阅读说明：本技术 温度传感器 (Temperature sensor ) 是由 夏天 陈飞 蔡化 芮松鹏 于 2021-09-17 设计创作，主要内容包括：本发明提供了一种温度传感器,用于测试CIS芯片的温度,包括：带隙基准和温度电流电路,用于获取CIS芯片的温度并将温度转换成两路正温度系数电流和两路负温度系数电流；电流控制电路,用于将两路所述正温度系数电流和两路所述负温度系数电流中三路电路电流进行组合,以输出组合电流；ADC,用于将所述组合电流积分并进行模数转换,最后输出CIS温度的量化结果。提升了温度传感器中ADC输入动态范围的利用率,减小了对ADC精度设计的要求,从而降低了ADC电路设计复杂度,最终降低了电路面积和功耗,提升电路可靠性。(The invention provides a temperature sensor for testing the temperature of a CIS chip, comprising: the band gap reference and temperature current circuit is used for acquiring the temperature of the CIS chip and converting the temperature into two positive temperature coefficient currents and two negative temperature coefficient currents; the current control circuit is used for combining the two positive temperature coefficient currents and the three circuit currents in the two negative temperature coefficient currents to output combined current; and the ADC is used for integrating the combined current, performing analog-to-digital conversion and finally outputting a quantification result of the CIS temperature. The utilization rate of the ADC input dynamic range in the temperature sensor is improved, and the requirement on ADC precision design is reduced, so that the design complexity of an ADC circuit is reduced, the circuit area and power consumption are finally reduced, and the reliability of the circuit is improved.)

1. A temperature sensor for testing the temperature of a CIS chip, comprising:

the band gap reference and temperature current circuit is used for acquiring the temperature of the CIS chip and converting the temperature into two positive temperature coefficient currents and two negative temperature coefficient currents;

the current control circuit is used for combining the currents of the three circuits in the two paths of positive temperature coefficient currents and the two paths of negative temperature coefficient currents and outputting combined currents;

and the ADC is used for integrating the combined current, performing analog-to-digital conversion and finally outputting a quantification result of the CIS temperature.

2. The temperature sensor of claim 1, wherein the bandgap reference and temperature current circuit comprises:

a bandgap reference circuit for generating a reference voltage;

and the temperature current source generating circuit is used for generating two paths of positive temperature coefficient current and two paths of negative temperature coefficient current.

3. The temperature sensor of claim 1, wherein the two positive temperature coefficient currents comprise: a first path of positive temperature coefficient current and a second path of positive temperature coefficient current; the two negative temperature coefficient currents comprise: a first path of negative temperature coefficient current and a second path of negative temperature coefficient current; the combined current includes: the first path of positive temperature coefficient current, the second path of positive temperature coefficient current and the second path of negative temperature coefficient current, or the first path of negative temperature coefficient current, the second path of positive temperature coefficient current and the second path of negative temperature coefficient current.

4. The temperature sensor of claim 3, wherein the current control circuit comprises:

the first switch is connected with the first path of positive temperature coefficient current, and the second switch is connected with the first path of negative temperature coefficient current;

controlling whether the first path of positive temperature coefficient current is connected with the combined current or not by controlling the on/off of the first switch;

and controlling whether the first path of negative temperature coefficient current is connected with the combined current or not by controlling the on/off of the second switch.

5. The temperature sensor of claim 4, wherein when the first switch is closed, the second switch is open; when the second switch is closed, the first switch is turned off.

6. The temperature sensor of claim 3, wherein the current control circuit comprises:

the device comprises a first branch circuit and a second branch circuit which are connected in parallel, wherein the first branch circuit and the second branch circuit are provided with two ends;

one end of the first branch is connected with the first positive temperature coefficient current, and the other end of the first branch is connected with the first negative temperature coefficient current;

one end of the second branch is connected with the first positive temperature coefficient current, and the other end of the second branch is connected with the first negative temperature coefficient current;

the first branch includes: the output end of the combined current is connected between the first switch and the second switch;

the second branch circuit includes: the first switch and the second switch are connected in series, and the fixed reference voltage is connected between the first switch and the second switch at one end and grounded at the other end;

controlling whether the first path of positive temperature coefficient current is connected with the combined current or not by controlling the first switch and the fourth switch to be simultaneously closed or simultaneously opened;

and controlling whether the first path of negative temperature coefficient current is connected with the combined current or not by controlling the second switch and the third switch to be simultaneously closed or simultaneously opened.

