A CMOS Bandgap Temperature Sensor for Cryogenic Applications

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Cryogenic temperature sensors are finding broadened applications. Such applications include: Cryosurgery [1.3], quantum computing, deep-space probes and planetary missions, satellite communications systems and space-based radar, ultra-high-speed/high sensitivity instrumentation systems, medical electronics (e.g. CT scanner), superconductor-semiconductor hybrids [1.4], very low-noise receivers (radio astronomy), cooled IR detector arrays etc [1.4]. Temperature sensors that operate at cryogenic temperatures are commercially available. Such sensors include: Platinum resistance sensors, diodes, thermocouples et.c. These sensors can achieve high accuracy (better than 0.1 K) but at the cost of expensive calibration. The analog nature of these sensors, mean they are prone to interference, which can considerably perturb the measuring result. Those disadvantages can be overcome by CMOS integrated cryogenic temperature sensors. This thesis presents a CMOS bandgap based temperature sensor that is fully operational at cryogenic temperatures (77 K). The sensor was fabricated in CMOS 0.16 µm technology and achieves a temperature inaccuracy of ±0.25? within the temperature range of -65 ? to 30 ? and an inaccuracy of ±0.15? at 77K.