A switched-current, switched-capacitor temperature sensor in0.6-Μm CMOS

摘要

A temperature-to-digital converter is described which uses ansensor based on the principle of accurately scaled currents in thenparasitic substrate p-n-p in a standard fine-line CMOS process. Thenresulting PTAT ΔVBE signal is amplified in annauto-zeroed switched-capacitor circuit, sampled, and converted to andigital output by a low-power 10-bit SAR ADC providing a resolution ofn0.25° from -55°C to 125°C with an error of less than 1°.nA single adjustment of temperature error is provided for wafer probe. Nonfurther calibration is required. A switching bandgap reference circuitnwill also be described which uses similar techniques to generate annaccurate low-noise reference voltage for the ADC. The circuits are partnof a multichannel data-acquisition system where other input voltagesnmust also be sampled and measured, and so the speed and power of the ADCnis not determined by the temperature sensor alone. For continuousnoperation, the supply current is 1 mA, but a low-power mode is providednwhere the part is normally in shut down and only powers up whennrequired. In this mode, the average power supply current at 10nconversions/s is 0.3 ΜA. The supply voltage is 2.7-5.5 V