say "not bad"
in front of any Limeys, or they will surely misinterpret this as
the highest possible praise. Can you dig all that? For this excellent
use of the quirks of the English language, we dedicate this page
to Heidi and Eric who are masters of many two syllable responses.
It is only fair
to warn you, the information provided here was surely fueled by
one of "Mr. Gordon's excellent products" (to quote Hemingway).
If you disagree, or have some other suggestions, chime in mate,
or sponsor a page on your particular sacred cow and maybe we'll
change our opinion. Our apologies if we step on someone's sacred
cow and they can't take a joke, but better you hear about what people
really think here at Microwaves101 than you hear from Mayor McCheese
later when he figures out he's been wearing the Emperors New Clothes.
There's an image we didn't need!
Like Charles Dickens'
best work, we'll divide the topic into three tenses: past, present
and future. Perhaps another way to look at these technologies is
in the three chronological phases of technology: unbridled enthusiasm,
backpedaling, despair, and blame. Hey, that's four!
The ghost of career
These are technologies that you
might not even have heard of if you are young.
diodes (so called "solid-state transmitters")
diodes have some interesting properties. Under certain conditions
they can amplify a signal by about one dB. So to make a transmitter,
you need to efficiently combine a chain of one zillion IMPATT diodes,
using a low-loss technology such as machined waveguide. Forgedaboudit.
Figure out another way. You are out of your mind.
Does anyone even
remember this stuff? Or was it just a nightmare like cold fusion?
2011. Here's the answer, according to Colin (thanks!)
So you asked whatever happened
to Josephson Junctions...... here's the latest:
Yep, quantum supercomputers
use them. And LockMart (home of everyday low prices for all your
defense needs) just bought one.
silicon carbide (AlSiC)
AlSiC was received
with great fanfare in the 1990s. Net-shaped housing with matched
CTE to GaAs. Where are the purveyors and early adopters of this
technology now? Haven't seen them!
The problems that
have persisted include the inability to maintain a minimum aluminum
skin thickness. Wherever the silicon carbide pokes through, plating
won't stick. Poor plating means no chance of hermeticity, because
you will have to braze in some feedthroughs because you sure can't
fire in glass above the melt temperature of the housing. Also, the
reality of net-shaped eventually meant "near-net-shaped",
which means you might as well go to a machine shop, but you should
pick something to machine that won't ruin your tools like silicon
carbide will. Recall that silicon carbide is the main ingredient
Over the years several
thin-film vendors have tried to move up the food chain, offering
filled "hermetic" via holes, airbridges, multilayer interconnects
and even MIM capacitors. Guess what? This technology is low yielding
and tres expensive.
These are technologies that still
persist in the industry, but have lost some of their original luster.
Sort of like an aging stripper that keeps on keeping on because she
hasn't bothered to develop any other marketable talents...
radar (a.k.a. adaptive cruise control or "car radar")
New for September
2009! It is long past time to request a fork and spoon to eat our
words. Not that long ago, automotive radar looked like a dead end.
Then along came RF silicon.
Now with 90 nanometer (or less) CMOS and 130 nm silicon germanium,
it's now possible to create a radar cheap enough for the car market.
We had all but forgotten about the topic, until Ben sent us an email.
These are his words:
I would like to doubt that
Automotive Radar is a microwave career killer. You can you buy
a fully integrated automotive radar chipset in silicon from Infineon,
Freescale trying to catch up, Fujitsu trying to do it in CMOS.
Third generation automotive radar is on the market and is delivered
in the Porsche Panamera designed by Bosch and including the Infineon
Chipset. However, I think this is not the kind of mass selling
car, but this system will be delivered in new Audis too.
This is what we
originally said... Maybe car radar should already move to the "past
tense". Sure would be nice to be able to kick back and let
some Gunn diode apply the brakes when
you're creeping up on the car in front of you. Better yet, why don't
you put down the cell phone and pay attention to what you are doing?
The automotive radar
idea has been around for decades. As near as we can tell, no one
in North America ever made a dime off of this. One problem is that
radar companies are used to dealing with juicy defense contracts
which pay cost-plus for development. If you ask Ford for such a
contract, they will respond "good one!"
Anyone else care
to join in on this discussion? Here's Uncle Jam's take on this:
The career killers page
is pretty spot on, but I have to disagree with you on Automotive
Radar... first, building a whole radar system on your own is a
pretty impressive point on your resume, and extends to other job
sectors. I think you'll agree when I say that radar is generally
used on things other than cars! This is what I mean when I say
that an Automotive Radar is a system, it isn't locked in to any
technology choice. I can assure you, that I've seen and done evaluations
myself on forcing in no less than 7 of the technologies you list
on the career killers page into this car radar! Based on this
experience, I can say you're pretty spot on with everything else
on that list.
However, these days alternate
ways of doing things are really starting to transform the radar
from something of luxury and long haul trucking to everyday driving.
SiGe and CMOS development are starting to catch up with our frequency
band (and as already pointed out on your site, SiGe is already
in some current generations of radar). It's sort of like Automotive
Radar is the St. Peter of microwave technology, deciding what
sinks or swims.
