A temperature sensing circuit based on double-loop clamping structure

Abstract

This specification provides a temperature sensing circuit based on a dual-loop clamping structure, including a reference voltage generation circuit, a reference current generation circuit, a PTAT temperature sensing voltage generation circuit, and a CTAT temperature sensing voltage generation circuit. The reference voltage generation circuit is connected to the reference current generation circuit to generate a reference voltage. The reference current generation circuit has a dual-loop clamping structure, including two operational amplifiers connected to two ends of a resistor to clamp the voltage across the resistor, generating a reference current through the resistor. The reference current biases the PTAT and CTAT temperature sensing voltage generation circuits. The PTAT and CTAT temperature sensing voltage generation circuits use a diode stacking structure to double the first-order temperature coefficients of the PTAT and CTAT voltages. This invention improves the resolution of the temperature sensing circuit, reduces the circuit area, and lowers the power consumption of the temperature sensing circuit.

Description

Technical Field

[0001] This document relates to the field of integrated circuit technology, and in particular to a temperature sensing circuit based on a dual-loop clamping structure. Background Technology

[0002] Since high temperatures can negatively impact the performance of IC components, it is crucial to effectively monitor the temperature of operating circuits within integrated circuits. With the rapid development of my country's integrated electronic circuit industry, the technology for temperature detection using integrated circuits has become increasingly mature, and the types of temperature sensors have also increased. However, many challenges still remain.

[0003] Currently, existing temperature sensor circuits typically generate a voltage proportional to the absolute temperature using a 2-T structure to produce a signal indicating the temperature. Although this structure can generate voltages with positive and negative temperature coefficients, the first-order characteristics of the voltage are poor, and the voltage variation range is also small due to voltage margin limitations, resulting in low resolution. Therefore, low-cost, high-performance temperature sensors have a very broad market prospect. Summary of the Invention

[0004] This specification provides one or more embodiments of a temperature sensing circuit based on a dual-loop clamping structure, the circuit including a reference voltage generation circuit, a reference current generation circuit, and a temperature sensing voltage generation circuit;

[0005] The reference voltage generation circuit is connected to the reference current generation circuit and is used to generate a reference voltage, which serves as the input voltage of the reference current generation circuit. The reference current generation circuit has a dual-loop clamping structure, including two operational amplifiers. The two operational amplifiers form two feedback loops, and the two operational amplifiers are respectively connected across the resistor to clamp the voltage across the resistor. The temperature sensing voltage generation circuit includes a positive temperature coefficient (PTAT) temperature sensing voltage generation circuit and a negative temperature coefficient (CTAT) temperature sensing voltage generation circuit. The PTAT temperature sensing voltage generation circuit and the CTAT temperature sensing voltage generation circuit are biased by the reference current and connected to the two operational amplifiers. The PTAT temperature sensing voltage generation circuit and the CTAT temperature sensing voltage generation circuit respectively use a diode stacking structure to double the first-order temperature coefficient of the PTAT voltage and the CTAT voltage.

[0006] Furthermore, the reference voltage generation circuit includes multiple PMOS transistors connected in series, and the reference voltage generation circuit is used to generate two reference voltages V. REF1 and V REF2 Reference voltage V REF1 and V REF2 It is connected to the input terminals of two operational amplifiers respectively, serving as the input voltage V of the operational amplifiers.REF1 V REF2 .

[0007] Furthermore, the operational amplifier is a two-stage operational amplifier.

[0008] Furthermore, the reference current generation circuit uses the clamping action of two operational amplifiers to make the voltage V across the resistor... TOP V BOTTOM The input voltage V of the operational amplifier connected across the resistor is respectively equal to the input voltage V of the operational amplifier. REF1 V REF2 The input voltage V is obtained through the two ends of the resistor. TOP V BOTTOM The difference is used to calculate the reference current.

[0009] Furthermore, the CTAT temperature sensing voltage generation circuit includes two NMOS transistors M5 and M6 and a first current mirror M1 and M2. The gate of the first current mirror M1 is connected to the reference current generation circuit, and the gate of M2 is connected to the NMOS transistor.

[0010] Furthermore, the PTAT temperature sensing voltage generation circuit includes two PMOS transistors M7 and M8 and a second current mirror M3 and M4. The drain of the second current mirror M3 is connected to the reference current generation circuit, and the drain of M4 is connected to the PMOS transistors.

[0011] Furthermore, the first current mirror is used to copy the reference current to the branch where M2 is located through M1, and to provide bias current for the NMOS transistors M5 and M6 of the CTAT temperature sensing voltage generation circuit, so that M5 and M6 operate in the subthreshold region, and M1 and M2 are PMOS transistors.

[0012] Furthermore, the second current mirror is used to copy the reference current to the branch where M4 is located through M3, and to provide bias current for the NMOS transistors M7 and M8 of the PTAT temperature sensing voltage generation circuit, so that M7 and M8 operate in the subthreshold region, and M3 and M4 are NMOS transistors.

