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3h rule

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  • 3h rule

    hello every one . in my stackup the h1(distance between signal layer and upper ground) is 3.2 mil and h2(distance between signal layer and downer ground) is 4.2 . if i want to use 3h rule for minimize crosstalk i should use 3h1 or 3h2?

  • #2
    Your stripline configuration is more or less symmetric. Both planes will act as return planes. Normally you would take the lesser among h1 and h2.

    How wide are your traces ? Normally for 50 ohm configuration:

    (a) if edge to edge spacing (s) = trace width (w), we call it tightly coupled
    (b) if s = 2w, we call it loosely coupled
    (c) if s = 3w or more, we call it uncoupled

    PS. Look at Dr. Eric Bogatin's "Signal integrity and power integrity simplified" for more information.


    • #3
      nearest reference plane:

      "It is called the 3H rule. You may already be familiar with an implementation of this rule. 3H stands for three times the dielectric thickness or Height in the Z-axis from the signal layer to the nearest reference ground plane."
      “Circle the wagons.” We can find wisdom in these Pilgrim words. The majority of multi-layer printed circuit boards feature at least one, and often a few or several layers that are a ground pour....