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Ransom’s notes on signal integrity and more. . .
Jump to topics on this page:
PAM4, crosstalk, ISI, Eq, COM
Jitter, noise, BER
Tools for innovation & insight
Jitter, noise, BER analysis
Intersymbol interference occurs when symbols overlap with each other:
It’s Not Jitter, It’s Noise
Tips from the pros on how to compare circuit simulations to measurements:
How do I know if my simulation correlates to reality?
Is the PRBS31 a good fit for high speed serial testing? Long test patterns cause mistakes no matter what equipment you use:
Part 0 Test patterns are supposed to stress you out
Part 1 PRBS31: Slower, costlier, worse
Part 2 Test Pattern Redemption!
The idea behind receiver tolerance testing is to submit the receiver to “the worst case but compliant” stress:
Deterministic Jitter for High Speed Serial Receiver Tolerance Testing
Receiver Tolerance Testing – with crosstalk!
The Rules of Jitter Analysis
- published in the online trade magazine, AnalogZone for Agilent Technologies.
Analyzing Jitter at High Data Rates
- published in IEEE Optical Communications.
Conference papers, white papers & application notes
(sponsored where noted)
Jitter analysis on Oscilloscopes and BERTs
, White paper published and distributed by Anritsu Corp., 2014.
Crossing the Digital-Analog Divide
, a white paper for Agilent Technologies, 2012.
Introduction to Precision Analysis of High Speed Serial Systems and Components
, a webinar and Tech Note for Picosecond Pulse Labs, 2011.
Signal Integrity Analysis at Extreme Data Rates
- focusing on 100 Gb Ethernet to see where we're headed and what we need to anticipate, a White Paper written for Anritsu, 2010.
Analysis of Random Noise and the Effect of Band-Limited Noise on Stressed-Eye Receiver Tolerance Tests
- with Marcus Mueller, DesignCon 2009.
Characterization of Gaussian Noise Sources
- with Bob Muro, NoiseCom, DesignCon 2008.
The Future of Multi-Clock Systems
- with Roman Boroditsky and Juan Gomez of NEL, DesignCon2008; also available as a White Paper for NEL Frequency Controls, Inc., 2007.
Using Clock Jitter Analysis to Reduce BER in Serial Data Applications
- an Application Note written without a byline for Agilent Technologies, 2006.
Measurement of Total Jitter at Low Probability Levels Using the Optimized BERT Scan Method
- with Marcus Mueller and Russ McHugh, this paper presented a new technique
invented by Ransom that reduced test time by a factor of ten with improved accuracy and won a DesignCon paper award.
Jitter Analysis: The dual-Dirac model, RJ/DJ, and Q-scale
- a Keysight white paper Ransom wrote that is the most frequently referenced paper on dual-Dirac and Q-scale by standards
groups and other authors.
Keysight white papers describing the techniques and results of an exhaustive comparison of jitter analysis techniques, a project that Ransom conceived and led, which solved the long-
standing problem of how jitter ought to be measured:
Precision Jitter Transmitter
documents the most accurate jitter transmitter ever made.
Comparison of Different Jitter Analysis Techniques with a Precision Jitter Transmitter
- provides results of the study.
Three part knowledge series sponsored by Tektronix (2008):
Answering Gen-2 and Gen-3 Serial Challenges
Jitter 360 - Six-part series on jitter analysis sponsored by Tektronix, 2005-2006 (download the whole series
The Meaning of Total Jitter
What the Dual-Dirac Model is and What it is Not
All About the Acronyms: RJ, DJ, DDJ, ISI, DCD, ...
Jitter Analysis in Systems with Crosstalk
Clock Recovery in Serial-Data Systems
Reference Clock Jitter and Data Jitter
research with concepts that you can use
A bluffers guide to evaluating scientific results:
How to determine the accuracy of scientific results reported by journalists:
Part 1: Systematic Bias
Rules of thumb for estimating the significance of research results:
Part 2: Rules of Thumb
Irreproducible results have come under attack but sometimes that's just how nature rolls:
Part 3: Why Some Results are Irreproducible
It's time for educating technology to make a sharp turn from problem solving to simulating systems. It will be expensive but will have the greatest RoI of any investment in history:
Simulated Education: STEM must change!
The ultimate signal-to-noise problem:
1.) When neutrinos pass through matter, they rarely leave a trace, but when they do, it comes in the form of a ghostly ultra-violet cone of light:
Measure of neutrinos, nature's most elusive
2.) Evidence for dark matter has been building for decades—it’s about time it showed up:
Is dark matter about to be discovered?
