### Autor Tema: Reglas de oro para mantener la integridad de la señal  (Leído 5193 veces)

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#### Carlos

•    • Mensajes: 294 ##### Reglas de oro para mantener la integridad de la señal
« 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.

Rule 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
Here is the first rule of thumb and first challenge.

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
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
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
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
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
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
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
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?
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?
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?
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
Learn how to quickly calculate the resistance of power planes.

Rule of Thumb #14: Resistance of a copper trace
Quickly calculate copper trace resistance.

Rule of Thumb #15: Estimating wire & loop inductance
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
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
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?
Identify the maximum stub length a high-speed data trace will tolerate.

Rule of Thumb #19: Crosstalk: How much is too much?
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
Learn the PCB rule of thumb for trace spacing versus crosstalk.

Rule of Thumb #21: How to engineer acceptable far-end crosstalk
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?
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
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
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?
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?
The relation between ringing period and line length is derived.

Un saludo.
« Última modificación: 27/Ago/2015, 17:44:09 pm por Carlos »

#### Carlos

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