As examples of end product
from these advances, radar is now available on Ford Taurus and
Toyota Prius cars. These cars aren't 'cheap', but they're not
Mercedes either. VW and Audi have their own ones now. Also, the
radar is not a single application of Automated Cruise Control.
They are also used for Blindspot detection, and collision preparation.
These applications are much cheaper than ACC because a lot of
the supporting electronics used in ACC (like the car controlling
the brakes and reading many other necessary sensors for the algorithm)
are not needed. Collision preparation looks like it will become
very cheap soon. This helps out by readying the car before the
accident happens, instead of passively detecting the collision
and taking advantage of the speed of light. One advantage I'll
point out is that the airbag can deploy slower and avoids slapping
people in the head. Another is emergency braking assist. Don't
be surprised if in the future there is a push to have the government
standardize sensors like these. Although with congressional hearings
on EMI and car electronics, who knows!?
After watching the Toyota sudden
acceleration debacle of 2010 unfold, I really don't want any electronics
involved in braking decisions... also, with ROHS eliminating lead
from electronics without a suitable substitute, the chances of any
electronics working perfectly as a car ages grows less and less.
Cheapskates like me have been known to drive cars for decades. -
This tip also came
from Ben, the same engineer who debated our car-radar is a career-killer
I think UWB (ultra wide
band) is such a career killer. It was a big buzz word last years,
we did not hear much about the topic. Of course, there are some
applications where you can buy it. They all have one thing in
common: they don't have much to do with the idea of a pulse based
system. Systems on the market only can achieve the high datarates
with OFDM modulation, which is not the basic idea of UWB.
temperature co-fired ceramic (LTCC)
offered to provide us all with a low-cost, three-dimensional interconnects
for microwave modules. No doubt about it, some of the coolest hardware
to ever be demonstrated uses LTCC. So what is the problem?
Shrinkage is one
issue. Or rather, shrinkage tolerance. If every circuit shrank the
same way, every time, maybe you could talk about high yield. Or
you could just put up with it and accept low performance.
is another problem. The cofired metal doesn't always have the properties
that one would want, for example, for soldering or wirebonding.
Last we checked,
the price of gold was over $1000 per ounce. Imagine wastefully screen
printing thick-film gold interconnects, including solid-filled vias,
whose conductivity is significantly reduced by organic binders that
must be burned out, such that you can never compete with the loss
characteristics of the cheap copper used on soft boards. It's no
wonder that the LTCC scrap pile in your factory is always empty,
the employees are stealing it, selling it to reclaimers, and spending
the money on Las Vegas High-Roller vacations!
But the primary
problem is: ceramic sure is expensive compared to soft substrates
like PTFE... so what happens when you evolve to a multilayer ceramic?
It gets more expensive! What happens when you evolve to multilayer
soft-board? You kick ass and take names! If someone tells you LTCC
is affordable, you can quote us here... "good one!" Sure
you can make some hero results with LTCC, but it will never be cheap.
Look for a soft-board solution.
It is fair to say
that MEMS may yet prove to
become a billion dollar per year microwave component, especially
in the past "00" decade when many of the shortcomings
seem to have been addressed. But so far we have been less than impressed
with the notion that MEMS was going to revolutionize microwave industry.
Wake us up when this happens! Check out the Riddle
Here's a musical
tribute to stiction!
High voltage GaAs
(This was contributed
by someone that surely wants to remain anonymous...) For a few million
bucks you can always tease another volt of operation out of GaAs
pHEMT power amps. But read the writing on the wall. GaN transistors
are coming that will operate at 50 volts, and GaAs pHEMT will slowly
but surely become a niche market, the way MESFET is treated today.
GaAs for anything
other than RF
Because GaAs is
so "fast" you'd think it would be used to create the world's
fastest computer. Some companies spent a lot of research money on
this. As it turns out, they didn't follow an important corollary
of Moores Law: anything that can be made of silicon, should
be made of silicon. There's no way that a compound semi is going
to displace silicon for computing power.
Future career killers
These technologies are still in
the "enthusiasm stage" so they might represent sweet music
to you for now, but musical chairs on the associated change number
will commence sooner or later.
CNTs: the most unfortunate acronym of all, there to remind us about the joke about the difference between a pack of girl scouts and a tribe of pygmies... Here is a lab curiosity
that is looking for a problem to solve... is it a transistor? or
a heat sink? or a mixer? All together now: "good one!"
From Uncle Jam:
I once saw a guy simming
in HFSS a patch antenna made out of carbon nanotubes without any
substrate. When I asked him about it he told me they had no idea
how to grow them onto a substrate so this is what they were settling
Actually, there has been some real progress in CNTs in 2013. HRL Labs actually make a CNT transistor that pinches off. They must have cheated, as CNT has no bandgap. But wait, that's not true according to Gabriel:
I really appreciate all the work that has gone into Microwaves101 and it has helped me a lot the past couple of years (We wanted to use superconducting stub tuners to investigate single molecule devices at 4-8 GHz). I just happened to enjoy reading the career-killers page and saw you mention CNTs (which I'm working on now, we can actually impedance match a CNT device with a resistance of 200 kOhm), where you stated CNTs have no bandgap, which is not true, they come metallic (yes, no bandgap) and semiconducting (has a bandgap), when just growing them, 1/3 will be metallic, 2/3 semiconducting.
