Crosstalk Associated with the Mingling of Current Returned Paths through the Vertical Bonding Structures

This paper shows the problem-solving case of on-die crosstalk associated with magnetic coupling through the vertical c4-bumps. Designing a high-speed serializer transmitter (TX) over 50 ohm system requires large current consumption. This naturally calls for careful consideration of signal and power integrity since transceiver also use large inductors in the low noise LC PLL circuits in close proximity to the TX. The 3D-electromagnetic (3D-EM) solver shows it is often necessary to include the package and the nearby grounding bumps, the main reason is that the return current path of this current hungry circuitry can permeate in a large area through multiple routes existing in both planar (like layout) or 3D (like package's c4-bumps or extra silicon layers) structure.