Backward And Forward Coupling Coefficient Calculation; Figure 5. Backward Coupling Coefficient; Table 3. Stackup Details - Intel Quark SE Series Platform Manual

System Assumptions
Table 3. Stackup Details
2.2

Backward and Forward Coupling Coefficient Calculation

Some designs require a stackup build that is outside of the ranges provided. In this
case, compare the routing electrical characteristics to the Intel recommendation. It
is important to compare the single-ended and differential impedances. However,
crosstalk level, which is governed by trace spacing, is not implied by the impedance
target. In cases where the selected stackup varies from the Intel recommendation,
we recommend calculating and comparing the backward coupling coefficient to
choose proper trace spacing. The coupling coefficient represents the source voltage
percentage that is coupled to victim lines. As shown in
backward coupling coefficient. For backward (near-end) crosstalk, inductive and
capacitive coupling are of the same polarity and the noise magnitude is not a
function of trace length. The backward coupling coefficient (Kb) values can be used
to determine trace spacing. For forward (far-end) crosstalk, Kf inductive and
capacitive coupling are of opposite polarity, and the crosstalk magnitude (Vfe) is
proportional to both trace length and edge rate.
Kf is typically a very small value in most practical designs. Therefore, we have not
included the Kf values in the design guide. However, if the value is desired, the
equation for calculating Kf is provided in

Figure 5. Backward Coupling Coefficient

June 2017
Document Number: 334715-004EN
Figure 5, Kb is defined as the
Figure 6.
Intel® Quark™ SE Microcontroller C1000
Platform Design Guide
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