7. The temperature sensor of claim 6, wherein when the first switch and the fourth switch are closed, both the second switch and the third switch are open; when the second switch and the third switch are closed, the first switch and the fourth switch are both off.

8. The temperature sensor of claim 4, wherein the ADC comprises:

an integrator for converting the combined current into an integrated voltage;

the comparator is used for comparing the integral voltage with a fixed reference voltage and outputting a comparison result, meanwhile, a loop formed by the integrator and the comparator forms a continuous first-order one-bit quantization Delta-Sigma modulator, and the Delta-Sigma modulator outputs a modulation signal;

and the counter is used for counting the comparison result, outputting the counting result, and demodulating and outputting the modulation signal.

9. The temperature sensor of claim 8, wherein a first input of the integrator is coupled to the combined current and a second input of the integrator is coupled to the fixed reference voltage such that the voltage at the first input is the same as the fixed reference voltage.

10. The temperature sensor according to claim 8, wherein the output result of the comparator is further fed back to the first switch and the second switch to control opening or closing of the first switch and the second switch.

Technical Field

The invention relates to the technical field of integrated circuits, in particular to a temperature sensor.

Background

CMOS image sensor chips have been developed in recent years, and have gradually replaced CCDs and been widely used in various portable imaging electronic devices, security monitoring devices, vehicle-mounted electronics, and the like.

Many circuit modules and functions in a CMOS image sensor chip system are very sensitive to temperature. Therefore, it is necessary to change the operation configuration in real time according to the change in the chip temperature. For example, the dark level correction function controls the output of the correction amount using an algorithm based on the actual temperature. In practical application, the temperature sensor is mostly realized by an external temperature sensor outside the chip, and the actually detected temperature has deviation due to the fact that the temperature sensor is actually different from the CIS chip in physical position. Most of the conventional temperature sensors integrated in the CIS chip use VPTAT (proportional to absolute temperature) voltage and a VREF (reference) voltage to compare and generate temperature output. The specific implementation is that an ADC (Analog Digital Converter) is commonly used to sample and quantize the VPTAT voltage, and because the VPTAT voltage has a very narrow range of variation with temperature, the input voltage range for the ADC to effectively utilize is also very narrow, and the utilization efficiency is usually only about 20% to 30%. Therefore, in the design requirement of the high-precision temperature sensor, a higher-bit ADC is required to meet the design requirement, which greatly increases the design cost.

Disclosure of Invention

The invention aims to provide a temperature sensor, which can improve the utilization rate of an ADC input dynamic range in the temperature sensor, thereby reducing the requirement on ADC precision design, reducing the design complexity of an ADC circuit, finally reducing the circuit area and power consumption and improving the circuit reliability.

In order to achieve the above object, the present invention provides a temperature sensor for testing a temperature of a CIS chip, comprising: the band gap reference and temperature current circuit is used for acquiring the temperature of the CIS chip and converting the temperature into two positive temperature coefficient currents and two negative temperature coefficient currents;

the current control circuit is used for combining the two positive temperature coefficient currents and the three circuit currents in the two negative temperature coefficient currents to output combined current;

and the ADC is used for integrating the combined current, performing analog-to-digital conversion and finally outputting a quantification result of the CIS temperature.

Optionally, in the temperature sensor, the bandgap reference and temperature current circuit includes:

a bandgap reference circuit for generating a reference voltage;

and the temperature current source generating circuit is used for generating two paths of positive temperature coefficient current and two paths of negative temperature coefficient current.

Optionally, in the temperature sensor, the two paths of positive temperature coefficient currents include a first path of positive temperature coefficient current and a second path of positive temperature coefficient current; the two paths of negative temperature coefficient currents comprise a first path of negative temperature coefficient current and a second path of negative temperature coefficient current; the combined current includes: the first path of positive temperature coefficient current, the second path of positive temperature coefficient current and the second path of negative temperature coefficient current, or the first path of negative temperature coefficient current, the second path of positive temperature coefficient current and the second path of negative temperature coefficient current.

Optionally, in the temperature sensor, the current control circuit includes:

the first switch is connected with the first path of positive temperature coefficient current, and the second switch is connected with the first path of negative temperature coefficient current;

controlling whether the first path of positive temperature coefficient current is connected with the combined current or not by controlling the on/off of the first switch;

and controlling whether the first path of negative temperature coefficient current is connected with the combined current or not by controlling the on/off of the second switch.

Optionally, in the temperature sensor, when the first switch is closed, the second switch is opened; when the second switch is closed, the first switch is turned off.

