Temperature sensor circuit, thermometer and chip integrating CMOS tubes

Abstract

The application provides a temperature sensor circuit integrated with CMOS tubes, a thermometer and a chip, which comprises: a first load tube and a second load tube connected with a power voltage respectively; an operational amplifier connected with the first load tube and the second load tube to form a feedback loop, which is used for clamping the voltage corresponding to two input ends of the operational amplifier to make the voltage of the two input ends the same; a first temperature sensing tube and a second temperature sensing tube connected with the two input ends of the operational amplifier to make the first temperature sensing tube and the second temperature sensing tube work in a sub-threshold region, and the temperature is sensed according to the current ratio between the first temperature sensing tube and the second temperature sensing tube. The temperature is sensed through a new low-power temperature sensor circuit, meanwhile, the circuit itself is integrated with MOS tubes, which effectively reduces the area of the temperature sensor circuit and greatly improves the chip integration. Compared with the Bipolar triode temperature acquisition, the temperature can be sensed even in a low-voltage system by controlling the temperature sensing tube to work in the sub-threshold region.

Description

Technical Field

[0001] This invention relates to the field of integrated circuits, and in particular to a temperature sensor circuit, thermometer, and chip with an integrated CMOS transistor. Background Technology

[0002] In related technologies, traditional temperature sensor circuits typically utilize bandgap reference circuits (BGRs), which usually employ the principle of bipolar transistors to generate voltages that are positively correlated with temperature (PTAT) and negatively correlated with temperature (CTAT). For example, existing on-chip PTAT current sources often use bandgap reference circuits. As the current supply module for the entire on-chip system, this current source affects the overall chip functionality. Existing PTAT current sources mostly adopt a bandgap reference structure, utilizing the voltage drop across an on-chip resistor caused by the voltage difference between two diodes to generate a current proportional to temperature, aiming to solve problems such as circuit reliability and high cost.

[0003] However, temperature sensor circuits in this scenario typically require a large current to conduct, resulting in a higher power supply voltage for such temperature sensors. Additionally, BJT (bipolar junction transistor) transistors are usually large, which is not conducive to chip integration and also increases the chip area. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an integrated CMOS tube temperature sensor circuit, thermometer and chip to solve the problems that the temperature sensor circuit in the prior art requires high current and voltage and is too large to be integrated onto a chip.

[0005] To achieve the above and other related objectives, a first aspect of the present invention provides a temperature sensor circuit with an integrated CMOS transistor, comprising:

[0006] The first load transistor and the second load transistor are respectively connected to the power supply voltage;

[0007] An operational amplifier is connected to the first load transistor and the second load transistor respectively to form a feedback loop, which is used to clamp the voltages corresponding to the two input terminals of the operational amplifier so that the voltages of the two input terminals are the same.

[0008] The first and second temperature sensing tubes are respectively connected to the two input terminals of the operational amplifier so that the first and second temperature sensing tubes operate in the subthreshold region and sense the temperature based on the current ratio between the first and second temperature sensing tubes; wherein, the first load tube, the second load tube, the first temperature sensing tube, and the second temperature sensing tube are all field-effect transistors.

[0009] In some embodiments of the present invention, the sources of the first load transistor and the second load transistor are respectively connected to a power supply voltage, the gates of the first load transistor and the second load transistor are respectively connected to the output terminal of the operational amplifier, and the two input terminals of the operational amplifier are correspondingly connected to the drains of the first load transistor and the drains of the second load transistor to form a feedback loop.

[0010] In some embodiments of the present invention, both the first load transistor and the second load transistor are PMOS transistors, and the first load transistor and the second load transistor have different sizes.

[0011] In some embodiments of the present invention, the temperature sensor circuit further includes: a detection and calibration module, used to detect the output voltage at the output terminal of the operational amplifier, and if the output voltage exceeds a preset voltage range, adjust the voltages at the two input terminals of the operational amplifier to calibrate the output voltage until the output voltage reaches the preset voltage range.

[0012] In some embodiments of the present invention, the first temperature sensing tube and the second temperature sensing tube are NMOS transistors.

