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http://www.union-ic.com

Rev.03 Apr.2012

5/7

UM8411/8411Z

Figure 3 shows the recommended device layout. The ground pad vias have a diameter of 0.008

inches (0.20 mm) while the two external vias have a diameter of 0.010 inches (0.250mm). The

internal vias are spaced approximately evenly from the center of the pad. The designer may

choose to use more vias with a smaller diameter (such as 0.005 inches or 0.125mm) since

changing the diameter of the via will result in little change in inductance (i.e. the log function in

Equation 2 in highly insensitive to parameter d) .

Figure 3 – Recommended Layout Using Ground Vias