Optionally, in the temperature sensor, the current control circuit includes:

the device comprises a first branch circuit and a second branch circuit which are connected in parallel, wherein the first branch circuit and the second branch circuit are provided with two ends;

one end of the first branch is connected with the first positive temperature coefficient current, and the other end of the first branch is connected with the first negative temperature coefficient current;

one end of the second branch is connected with the first positive temperature coefficient current, and the other end of the second branch is connected with the first negative temperature coefficient current;

the first branch includes: the output end of the combined current is connected between the first switch and the second switch;

the second branch circuit includes: the first switch and the second switch are connected in series, and the fixed reference voltage is connected between the first switch and the second switch at one end and grounded at the other end;

controlling whether the first path of positive temperature coefficient current is connected with the combined current or not by controlling the first switch and the fourth switch to be simultaneously closed or simultaneously opened;

and controlling whether the first path of negative temperature coefficient current is connected with the combined current or not by controlling the second switch and the third switch to be simultaneously closed or simultaneously opened.

Optionally, in the temperature sensor, when the first switch and the fourth switch are closed, both the second switch and the third switch are opened; when the second switch and the third switch are closed, the first switch and the fourth switch are both off.

Optionally, in the temperature sensor, the ADC includes:

an integrator for converting the combined current into an integrated voltage;

the comparator is used for comparing the integral voltage with a fixed reference voltage and outputting a comparison result, meanwhile, a loop formed by the integrator and the comparator forms a continuous first-order one-bit quantization Delta-Sigma modulator, and the Delta-Sigma modulator outputs a modulation signal;

and the counter is used for counting the comparison result, outputting the counting result, and demodulating and outputting the modulation signal.

Optionally, in the temperature sensor, the first input terminal of the integrator is connected to the combined current, and the second input terminal of the integrator is connected to the fixed reference voltage, so that when no current is connected to the first input terminal, the potential of the first input terminal of the integrator can be maintained unchanged.

Optionally, in the temperature sensor, the output result of the comparator is further fed back to the first switch and the second switch to control the opening or closing of the first switch and the second switch.

In the temperature sensor provided by the embodiment of the invention, the three circuit currents in the two positive temperature coefficient currents and the two negative temperature coefficient currents are combined to output the combined current. The combined current is then used as the input current for the ADC and finally the combined current is applied to the ADC pair. Compared with the prior art that only one positive temperature coefficient voltage and one negative temperature coefficient voltage are input, the input current of the embodiment of the invention is four, the superposition of signals is convenient, the superposed current enlarges the temperature current variation range, covers most range of the amplitude of the ADC input voltage, and can improve the utilization rate of the ADC input dynamic range in the temperature sensor, thereby reducing the requirement on ADC precision design, reducing the design complexity of an ADC circuit, finally reducing the circuit area and power consumption, and improving the circuit reliability.

Drawings

FIG. 1 is a schematic diagram of a reference voltage source in the prior art;

FIG. 2 is a schematic diagram of temperature voltage dynamic range;

FIG. 3 is a block diagram of a temperature sensor according to an embodiment of the present invention;

fig. 4 to 5 are schematic structural views of a temperature sensor according to an embodiment of the present invention;

FIG. 6 is a diagram of a current control circuit according to a second embodiment of the present invention;

in the figure: 100-bandgap reference and temperature current circuit, 200-current control circuit, 230-inverter, 300-ADC, 310-integrator, 320-comparator, 330-counter, M1-first transistor, M2-second transistor, M3-third transistor, M4-fourth transistor, M5-fifth transistor, M6-sixth transistor, M7-seventh transistor, M8-eighth transistor, M9-ninth transistor, M10-tenth transistor, M11-eleventh transistor, M12-twelfth transistor, M13-thirteenth transistor, M14-fourteenth transistor, M15-fifteenth transistor, M16-sixteenth transistor, R1-first resistor, R2-second resistor, R3-third resistor, M3-fourth transistor, R4-fourth resistor, R5-fifth resistor, R6-sixth resistor, Q1-first triode, Q2-second triode, Q3-third triode, AMP-amplifier, S211-first switch, S212-second switch, S221-first switch, S222-second switch, S223-third switch and S224-fourth switch.

Detailed Description

The following describes in more detail embodiments of the present invention with reference to the schematic drawings. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

In the following, the terms "first," "second," and the like are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances. Similarly, if the method described herein comprises a series of steps, the order in which these steps are presented herein is not necessarily the only order in which these steps may be performed, and some of the described steps may be omitted and/or some other steps not described herein may be added to the method.

