OFC 2023 saw the world premiere of Credo’s DOVE 800 family, teamed with a Samtec Flyover cable assembly, and a Samtec blockchain ISI board, both demonstrating outstanding performance at 112 Gbps PAM4. The DOVE 800 is a retimer, with eight lanes of 100 G to 100 G.
Ralph Page, Systems Architect at Samtec, walks us through the two signal paths.
In channel one, a BERT is generating eight lanes of 112 Gbps PAM4, PRBS 31-bit data, which travels through low-loss coax cable to a Samtec NovaRay® SI Evaluation Kit. The evaluation kit consists of two boards, connected by a 6” Samtec NovaRay high-speed cable assembly.
The signal then travels to the Dove 800 evaluation board, to Credo’s 800 G silicon, where it is retimed and then transmitted out of the silicon, where it loops back through 6” of low loss coax, back to Credo’s silicon, where its again processed before being re-transmitted back to the NovaRay cable, and back to the BERT.
The signal loss in the Credo board is 5.5 dB, of which 2 dB is through the package. The board and the coax are approximately 5 dB; this includes both RX and TX. Signal loss through the Samtec NovaRay assembly is mostly in the board, and it’s 10 dB.
The total signal loss is 20.5 dB, and the results are impressive: 112 Gbps PAM4 data is running virtually error-free, e-12 or better, Pre-FEC.
The signal path of channel two is similar to channel one. The BERT is generating two lanes of 112 Gbps PAM4, PRBS 31-bit data, which travels to a Samtec BE70A, a Bulls Eye® high-performance test assembly. The Bulls Eye is on an eight differential pair, variable insertion loss Samtec block chain board.
The signal travels through 10” of trace, to another Bulls Eye connector, to the Dove 800 evaluation board, to Credo’s 800 G silicon where it is retimed and then transmitted out of the silicon, and then it loops back to Credo’s silicon, where its again retimed and retransmitted back through the blockchain ISI board, and back to the BERT.
The total signal loss is 25.5 dB; 15 dB of this is in the trace on the blockchain board. The channel two results are strong: 112 Gbps PAM4 data is running virtually error-free, e-11 or better, Pre-FEC.
The Samtec NovaRay system has a unique BGA-style connector construction, two points of contact on each mated pin, dedicated differential pairs, and shields and grounding around each differential pair.
Bulls Eye is a compression mount test assembly with a small footprint and high cycle count.
If you have any questions about this demo, please contact us at SIG@samtec.com. For more information on the Credo Dove 800, contact Sales@CredoSemi.com.
Two recent demonstrations about 112 Gbps PAM4 that might interest you:
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