Connectors and Sockets Tackle High-Speed Serial Connections

<p><a href="https://sourceesb.com/teconnectivity/distributors-and-vendors" style="color:navy; text-decoration:none" target="_blank"><span style="color:#e67e22">TE Connectivity</span></a> thinks that putting optics closer to the chip via co-packaging will provide a more compact and efficient system. This example on display at DesignCon highlights how the technology would work. The optical transceiver electronics would connect directly to the die. The heatsink on top holds everything in place, much like the socket on the bottom that provides connections for other ports. This provides high-speed serial links with minimal distance from the chip to the transceivers, which simplifies PCB design since the higher-speed optical connections are going out the top of the chip. It’s still a work in progress, but it provides an interesting take on high-speed chip-to-chip connections.</p>

<p><a href="https://reflexphotonics.com/" style="color:navy; text-decoration:none" target="_blank"><span style="color:#e67e22">Reflex Photonics</span></a>’ LightVISION VM is an MPO-compatible rugged optical transceiver interface targeting the steadily expanding self-driving car applications, where machine learning and massive sensor suites have high bandwidth requirements.</p>

<p>The LightVISION VM is a screw-in, robust industrial and RoHS optical module. The system allows for a standard MPO cable to be plugged into the optical module that’s mounted on the faceplate of a box or line-card. The MPO connector is covered by an outside cover boot to minimize water and dust contamination. This system provides a standard MPO cable connection to a board-mounted optical engine in a compact footprint.</p>

<p>The transceivers use less than 100 mW per lane. It can handle up to a dozen bidirectional lanes providing 150 Gbit/s, with each lane running at 12.5 Gb/s.</p>

<p><a href="https://sourceesb.com/teconnectivity/distributors-and-vendors" style="color:navy; text-decoration:none" target="_blank"><span style="color:#e67e22">TE Connectivity's</span></a> thermal bridge demo at DesignCon cooled a Quad Small Form Factor Pluggable Double Density (QSFP-DD) connection. The compressible thermal bridge efficiently transfers heat across a gap of variable size while controlling the force applied to surrounding components. Most alternatives employ a thermal paste to handle movement between the heat source and sink.</p>

<p>The demo displays bridge and interface thermal resistances in real time, while allowing adjustment of the bridge height as heat is transferred between a pluggable module and heat sink. QSFP-DD connections are utilized in the data center, and that requires high-density switches to keep them cool.</p>

<p><a href="https://sourceesb.com/samtec/distributors-and-vendors" style="color:navy; text-decoration:none" target="_blank"><span style="color:#e67e22">Samtec's</span></a> Flyover Twinax cabling system has continued to improve. It can handle speeds from 10 to 112 Gb/s. One needs to trade off maximum distance for speed when using micro Twinax cabling, with 112 Gb/s being limited to a six-inch cable. Cut the bandwidth in half to 56 Gbit/s and double the distance.</p>

<p>Optical connections are available as well. The 10-Gb/s support handles cables over 100 m while 28-Gb/s systems top out at 100 m.</p>

<p>The twinax cable technology is co-extruded to eliminate performance limitations and inconsistencies that occur with individually extruded dielectric twinax cabling. Samtec's approach improves signal integrity, bandwidth, and distance needed for the latest crop of high-performance system architectures.</p>

<p><a href="https://sourceesb.com/molex/distributors-and-vendors" style="color:navy; text-decoration:none" target="_blank"><span style="color:#e67e22">Molex</span></a> and <a href="http://www.credosemi.com/" style="color:navy; text-decoration:none" target="_blank"><span style="color:#e67e22">Credo Semiconductor</span></a> were demonstrating 112-Gb/s connectivity using Molex's Impulse Orthogonal Direct (OD) Backplane Connector System and Credo's PAM4 single-lane SerDes. The Molex Impulse OD connectors are designed to handle 56-Gb/s NRZ and 112-Gb/s PAM 4 signals. The direct orthogonal connectors eliminate the need for mid-plane connections. This can improve airflow because of the connector’s open structure.</p>

<p><a href="https://sourceesb.com/amphenolacd/distributors-and-vendors" style="color:navy; text-decoration:none" target="_blank">Amphenol's</a> OverPass utilizes the company’s LinkOver technology to provide a range of options for high-speed, low-loss connections targeting mezzanine applications. LinkOver supports direct-to-PCB compression mount options, eliminating the need for lossy paddle cards. Solutions are available with screw-down or surface-mount-technology (SMT) connections. Application areas include 100/200/400G PCI Express, Infiniband, 5G, and chip-to-chip links. As with most cabling solutions, OverPass allows high-speed signals to bypass the PCB, simplifying PCB design while providing high-speed connections.</p>

<p>CPUs are massive these days, as are their connectors, due to the number of signals needed to interface with the outside world. One might think that other sockets devices would be smaller and easier to contend with—unless one looks at the networking world where switches are often implemented in a single massive chip.</p>

<p>This is done to keep as much of the high-speed communication on-chip, but it does have a downside. <a href="https://sourceesb.com/teconnectivity/distributors-and-vendors" style="color:navy; text-decoration:none" target="_blank"><span style="color:#e67e22">TE Connectivity</span></a> is targeting its new socket technology specifically at this space, making it possible to do upgrades. The XLA 56G PAM4 socket is designed to handle chips, like the one shown above, that are over 100 mm on a side. The socket uses a PCB substrate instead of a plastic molded housing for a more reliable and flexible attachment of such a large number of connections. It’s designed to handle 56-Gb/s PAM4 signals.</p>