Temperature sensor

Abstract

The invention discloses a temperature sensor which comprises a band gap circuit, a subtracter, an adder, a DAC module, a comparator and an SAR logic module. The band gap circuit generates two voltages which are in negative correlation with the temperature, inputs the two voltages to the subtracter to generate a voltage k delta VBE, inputs the VBE2 and the k delta VBE to the summator to generate a voltage irrelevant to the temperature, inputs the voltage output by the summator to the DAC module for digital-to-analog conversion, and obtains a voltage VDAC output by the DAC module. The VDAC and the k delta VBE are output to the input end of the comparator for comparison, the comparator outputs a comparison result to the SAR logic module, and the SAR logic module outputs a control signal to the DAC module and outputs a digital code at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of integrated circuits, and in particular relates to a temperature sensor. Background Art

[0002] Temperature, as a physical quantity, plays a vital role in many physical and chemical conversion processes. Temperature sensors, as indispensable temperature detection equipment, are also widely used. Traditional temperature sensors are often based on discrete components such as thermistors or thermocouples. However, in the past few decades, with the rapid development of integrated circuits, integrated temperature sensors have received more and more attention and applications due to their ability to integrate temperature sensing circuits and readout circuits on one chip, and their low cost and small size.

[0003] With the advancement of integrated circuit technology, the scale of chips is increasing, the complexity of systems is also increasing, and on-chip systems are susceptible to extreme high and low temperatures. In this case, temperature monitoring has been widely used to obtain reliable performance by compensating for the thermal sensitivity of circuit operations. For example, in the RTC chip, its internal crystal oscillator generates a 32.768KHz clock, but as the temperature changes, the frequency will shift significantly. The temperature sensor can compensate for the frequency offset caused by the ambient temperature in real time. However, the temperature reference of existing temperature sensors mostly uses SC amplifiers to linearly amplify ΔVBE to ensure that the subsequent circuit accurately quantifies the temperature information, but the disadvantages of SC amplifiers are: additional clocks and amplification time are required, the capacitors occupy a large layout area, and the differential input and output cannot meet the single-ended sampling requirements of the subsequent stage. Summary of the invention

[0004] Purpose of the invention: In order to solve the problems existing in the above-mentioned prior art, the present invention provides a temperature sensor.

[0005] Technical solution: The present invention provides a temperature sensor, including: a bandgap circuit, a subtractor, an adder, a DAC module, a comparator and a SAR logic module; the bandgap circuit generates a voltage V that is negatively correlated with the temperature BE1 and V BE2 , V BE1 Input to the first input terminal of the subtractor, V BE2 Input to the second input terminal of the subtractor, V BE1 With V BE2 The voltage kΔV is generated by the subtractor BE , k represents the proportional coefficient of the subtractor, V BE2 and kΔV BE Input to the adder to generate a temperature-independent voltage V REF , V REFInput to the DAC module for digital-to-analog conversion to obtain the voltage V output by the DAC module DAC , V DAC and kΔV BE The input is sent to the comparator for comparison. The comparator compares the result V C The SAR logic module outputs the control signal to the DAC module and outputs the digital code at the same time.

[0006] Furthermore, the bandgap circuit includes a first operational amplifier, first to fourth MOS tubes, first to fourth triodes and a first resistor; the emitter of the first triode is connected to one end of the first resistor, the collector and base of the first triode are interconnected and grounded, and the collector of the first triode is also connected to the collector and base of the second triode, the collector and base of the third triode, and the collector and base of the fourth triode; the other end of the first resistor is connected to the non-inverting input end of the first operational amplifier and the drain of the first MOS tube, the emitter of the second triode is connected to the inverting input end of the first operational amplifier and the drain of the second MOS tube, and the output end of the first operational amplifier is connected to the gates of the first to fourth MOS tubes; the sources of the first to fourth MOS tubes are connected to each other and then connected to the power supply voltage, the drain of the third MOS tube is connected to the emitter of the third triode, and the drain of the third MOS tube is used as the first output end of the bandgap circuit to output the voltage V BE1 The drain of the fourth MOS tube is connected to the emitter of the fourth triode, and the drain of the fourth MOS tube is used as the second output terminal of the bandgap circuit to output the voltage V BE2 .

[0007] Furthermore, the first to fourth MOS tubes are all PMOS tubes.

[0008] Furthermore, the subtractor includes a second operational amplifier and second to fifth resistors, one end of the second resistor serves as the first input end of the subtractor, and the other end is connected to the inverting input end of the second operational amplifier and one end of the fourth resistor, one end of the third resistor serves as the second input end of the subtractor, the other end of the third resistor is connected to the non-inverting input end of the second operational amplifier and one end of the fifth resistor, the other end of the fourth resistor is connected to the output end of the second operational amplifier, and the other end of the fifth resistor is grounded.