As described in the background, if the voltage range varying with temperature can be covered in the whole input range of the ADC, the utilization rate of the input range of the ADC can be improved, and the requirement for the accuracy of the ADC can be reduced. Therefore, in order to improve this problem, a temperature sensor circuit that expands the temperature voltage variation range may be proposed as a temperature detection module inside a chip.

Referring to fig. 1, a reference voltage source of the prior art is shown, and a first-order expression of an output voltage of the structure is as follows:

ΔV_BE＝V_Tln(N)；

wherein VREF is output voltage, VBE3 is Q3 emitter voltage, and is negative temperature coefficient characteristic; the first resistor R1 and the second resistor R2 are corresponding resistor values, VT is a thermal voltage with positive temperature coefficient characteristics, and N is the quantity ratio of Q1 to Q2. In the above expression, the negative temperature coefficient and the positive temperature coefficient characteristic voltage are superimposed to generate the output voltage VREF with an approximately zero temperature coefficient. VPTAT is used as the input signal to the ADC, and the voltage is proportional to absolute temperature. VREF is used as the reference voltage for the ADC, which approximates a zero temperature coefficient characteristic. The quantization result of the ADC can be expressed as follows:

referring to FIG. 2, refer to the curves VPTAT and VBE, V_PTATIn the temperature range of-55 to 125 ℃, the voltage variation range is only about 300mV, and V is_REFTypically 1.2V, this results in an ADC input range of only around 25% being effectively used, with the remaining input dynamic range being wasted.

Therefore, the input signal of the ADC is improved, and the improved ADC quantization result is as follows:

where A, B is a constant, e.g., a-2, B-1. FIG. 2 shows a temperature range V of-55 deg.C to 125 deg.C_PTAT、V_BE3、V_REFAnd combinations A and V_PTAT-B·V_BE3As a function of temperature.

A·V_PTAT-B·V_BE3This curve is a curve where the temperature voltage signal after recombination can cover the dynamic range of the ADC input,it can be seen that it can cover 90% of the input dynamic range of the ADC, thus reducing the ADC resolution requirement by a factor of 3.

The equation is equivalently changed, when A is 2 and B is 1, the numerator and denominator are simultaneously divided by R₃Then let R₃＝R₂Then, the following equation is given:

it is concluded that:

it can be seen that the equation μ' is transformed into a proportional equation with respect to the current, i.e. the ADC input is a current signal, which facilitates the superposition of signals and can greatly simplify the circuit implementation. Based on this, referring to fig. 3 to 5, the present invention provides a temperature sensor for testing the temperature of a CIS chip, including:

the band-gap reference and temperature current circuit 100 is used for acquiring the temperature of the CIS chip and converting the temperature into two positive temperature coefficient currents and two negative temperature coefficient currents;

a current control circuit 200 for combining the two positive temperature coefficient currents and the three circuit currents of the two negative temperature coefficient currents to output a combined current;

and the ADC300 is configured to integrate the combined current, perform analog-to-digital conversion, and finally output a quantization result of the CIS temperature.

Furthermore, the two positive temperature coefficient currents comprise a first positive temperature coefficient current and a second positive temperature coefficient current, and the two negative temperature coefficient currents comprise a first negative temperature coefficient current and a second negative temperature coefficient current.

Further, the bandgap reference and temperature current circuit 100 includes: a bandgap reference circuit for generating a reference voltage;

and the temperature current source generating circuit is used for generating two paths of positive temperature coefficient currents and two paths of negative temperature coefficient currents.

The bandgap reference circuit includes: the driving circuit comprises a first transistor M1, a second transistor M2, a third transistor M3, a fourth transistor M4, a fifth transistor M5, a sixth transistor M6, a seventh transistor M7, an eighth transistor M8, a ninth transistor M9, a tenth transistor M10, a first resistor R1, a second resistor R2, a fifth resistor R5, a sixth resistor R6, a first triode Q1, a second triode Q2 and a third triode Q3.

The temperature current source generating circuit includes: the circuit comprises a first positive temperature coefficient current generating circuit, a second positive temperature coefficient current generating circuit, a first negative temperature coefficient current generating circuit and a second negative temperature coefficient current generating circuit. Further, the structure for generating the positive temperature coefficient current: the positive temperature coefficient current is obtained by copying working currents of a fifth transistor M5-an eighth transistor M8 through a current mirror, and the negative temperature coefficient current is obtained by dividing the voltage of the base electrode-emitter electrode of the third triode Q3 by the values of a third resistor R3 and a third resistor R4 respectively.

