Co-packaged optics (CPO) is a new technology that provides a cost and power advantage over using DSP based pluggable optical modules in large data center and AI applications. Silicon photonic PICs are placed close to the switch IC such that the interface from the switch module to the front panel and beyond is fully optical. For thermal management and maintenance reasons, the CW laser sources are kept separate in ELSFP pluggable modules as defined by the OIF. Sixteen ELSFP modules, each with eight lasers, are used to support the latest 51.2T CPO switches. Each laser supports a high output power to enable splitting of the light into multiple channels within the PIC. Efficient biassing is hence critical.
The PI12030 is a high-efficiency, high-current, 4-channel current DAC (IDAC) ideally suited to use within ELSFP and similar applications as high power CW Laser driver. It is unique in that it can deliver high laser bias currents with over 91% efficiency directly from the 3.3V module supply. The total solution, including all external components, is designed to fit within the ELSFP’s form-factor, thermal constraints, and electrical requirements.
The PI12030 is highly integration with all setup and monitoring through SPI or I2C. An internal ADC monitors a wide range of internal and external information and the results, compared to programmable thresholds, can generate alarms and warnings. Fast shutdown is also provided. Transimpedance amplifiers (TIAs) are included which can be used to maintain the laser bias loop at constant optical power.
Features
• Four High-efficiency IDACs
– 1.25A maximum output current per channel
– Low Noise generation and High Noise Rejection
• 20nA/sqrt(Hz) rms output noise density at 10kHz
• <200 uVpp noise generation at 2MHz
• >60B ACPSRR from 100kHz to 4MHz
– > 91% total efficiency from the voltage supply input to each load
• Internal 15ppm/°C Voltage Reference.
• Overtemperature protection.
• Digital Diagnostic reporting of all parameters for each channel
– laser bias current, laser voltage, supply voltage, laser power (if MPD is connected), external temperature sensor, internal die temperature
– Alarm/Warning level comparators
• Flexible Slave Interface.
– Both SPI and I2C interface supported.
– Digital inputs support ELSFP, OSFP, QSFP-DD timing for Low Power Mode and Fast Disable
– Digital outputs support Fault and Warning interrupts to the MCU
• Small Solution Size for a given efficiency target
– < 6.6 x 10.5 mm total PCB implementation size for > 90% efficiency and ultra-low-noise output.
– 3.21 mm x 5.375mm WLCSP.