3.) How physicists try to detect dark matter is a good example of how the humans roll:
Measuring dark matter: The ultimate signal-to-noise problem
Quarks follow a whole different set of rules than electrons. Electrons repel and the farther you separate them, the less force they feel—these behaviors are probably synonymous with
your concept of “force,” but not after you read this article:
The quirks of quarks
Atomic wave functions have finally been measured and it’s now time to put the Bohr Model of the atom to rest, once and for all:
Quantum wave functions come alive! May the Bohr Model
rest in peace
By solving a 10th grade science homework problem you can decide for yourself whether or not human beings are causing global warming/climate change by burning fossil fuels:
warming/climate change: an easy calculation
Properties of the calm before a storm can be measured and used to predict the transition from tranquility to disaster:
Measuring the transition to disaster
Can a butterfly flapping its wings in Japan cause a tornado in Silicon Valley? Ransom explains the roots of chaos with a simple carpentry metaphor:
Measure of chaos: When uncertainty
(1) Gravitational radiation must exist, but through a dozen years of searching, they have yet to be seen:
Measuring gravitational radiation
(2) We see electromagnetic waves, why not gravity waves?
In search of gravity waves
Flicker shows up in electric circuits, music, stars, brain waves, and the stock market and seems to indicate a significant relationship between distant events—but no one knows what it is:
Noise in the time dimension: the strange case of flicker
Discovery of the Higgs Boson:
Pt 1, Herding cats on the Franco-Swiss border
Pt 2, What they detect
Pt 3, What they actually measure
Pt 4, Identifying the stuff in the detectors
Pt 5, ATLAS and CMS - the biggest test devices on earth
Pt 6, ATLAS and CMS - catching muons and neutrinos
Pt 7, What a Higgs Boson looks like
Pt 8, Is the particle observed at CERN really the HIggs Boson?
Pt 9, What makes King Carl XVI Gustaf think it’s the Higgs Boson?
PAM4, crosstalk, ISI, equalization, channel operating margin
Transmitter FFE tricks the channel into doing its own equalizing:
Transmitter FFE makes the channel do the work
Keep your eyes open for subtlety because PAM4 signal quality is measured by SER, not BER:
Don’t confuse PAM4 SER and BER
PAM4 measurements continue to evolve. Here are two ways to measure symbol level, separation, and nonlinearity, and which is best:
PAM4: Symbol levels and voltage compression
Does COM set us up for failure in SerDes measurements?
Can we avoid COMmitting the same mistakes we made with jitter?
Eyes closed at high data rates, one way to analyze them is to remove the biggest cause of eye closure and see what’s left over:
Analyzing closed eyes: CRJ and CDJ
How emerging high speed specifications provide designers flexibility in how they balance loss and crosstalk:
The tradeoff between crosstalk and loss
Equalization rescues BER, but optimizing your Eq design at both the transmitter and receiver can be tricky:
Optimize equalization for FFE, CTLE, DFE, and crosstalk
FEC (Forward Error Correction) spends bandwidth to buy BER (bit error ratio), but it has to work just right or the whole thing falls apart:
Why FEC plays nice with DFE
At what cost did we recover almost 20% bandwidth in switching from 8B/10B encoding to 128B/130B?
Trading signal complexity for bandwidth
Channel Operating Margin provides a more flexible way to characterize channels and receivers in the presence of FEC, but what you get in flexibility you pay for in complexity:
things to COM
Every year, PAM4 threatens to replace non-return to zero signaling. It’s going to happen when multimoding kicks in:
When will PAM4 take over from NRZ?
Measuring ISI at high data rates is impossible
Crosstalk problems are back
, feature article for Test & Measurement World, July, 2012.
Conference papers, white papers & application notes
(Two+ year delay, sponsored where noted)
Physical Layer Tests of 100 Gb/s Communications Systems
, Tektronix Application Note, 2012, fully revised and re-released in 2015.
Critical 100 Gigabit Ethernet Testing: Equalization, Dp-QPSK, and Crosstalk Compliance
, a webinar and App Note for Picosecond Pulse Labs, 2012.
A new Technique for Stessed Receiver Tolerance Testing Using Crest Factor Emulation
, with John Calvin, Winner of the 2010 DesignCon Best Paper Award.
