Digital output temperature sensor
First Claim
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1. A digital output temperature sensor comprising:
- a first circuit configured to generate a first signal, the first signal varying complementary to a temperature of the sensor;
a second circuit configured to generate a second signal, the second signal varying proportionally to the temperature of the sensor, the second circuit comprising;
i) a PTAT current control reference voltage generating circuit configured to generate a PTAT current control reference voltage signal;
ii) a digital to analog converter circuit including a plurality of current sources receiving the PTAT current control reference voltage signal and being selectively switchable between a conductive state and a non-conductive state, wherein each of the plurality of current sources in the conductive state sources a partial current;
iii) a current summing junction summing each of the plurality of partial currents as a PTAT current signal; and
iv) a circuit component configured to convert the PTAT current signal to a PTAT voltage signal as the second signal;
a comparator operatively associated with the first and second circuits and configured to receive the first and second signals and generate a comparison signal based on a comparison between the first and second signals; and
,a converter circuit operatively associated with the comparator and configured to receive the comparison signal and generate a digital output signal based on the comparison signal, the digital output signal being representative of the temperature of the sensor.
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Abstract
A temperature sensor generates a digital output signal representative of the absolute temperature of the sensor. The sensor includes a first circuit configured to generate a complementary to absolute temperature (CTAT) voltage signal and a second circuit configured to generate a proportional to absolute temperature (PTAT) current signal. A comparator receives the CTAT and PTAT signals and generates a comparison signal based on a comparison between the signals. A converter circuit receives the comparison signal and generates a digital output signal based on the comparison signal. The digital output signal is representative of the temperature of the sensor.
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Citations
16 Claims
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1. A digital output temperature sensor comprising:
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a first circuit configured to generate a first signal, the first signal varying complementary to a temperature of the sensor; a second circuit configured to generate a second signal, the second signal varying proportionally to the temperature of the sensor, the second circuit comprising; i) a PTAT current control reference voltage generating circuit configured to generate a PTAT current control reference voltage signal; ii) a digital to analog converter circuit including a plurality of current sources receiving the PTAT current control reference voltage signal and being selectively switchable between a conductive state and a non-conductive state, wherein each of the plurality of current sources in the conductive state sources a partial current; iii) a current summing junction summing each of the plurality of partial currents as a PTAT current signal; and iv) a circuit component configured to convert the PTAT current signal to a PTAT voltage signal as the second signal; a comparator operatively associated with the first and second circuits and configured to receive the first and second signals and generate a comparison signal based on a comparison between the first and second signals; and
,a converter circuit operatively associated with the comparator and configured to receive the comparison signal and generate a digital output signal based on the comparison signal, the digital output signal being representative of the temperature of the sensor. - View Dependent Claims (2, 3, 4, 5)
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6. A digital output temperature sensor comprising:
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a reference voltage generator circuit configured to generate a first signal varying complimentary to a temperature of the sensor, the reference voltage generator circuit comprising a pair of stacked diodes configured to generate a complementary to absolute temperature (CTAT) voltage signal as said first signal; a second circuit configured to generate a proportional to absolute temperature (PTAT) current signal varying proportionally to the temperature of the sensor as a second signal, the second circuit including;
i) a PTAT current control reference voltage generating circuit configured to generate a PTAT current control reference voltage signal;
ii) a digital to analog converter circuit including a plurality of current sources receiving the PTAT current control reference voltage signal and being selectively switchable between a conductive state and a non-conductive state, wherein each of the plurality of current sources in the conductive state sources a partial current;
iii) a current summing junction summing each of the plurality of partial currents as said PTAT current signal; and
iv) a resistor between the current summing junction and a ground, the resistor being configured to convert the PTAT current signal to a PTAT voltage signal for use by said comparator;a comparator operatively associated with the first and second circuits and configured to receive the first and second signals and generate a comparison signal based on a comparison between the first and second signals; and
,a converter circuit operatively associated with the comparator and configured to receive the comparison signal and generate a digital output signal based on the comparison signal, the digital output signal being proportional to an absolute temperature of the sensor. - View Dependent Claims (7, 8)
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9. A method in a temperature sensor of sensing a temperature, the method comprising:
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generating a first signal varying complementary to a temperature of the sensor; generating a second signal varying proportionally to the temperature of the sensor by; i) using a PTAT current control reference voltage generating circuit, generating a PTAT current control reference voltage signal; ii) using a digital to analog converter circuit including a plurality of current sources receiving the PTAT current control reference voltage signal and being selectively switchable between a conductive state and a non-conductive state, sourcing a partial current by each of the plurality of current sources in the conductive state; iii) using a current summing junction, summing each of the plurality of partial currents as a PTAT current signal; and iv) converting the PTAT current signal to a PTAT voltage signal as the second signal; generating a comparison signal based on a comparison between the first and second signals; and
,generating a digital output signal based on the comparison signal, the digital output signal being representative of the temperature of the sensor. - View Dependent Claims (10, 11, 12, 13)
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14. A method in a temperature sensor of sensing a temperature, the method comprising:
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generating a first signal varying complementary to a temperature of the sensor, the generating the first signal comprising generating a complementary to absolute temperature (CTAT) voltage signal as said first signal; generating a second signal varying proportionally to the temperature of the sensor, the generating the second signal comprising generating a proportional to absolute temperature (PTAT) current signal as said second signal by;
i) using a PTAT current control reference voltage generating circuit, generating a PTAT current control reference voltage signal;
ii) using a digital to analog converter circuit including a plurality of current sources receiving the PTAT current control reference voltage signal and being selectively switchable between a conductive state and a non-conductive state, sourcing a partial current by each of the plurality of current sources in the conductive state;
iii) using a current summing junction, summing each of the plurality of partial currents as said PTAT current signal; and
iv) using a resistor between the current summing junction and a ground, converting the PTAT current signal to a PTAT voltage signal as the second signal;generating a comparison signal based on a comparison between the first and second signals; and
,based on the comparison signal, generating a digital output signal representative of the temperature of the sensor, the generating the digital output signal comprising generating the digital output signal proportional to an absolute temperature of the sensor. - View Dependent Claims (15)
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16. A method in a temperature sensor of sensing a temperature, the method comprising:
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generating a first signal varying complementary to a temperature of the sensor, the generating the first signal comprising generating a complementary to absolute temperature (CTAT) voltage signal as said first signal using a pair of grounded emitter PNP transistors; generating a second signal varying proportionally to the temperature of the sensor, the generating the second signal comprising generating a proportional to absolute temperature (PTAT) current signal by counting clock pulses of an associated clock signal as said digital output signal in response to said comparison signal as said second signal; generating a comparison signal based on a comparison between the first and second signals; and
,based on the comparison signal, generating a digital output signal representative of the temperature of the sensor, the generating the digital output signal comprising generating the digital output signal proportional to an absolute temperature of the sensor by;
i) using a PTAT current control reference voltage generating circuit, generating a PTAT current control reference voltage signal;
ii) using a digital to analog converter circuit including a plurality of current sources receiving the PTAT current control reference voltage signal and being selectively switchable between a conductive state and a non-conductive state, sourcing a partial current by each of the plurality of current sources in the conductive state;
iii) using a current summing junction, summing each of the plurality of partial currents as said PTAT current signal; and
iv) using a resistor between the current summing junction and a ground, converting the PTAT current signal to a PTAT voltage signal, wherein the generating the PTAT partial currents by each of the plurality of current sources in the conductive state comprises generating the PTAT partial currents by transistors having varied lengths for adjusting a linearity of the digital to analog converter circuit over a range of temperatures of the sensor.
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Specification