CSE 464 Digital Systems Engineering L 0 Logistics

CSE 464 Digital Systems Engineering L 0: Logistics and Introduction David M. Zar Computer Science and Engineering Washington University dzar@wustl. edu (Based on Original Work of Fred Rosenberger)

Logistics EE 464, Spring 2011 Lectures: Textbook: Grading: MW 2: 30 -4: 00 in Urbauer 116 Dally and Poulton, Digital Systems Engineering Approximate weighting for grade determination 25% Homework (exams based on homework) 35% First midterm exam 45% Final exam Collaboration: Academic integrity will be taken seriously. You may collaborate on homework with other students, use solutions from last year, or get help from anyone but you are to state who you worked with or got help from, and give an estimate of contribution from other sources to what you submit. This is just acknowledgement of source of material, and recognition of the work contributed by others, it has no effect on your grade. Exceptions to this rule will be specified in the assignments. Tests and projects are to be entirely your own work. Intro-2 - DMZ - 11/3/2020

More Logistics Exams: Closed book. One handwritten (no photocopies) sheet (both sides) allowed on first exam, two sheets final exam. Homework: Usually due in class (2: 30 p. m. ) on assigned date. Instructor: David M. Zar Bryan 307 C GPS: N 38 38. 979' W 90 18. 360' Elevation: 550' Office Hours: by appointment. dzar@wustl. edu (best contact method) http: //www. cse. wustl. edu/~dzar http: //tinyurl. com/wucse 464 Attendance: Class attendance is important, material will covered in class that is not in text. You will wish to get copies of notes from classmate if you miss class. Intro-3 - DMZ - 11/3/2020

Discussion Topics n Class attendance n Class participation (please!) n Dally (Dally, not Daily) lecture notes n Textbook cost, errata, etc. n Homework length and style n EE 314: Engineering Electromagnetics 1: Fundamentals n Goal: Extremely practical backed up by theory and analysis Intro-4 - DMZ - 11/3/2020

Interesting Links and Sources – Links l http: //www. signalintegrity. com/ l http: //www. nesa. com/ l http: //www. sigrity. com/ l http: //www. ultracad. com/ (careful here) l http: //groups. yahoo. com/group/si-list (this is the signal integrity mailing list archive; lots here, good and bad) – Books – High-Speed Digital Design, A Handbook of Black Magic, Howard W. Johnson and Martin Graham, Prentice Hall, ISBN 0 -13 -395724 -1, 1993. – High-Speed Signal Propagation, Advanced Black Magic, Howard W. Johnson and Martin Graham, ISBN 0 -13 -084408 -X, 2003 – Brooks, Bogatin, Ritchey, Granberg, . . . – Transmission Lines with Pulse Excitation, Georges Metzger and Jean. Paul Vabre, Academic Press, New York, NY, 1969. (Bergeron Diagrams) Intro-5 - DMZ - 11/3/2020

Today’s Assignment n Reading » Complete before Wednesday, Jan 24 class – Preface, Chapter 1 » Complete before Wednesday, Jan 26 class – Chapter 2 » Complete before Monday, Jan 31 class – Chapter 3, Sections 3. 1 through 3. 3. 3 Intro-6 - DMZ - 11/3/2020

Digital Systems Engineering n From Dally » noise management – keeping signals clean » signaling – moving bits from here to there » timing – how we know when a new bit is here » power distribution – DC voltage with AC current Rules of Thumb (e. g. : C/inch, L/inch) Analytical/Calculation Simulation (HSPICE) Measurement Tools (don’t be a “tool driver”): Intro-7 - DMZ - 11/3/2020 » Signal integrity – High-Speed signals – low speed signals – reset – … – All Signals » Signaling (electrical representation of signals) » Timing/Clocking » Power distribution » Cooling/Packaging as part of above

Wires n Advanced components: Wires n Care and feeding of wires n Wires can be expensive, even if it’s a scam » http: //www. monstercable. com » http: //www. jpslabs. com/aluminata. shtml (they claim “Pricing - If you have to ask. ”) – "The shear mass of the particle shield alone proves that JPS has the transfer of noise taken care of- Nothing gets through this cable's shield and into the conductors beneath- NOTHING. . . “ » The truth about Monster Cables Intro-8 - DMZ - 11/3/2020