[0009] Furthermore, the adder includes a third operational amplifier, sixth to ninth resistors, and one end of the sixth resistor is connected to a voltage kΔV BE , the other end is connected to the non-inverting input terminal of the third operational amplifier, and one end of the seventh resistor is connected to the voltage V BE2 The other end of the seventh resistor is connected to the inverting input terminal of the third operational amplifier, one end of the ninth resistor and one end of the eighth resistor; the other end of the ninth resistor is grounded, and the other end of the eighth resistor is connected to the output terminal of the third operational amplifier.

[0010] Furthermore, the ADC module is a resistance type ADC module.

[0011] Beneficial effect: The present invention adopts a subtractor linear amplification scheme, that is, the voltage V which is negatively correlated with the temperature is amplified by a subtractor. BE1 With V BE2 Subtract and linearly amplify to get the voltage kΔV BE , and then quantized, expanding the sampling voltage range of the SAR module and the ADC module, and improving the accuracy of the temperature sensor. The present invention can not only effectively eliminate the error caused by temperature, but also has good anti-interference ability and signal processing stability, ensuring the stability and reliability of the sensor in complex environments. In this way, the present invention significantly improves the accuracy and stability of the measurement while maintaining sensitivity, and is particularly suitable for scenes with high requirements for accuracy and stability, such as industrial automation and automotive electronics. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a main block diagram of a high-precision temperature sensor designed by the present invention; Figure 2 It is a circuit structure diagram of a high-precision temperature sensor designed by the present invention; Figure 3 It is the block diagram of the subtractor; Figure 4 It is the block diagram of adder; Figure 5 This is a linearity simulation diagram of a high-precision temperature sensor; Figure 6 It is the temperature error simulation diagram of the high-precision temperature sensor. DETAILED DESCRIPTION

[0013] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0014] like Figure 1 As shown, the present invention discloses a high-precision temperature sensor, including a bandgap circuit, a subtractor, an adder, a DAC module, a comparator and a SAR logic module. The voltage generated by the bandgap circuit and negatively correlated with the temperature is recorded as V BE1 、V BE2 ; The input of the subtractor is connected to V BE1 、V BE2 The output of the subtractor is kΔV BE , k represents the proportional coefficient of the subtractor, and one end of the adder input is connected to V BE2 connected, and the other end is connected to kΔV BEconnected, the output of the adder is recorded as V REF ; One end of the DAC module input is connected to V REF One end of the comparator input is connected to the output of the DAC module, and the other end of the input is connected to the output of the digital SAR logic module. BE The output of the comparator is connected to the SAR logic module. In this embodiment, the DAC module adopts a resistor type DAC module.

[0015] like Figure 2 As shown, the bandgap circuit used in the present invention includes PMOS tube MP1, PMOS tube MP2, PMOS tube MP3, PMOS tube MP4, BJT tube BJT1, BJT tube BJT2, BJT tube BJT3, BJT tube BJT4, operational amplifier Amp1 and resistor R1, the output of Amp1 is connected to the gate of MP1, the gate of MP2, the gate of MP3 and the gate of MP4; the source of MP1, the source of MP2, the source of MP3 and the source of MP4 are connected to the power supply voltage AVDD; the non-inverting input terminal of Amp1 is connected to the drain and One end of the resistor R1 is connected; the inverting input end of Amp1 is connected to the drain of MP2 and the emitter of BJT2; the other end of R1 is connected to the emitter of BJT1; the collectors of BJT1, BJT2, BJT3 and BJT4 are connected to GND; the bases of BJT1, BJT2, BJT3 and BJT4 are connected to GND; the drain of MP3 is connected to the inverting input end of the subtractor and the emitter of BJT3; the drain of MP4 is connected to the non-inverting input end of the subtractor, the inverting input end of the adder and the emitter of BJT4; the output of the subtractor is connected to the non-inverting input end of the adder.

[0016] The emitter voltage of BJT2 is clamped to the non-inverting input terminal through the inverting input terminal of Amp1. The emitter voltage of BJT1 generates a current I in R1 that is positively correlated with the temperature. PTAT , I PTAT The current mirrors MP3 and MP4 are used to copy the voltage, and the voltage V flows through BJT3 and BJT4 respectively, which is negatively correlated with the temperature. BE1 With V BE2 . V BE1 With V BE2 The voltage kΔV is generated by the subtractor BE , kΔV BE With V BE2 The output is sent to the adder to generate a temperature-independent voltage V REF . V REF Output to the resistor DAC module as the reference voltage of the DAC module. DAC and kΔV BEThe output is sent to the input of the comparator for comparison. The comparator outputs the comparison result to the SAR logic module. The SAR logic module outputs the Ctrl<8:0> control signal to the DAC module for successive comparison and outputs the digital code Dout<8:0> at the same time.

