Temperature sensor and calibration method thereof having high accuracy
Disclosed is a temperature sensor including a first current generator configured to generate a proportional to absolute temperature (PTAT) current, a second current generator configured to generate an inverse PTAT (IPTAT) current, the PTAT current and IPTAT current being combined to form a reference current having a sensitivity relative to temperature, a plurality of current mirrors to adjust the sensitivity and gain of the reference current, and a variable resistor to set an output calibration voltage based on the generated current.
1. A temperature sensor, comprising:
a first current generator first voltage source in a first circuit portion having a first value configured to generate a proportional to absolute temperature (PTAT) current;
a second current generator configured to generate an inversely proportional to absolute temperature (IPTAT) current, the PTAT current and IPTAT current being combined to form a reference current having a sensitivity relative to temperature;
a first voltage source in a first circuit portion having a first value to generate the PTAT current and IPTAT current;
a second voltage source in a second circuit portion having a second value higher than the first value configured to calibrate a high output voltage;
a plurality of current mirrors comprising one or more first current mirrors configured to adjust the sensitivity of the reference current and one or more second current mirrors connected to receive the reference current and to produce a generated current; and
a variable resistor configured to generate an output voltage based on the generated current, the output voltage having a magnitude that corresponds to a temperature value.
2. The temperature sensor of claim 1 , further comprising a digital controller configured to control adjustment of the sensitivity of the reference current by further being configured to control a gain setting of each of the plurality of current mirrors.
3. The temperature sensor of claim 2 , wherein the variable resistor is controlled by the digital controller.
4. The temperature sensor of claim 2 , wherein the plurality of current mirrors include a plurality of MOS transistors.
5. The temperature sensor of claim 4 , further comprising a subtractor configured to control at least one MOS transistor to keep the sensitivity of the reference current constant.
6. The temperature sensor of claim 1 , further comprising a high voltage current mirror disposed between the first voltage source and the second voltage source to support high voltage at the output of the temperature sensor.
7. The temperature sensor of claim 6 , wherein the high voltage current mirror is a bipolar transistor pair.
8. The temperature sensor of claim 1 , comprising a plurality of bipolar transistors to generate the PTAT and IPTAT currents.
9. A method of calibrating a temperature sensor, comprising:
generating a proportional to absolute temperature (PTAT) current using a first current generator of the temperature sensor which is connected to a first voltage source in a first circuit portion having a first value to generate the PTAT current;
generating an inversely proportional to absolute temperature (IPTAT) current using a second current generator of the temperature sensor which is connected to the first voltage source in a first circuit portion having a first value to generate the PTAT current, the PTAT current and IPTAT current being combined to form a reference current having a sensitivity relative to temperature;
adjusting the sensitivity of the reference current to produce an adjusted current; and
generating an output voltage based on the adjusted current using a second voltage source in a second circuit portion having a second value higher than the first value configured, the output voltage having a magnitude that corresponds to a temperature value.
10. The method of claim 9 , wherein the adjusting the sensitivity uses a digital controller.
11. The method of claim 10 , wherein the digital controller adjusts at least one transistor of a current mirror to adjust a gain setting of the current mirror to vary the sensitivity of the reference current.
12. The method of claim 10 , further comprising:
exposing the temperature sensor to a predetermined temperature, and
trimming a variable resistor to set the output voltage of the temperature sensor to a calibrated output voltage, wherein the calibrated output voltage corresponds to the predetermined temperature.
13. A temperature sensor, comprising:
a first current generator configured to generate a proportional to absolute temperature (PTAT) current;
a second current generator configured to generate an inversely proportional to absolute temperature (IPTAT) current, the PTAT current and IPTAT current being combined to form a reference current having a sensitivity relative to temperature;
a plurality of current mirrors configured to adjust the sensitivity of the reference current to produce a generated current;
a first voltage source in a first circuit portion having a first value to generate the PTAT current and IPTAT current;
a second voltage source in a second circuit portion having a second value higher than the first value configured to calibrate an output voltage; and
a variable resistor configured to generate the output voltage based on the generated current, the output voltage having a magnitude that corresponds to a temperature value.
14. The temperature sensor of claim 13 , further comprising a high voltage current mirror disposed between the first voltage source and the second voltage source to support high voltage at the output of the temperature sensor.
15. The temperature sensor of claim 14 , wherein the high voltage current mirror is a bipolar transistor pair.