A CMOS Temperature Sensor With Wide Range And Low Deviation

Temperature sensor is the element to transform temperature signals to electrical signals. It measures temperature according to the special relationship between temperature and transistors, and then transforms the temperature signals to electrical signals as an output. Temperature sensors are widely used in our daily life. The traditional temperature sensors, such as thermistors or platinum resistors, have been widely applied in many electrical fields or auto-control systems. Comparatively, under the complementary metal oxide semiconductor(CMOS) process, the designation of temperature sensors set in integrated circuits have the unique advantages of small area and low cost. However, two important indicators of this kind of temperature sensor are weak: precision and temperature measurement range.A CMOS temperature sensor within ±0.4℃ over the full military temperature range of-45℃ to 125℃ is been designed in this paper under TSMC90 nm process for precision and temperature measurement range, these two important indicators. The circuit schematic of the temperature sensor includes two parts, the temperature sensing part and the sigmadelta analog to digital converter(ΣΔADC) part. The theory and the schematic of these two parts are introduced in this paper.To achieve the accuracy of the temperature sensor, many error correction methods are used for different sources of error in this paper, including curvature correction, dynamic element matching(DEM), resistor’s accuracy correction, current-gain offset cancellation, and the designs to cancel the mismatches from layouts and CMOS technics.