CPC G01K 7/00 (2013.01) [H03K 17/60 (2013.01); G01K 2219/00 (2013.01)] | 22 Claims |
1. A temperature sensing circuit, comprising:
a voltage generation circuitry comprising:
first and second bipolar junction transistors having coupled collectors and bases, and biased at different current densities;
a third bipolar junction transistor having its collector coupled to its base, the third bipolar junction transistor biased by a calibrated current and having a base-emitter voltage that is a voltage complementary to absolute temperature, the voltage complementary to absolute temperature having a curved non-linearity across temperature; and
fourth and fifth bipolar junction transistors having coupled collectors and bases, the fifth bipolar junction transistor biased by a temperature independent constant current, the fourth bipolar junction transistor biased by a current proportional to absolute temperature;
a switched capacitor circuit configured to selectively sample voltages produced by the voltage generation circuitry and provide the sampled voltages to inputs of an integrator;
a quantization circuit configured to quantize outputs of the integrator to produce a bitstream;
wherein the switched capacitor circuit cooperates with the integrator under control of the bitstream to:
when a most recent bit of the bitstream is a logic zero, cause integration of a difference between a base-emitter voltage of the first bipolar junction transistor and a base-emitter voltage of the second bipolar junction transistor to thereby produce a voltage proportional to absolute temperature; and
when the most recent bit of the bitstream is a logic one, cause integration of a difference between a base-emitter voltage of the fourth bipolar junction transistor and a sum of the voltage complementary to absolute temperature and a base-emitter voltage of the fifth bipolar junction transistor to thereby produce a negative voltage complementary to absolute temperature having negligible non-linearity across temperature; and
a low pass filter and decimator configured to filter and decimate the bitstream produced by the quantization circuit to produce a voltage indicative of a temperature of a chip into which the temperature sensing circuit is placed.
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