Temperature sensing circuit
First Claim
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1. A temperature sensing circuit comprising:
- a first insulated gate field effect device, a second insulated gate field effect device, means for operating the first insulated gate field effect device in its subthreshold region so that the voltage across the first insulated gate field effect device varies with temperature, means for comparing the voltages across the first and second insulated gate field effect devices, and means for operating the second insulated gate field effect device in an area of its square law region where the voltage across the second insulated gate field effect device is substantially independent of temperature so that the comparing means provides a signal indicative of the temperature sensed by the first insulated gate field effect device.
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Abstract
A temperature sensing circuit has a first insulated gate field effect device which is operated deep into its subthreshold region where the voltage across the device varies with temperature and has a second insulated gate field effect device which is operated in an area of its square law region where the voltage across the second insulated gate field effect device is substantially independent of temperature. A comparator compares the voltages across the first and second field effect devices and provides a signal OT indicating the temperature sensed by the first insulated gate field effect device.
32 Citations
25 Claims
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1. A temperature sensing circuit comprising:
- a first insulated gate field effect device, a second insulated gate field effect device, means for operating the first insulated gate field effect device in its subthreshold region so that the voltage across the first insulated gate field effect device varies with temperature, means for comparing the voltages across the first and second insulated gate field effect devices, and means for operating the second insulated gate field effect device in an area of its square law region where the voltage across the second insulated gate field effect device is substantially independent of temperature so that the comparing means provides a signal indicative of the temperature sensed by the first insulated gate field effect device.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A temperature sensing circuit comprising:
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a first field effect transistor device arranged to respond to a temperature to be sensed, a second field effect transistor device, means for operating the first field effect transistor device in its subthreshold region where the voltage across the device varies with temperature and for operating the second field effect transistor device in an area of its square law region where the voltage across the second field effect transistor device substantially independent of temperature, and means for comparing the voltages across the first and second field effect transistor devices thereby to derive at an output of the comparing means a signal indicative of the temperature to be sensed. - View Dependent Claims (25)
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Specification