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High accuracy multi-range ultra-low power/ non-calibrated CMOS smart temperature sensor design

English Abstract

HIGH ACCURACY MULTI-RANGE ULTRA-LOW POWER/ NON-CALIBRATED CMOS SMART TEMPERATURE SENSOR DESIGN by LU SANFENG Thesis Supervisor: Dr. Law Man-Kay Master of Science in Electrical and Computer Engineering Temperature signal is one of the key parameters in our nature. Its value can effectively reflect the human or machine’s “working” conditions, which gives rise to the large markets of temperature sensors in the measurement, instrumentation and control system. These kinds of sensors must be “smart” since they should be capable of communicating with other electronics devices. Besides, in new emerging applications such radio frequency identification (RFID), wearable devices, various design specifications are necessitated but generally they are lower power consumption for extended operation time and high accuracy for precise temperature measurement. In this thesis, from these two aspects, two works are presented respectively. Firstly, since the measuring range becomes narrow due to the fact that it’s more and more application-defined, a multi-range ultra-low power with high accuracy can match better with this trend. The proposed work is based on substrate BJTs and a first-order incremental delta-sigma analog-to-digital converter (I-ADC). It trade off the accuracy and power with the sensing range and conversion speed. By employing a reconfigurable pre-gain stage, the input range of the I-ADC can be optimized for different application specific temperature sub-ranges, relaxing the resolution as well as power requirements for subsequent analog-to-digital conversion. An accuracy of ±0.1°C from -20°C to 60°C can be achieved using only one-point calibration with just ~ 1W power consumption. For sub-range applications, such as cold-chain, biomedical use, this error can be further suppressed to ±0.05°C at the cost of calibration at extra points. In the second work, it’s under no calibration condition that we make efforts to increase the sensing accuracy by reducing the temperature errors sources. Without calibration it’s known that the dominate error source is the saturation current process spread for a BJT-based temperature sensor. By introducing compensation current to track the saturation current process spread, the complementary to absolute temperature (CTAT) voltage 𝑉𝐵𝐸 process spread in the frontend can be significantly suppressed. With this method, it’s promising to achieve a high accuracy of about 1℃ without any calibrat

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Lu, San Feng,


Faculty of Science and Technology


Department of Electrical and Computer Engineering




Temperature measuring instruments -- Design and construction

Integrated circuits -- Design and construction

Detectors -- Design and construction


Law, Man Kay

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