AN 555: True Differential Signaling Termination and Biasing for Intel Agilex® 7 M-Series and Intel Agilex® 5 FPGAs

Download PDF
ID 776775
Date 5/19/2023
Public
Document Table of Contents
Document Table of Contents x
True Differential Signaling Termination and Biasing for Intel Agilex® 7 M-Series and Intel Agilex® 5 FPGAs
True Differential Signaling Termination and Biasing for Intel Agilex® 7 M-Series and Intel Agilex® 5 FPGAs x
AC Coupling and DC Coupling TDS I/O On-Chip Termination TDS I/O External Termination Termination and Biasing Schemes for TDS Transmitters and Receivers Simulation: Intel Agilex® 7 M-Series FPGA as TDS Receiver Simulation: Intel Agilex® 7 M-Series FPGA as TDS Transmitter Summary Document Revision History for AN 555: True Differential Signaling Termination and Biasing for Intel Agilex® 7 M-Series and Intel Agilex® 5 FPGAs
AC Coupling and DC Coupling x
Capacitors and Components Selection
Termination and Biasing Schemes for TDS Transmitters and Receivers x
Schematic Topology for Transmitter and Receiver Buffers Recommended Topologies for TDS, LVDS, RSDS, Mini-LVDS, and LVPECL
Simulation: Intel Agilex® 7 M-Series FPGA as TDS Receiver x
Simulation Results
Simulation: Intel Agilex® 7 M-Series FPGA as TDS Transmitter x
Simulation Results
True Differential Signaling Termination and Biasing for Intel Agilex® 7 M-Series and Intel Agilex® 5 FPGAs

Capacitors and Components Selection

When selecting the coupling capacitor, consider the capacitor size:

  • Capacitor too big—the capacitor slows down the signal and responds poorly to fast-changing input signals because of its long charge and discharge times.
  • Capacitor too small—the capacitor adds impedance and increases attenuation, changing the characteristic impedance of the path.

When selecting components:

  • Use the smallest size possible. Smaller components have smaller pads, reducing the discontinuity. Intel recommends that you use 0402 components (40×20 mils).
  • Use precision resistors (≤1% tolerance) for differential signals so that the restored DC levels on the positive and negative signals matches very closely.
Level Two Title