[0017] like Figure 3 As shown, the subtractor used in the present invention includes resistors R2, R3, R4, R5 and amplifier Amp2. The in-phase input terminal of Amp2 is connected to one end of R3 and R5; the inverting input terminal of Amp2 is connected to one end of R2 and R4; the other end of R5 is connected to GND, and the other end of R4 is connected to the output of Amp2.

[0018] like Figure 4 As shown, the adder used in the present invention includes resistors R6, R7, R8, R9 and amplifier Amp3. The in-phase input end of Amp3 is connected to one end of R6; the inverting input end of Amp3 is connected to one end of R9, R7 and R8; the other end of R9 is connected to GND, and the other end of R8 is connected to the output of Amp3.

[0019] Figure 5 This is a linearity simulation diagram of the high-precision temperature sensor designed by the present invention. Under the TT process angle, the differential nonlinearity (DNL) of the output code is ±0.02LSB, and the integral nonlinearity (INL) is 0.32LSB.

[0020] Figure 6 This is a temperature error simulation diagram of the high-precision temperature sensor designed by the present invention. The three curves represent three high-precision temperature sensors respectively. Figure 6 It can be seen that at -40 to 105 degrees Celsius, the temperature errors of the three high-precision temperature sensors are within ±2.4°C, which shows that the present invention can effectively eliminate the error caused by temperature.

[0021] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A temperature sensor, characterized in that: include: Bandgap circuits, subtractors, adders, DAC modules, comparators, and SAR logic modules; The bandgap circuit generates a voltage V that is negatively correlated with temperature. BE1 and V BE2 , V BE1 Input to the first input terminal of the subtractor, V BE2 Input to the second input terminal of the subtractor, V BE1 With V BE2 The voltage kΔV is generated by the subtractor BE , k represents the proportional coefficient of the subtractor, V BE2 and kΔV BE Input to the adder to generate a temperature-independent voltage V REF , V REF Input to the DAC module for digital-to-analog conversion to obtain the voltage V output by the DAC module DAC , V DAC and kΔV BE The input is sent to the comparator for comparison. The comparator compares the result V C The SAR logic module outputs the control signal to the DAC module and outputs the digital code at the same time.

2. A temperature sensor according to claim 1, characterized in that: The bandgap circuit comprises a first operational amplifier, first to fourth MOS tubes, first to fourth triodes and a first resistor; the emitter of the first triode is connected to one end of the first resistor, the collector and base of the first triode are connected to each other and grounded, and the collector of the first triode is also connected to the collector and base of the second triode, the collector and base of the third triode and the collector and base of the fourth triode; the other end of the first resistor is connected to the in-phase input end of the first operational amplifier and the drain of the first MOS tube, the emitter of the second triode is connected to the inverting input end of the first operational amplifier and the drain of the second MOS tube, and the output end of the first operational amplifier is connected to the gates of the first to fourth MOS tubes; the sources of the first to fourth MOS tubes are connected to each other and then connected to the power supply voltage, the drain of the third MOS tube is connected to the emitter of the third triode, and the drain of the third MOS tube is used as the first output end of the bandgap circuit to output the voltage V BE1 The drain of the fourth MOS tube is connected to the emitter of the fourth triode, and the drain of the fourth MOS tube is used as the second output terminal of the bandgap circuit to output the voltage V BE2 .

3. A temperature sensor according to claim 2, characterized in that: The first to fourth MOS tubes are all PMOS tubes.

4. A temperature sensor according to claim 1, characterized in that: The subtractor includes a second operational amplifier and second to fifth resistors, one end of the second resistor serves as a first input end of the subtractor, and the other end is connected to the inverting input end of the second operational amplifier and one end of the fourth resistor, one end of the third resistor serves as a second input end of the subtractor, the other end of the third resistor is connected to the non-inverting input end of the second operational amplifier and one end of the fifth resistor, the other end of the fourth resistor is connected to the output end of the second operational amplifier, and the other end of the fifth resistor is grounded.

5. A temperature sensor according to claim 1, characterized in that: The adder includes a third operational amplifier, sixth to ninth resistors, and one end of the sixth resistor is connected to a voltage kΔV BE , the other end is connected to the non-inverting input terminal of the third operational amplifier, and one end of the seventh resistor is connected to the voltage V BE2 The other end of the seventh resistor is connected to the inverting input terminal of the third operational amplifier, one end of the ninth resistor and one end of the eighth resistor; the other end of the ninth resistor is grounded, and the other end of the eighth resistor is connected to the output terminal of the third operational amplifier.

6. A temperature sensor according to claim 1, characterized in that: The ADC module is a resistor type ADC module.

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