Foro Tecno Recursos

Tecnología => Electricidad y Electrónica => Mensaje iniciado por: Carlos en 27/Ago/2015, 17:23:12 pm

Título: Reglas de oro para mantener la integridad de la señal
Publicado por: Carlos en 27/Ago/2015, 17:23:12 pm
He encontrado en EDN un conjunto de reglas de oro que sirven para simplificar los cálculos en el campo de la transmisión de señales.


Indice: Bogatin's Rules of Thumb. (http://www.edn.com/collections/4435129/Bogatin-s-Rules-of-Thumb)


Rule of Thumb #0: Using Rules of Thumb Wisely (http://www.edn.com/electronics-blogs/all-aboard-/4424571/Rules-of-Thumb--0--Using-Rules-of-Thumb-Wisely)
Eric Bogatin, Signal Integrity Evangelist, Teledyne LeCroy, embarks on a mission to spell out some common rules of thumb for electrical engineers in a new series of columns. This column kicks off the series by outlining Rules of Thumb “Do” and “Don’t” suggestions.

Rule of Thumb #1: Bandwidth of a signal from its rise time (http://www.edn.com/electronics-blogs/all-aboard-/4424573/Rule-of-Thumb--1--The-bandwidth-of-a-signal-from-its-rise-time)
Here is the first rule of thumb and first challenge.

Rule of Thumb #2: Signal bandwidth from clock frequency (http://www.edn.com/electronics-blogs/all-aboard-/4425691/Rule-of-Thumb--2--Signal-bandwidth-from-clock-frequency)
Here’s a quick way to determine the bandwidth of a signal when all you know is the clock frequency.

Rule of Thumb #3 Signal speed on an interconnect (http://www.edn.com/electronics-blogs/all-aboard-/4426188/Rule-of-Thumb--3-Signal-speed-on-an-interconnect)
Eric Bogatin, Signal Integrity Evangelist, Teledyne LeCroy, explains a rule of thumb that estimates the speed of a signal on an interconnect.

Rule of Thumb #4: Skin depth of copper (http://www.edn.com/electronics-blogs/all-aboard-/4426470/Rule-of-Thumb--4--Skin-depth-of-copper)
This rule of thumb estimates the effective current distribution in a conductor at high frequency.

Rule of Thumb #5: Capacitance per length of 50 Ohm transmission lines in FR4 (http://www.edn.com/design/pc-board/4427201/Rule-of-Thumb--5--Capacitance-per-length-of-50-Ohm-transmission-lines-in-FR4)
This rule of thumb estimates the capacitance per length of all 50 Ohm lines in FR4.

Rule of Thumb #6: Total loop inductance/length in 50 Ohm transmission lines (http://www.edn.com/electronics-blogs/all-aboard-/4428080/Total-loop-inductance-per-length-in-all-50-Ohm-transmission-lines-in-FR4--Rule-of-Thumb--6)
This rule of thumb estimates the loop inductance per length in all 50 Ohm transmission lines in FR4.

Rule of Thumb #7: Total inductance in the return path (http://www.edn.com/electronics-blogs/all-aboard-/4428560/Total-inductance-in-the-return-path--Rule-of-Thumb--7)
This rule of thumb estimates the total inductance in the return path of a flat, wide conductor.

Rule of Thumb #8: How to estimate ground bounce in a connector (http://www.edn.com/electronics-blogs/all-aboard-/4429476/How-to-estimate-ground-bounce-in-a-connector--Rule-of-Thumb--8)
This rule of thumb estimates the amount of ground bounce to expect in a connector or package lead.

Rule of Thumb #9: Loss in a channel (http://www.edn.com/electronics-blogs/all-aboard-/4429778/Loss-in-a-channel--Rule-of-Thumb--9)
This rule of thumb enables us to estimate the attenuation at the Nyquist for a lossy, uniform channel.

Rule of Thumb #10: How much attenuation is too much? (http://www.edn.com/electronics-blogs/all-aboard-/4429922/How-much-attenuation-is-too-much--Rule-of-Thumb--10)
This rule of thumb enables us to estimate how much attenuation is in the loss budget of a serial channel.

Rule of Thumb #11: What is the bandwidth of a high speed serial-link signal? (http://www.edn.com/electronics-blogs/all-aboard-/4430181/What-is-the-bandwidth-of-a-high-speed-serial-link-signal--Rule-of-Thumb--11)
This rule of thumb enables us to estimate the highest frequency to worry about for a data signal.

