This video from DesignCon 2022 shows a proof-of-concept for an on-package, or near-package, direct-drive electrical channel that can support 100 G + signaling.
These drives could be used in mid-board optical and copper designs using Samtec Flyover® cable assemblies or mezzanine connector sets, or for full-channel front-panel and back-panel cable applications.
Samtec’s Kevin Burt walks us through the demo, the results, and a brief discussion of the benefits.
What’s Going On
On board #1, an Alphawave IP SERDES generates 56 Gbps NRZ signals, which travel through approximately 10” of trace in a PCB made of Isola I-Tera MT40. The signals travel to a Samtec Bulls Eye® BE70A test point system, through 6” of low-loss coax cable, to another Bulls Eye connector on board #2. This second board is made of Tachyon 100G.
The signals then travel through another 1” of PCB trace, to a Macom 4 X 112 Gbps bi-directional driver and TIA.
After the standard MTP connector, the optical path consists of 25 meters of OM4 fiber, with an optical loopback. The overall optical signal path is 50 meters long. After returning by the same path, the signal is analyzed at the SERDES receiver.
Looking at the performance, on the left we see error-free bit error rate (BER) performance. On the right we see a wide-open eye, demonstrating plenty of margin.
Benefits of Linear Direct Drive
There are many benefits to a linear direct drive:
First, eliminating retimers significantly reduces costs. A typical 32 QSFP-DD port Ethernet switch containing 256 lanes could see a cost savings of up to $20,000.
Also, optical transceiver module DSPs are no longer necessary, which can reduce transceiver module costs by up to 50%.
There are also the benefits of reduced power and heat. Next-gen 112 G active optical transceiver modules will consume 20 to 25 watts of power. Removing the DSP and supporting hardware could reduce the power required by 60% per module.
And obviously, the reduction in heat provides improved reliability.
If you want to learn more about this Linear Direct Drive approach contact the Samtec Signal Integrity Group at SIG@samtec.com.
The signal integrity group can assist you with full system SI optimization, signal integrity testing, simulation and analysis, PDN / thermal modeling, simulation and testing, and power architecture, system design and routing.