GPU Chip and Board Simulation

Model

In this example a graphics card is simulated with the main focus on the 76 pin GPU processing chip and digital PCB lines. The board is imported into SEMCAD X as CAD data, while the actual digital layout is imported from the Gerber file data. The GPU chip is modeled as a PEC ground plane, connecting the 76 pins with load resistors. The whole chip is embedded in a lossy dielectric housing.

Simulation

8 different excitation ports are modeled to excite different digital lines and to drive certain pins into the high state and  interline cross coupling effects are investigated. A very high grid resolution is used to resolve the detailed digital lines and the chip pins. The resulting grid has 14 MCells with a minimum step of 65 um.

Results

Broadband simulations shows that the cross coupling may be a problem between certain ports at certain frequencies, e.g., S85 shows that at 5 GHz the coupling between ports 5 and 8 is significant. This is also clearly illustrated by the field distributions, where very high fields occur on the line of port 8, when port 5 is excited.