Rule of Thumb #12: How much return loss is too much? (http://www.edn.com/electronics-blogs/all-aboard-/4430355/How-much-return-loss-is-too-much--Rule-of-Thumb--12)
Return loss and S-parameters are mysterious, even to many practitioners. Learn how return loss equates to signal loss – S11 to S21 – and how much is too much.

Rule of Thumb #13: Sheet resistance of copper foil (http://www.edn.com/electronics-blogs/all-aboard-/4431390/Sheet-resistance-of-copper-foil--Rule-of-Thumb--13)
Learn how to quickly calculate the resistance of power planes.

Rule of Thumb #14: Resistance of a copper trace (http://www.edn.com/electronics-blogs/all-aboard-/4433438/Resistance-of-a-copper-trace--Rule-of-Thumb--14)
Quickly calculate copper trace resistance.

Rule of Thumb #15: Estimating wire & loop inductance (http://www.edn.com/electronics-blogs/all-aboard-/4434214/Estimating-wire---loop-inductance--Rule-of-Thumb--15)
Get a grasp of some inductance fundamentals, and look specifically at straight-wire and loop self-inductance.

Rule of Thumb #16: Sheet inductance of a cavity (http://www.edn.com/electronics-blogs/all-aboard-/4434907/Sheet-inductance-of-a-cavity--Rule-of-Thumb--16)
Separating power planes by as little as possible is ideal, but maybe not why you think it is.

Rule of Thumb #17: The quarter-wave stub frequency (http://www.edn.com/electronics-blogs/all-aboard-/4435610/The-quarter-wave-stub-frequency--Rule-of-Thumb--17)
High frequencies and bit-rates require point-to-point routing. Learn how to estimate the suckout caused by a via or stub, and therefore, what signals the line can handle.

Rule of Thumb #18: How long a stub is too long? (http://www.edn.com/electronics-blogs/all-aboard-/4436423/How-long-a-stub-is-too-long--Rule-of-Thumb--18)
Identify the maximum stub length a high-speed data trace will tolerate.

Rule of Thumb #19: Crosstalk: How much is too much? (http://www.edn.com/electronics-blogs/all-aboard-/4437642/Crosstalk--How-much-is-too-much--Rule-of-Thumb--19)
Minimizing NEXT between strong transmitters and weak Rx signals is critical to system performance.

Rule of Thumb #20: How far is far enough? Signal line spacing for acceptable near end crosstalk (http://www.edn.com/electronics-blogs/all-aboard-/4437717/How-far-is-far-enough--Signal-line-spacing-for-acceptable-near-end-crosstalk--Rule-of-Thumb--20)
Learn the PCB rule of thumb for trace spacing versus crosstalk.

Rule of Thumb #21: How to engineer acceptable far-end crosstalk (http://www.edn.com/electronics-blogs/all-aboard-/4437930/How-to-engineer-acceptable-far-end-crosstalk--Rule-of-Thumb--21)
Far-end crosstalk can often cause a product to fail. Unless you select the transmission line features carefully, FEXT will likely be an issue.

Rule of Thumb #22: What is the frequency of the S21 dip in microstrip? (http://www.edn.com/electronics-blogs/all-aboard-/4438222/What-is-the-frequency-of-the-S21-dip-in-microstrip--Rule-of-Thumb--22)
In every measurement of the single ended insertion loss of a microstrip differential pair, there is a sharp dip.

Rule of Thumb #23: When to worry about a capacitive discontinuity (http://www.edn.com/electronics-blogs/all-aboard-/4438435/When-to-worry-about-a-capacitive-discontinuity--Rule-of-Thumb--23)
Capacitive discontinuities will act as RC filters with the impedance of a line, introducing single-pole filters, decreasing the signal bandwidth, and increasing the rise time of a signal.

Rule of Thumb #24: When to worry about trace corners (http://www.edn.com/electronics-blogs/all-aboard-/4438573/When-to-worry-about-trace-corners--Rule-of-Thumb--24)
We all know never to use 90 degree corners in PCB traces. But is this really a concern?

Rule of Thumb #25: How much is impedance affected by an adjacent trace? (http://www.edn.com/electronics-blogs/all-aboard-/4438688/How-much-is-impedance-affected-by-an-adjacent-trace--Rule-of-Thumb--25)
Line spacing affects impedance as well as crosstalk. But by how much?

Rule of Thumb #26: What is the ringing period on an unterminated line? (http://www.edn.com/electronics-blogs/all-aboard-/4438918/What-is-the-ringing-period-on-an-unterminated-line--Rule-of-Thumb--26)
The relation between ringing period and line length is derived.

Un saludo.
Título: Re:Reglas de oro para mantener la integridad de la señal
Publicado por: Carlos en 28/Ago/2015, 10:41:09 am
Archivos en PDF