[0013] In some embodiments of the present invention, the drain gate of the first temperature sensing tube and the drain gate of the second temperature sensing tube are respectively connected to the two input terminals of the operational amplifier; the source terminals of the first temperature sensing tube and the second temperature sensing tube are grounded.

[0014] In some embodiments of the present invention, the first temperature sensing tube and the second temperature sensing tube have different sizes.

[0015] In some embodiments of the present invention, the expression for the current ratio between the first temperature sensing tube and the second temperature sensing tube is:

[0016]

[0017]

[0018] In the formula, I1 and I2 are the currents of the first temperature sensing tube and the second temperature sensing tube, respectively; W1 and L1 are the width and channel length of the first temperature sensing tube, respectively; W2 and L2 are the width and channel length of the second temperature sensing tube, respectively; m is the subthreshold slope factor; k is the Boltzmann constant; a and b are constants; q is the electron charge; T0 is the reference temperature; and T is the actual temperature.

[0019] In a second aspect, the present invention provides a thermometer comprising the aforementioned integrated CMOS transistor temperature sensor circuit.

[0020] In a third aspect, the present invention provides a chip comprising the temperature sensor circuit of the aforementioned integrated CMOS transistor.

[0021] As described above, the integrated CMOS transistor temperature sensor circuit, thermometer, and chip of the present invention have the following beneficial effects:

[0022] This invention discloses a MOS transistor integrated temperature sensor circuit, which senses temperature through a novel low-power temperature sensor circuit structure. Since the circuit itself is entirely integrated with MOS transistors, the area of ​​the temperature sensor circuit is effectively reduced, greatly improving the chip integration. Compared with the bipolar transistor method for acquiring temperature, by controlling the temperature sensing tube to work in the subthreshold region, it can sense temperature normally even in a low-voltage system. Attached Figure Description

[0023] Figure 1 The diagram shown is a temperature sensor circuit diagram with an integrated CMOS transistor in this invention.

[0024] Figure 2 This is another circuit diagram of the temperature sensor with integrated CMOS transistor in this invention;

[0025] Figure 3 The diagram shows the AMP circuit structure in the temperature sensor circuit with integrated CMOS transistor in this invention.

[0026] Figure 4 The diagram shows the temperature sensing result of the integrated CMOS tube temperature sensor circuit in this invention.

[0027] Figure 5 The diagram shown is a current simulation diagram of the temperature sensor circuit with integrated CMOS transistor in this invention.

[0028] Figure 6 The diagram shown is a simulation of the current ratio of the temperature sensor circuit with integrated CMOS transistor in this invention. Detailed Implementation

[0029] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0030] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0031] Please see Figure 1 This is a circuit diagram of the temperature sensor integrated with a CMOS transistor in this invention, used to monitor the ambient temperature within the chip. The circuit is described in detail below:

[0032] The first load transistor MP1 and the second load transistor MP2 are respectively connected to the power supply voltage VDD;

[0033] The operational amplifier AMP is connected to the first load transistor MP1 and the second load transistor MP2 to form a feedback loop, which is used to clamp the voltages corresponding to the two input terminals of the operational amplifier AMP so that the voltages of the two input terminals are the same.

[0034] Specifically, the sources of the first load transistor MP1 and the second load transistor MP2 are respectively connected to the power supply voltage VDD, and the gates of the first load transistor MP1 and the second load transistor MP2 are respectively connected to the output terminal of the operational amplifier AMP as their gate voltages. The two input terminals of the operational amplifier AMP are respectively connected to the drain of the first load transistor MP1 and the drain of the second load transistor MP2 to form a feedback loop, that is, the positive input terminal is connected to the drain of the first load transistor MP1, and the negative input terminal is connected to the drain of the second load transistor MP2.

[0035] It should be noted that the feedback loop can not only clamp the voltages at the two input terminals to make them the same, but also clamp the voltage at the output terminal of the operational amplifier AMP, thereby stabilizing the input and output voltages of the operational amplifier AMP.

