How to Request S-Parameters for High-Speed Board-to-Board Connectors

📅 March 31, 2026 | 📂 High-Speed Connector | 👤 Richmon

When working with high-speed board-to-board connectors, getting the right S-parameter data is essential for signal integrity analysis. Whether you are a procurement manager or project engineer, knowing what to ask for can save time and avoid costly design issues.

S-parameters, or scattering parameters, describe how electrical signals behave in a connector. They help engineers predict signal loss, reflection, and crosstalk. This guide explains what you need to request and how to use the data effectively.

What Are S-Parameters and Why They Matter

S-parameters are a standard way to describe the electrical behavior of high-frequency components. For connectors, they show how signals pass through or reflect back at different frequencies.

For board-to-board connectors used in high-speed applications, S-parameter data is critical for:

• Simulating signal integrity in PCB design
• Understanding insertion loss across frequency ranges
• Predicting return loss and impedance matching issues
• Evaluating crosstalk between adjacent signal paths

Without accurate S-parameter models, engineers may face signal integrity problems during prototype testing. This can lead to design changes, delayed projects, and increased costs.

Key S-Parameter Data to Request

When requesting connector specifications, you should ask for specific S-parameter data. Not all manufacturers provide the same level of detail, so being clear about your needs is important.

Essential Parameters

The most important S-parameters for connector evaluation include:

Parameter	Description	What It Tells You
S11	Return loss (input reflection)	How much signal reflects back at the input port
S21	Insertion loss (forward transmission)	How much signal passes through the connector
S12	Reverse transmission	Signal transmission from output to input
S22	Output reflection	How much signal reflects at the output port

Data Format Requirements

S-parameter files come in different formats. The most common formats include:

• Touchstone (.sNp) files: Industry standard format, compatible with most simulation tools
• S-Parameter files: Can include single-ended or mixed-mode data
• SPICE models: Some suppliers provide circuit models for simulation

Ask for Touchstone format files, as they are widely supported by simulation software like Ansys HFSS, Cadence Sigrity, and Keysight ADS.

How to Make Your Request Clear

To get the right S-parameter data from your connector supplier, prepare a clear request. This helps avoid back-and-forth communication and ensures you receive usable data.

Information to Include in Your Request

Category	Details to Specify
Connector Part Number	Complete part number including pitch, pin count, and height
Operating Frequency	Maximum frequency range needed (e.g., up to 25 GHz)
Signal Configuration	Single-ended or differential pair requirements
Data Format	Touchstone .s4p format preferred
Test Conditions	Temperature range, mounting conditions if relevant

Being specific about your application helps suppliers provide the most relevant data. For example, if you are designing a 25 Gbps backplane system, mention the data rate and protocol.

Understanding the S-Parameter Data You Receive

Once you receive the S-parameter files, you need to interpret them correctly. Here are key points to check:

Insertion Loss (S21)

Insertion loss shows how much signal power is lost as it passes through the connector. Lower values are better. For high-speed connectors, insertion loss should typically be below 1 dB at your operating frequency.

A good insertion loss curve should be relatively flat across the frequency range. Sudden drops or peaks may indicate resonance issues.

Return Loss (S11)

Return loss indicates how much signal reflects back from the connector. Higher negative values are better. A return loss of -10 dB or better (more negative) is generally acceptable for most applications.

Poor return loss can cause signal integrity issues and affect overall system performance.

Working With Differential Pairs

Many high-speed applications use differential signaling. For these designs, you need mixed-mode S-parameters that show both differential and common-mode behavior.

What to Request for Differential Applications

Parameter	Purpose
SDD21	Differential insertion loss
SCC21	Common-mode transmission
SCD21	Differential to common-mode conversion
SDC21	Common-mode to differential conversion

Mixed-mode S-parameters help you understand how well the connector maintains signal balance and rejects common-mode noise.

Tips for Successful S-Parameter Requests

Follow these best practices when requesting connector characterization data:

1. Ask early: Request S-parameter data during the connector selection phase, not after design completion.
2. Be specific: Clearly state your frequency range, data rate, and signal configuration needs.
3. Verify compatibility: Confirm the file format works with your simulation tools.
4. Check test conditions: Understand how the data was measured and under what conditions.
5. Request application support: Some suppliers offer technical support for simulation setup.

Having accurate S-parameter data early in your design process helps avoid signal integrity surprises and reduces development time.

Conclusion

Requesting S-parameters for high-speed board-to-board connectors requires clear communication with your supplier. By understanding what parameters to request and what format works best for your tools, you can ensure successful signal integrity analysis.

Always specify your application requirements clearly, verify the data format compatibility, and review the received parameters for your frequency range of interest. This approach helps you make informed connector selection decisions and supports reliable high-speed designs.

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