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30/10/2026 by Kvaser

Why CAN FD needs SIC – and how Kvaser interfaces address signal integrity challenges

CAN FD gives applications more bandwidth while retaining CAN’s familiar communication model. It carries more data per frame and can use a higher bit rate during the data phase.

That extra performance places greater demands on the physical network. Shorter bit times leave signals less time to settle before a receiver samples them. As networks become longer or more complex, signal integrity can become a limiting factor.

During 2026, we upgraded Kvaser Leaf v3 and Kvaser U100* with Signal Improvement Capability, or SIC, transceivers. These transceivers reduce ringing and increase timing margin on demanding CAN FD networks.

Why are SIC transceivers necessary?

Cables, connectors, stubs, and branches can reflect signals along the CAN bus. As the signal changes from a dominant to a recessive state, the reflections can cause ringing.

At lower bit rates, the ringing may settle before the sample point. During the faster CAN FD data phase, it can:

  • Delay the detection of a recessive bit.
  • Cause repeated receiver-threshold crossings.
  • Reduce the stable sampling window.
  • Contribute to error frames and retransmissions.

A SIC transceiver actively reduces this ringing. The signal settles faster, giving receivers more time to sample the correct value.

Not every CAN FD network requires SIC. A short, linear, correctly terminated network may work reliably with conventional transceivers. SIC becomes valuable when higher bit rates combine with long stubs, multiple connectors, branched layouts, or wiring that cannot easily be changed.

Where do SIC-enabled Kvaser interfaces help?

When a CAN interface transmits, it becomes part of the physical network. Current versions of Kvaser Leaf v3 and Kvaser U100 reduce ringing in their own transmissions. As a result, using the interfaces for testing and diagnostics is less likely to add ringing that could affect the network’s signal integrity.

Developing and validating networks

Raising the CAN FD data-phase bit rate can expose reflections that cause no problems at lower speeds. Kvaser Leaf v3 provides a compact way to send and receive test traffic while minimizing the interface’s contribution to network ringing.

Testing complex network layouts

Long stubs, multiple connectors, and branches can limit reliable CAN FD communication. The SIC transceivers in Kvaser Leaf v3 and Kvaser U100 reduce reflection-related ringing and give receiving nodes more time to sample each bit.

Troubleshooting installed systems

Installed networks often have longer cables and more connections. Kvaser U100 combines SIC-enabled CAN FD communication with a rugged design. Kvaser Leaf v3 provides the same SIC benefit in a compact format for portable service work.

What SIC does – and does not – solve

SIC improves only the signal sent by the SIC-equipped transmitter. It cannot reshape frames sent by another node with a conventional transceiver. SIC also cannot compensate for incorrect termination, unsuitable cable, excessive stub lengths, grounding problems, or incorrect CAN FD bit timing.

Within a correctly designed network, Kvaser Leaf v3 and Kvaser U100 address one specific interface-side challenge: ringing in the frames they transmit. The result is cleaner transitions, a wider table sampling window, and more CAN FD timing margin.

Learn more about CAN SIC

For a deeper look at CAN FD reflections, ringing, and signal improvement, read our technical white paper on CAN SIC.

To put SIC into practice, explore Kvaser Leaf v3 and Kvaser U100, or contact our sales team to discuss your CAN FD application.

*All Kvaser Leaf v3 units and most Kvaser U100 units now include SIC transceivers. If you want to ensure that the unit you purchase has a SIC transceiver, please contact us.

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