Specifically, the first positive temperature coefficient current I_PTAT1The generation circuit includes: an eleventh transistor M11, and a twelfth transistor M12. Second positive temperature coefficient current I_PTAT2The generation circuit includes: a thirteenth transistor M13 and a fourteenth transistor M14. The first path of negative temperature coefficient current I_CTAT1The generation circuit includes: a fifteenth transistor M15 and a third resistor R3. The second path of negative temperature coefficient current I_CTAT2The generation circuit includes: a sixteenth transistor M16 and a fourth resistor R4.

Wherein: a gate of the seventh transistor M7, a gate of the eighth transistor M8, a gate of the tenth transistor M10, and a gate of the twelfth transistor M12The gate, the gate of the fourteenth transistor M14, the drain terminal of the fifth transistor M5 and the first terminal of the fifth resistor R5 are connected, and the gate of the fifth transistor M5, the gate of the sixth transistor M6, the gate of the ninth transistor M9, the gate of the eleventh transistor M11, the gate of the thirteenth transistor M13 and the second terminal of the fifth resistor R5 are connected. The gate of the third transistor M3 and the gate of the fourth transistor M4 are connected to the drain terminal of the sixth transistor M6 and the first end of the sixth resistor R6, and the gate of the first transistor M1 and the gate of the second transistor M2 are connected to the second end of the sixth resistor R6. The source of the first transistor M1 is connected with the first end of the first resistor R1, the second end of the first resistor R1 is connected with the emitter of the first triode Q1, the base and the collector of the first triode Q1 are connected, the source of the second transistor M2 is connected with the emitter of the second triode Q2, and the base and the collector of the second triode Q2 are connected. The drain of the ninth transistor M9 generates the reference voltage. The drain of the ninth transistor M9 is connected to the first terminal of the second resistor R2, the second terminal of the second resistor R2 is connected to the non-inverting input terminal of the amplifier and the emitter of the third transistor Q3, and the base and collector of the third transistor Q3 are connected. The drain electrode of the eleventh transistor M11 generates a first positive temperature coefficient current I_PTAT1The drain of the thirteenth transistor M13 generates a second positive temperature coefficient current I_PTAT2The output terminal of the amplifier AMP is connected to the gate of the fifteenth transistor M15 and the gate of the sixteenth transistor M16, and the negative input terminal of the amplifier AMP is connected to the source of the fifteenth transistor M15 and the source of the sixteenth transistor M16. A first end of the third resistor R3 is connected to the source of the fifteenth transistor M15, a second end of the third resistor R3 is grounded, a first end of the fourth resistor R4 is connected to the source of the sixteenth transistor M16, and a second end is grounded. The drain of the fifteenth transistor M15 generates a first negative temperature coefficient current I_CTAT1The drain electrode of the sixteenth transistor M16 generates a second negative temperature coefficient current I_CTAT2。

Referring to fig. 4, a first embodiment of the current control circuit of the present invention includes: and the first positive temperature coefficient current I_PTAT1The first switch S211 is connected in, and the first negative temperature coefficient current I_CTAT1AccessThe second switch S212; controlling the first positive temperature coefficient current I by controlling the on/off of the first switch S211_PTAT1Whether the combined current is switched on or not; controlling the first negative temperature coefficient current I by controlling the on/off of the second switch S212_CTAT1Whether a combined current is switched in. When the first switch S211 is closed and the second switch S212 is opened, the first path of positive temperature coefficient current I_PTAT1The second circuit of positive temperature coefficient current I_PTAT2And a second negative temperature coefficient current I_CTAT2As a combined current; when the first switch S211 is turned off and the second switch S212 is turned on, the first negative temperature coefficient current I_CTAT1The second circuit of positive temperature coefficient current I_PTAT2And a second negative temperature coefficient current I_CTAT2As a combined current.

