Temperature measurement circuit, temperature and light intensity measurement circuit, temperature measurement method and temperature and light intensity measurement method

Patent metadata

Field	Value
Publication number	US-12123788-B2
Application number	US-202117498219-A
Country	US
Kind code	B2
Filing date	Oct 11, 2021
Priority date	Aug 25, 2020
Publication date	Oct 22, 2024
Grant date	Oct 22, 2024

Abstract

The present disclosure relates to the field of biometric parameter measurement, and in particular, to a temperature measurement circuit, a temperature measurement method, a temperature and light intensity measurement circuit, a temperature and light intensity measurement method, a chip, a module, and an electronic device. A temperature signal is obtained based on an output voltage of a differential amplifier circuit when a non-inverting input terminal of the differential amplifier circuit is unload, an output voltage of the differential amplifier circuit when the non-inverting input terminal of the differential amplifier circuit is connected to a calibration resistor, and the output voltage of the differential amplifier circuit when the non-inverting input terminal of the differential amplifier circuit is connected to a thermistor, which improves the accuracy of the temperature measurement.

First claim

What is claimed is:

1. A temperature measurement circuit, comprising:
an unloaded contactor;
a differential amplifier circuit, wherein a non-inverting input terminal of the differential amplifier circuit is selectively connected to one of the following components: the unloaded contactor, a thermistor and a calibration resistor, and the thermistor is configured to convert a temperature signal of a measured object to a resistance signal; and
a conversion circuit connected to the differential amplifier circuit,
wherein in a first period, the non-inverting input terminal of the differential amplifier circuit is connected to the unloaded contactor, and the differential amplifier circuit outputs an offset voltage,
in a second period, the non-inverting input terminal of the differential amplifier circuit is connected to the calibration resistor, and the differential amplifier circuit outputs a calibration voltage, and
in a third period, the non-inverting input terminal of the differential amplifier circuit is connected to the thermistor, and the differential amplifier circuit outputs a temperature measurement voltage of the measured object; and
wherein the conversion circuit is configured to obtain the temperature signal of the measured object based on the offset voltage, the calibration voltage, and the temperature measurement voltage.

2. The temperature measurement circuit according to claim 1 , wherein the conversion circuit comprises: a first resistance determiner configured to output a resistance signal of the thermistor based on the offset voltage, the calibration voltage, and the temperature measurement voltage;
a first temperature determiner connected to the first resistance determiner and configured to convert the resistance signal to the temperature signal; and a first analog-to-digital converter connected to both the first resistance determiner and the first temperature determiner, and configured to convert the resistance signal to a digital resistance signal, wherein the first temperature determiner is further configured to convert the digital resistance signal to the temperature signal; or
the conversion circuit further comprises: a second analog-to-digital converter configured to perform analog-to-digital conversion on the offset voltage, the calibration voltage, and the temperature measurement voltage to obtain a digital offset voltage, a digital calibration voltage, and a digital temperature measurement voltage, respectively; and a control circuit connected to the second analog-to-digital converter and configured to convert the digital offset voltage, the digital calibration voltage, and the digital temperature measurement voltage to the temperature signal; and
the control circuit comprises:
a second resistance determiner configured to convert the digital offset voltage, the digital calibration voltage and the digital temperature measurement voltage to a digital resistance signal of thermistor; and
a second temperature determiner connected to the second resistance determiner and configured to convert the digital resistance signal to the temperature signal.

3. The temperature measurement circuit according to claim 2 , wherein the first resistance determiner comprises:
a first subtractor configured to calculate a first difference and a second difference, the first difference being a difference between the calibration voltage and the offset voltage, and the second difference being a difference between the temperature measurement voltage and the offset voltage;
a first multiplier configured to calculate a first product, the first product being a product of the first difference and a resistance of the calibration resistor; and
a first divider configured to calculate the resistance signal, the resistance signal being the first product divided by the second difference.

4. The temperature measuring circuit according to claim 1 , wherein an inverting input terminal of the differential amplifier circuit is connected to a first voltage; a second terminal of the thermistor is supplied with a second voltage; a second terminal of the calibration resistor is supplied with the second voltage; and the second voltage is greater than or smaller than the first voltage; and
the differential amplifier circuit further comprises a feedback resistor and a differential amplifier, wherein the feedback resistor is a non-sensitive resistor, and two terminals of the feedback resistor are connected to a non-inverting input terminal and an inverting output terminal of the differential amplifier, respectively; and
wherein in the first period, the non-inverting input terminal of the differential amplifier is connected to the unloaded contactor, and the differential amplifier outputs the offset voltage;
in the second period, the non-inverting input terminal of the differential amplifier is connected to a first terminal of the calibration resistor, and the differential amplifier outputs the calibration voltage; and
in the third period, the non-inverting input terminal of the differential amplifier is connected to a first terminal of the thermistor, and the differential amplifier outputs the temperature measurement voltage.

5. The temperature measuring circuit according to claim 4 , wherein a resistance of the calibration resistor is greater than a product of twice a resistance of the feedback resistor multiplied by a first preset absolute value, and the first preset absolute value is an absolute value of a quotient of a difference between the first voltage and the second voltage divided by a power supply voltage.

6. The temperature measurement circuit according to claim 4 , wherein a gain of the differential amplifier circuit is 0 when the non-inverting input terminal of the differential amplifier is connected to the unloaded contactor;
the gain of the differential amplifier circuit is twice a resistance of the feedback resistor divided by a resistance of the calibration resistor when the non-inverting input terminal of the differential amplifier is connected to the first terminal of the calibration resistor; and
the gain of the differential amplifier circuit is twice the resistance of the feedback resistor divided by the resistance of the thermistor when the non-inverting input terminal of the differential amplifier is connected to the first terminal of the thermistor.

7. The temperature measurement circuit according to claim 4 , wherein the second voltage is a ground voltage; the first voltage is a common mode voltage; and a resistance of the feedback resistor is smaller than a resistance of the calibration resistor.

8. The temperature measurement circuit according to claim 1 , wherein the thermistor and the calibration resistor are connected to a switch circuit connected to the differential amplifier circuit; and
the switch circuit comprises at least one switch unit.

9. The temperature measurement circuit according to claim 8 , wherein the switch circuit comprises a first switch unit and a second switch unit;
the non-inverting input terminal of the differential amplifier circuit is unloaded when the first switch unit and the second switch unit are both in an OFF state;
the non-inverting input terminal of the differential amplifier circuit is connected to the first terminal of the calibration resistor when the first switch unit is in an ON state; and
the non-inverting input terminal of the differential amplifier circuit is connected to the first terminal of the thermistor when the second switch unit is in an ON state.

10. The temperature measurement circuit according to claim 1 , wherein the calibration resistor is a precision resistor, a temperature drift of the calibration resistor is smaller than or equal to 10 ppm

Assignees

• Shenzhen Goodix Tech Co Ltd

Inventors

• Li Chuanlin
• Li Fulin
• Wang Haixiang

Classifications

• H03F3/45475

  using IC blocks as the active amplifying circuit · CPC title

• G01J2001/446

  Photodiode · CPC title

• G01J2001/444

  Compensating; Calibrating, e.g. dark current, temperature drift, noise reduction or baseline correction; Adjusting · CPC title

• G01J1/44

  Electric circuits {(for command of an exposure part G03B7/02)} · CPC title

• G01K15/005

  Calibration · CPC title