Altera Stratix IV GX Manual page 16

1–12
■ Placing the capacitors closer to the FPGA from an electrical standpoint.
■ Minimizing via perforations in the power/ground sandwich in the current path
from the decoupling caps to the FPGA device.
Due to layout and design constraints, the PDN design may not be optimal. In this
case, you can choose either a Medium or High value of spreading R and L. You also
have the option of changing the default values or using the Custom field listed in the
library specific to the design.
Dielectric Material Library
The dielectric materials section lists the dielectric constant values for the various
commonly used dielectric materials. These values are used in the plane capacitance
calculations listed under the Plane Cap tab. You can change the values listed in this
section.
If you change the default values listed in the various sections in the Library tab, you
can save the changes by clicking Save Custom. You can restore the default library by
clicking Restore Default located at the top right-hand corner of the Library page. You
can also restore the saved custom library by clicking Restore Custom.
Power Delivery Network (PDN) Tool for Stratix IV Devices User Guide
Chapter 1: Power Delivery Network (PDN) Tool User Guide for Stratix IV Devices
Major Tabs of the PDN Tool
© March 2009 Altera Corporation