Referring to fig. 6, a second embodiment of the current control circuit of the present invention includes: the first branch circuit and the second branch circuit are connected in parallel, and both the first branch circuit and the second branch circuit are provided with two ends; one end of the first branch is connected with the first positive temperature coefficient current I_PTAT1The other end is connected with the first path of negative temperature coefficient current I_CTAT1(ii) a One end of the second branch is connected with the first branch of positive temperature coefficient current I_PTAT2The other end is connected with the first path of negative temperature coefficient current I_CTAT2(ii) a The first branch includes: a first switch S221 and a second switch S222 connected in series, an output terminal I of the combined current_{INT_IN}The switch is connected between the first switch and the second switch; the second branch circuit includes: third and fourth switches S223 and S224 in series and a fixed reference voltage V_DCThe fixed reference voltage V_DCOne end is connected between the first switch S221 and the second switch S222, and the other end is grounded. The fixed reference voltage V_DCThe third switch S223 maintains the voltage at the drain terminal of the eleventh transistor M11 (outputs the first positive temperature coefficient current I)_PTAT1Port of) and a fixed reference voltage V_DCSimilarly, the effect of maintaining the voltage at the drain terminal of the eleventh transistor M11 constant is achieved. Alternatively, the voltage at the drain terminal of the fifteenth transistor M15 is maintained by the fourth switch S224 (outputting the first negative path)Temperature coefficient current I_CTAT1Port of) and a fixed reference voltage V_DCSimilarly, the effect of maintaining the voltage at the drain terminal of the fifteenth transistor M15 constant is achieved. The first switch S221 and the fourth switch S224 are simultaneously closed or simultaneously opened to control the first positive temperature coefficient current I_PTAT1Whether the combined current is switched on or not; the second switch S222 and the third switch S223 are turned on or turned off simultaneously to control the first negative temperature coefficient current I_CTAT1Whether a combined current is switched in. Specifically, when the first switch S221 and the fourth switch S224 are closed, the second switch S222 and the third switch S223 are both opened, and the first path of positive temperature coefficient current I is connected to the first path of positive temperature coefficient current I_PTAT1The second circuit of positive temperature coefficient current I_PTAT2And a second negative temperature coefficient current I_CTAT2Connecting a combined current; when the second switch S222 and the third switch S223 are closed, the first switch S221 and the fourth switch S224 are both opened, and the second path of the ptc current I is closed_PTAT2The first path of negative temperature coefficient current I_CTAT1And a second negative temperature coefficient current I_CTAT2The combined current is switched in.

Further, the ADC300 includes:

an integrator 310 for converting the combined current into an integrated voltage;

a comparator 320 for comparing the integrated voltage with a fixed reference voltage V_DCComparing and outputting a comparison result, wherein a loop formed by the integrator, the comparator and the control switch forms a continuous first-order one-bit quantization Delta-Sigma modulator, and the Delta-Sigma modulator outputs a modulation signal;

the counter 330 counts the comparison result and outputs the count result, and at the same time, demodulates and outputs the modulation signal. That is, the counter 330 may be equivalent to a down-sampling digital filter, and demodulates the modulated signal output by the Delta Sigma modulator into a normal signal for outputting, and then combines with the modulator to form a complete ADC, and finally outputs the quantized result of the CIS temperature.

Further, if the current control circuit is the first embodiment of the current control circuit of the present invention, the output result of the comparator 320 is also fed back to the first switch S211 and the second switch S212 to control the opening or closing of the first switch S211 and the second switch S212. The output result of the comparator is divided into two paths, one path is directly connected with the second switch, the other path is connected with the first switch S211 through the phase inverter 230, when the output result of the comparator is in a high level, the first switch is disconnected, and the second switch S212 is closed; when the output result is low, the first switch S211 is closed and the second switch S212 is closed. The first switch S211 and the second switch S212 cannot be opened or closed at the same time.

Further, a first input terminal of the integrator 310 is coupled to the combined current, and a second input terminal of the integrator is also coupled to a fixed reference voltage, such that the voltage at the first input terminal is the same as the fixed reference voltage.

Further, the reference voltage V is fixed_DCTypically one-half of the supply voltage. The supply voltage is typically 3.3V or 2.8V, so the reference voltage V is fixed_DCTypically 1.65V or 1.4V.

In summary, in the temperature sensor provided in the embodiment of the present invention, the three circuit currents of the two positive temperature coefficient currents and the two negative temperature coefficient currents are combined to output the combined current. The combined current is then used as the input current for the ADC and finally the combined current is applied to the ADC pair. Compared with the prior art that only one positive temperature coefficient voltage and one negative temperature coefficient voltage are input, the input current of the embodiment of the invention is four, the superposition of signals is convenient, the superposed current enlarges the temperature current variation range, covers most range of the amplitude of the ADC input voltage, and can improve the utilization rate of the ADC input dynamic range in the temperature sensor, thereby reducing the requirement on ADC precision design, reducing the design complexity of an ADC circuit, finally reducing the circuit area and power consumption, and improving the circuit reliability.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any way. It will be understood by those skilled in the art that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.