[0036] The first temperature sensing tube MN1 and the second temperature sensing tube MN2 are respectively connected to the two input terminals of the operational amplifier AMP, so that the first temperature sensing tube MN1 and the second temperature sensing tube MN2 operate in the subthreshold region, and the temperature is sensed according to the current ratio between the first temperature sensing tube MN1 and the second temperature sensing tube MN2; wherein, the first load tube MP1, the second load tube MP2, the first temperature sensing tube MN1 and the second temperature sensing tube MN2 are all field-effect transistors.

[0037] Specifically, the drain gate of the first temperature sensing tube MN1 and the drain gate of the second temperature sensing tube MN2 are respectively connected to the two input terminals of the operational amplifier AMP; the source of the first temperature sensing tube MN1 and the source of the second temperature sensing tube MN2 are grounded.

[0038] In this embodiment, the sources of the first load transistor MP1 and the second load transistor MP2 are connected to a VDD power supply as load transistors. The voltage across the two input terminals (A and B) of the operational amplifier AMP is clamped, ensuring that the voltages at A and B are the same. The output terminal of the operational amplifier AMP is connected to the gates of MP1 and MP2. Simultaneously, the A and B terminals form a feedback loop with MP1 and MP2, stabilizing the voltages at points A and B and the output voltage of the operational amplifier AMP. The gates and drains of transistors MN1 (the first temperature sensing transistor) and MN2 (the second temperature sensing transistor) are connected together, forming a diode connection, so that MN1 and MN2 operate in the subthreshold region, resulting in a novel temperature sensing method.

[0039] Please see Figure 2 This is another circuit diagram of the temperature sensor with integrated CMOS transistor in this invention. Compared with the above embodiment, the temperature sensor circuit further includes:

[0040] The detection and calibration module is used to detect the output voltage at the output terminal of the operational amplifier. If the output voltage exceeds (is not) the preset voltage range, the voltage at the two input terminals of the operational amplifier is adjusted to calibrate the output voltage until the output voltage reaches the preset voltage range.

[0041] Specifically, by sampling the output voltage, it is determined whether the sampled output voltage is within the preset voltage range. If it is not within the preset voltage range, or if the output voltage is greater than or less than the preset voltage range, the voltages at the two input terminals of the operational amplifier are adjusted respectively, and the output voltage is calibrated in real time until the output voltage reaches the preset voltage range. In this way, the output voltage can be accurately ensured to be within the appropriate range. By stabilizing the output voltage, the voltage output of the feedback loop is ensured to be accurate. By monitoring and adjusting the output voltage through the feedback control loop, the performance, stability, and accuracy of the circuit are ensured.

[0042] Please see Figure 3 This is a schematic diagram of the AMP circuit structure in an integrated CMOS temperature sensor circuit, including: PMOS transistor M1, PMOS transistor M2, NMOS transistor M3, NMOS transistor M4, and NMOS transistor M5. The sources of PMOS transistors M1 and M2 are connected to the power supply voltage, and the gates of PMOS transistors M1 and M2 are interconnected. The drain of PMOS transistor M1 is interconnected with the drain of NMOS transistor M3 and the gates of PMOS transistors M1 and M2. The drains of PMOS transistor M2 and NMOS transistor M4 are interconnected. The sources of NMOS transistors M3 and M4 are connected to the drain of NMOS transistor M5. The source of NMOS transistor M5 is grounded. The gate of NMOS transistor M3 is connected to the positive input terminal, the gate of NMOS transistor M4 is connected to the negative input terminal, and the gate of NMOS transistor M5 is connected to the reference voltage VB.

[0043] In this embodiment, the operational amplifier can not only amplify the weak input signal to the required voltage level, but also compare the two input signals to generate an output signal that indicates the difference between the two input signals.

[0044] Optionally, in some embodiments, both the first load transistor and the second load transistor are PMOS transistors, and the first load transistor and the second load transistor have different dimensions.

[0045] In this embodiment, since PMOS transistors of different sizes have different performance parameters, it is necessary to consider multiple aspects such as power supply voltage, driving capability, and stability. The selection should be based on the matching between the power supply voltage and the PMOS transistor to ensure that the power supply voltage is connected to the source of the PMOS transistor as a load transistor, so as to avoid potential mismatch. At the same time, it can effectively improve the driving capability and stability of the circuit.

