DSP-Based Optical Transceivers

Overview

DSP-Based Optical Transceivers (also called fully retimed transceivers) use an on-board digital signal processor (DSP) for full equalization on both the transmit and receive paths. This architecture provides robust signal integrity, mature diagnostics, strong monitoring features, and proven multi-vendor interoperability — making DSP the currently dominant pluggable optics technology in production AI data centers. The tradeoff is higher power consumption and latency versus linear alternatives (LPO and LRO).

Power consumption: at 800G DR8, DSP transceivers measure 13.0 W (16.3 pJ/bit); at 1.6T 2xDR4, 21.0 W (13.1 pJ/bit). For a 51.2T switch, optical modules as a whole consume approximately 49% of total switch power, making DSP-heavy transceivers a major contributor to AI cluster energy budgets. A 400,000 GB300 GPU cluster using DSP transceivers requires 492 MW total, compared to 434 MW with CPO (-10%) and 480 MW with LPO (-2%).