Controlled curvature correction in high accuracy thermal sensor

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;
• and
• 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 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, or 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.

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;
• 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.