Anticipating, Characterizing, and Avoiding Problems with Crosstalk
Equalization: The Correction and Analysis of Degraded Signals
- a Keysight white paper also presented at DesignCon 2008 as Opening Closed Eyes: Analysis and Equalization of High
Data Rate Signals on Buses and Backplanes.
Quick update on what’s hot in PCIe from the 2015 PCI-SIG Developer’s Conference:
PCIe Update: Power, IoT, storage, OCuLink, simulation, and equalization
Silicon photonics is sort of like fusion energy, always right around the corner. But this time, it's for sure:
Silicon photonics: Will the hare finally catch the tortoise?
With 100 GbE now developed and in deployment, we can now peek ahead to what's next:
Four 400G quandaries to look forward to
Logo testing lays down the law on not just compliance tests but how those tests must be performed. So if you’re a test engineer, why go to work? If you’re a tech company, why innovate?
The Man has decided and you must conform!
Are standards technological socialism?
The big news at the PCIe-SIG Developers Conference was the announcement of a new specification for mobile applications: M-PCIe, here are the major details:
M-PCIe – Goin’ mobile!
How the OIF-CEI very short reach 25+ Gb/s conductor technology plugs a big hole in 100G communications:
The very short reach of 25 Gb/s
PCIe is twenty years old and PCIe 4.0 supports 16 GT/s:
PCI Express update: the next, next, next generation
Top ten reasons to love (and hate) 100 Gigabit Ethernet
Peace at the plugfest
Tools and concepts for innovation and insight
5 keys to unlocking your innate creativity
The three timescales of thought dictate the time it takes to hit the brakes or to run from a tiger, but it takes longer to have an idea and much longer to learn how to do things quickly:
The speed of thought
Answer resolution combines the intense focus needed to find nuance in the very similar with the intense defocus needed to find relationships among the very dissimilar:
answer resolution and unleash innovation
The biggest obstacle to innovation is our own internal prejudice systems and the "not invented here" mentality. Fortunately, we can get around them:
Reduce your prejudice to
Success in the 21st century is built on innovation but every industry builds TLA walls that stifle creativity:
You can't think out of a box built of TLAs
Moore's Law comes from the way people work and we can derive Moore’s-like laws for almost any developing technology or human endeavor:
Moore's Law extends to cover human
Do you go for sales leads? Networking? Solutions to your problems? Swag? Free beer? No, you’re there to get lucky, here’s how:
Getting lucky at trade shows
Diversifying the tech workforce means more than political appeasement; diversity sets the stage for innovation:
The high tech diversity problem’s bottom line
If you can possibly finagle this opportunity, do it right now!:
Measure career advancement by blowing your mind
Steve Weir shares the strategy that has made him a highly successful EE consultant for over 13 years:
10 tips on being a consultant
Is it impossible in principle to create accurate economic models?
Mismeasure of econoimcs
Why do we pretend that small sheets of paper and cheap metal disks have inordinate value? It’s like the Emperor’s money is made of the same stuff as his new clothes, right? Well,
Measuring money—the beer standard
It's time for educating technology to make a sharp turn from problem solving to system simulation. It will be expensive but have the greatest RoI of any investment in history:
Simulated Education: STEM must change
From bee hives to consciousness, emergence seems like magic, but if you apply serious computing power, you can make sense of it:
Measure of Emergence
Are electronic health care records another inane federal boondoggle or are they a health care cure-all? The answer has more to do with Netflix than you might think:
health records save your world?
The value of creativity far outweighs any other trait. Measures of creativity are elusive but the four key ingredients:
Measuring and generating creativity
Philosophies, codes of ethics, and religion all assume that we act with free will. Newton replaced free will with determinism; Heisenberg brought it back—or did he?
The measure of
free will and red herrings
In a new eco-techno-science fiction thriller, three Si Valley geeks develop VR technology based on the relationship between the senses and the mind:
The science and technology of
UC Berkeley neuroscientists posted a YouTube video that demonstrates rudimentary mind reading—We explain what they did:
Decoding the brain using fMRI and YouTube
Sure, the BRAIN initiative will cure diseases, but it will also open a Pandora’s box of philosophical issues from accurate lie detection to the existence of free will, but the technology
begins with improving brain scan resolution:
Resolving to map the brain: resolution, resolution, resolution
If the position and function of every neuron is known, then a person’s thoughts and reactions can be predicted. Or not:
Measure of the mind: connectome
And you thought EDN was above proposing a diet for the holidaze:
Measure of holiday calories - the thermodynamic diet
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