[0046] Optionally, in some embodiments, the first temperature sensing tube and the second temperature sensing tube are NMOS transistors; the first temperature sensing tube and the second temperature sensing tube have different sizes.

[0047] Specifically, MN1 and MN2 (the first and second temperature sensing tubes) operate in the subthreshold region and serve as the core temperature sensing tubes of the temperature sensor to sense the temperature on the chip.

[0048] It should be noted that, according to the principle of virtual short at the input of the operational amplifier, the voltages at the inputs A and B of the operational amplifier are equal. Since the first temperature sensing tube MN1 and the second temperature sensing tube MN2 have different sizes, the currents in the two branches are also different. At the same time, the voltages at points A and B are both less than the threshold voltages of the first temperature sensing tube MN1 and the second temperature sensing tube MN2.

[0049] The formula for the subthreshold operating current is:

[0050]

[0051] In equation (1), C ox V is the unit gate oxide capacitance, μ is the carrier mobility, W and L are the width and channel length of the MOS transistor, respectively, m is the subthreshold slope factor, and V T =kt / q, where k is the Boltzmann constant, V gs V is the gate-source voltage difference of the MOSFET. th V is the threshold voltage of the MOSFET. ds This is the drain-source voltage difference of the MOSFET.

[0052] When V ds >3V T When the subthreshold current formula is used, it can be simplified to:

[0053]

[0054] Meanwhile, both MN1 and MN2 operate in the subthreshold region, and both are diodes connected, satisfying V... ds >3V T Given the given conditions, the subthreshold current I1 of transistor MN1 is:

[0055]

[0056] Similarly, the subthreshold current I2 flowing through transistor MN2 is:

[0057]

[0058] By comparing formulas (4) and (3), we obtain the following formula:

[0059]

[0060] Where W and L are adjustable constants, and since MN1 and MN2 use the same devices, we can consider m1≈m2=m, where m is a constant.

[0061]

[0062] in,

[0063] According to the virtual short principle at the input terminals of an operational amplifier, the voltages at points A and B are equal. Therefore, we obtain V. gs1 =V gs2 The following formula is further adjusted as follows:

[0064]

[0065] To achieve a PTAT relationship between I2 / I1, the threshold voltage must exhibit good linearity within a certain temperature range, allowing V to... th1 -V th2 =aT+b, where a and b are constants, T is the actual temperature, and T0 is the reference temperature at T=T0. A Taylor expansion of the exponent term in formula (7) yields the expression for the current ratio between the first temperature sensing tube I1 and the second temperature sensing tube I2:

[0066]

[0067]

[0068] In the formula, I1 and I2 are the currents of the first and second temperature sensing tubes, respectively; W1 and L1 are the width and channel length of the first temperature sensing tube, respectively; W2 and L2 are the width and channel length of the second temperature sensing tube, respectively; m is the subthreshold slope factor; k is the Boltzmann constant; a and b are constants; q is the electron charge; T0 is the reference temperature; and T is the actual temperature.

[0069] In this embodiment, temperature testing of the chip circuit is performed. Compared with other temperature measurement methods, a single operational amplifier is used to form a feedback loop to clamp the voltages corresponding to the input and output terminals. This method is more accurate, simpler, and has lower manufacturing costs compared to solutions with multiple operational amplifiers. Temperature measurement is performed using an integrated CMOS transistor, resulting in a smaller size and higher integration. At the same time, the driving voltage is lower, eliminating the need for high current to turn on the circuit, making it suitable for circuits or chips with lower voltage drives.

[0070] Please see Figure 4 The diagram below shows the temperature sensing results of the temperature sensor circuit with integrated CMOS transistor in this invention, and is described in detail below:

[0071] Under ideal conditions, the temperature variable shows that the two currents are exponentially related. Since the first and second temperature sensing tubes are different in size, the magnitudes of the currents obtained are also different. After comparing the currents, a sloping straight line is obtained, and thus the sensed temperature value can be obtained.

[0072] See details Figure 5 The figure shows the current simulation diagram of the temperature sensor circuit with integrated CMOS transistor in this invention; see details. Figure 6 The image shows a simulation of the current ratio of the temperature sensor circuit with an integrated CMOS transistor in this invention, which can serve as evidence. Figure 4 The correctness of the statement.

