Annual report 2008 - Europractice-IC

A Low-Power and Accurate CMOS Temperature SensorDelft University of Technology, Electronic Instrumentation Laboratory / DIMES,Mekelweg 4, 2628CD Delft, The NetherlandsContacts:Andre Aita, a.aita@tudelft.nlKofi Makinwa, k.a.a.makinwa@tudelft.nlTechnology: AMIS 0.7µ C07M-A 2M/1P/PdiffC/HRDie size: 4.5 mm 2DescriptionThis ASIC was developed as part ofa research project whose aim wasthe realization of low-power CMOStemperature sensors. Such sensorsare based on the well-defined temperaturedependence of the baseemittervoltages of parasitic bipolartransistors. By properly processingthese voltages, a digital representationof temperature can be derived.The ASIC consists of a precision biascircuit, which biases two substratePNP transistors in a well-definedmanner, and a 16-bit Delta-Sigma() modulator, which uses theresulting base-emitter voltages togenerate a digital representation oftemperature.The sensor was fabricated throughEuropractice in the AMIS 0.7µ C07M-A process. It draws only 25uA froma 2.5V supply and is fully functionalover a 200˚C temperature range:from -70˚C to 130˚C. Over this range,the sensor’s inaccuracy was lessthan 0.25˚C (3) after a low-costbatch calibration. By trimming individualdevices, the sensor’s inaccuracycould be reduced to less than0.1˚C over the military temperaturerange: -55˚C to 125˚C.More details about the sensor canbe found in a paper published atthe International Solid-State CircuitsConference (ISSCC), A. Aita et al.,“A CMOS Smart Temperature Sensorwith a Batch-Calibrated Inaccuracyof 0.25˚C (3) from -70˚C to130˚C,” Digest of Technical papers,ISSCC, Feb. 2009.Why Europractice?Through Europractice we gained affordableaccess to a stable CMOSprocess whose options, e.g. linearcapacitors and high ohmic resistors,are especially suited to mixed-signaldesign.europractice | examples17