Specifications
Product
Broadcom Sian3 BCM83628 optical DSP
Function
1.6T retiming and signal-conditioning DSP for pluggable optics
Process Node
3 nm
Aggregate Throughput
1.6 Tb/s
Lane Configuration
8 × 200 Gb/s PAM4
Signal Conditioning
Advanced PAM4 equalisation, host and line side
Bit Error Ratio
Ultra-low BER — enables links without extra optical-side FEC
Host Interface
8 × 200G electrical (OSFP224 cage)
Line Interface
8 × 200G optical drive
Module Types
OSFP224 1.6T DR8, 2xDR4, 2xFR4
Platform Pairing
NVIDIA Quantum-X800; 51.2T and 102.4T switch ASIC fan-outs
Management
CMIS-based module management and diagnostics
Why It Matters
Determines whether a 1.6T module needs extra FEC, and therefore latency and power
Power Class
Module power set by the DSP plus optical engine; LPO variants remove the DSP entirely
Ecosystem
Used across multiple third-party OSFP224 module vendors
Related Silicon
Broadcom Tomahawk switch family for the same fabric generation
Application
AI data center scale-out optical interconnect
Availability
In production in shipping 1.6T modules
Overview
The Broadcom Sian3 BCM83628 is the DSP inside most of the third-party OSFP224 1.6T modules now shipping for AI fabrics. It is the component that decides how much margin a 1.6T link has: a 3 nm eight-lane 200G PAM4 retimer with enough equalisation headroom to close the link without adding a second FEC stage on the optical side.
That matters commercially as much as technically. When a module needs no optical-side FEC, the fabric can run at lower latency and lower module power for the same reach — which is why Sian3-based DR8 parts are the default for 500 m pod cabling, and why the LPO alternative (no DSP at all) is only attractive where host-side equalisation can carry the link.
Practically, Sian3 is a selection marker rather than a stocked part for most buyers: it tells you which third-party OSFP224 modules are drop-in equivalents of the NVIDIA first-party PNs. QS Compute supplies both the NVIDIA MMS4A00 / MMS4A50 modules and the Sian3-based compatible portfolio, so the choice of DSP does not constrain the sourcing decision.
Key Benefits
3 nm efficiency keeps 1.6T module power inside cage budgets. Eight 200G PAM4 lanes with strong equalisation close 500 m and 2 km links without extra FEC, saving latency. Widely deployed, so spares and second sources are available across multiple module vendors rather than single-sourced.
Applications
1.6T OSFP224 module design and selection for AI fabrics; 500 m pod interconnect on DR8; 2 km structured-cable reach on FR4; and any 102.4T-switch fan-out that needs 200G-per-lane optical links.
Request a Quote — BROADCOM SIAN3 BCM83628 — 3 NM 1.6T OPTICAL DSP FOR OSFP224 MODULES
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