Low-skew twinax cable for 224 Gbps PAM4 applications

Samtec has recently expanded its Eye Speed cable family to include the Eye Speed Hyper Low Skew Twinax cable, specifically designed for 224 Gbps PAM4 applications. Currently, 32 AWG twinax cables are available for inside-the-box use, with 27 AWG cables in development for longer-reach cabled backplane systems.

Skew, which refers to delay differences within a differential pair, is a critical design consideration for high-speed applications like 224 Gbps PAM4. The development of Eye Speed cable is the result of extensive research and development focused on understanding and mitigating skew issues.

The Eye Speed cable family features tightly coupled, twinax cable co-extruded with drainless shield construction. This design ensures superior skew performance, stable impedance, and insertion loss, even under realistic bending conditions. Unlike other manufacturing techniques for twinax cables, the co-extruded construction of Eye Speed cables allows implementers to have complete control over skew.

Eye Speed Hyper Low Skew Twinax cable is specifically tailored for applications requiring optimal high-speed performance at 60+ GHz Nyquist frequencies. With a maximum intrapair skew of 1.75 ps/m and exceptional signal stability, this low-skew cable offers industry-leading digital differential pair transmission line performance.

The Eye Speed cable lineup includes four varieties: Twinax with 3.5 ps/meter maximum skew in 28-36 AWG sizes, Thinax which is 40% smaller in diameter than Eye Speed Twinax in 34 AWG, Hyper Low Skew Twinax providing 1.75 ps/meter maximum skew in 32 AWG size (with 27 AWG in development), and ThinSE, a thin micro-coax cable with a 0.024-inch outer diameter.

As part of the Sudden Service® initiative, Eye Speed cables offer a mix-and-match approach with popular connectors from Samtec. This flexibility allows designers to choose the connectors at each end of the cable assembly, catering to various system architectures such as mid-board to mid-board, near-chip/on-chip to front panel, or ASIC-adjacent to the backplane.