JAJS707E January 2001 – January 2018 DS92LV040A
PRODUCTION DATA.
Following the choice of dielectrics and design specifications, you must decide how many levels to use in the stack. To reduce the TTL/CMOS to multipoint LVDS crosstalk, it is a good practice to have at least two separate signal planes as shown in Figure 14.
NOTE
The separation between layers 2 and 3 should be 127 μm (0.005 in). By keeping the power and ground planes tightly coupled, the increased capacitance acts as a bypass for transients.
One of the most common stack configurations is the six-layer board, as shown in Figure 15.
In this particular configuration, it is possible to isolate each signal layer from the power plane by at least one ground plane. The result is improved signal integrity; however, fabrication is more expensive. Using the 6-layer board is preferable, because it offers the layout designer more flexibility in varying the distance between signal layers and referenced planes, in addition to ensuring reference to a ground plane for signal layers 1 and 6.