[0073] In a second aspect, the present invention provides a thermometer comprising the aforementioned integrated CMOS transistor temperature sensor circuit.

[0074] In a third aspect, the present invention provides a chip including the integrated CMOS temperature sensor circuit of any of the above embodiments. The chip also includes a processor and other functional circuits. The integrated CMOS temperature sensor circuit is connected to the processor, which controls the temperature sensor circuit to detect temperature values. The processor controls the operation based on the temperature values ​​reported by the integrated CMOS temperature sensor circuit.

[0075] In summary, this invention discloses a MOSFET-integrated temperature sensor circuit. It senses temperature through a novel low-power temperature sensor circuit structure. Since the circuit itself is entirely integrated with MOSFETs, the area of ​​the temperature sensor circuit is effectively reduced, greatly improving chip integration. Compared to temperature acquisition using bipolar transistors, by controlling the temperature sensing tube to operate in the subthreshold region, it can sense temperature normally even in low-voltage systems. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial applicability.

[0076] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A temperature sensor circuit with an integrated CMOS transistor, characterized in that, include: The first load transistor and the second load transistor are respectively connected to the power supply voltage; An operational amplifier is connected to the first load transistor and the second load transistor respectively to form a feedback loop, which is used to clamp the voltages corresponding to the two input terminals of the operational amplifier so that the voltages of the two input terminals are the same. The first temperature sensing tube and the second temperature sensing tube are respectively connected to the two input terminals of the operational amplifier so that the first temperature sensing tube and the second temperature sensing tube operate in the subthreshold region and sense the temperature based on the current ratio between the first temperature sensing tube and the second temperature sensing tube; wherein, the first load tube, the second load tube, the first temperature sensing tube and the second temperature sensing tube are all field-effect transistors. The detection and calibration module is used to detect the output voltage at the output terminal of the operational amplifier. If the output voltage exceeds the preset voltage range, the voltages at the two input terminals of the operational amplifier are adjusted to calibrate the output voltage until the output voltage reaches the preset voltage range. The expression for the current ratio between the first temperature sensing tube and the second temperature sensing tube is as follows: A = ，C 0= ，C 1= In the formula, I 1 、I 2. The current in the first temperature sensing tube and the second temperature sensing tube, W 1 、L 1 represents the width of the first temperature sensing tube and the channel length, respectively. W 2 、L 2 represents the width of the second temperature sensing tube and the channel length, respectively. m The slope factor in the subthreshold region. k Boltzmann's constant, a、b They are constants, q For electron charge, T 0 is the reference temperature. T This is the actual temperature.

2. The temperature sensor circuit with an integrated CMOS transistor according to claim 1, characterized in that, The sources of the first load transistor and the second load transistor are respectively connected to the power supply voltage, and the gates of the first load transistor and the second load transistor are respectively connected to the output terminal of the operational amplifier. The two input terminals of the operational amplifier are respectively connected to the drains of the first load transistor and the drains of the second load transistor to form a feedback loop.

3. The temperature sensor circuit with an integrated CMOS transistor according to claim 2, characterized in that, Both the first load transistor and the second load transistor are PMOS transistors, and the first load transistor and the second load transistor have different sizes.

4. The temperature sensor circuit with an integrated CMOS transistor according to claim 1, characterized in that, The first temperature sensing tube and the second temperature sensing tube are NMOS transistors.

5. The temperature sensor circuit with an integrated CMOS transistor according to claim 4, characterized in that, The drain gate of the first temperature sensing tube and the drain gate of the second temperature sensing tube are respectively connected to the two input terminals of the operational amplifier; the source terminals of the first temperature sensing tube and the second temperature sensing tube are grounded.

6. The temperature sensor circuit with an integrated CMOS transistor according to claim 5, characterized in that, The first temperature sensing tube and the second temperature sensing tube are of different sizes.

7. A thermometer, characterized in that, The thermometer includes a temperature sensor circuit with an integrated CMOS transistor as described in any one of claims 1 to 6.

8. A chip, characterized in that, The chip includes a temperature sensor circuit with an integrated CMOS transistor as described in any one of claims 1 to 6.

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