Why is Digital Systems Engineering/Design Harder Now Than Previously? n n Wires are not ideal (never were, but valid approximation sometimes) !!! Gross Simplification here: Long wires or High-Speed Design (delay ~> 0. 1 Clock Period) » » » » n n n 1968 1 MHz; >40 ft 1978 10 Mhz; >4 ft 1988 100 Mhz; >5 inches 1998 1 GHz; >0. 5 inch 2008 10 GHz? ? ? >0. 05 inch 2018 ? ? ? Overall size of system? approximately constant Ad hoc methods that worked in the past now fail To paraphrase Roy Jewell, President of TMA: “The rules of physics don’t change for high-speed design, they are just more strictly enforced”. The fact that long wires are harder to deal with does not imply short ones are easy, nor that they can be ignored. The fact that high-speed signals are harder to deal with does not imply that slow ones are easy, nor that they can be ignored (e. g. Reset). EMI: Even harder, we will not deal with this in CSE 464. Intro-9 - DMZ - 11/3/2020

Outrageous Statements n Propagation delay to closer device is longer n Slower is better (and faster) n A capacitor is an inductor unless you want inductor » Converse for inductor (or resistor) n Short wire is worse than long one (e. g. probe) n Negative characteristic impedance? n Square corners on PC traces are bad? n Vias on PC traces are bad? n Resistor networks: Bad? n We could not use perfect logic (Midas touch)! n Tune your absurdity detector!!! Intro-10 - DMZ - 11/3/2020

Thoughts to Remember (Models) n. A model is an artifice to make you think you understand a problem better than you actually do. n All models are wrong, but some models are useful. n Make everything as simple as possible, but no simpler (A. Einstein). n In theory there is no difference between practice and theory, but in practice there is! n An approximate answer to the right question is worth a good deal more than the exact answer to an approximate problem. John Tukey (FFT Fame) n Models are a really dangerous (and necessary) tool n Example: ground, ideal ground, logic ground, safety ground, … Intro-11 - DMZ - 11/3/2020

Ground is Fiction n At low frequency and low accuracy ground is a convenient model n Be very careful n What is “ideal ground” (see si-list)? : “What you draw with chalk on a blackboard!” Intro-12 - DMZ - 11/3/2020

Bonus: Safety Ground Intro-13 - DMZ - 11/3/2020

What is Wrong Here? Intro-14 - DMZ - 11/3/2020

What is Wrong Here? Lots!!! Try to avoid surprises!!! What worked last time may not work this time! Intro-15 - DMZ - 11/3/2020

Surprises n Invalid Assumptions n Individual effects don’t add linearly n Consider effects one at a time, not the sum » Coupling from multiple sources (lines) » PS noise » Reflection noise » Component tolerances » Temperature » Process » PC board noise » Package noise » Connectors » Vias Intro-16 - DMZ - 11/3/2020

More Surprises n Multiple backward xtalk coupling, increased V n Unaccounted for parasitics » Inductance » Resistance » Capacitance » ESR, ESL n Nonlinearities » Series termination with Capacitance load » Driver resistance when switching (1/4 wave) Intro-17 - DMZ - 11/3/2020

Still More n Transmission line n Manufacturer data sheets n Stubs n Split load and standing wave n Layout rules/communication/slip-up n Tolerances n T-line traces, return currents n R and C functions of frequency Intro-18 - DMZ - 11/3/2020

Last of Surprises? n System cost Vs. Design time Vs. Manufacturing time Vs. Reliability n Metastability Intro-19 - DMZ - 11/3/2020

Digital Systems Engineering n Designing systems that work by design, not by trial and error, with reasonable cost (dollars, time, effort, …). Using appropriate tools (analysis, simulation, measurement) to insure correct operation. Avoiding surprises. n Question: which is better? » Guess/Estimate? » Analysis (e. g. equations and calculation)? » Simulation (e. g. HSPICE)? » Measurement (e. g. oscilloscope, TDR)? Intro-20 - DMZ - 11/3/2020