I know it's pretty close to nitpicking, but I thought I'd tell you anyway. And yes, I guess it will be another 5-10 years until CNTs will move from the realm of research (1 in 20 devices working, everything "handmade") to an area where one can actually do engineering.
Career FOM: -3 dB
|An idea competing for nanotube attention is the space elevator. Nanotubes are so strong that they could form a tether from Earth out past geostationary orbit, if only you could make them 140,000 kilometers long rather than one micron. Climbing up the tether would save massive quantities of rocket fuel and pollution (did you think there was a catalytic convertor on a Proton rocket?) In the best scenario, this idea can be used in a future science fiction movie, it is at least plausible, unlike "warp drive". Here's the start of a screen play: a shipment of medical cannabis is needed desperately by the homeless shelter that was once the International Space Station, and the Space Elevator is called to action. Unfortunately, the Y10K calendar issue causes a mishap, sending cars up and down the same tether at the same time, similar to recent terrestrial train incidents. After a space hacker saves the day with his Google glasses, a secret plot to snatch the weed by aliens from the planet Bong goes awry when Space Lassie barks at them....
that involves diamond
We've seen two ways to use diamond
in microwave technology both of which are potential career killers.
The first is as a wide bandgap semiconductors. But diamond doesn't
offer a whole lot higher performance than silicon carbide, which
is cheaper by a factor of Avogadro's Number.
The second microwave application
that diamond might be bandied about is as a low-cost heat sink.
Hey, diamonds are called "ice" for a reason, this crystal
has staggeringly high thermal conductivity. But when deposited as
an amorphous film, the reduced thermal conductivity is not that
much better some cheap metals.
Last, any industrial application
of diamond will remind the public that diamond is just carbon, and
should be cheap. Then you will have to deal with the DeBeers family,
which wants us all to pretend that diamonds are worth multiple paychecks
per carat. Some South Afrikaner with a crooked nose might come and
break your knuckles for messing with diamond's artificially high
Career FOM: -2 dB
MEMS tunable matching networks
We can't wait to buy that 2-18 GHz
power amp with 50% efficiency! Too bad we'll have to package a computer
on top of it to optimize every possible operating point! Heck, throw
an onboard network analyzer on that as well. Maybe Agilent will help
us out and give us each a free copy of Eagleware to run the optimizer!
The premise here is that you
could drive down the cost of a MMIC power amp by using Group III-V
semiconductor only for active devices, and stacking matching networks
on multiple top layers. Good one!
You might notice the use of the
word "three-dimensional" implies horizontal and well as
vertical interconnects. And transitions thereof. The devil in these
details is that vertical/horizontal transitions always stink. Keeping
everything in the horizontal plane will give better performance,
It is hard to take seriously
any technology that might enter a conversation thusly: Remember
on Star Trek...? Some day metamaterials
will enable us to wear clothes that make us invisible. Good one!
Here's some meta-discussion from Uncle Jam:
About metamaterials: they're
going to end up like MEMS. There will be a very small niche area
where they work well in, but most of the things they were promised
for won't materialize. For example, MEMS can be found in very
small microphones, useful for laptops and phones and the like.
There are a few bulk metamaterial ideas that do work and provide
some advantage over existing technology, but they're going to
go into the black box and you won't really hear of them unless
you directly work on them. This paper pretty much made metamaterials
a complete joke for me:
It appeared on the BBC in
their science section, unfortunately. Basically these guys just
made a conformal matrix transformation with electromagnetics.
They keep publishing papers with it. This one is really bad. If
you smash a woman down to half her size, encase her in some lossless
metamaterial (lossless metamaterial, ha!), then a guy, who also
has a clone smashed into the box, stands next to the box, he looks
like a woman. Hong Kong has certainly heard of dressing in drag,
The whole topic of any wearable
technology is pretty lame. Below is a picture of the evolution of
wearable computers which we scarfed from Wikipedia.
One thing that is incorrect about the picture, is that the "wearer"
should be getting progressively fatter with each decade, ending
up in the "10s" sprawled on a bed 24-7, unable to wipe
himself. But he can watch 3D porn at the next department meeting,
thanks to his magic glasses!
We wrote that a few years back...now Google is involved. Maybe we spoke too soon.
Regarding wearable antennas (the
portmanteau is mantenna),
from Uncle Jam:
One technology that I keep
seeing at conferences and such but never a real product are wearable
antennas. I can't say I know much about the subject, but it seems
to me that since the physical size of an antenna defines its operation
characteristics, it seems counter productive to make one that
is always changing in shape. Can't you just move to a higher frequency
and make the antenna small enough to not matter? Especially since
this one is military centric and they can move into different
frequency bands much more easily...
Please send us more ideas for
this page, and feel free to disagree!