In-Sensor Self-Calibration Circuit of MEMS Pressure Sensors for Accurate Localization

This paper presents an innovative real-time self-calibration unit designed to enhance the accuracy of pressure sensors following thermal stress. In this way, its use has been enabled in the contest of personal assistance, in particular for the precise localization of people in case of emergencies or in situations where mobility is impaired. The proposed unit comprises a trigger module, which detects uncalibrations, and an error estimator module, which is activated by the trigger and estimates the error to be applied to pressure values through a compact reconfigurable neural network. The system offers reconfigurability, enabling adaptation to various scenarios, such as post-soldering and prolonged exposure to temperatures beyond the nominal range. Validation of the unit was conducted on LPS22HH pressure sensors at STMicroelectronics laboratories. Results demonstrate its capability to recover up to 1.6 hPa and effectively restore accuracy within a nominal range of 0.5 hPa. The system was implemented using STMicroelectronics BCD8 technology, featuring a core area of 0.55 mm² and dynamic power consumption of 4.46 n W in the best scenario. These findings underscore the potential for integrating the system near the sensor, thus realizing an enhanced smart pressure sensor, particularly suited for demanding applications in Industry 4.0, where accurate sensors are indispensable.