Chip-package co-design of power distribution network for system-in-package applications

A new figure of merit for chip-package co-design of a power distribution network (PDN) is needed, not merely a voltage difference between power and ground at each hierarchy. In order to measure power supply noise as it is actually seen by the circuits in various locations on a chip, we need to chase the power/ground voltage with reference to a system ground. A PDN has two current paths; a series path and a shunt path. While the shunt path determines the voltage difference, the series path controls the power/ground voltage itself. Therefore, a balnaced approach is strongly required rather than an excessive attention to the shunt path.