IEEE Sensors Journal · 2010 · 54 citations · 16 references
EngineeringComputer EngineeringElectrical EngineeringAnalog ElectronicsInstrumentationSensorsCalibrationSensor CalibrationSensor InterfacingTemperature MeasurementTemperature SensorsThermal SensorsCalibration Of Temperature SensorsCalibration TechniquesSmart Temperature SensorsTemperature CalibrationTemperature Sensor AccuracyThermal CalibrationThermal Sensor CalibrationVoltage Reference Design
Smart temperature sensors require trimming to achieve sub‑2 °C accuracy, but the conventional temperature calibration process is time‑consuming and expensive. This work introduces two rapid voltage‑based calibration methods for smart temperature sensors. Both methods exploit an on‑chip voltage proportional to absolute temperature (PTAT); the first measures the PTAT directly, while the second uses an external reference voltage and the on‑chip ADC to infer the PTAT and trim the sensor. Prototype tests in 0.7 µm CMOS show that the two techniques reduce measurement error to ±0.15 °C and ±0.25 °C, respectively, across –55 °C to 125 °C.
Smart temperature sensors generally need to be trimmed to obtain measurement errors below ±2°C. The associated temperature calibration procedure is time consuming and therefore costly. This paper presents two, much faster, voltage calibration techniques. Both make use of the fact that a voltage proportional to absolute temperature (PTAT) can be accurately generated on chip. By measuring this voltage, the sensor's actual temperature can be determined, whereupon the sensor can be trimmed to correct for its dominant source of error: spread in the on-chip voltage reference. The first calibration technique consists of measuring the (small) PTAT voltage directly, while the second, more robust alternative does so indirectly, by using an external reference voltage and the on-chip ADC. Experimental results from a prototype fabricated in 0.7 ¿m CMOS technology show that after calibration and trimming, these two techniques result in measurement errors (±3¿) of ±0.15°C and ±0.25°C, respectively, in a range from -55°C to 125°C.
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Michiel A. P. Pertijs, A. Niederkorn, Xu Ma et al. · IEEE Journal of Solid-State Circuits · 2005 · 365 citations
Engineering, Computer Engineering, Electrical Engineering +17