PCB High-Speed Signal Design Guidelines: Agilex™ 5 FPGAs and SoCs

ID 821801
Date 11/18/2024
Public
Document Table of Contents

3.7.1. ADM/F Connectors

Use ADM/F connectors to connect the SOM and carrier board, supporting signal data rates over 20 Gbps. Obtain a 3D model from the connector vendor and conduct a 3D simulation to optimize the breakout area according to your specific stack-up. Aim to reduce the return loss to lower than -15 dB at the Nyquist frequency (achieving lower than -20 dB is preferable) and keep the impedance variation of the cut-out area as minimal as possible (ideally within ±5 ohm). The following figure displays a 90 ohm L3 ADM connector breakout structure utilized on the SOM solely for simulation reference. For optimal performance, consider adopting a similar cut-out shape and adjust the size of the cut-out in your simulation structure based on your stack-up.

Figure 42. ADM Connector Cut-out Size for 90 Ω High Speed Traces Fan-out on L3