A 256Gbps Microring-Based WDM Transceiver with Error-Free Wide Temperature Operation for Co-Packaged Optical I/O Chiplets

We present a 256Gbps WDM transceiver macro for use in co-packaged AI scale-out interconnects. The macro adopts a $8\lambda\times 32\text{Gbps}$ configuration to achieve 256Gbps per fiber. The transceiver macro operates error-free across a dynamic temperature ramp of 50-110°C, has >4dB optical link margin with $4\text{dBm}/\lambda$ input laser power, and consumes 3.45pJ/b ($\text{TX}+\text{RX}$). All transmit, receive, thermal control, and optical components are monolithically integrated in a 45nm SOI process. An optical I/O chiplet with 8 WDM transceiver macros achieves <10⁻¹⁵ BER without FEC across 90 hours of operation in a 4Tbps duplex link configuration.