The characterization of SiPMs required a variable-temperature fridge ranging from -40°C to room temperature. Conventional chillers would have resulted in high temperature variations on the order of a hundred mK. For this application, a Peltier-based cooling system proved to be ideal. If designed correctly, it could achieve mK-level temperature variations. However, the Peltier driver which is a current source needed to accomplish a few objectives to be useful for this task:
- The SiPMs are connected to a high bandwidth (kHz-200MHz) high gain amplifier. The Peltier given its closeness to the SiPM which is required to minimize the thermal load and thermal parasitics can introduce noise to the system.Therefore, the Peltier driver had to induce no electrical noise into the system.
- Drive up to 6A of current from voltages ranging from 1V-12V.
- Be highly power efficient.
- Can be controlled remotely and PID friendly.
The Peltier driver demonstrated in this project not only successfully fulfills all the previous required conditions, but also exhibits exceptional stability, with no malfunctions observed throughout the entire characterization process, which is now completed.
Final observed specifications:
- Tied with a PID, 20mK stability was achieved.
- Up to 6A current can be drawn from a 12V power supply from voltages ranging all the way down to 0.6V up to 12V.
- Low voltage ripple (~mV)
The design can be done better: higher current resolution for lower temperature stability. The ripple can be improved if there is more variation in the types of the output capacitors.
