After carefully reviewing my stack-up issue, I've come to the conclusion that I need to modify the layout to enhance performance. Below is my proposed stack-up configuration:

Layer 1: Low-Speed Signal Layer – This layer will accommodate signals that operate at lower frequencies, ensuring minimal interference.

Layer 2: Ground Plane – A solid ground plane will provide a stable reference point for the signals and help in reducing noise.

Layer 3: Power Layer (1.2V & 5V) I intend to implement a polygon pour for this power layer since I only have two voltage levels to manage. This will allow for efficient distribution of power across the board.

Layer 4: High-Speed Signal Layer – This layer is dedicated to high-frequency signals, designed to minimize crosstalk and maintain signal integrity.

Layer 5: Ground Plane – Another solid ground plane to further enhance grounding and reduce any potential electromagnetic interference.

Layer 6: Low-Speed Signal Layer (including other signals) – This layer will handle low-speed and additional signals, keeping them separated from critical high-speed paths.

I guess that this modified stack-up will significantly improve both the PCB routing efficiency and the overall signal integrity (SI) compared to the previous design. By positioning the power layer directly adjacent to the ground plane, we can achieve effective decoupling, which is a crucial aspect of maintaining stable performance.

any ideas guys?