An Integrated Deep-Cryogenic Temperature Sensor in CMOS Technology for Quantum Computing Applications

On-chip thermometry at deep-cryogenic temperatures is vital in quantum computing applications to accurately quantify the effect of increased temperature on qubit performance. In this work, we present a sub-1 K temperature sensor in CMOS technology based on the temperature dependence of the critical current of a superconducting (SC) thin-film. The sensor is implemented in 22-nm fully depleted silicon on insulator technology and comprises a 6-nA-resolution current-output digital-to-analog converter (DAC), a transimpedance amplifier with a SC thin-film as a gain element, and a voltage comparator. The circuit dissipates 1.5 μW and is demonstrated operating at ambient temperatures as low as 15 mK, providing a variable temperature resolution reaching sub-10 mK.