[0013] Furthermore, the NMOS transistors M5 and M6 in the CTAT temperature sensing voltage generation circuit are connected in series, and M5 and M6 have the same width-to-length ratio.

[0014] Furthermore, the PMOS transistors M7 and M8 in the PTAT temperature sensing voltage generation circuit are connected in series, and M7 and M8 have the same width-to-length ratio.

[0015] The beneficial effects of this invention are as follows:

[0016] The reference voltage generation circuit uses a diode stacked structure, ensuring that the generated reference voltage remains almost unchanged with temperature. The reference current generation circuit generates a reference current through a dual-loop clamping structure, requiring fewer branches, resulting in lower power consumption and better temperature stability of the reference current. The high-gain operational amplifier in the dual-loop current reference circuit clamps the voltage across the resistor to the reference voltage, reducing the voltage drop across the resistor in this type of structure and thus reducing the overall power consumption of the circuit. The reference current is used to bias the temperature-sensing MOSFET, giving the output voltage good first-order temperature characteristics. Through MOSFET stacking, the voltage temperature coefficient is doubled, improving the resolution of the temperature sensing circuit. The entire circuit completes temperature-independent current and multi-temperature sensing signal output on only four branches, reducing the required circuit area and providing high process compatibility.

[0017] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in one or more embodiments of this specification or in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a temperature sensing circuit based on a dual-loop clamping structure, provided for one or more embodiments of this specification. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this document.

[0021] This invention provides a temperature sensing circuit based on a dual-loop clamping structure. Figure 1 A schematic diagram of a temperature sensing circuit based on a dual-loop clamping structure is provided for one or more embodiments of this specification, such as... Figure 1As shown, the temperature sensing circuit based on the dual-loop clamping structure according to an embodiment of the present invention specifically includes: a reference voltage generation circuit, a reference current generation circuit, and a temperature sensing voltage generation circuit;

[0022] The reference voltage generation circuit is connected to the reference current generation circuit and is used to generate a reference voltage, which serves as the input voltage of the reference current generation circuit. The reference current generation circuit has a dual-loop clamping structure, including two operational amplifiers. The two operational amplifiers form two feedback loops, and the two operational amplifiers are respectively connected across the resistor to clamp the voltage across the resistor. The temperature sensing voltage generation circuit includes a positive temperature coefficient (PTAT) temperature sensing voltage generation circuit and a negative temperature coefficient (CTAT) temperature sensing voltage generation circuit. The PTAT temperature sensing voltage generation circuit and the CTAT temperature sensing voltage generation circuit are biased by the reference current and connected to the two operational amplifiers. The PTAT temperature sensing voltage generation circuit and the CTAT temperature sensing voltage generation circuit respectively use a diode stacking structure to double the first-order temperature coefficient of the PTAT voltage and the CTAT voltage.

[0023] Specifically, the reference voltage generation circuit includes multiple PMOS transistors connected in series. In this embodiment, the reference voltage generation circuit is formed by stacking 36 PMOS transistors. The reference voltage generation circuit is used to generate two reference voltages V. REF1 and V REF2 In the dual-loop clamping structure, the operational amplifier is a high-gain (96.8dB) two-stage operational amplifier, which makes V TOP =V REF1 V BOTTOM =V REF2 Therefore, the reference current generated across the resistor is:

[0024] I REF =(V BOTTOM -V TOP ) / R;

[0025] Reference voltage V REF1 and V REF2 The input voltage V of each operational amplifier is connected to its input terminal, providing good temperature stability for both operational amplifiers. REF1 V REF2 ;

[0026] The reference current generation circuit uses two operational amplifiers to clamp the voltage V across the resistor. TOP V BOTTOM The input voltage V of the operational amplifier connected across the resistor is respectively equal to the input voltage V of the operational amplifier. REF1 V REF2 , where V TOP =V REF1 VBOTTOM =V REF2 Thus, a voltage V is input across the resistor. TOP V BOTTOM The difference calculation produces a reference current I that is almost unchanged with temperature:

[0027] ;

[0028] The CTAT temperature sensing voltage generation circuit includes two NMOS transistors M5 and M6 and a first current mirror M1 and M2. The gate of the first current mirror M1 is connected to the reference current generation circuit, and the gate of M2 is connected to the NMOS transistor.

[0029] The first current mirror replicates the reference current to the branch containing M2 through M1, making the current I in the branch containing M2... REF1 =I, therefore I REF1 It is also the reference current, and it provides bias current to the NMOS transistors M5 and M6 of the CTAT temperature sensing voltage generation circuit connected to the diode, so that M5 and M6 operate in the subthreshold region. Among them, M1 and M2 in the first current mirror are PMOS transistors, and the leakage current is calculated as follows:

[0030]

[0031] Where K is the aspect ratio of the MOS transistor, μ is the carrier mobility, and C... ox To remove the oxide layer capacitance, V T For thermal voltage, V GS V is the gate-source voltage of the MOSFET, η is the subthreshold coefficient, and V th V is the threshold voltage of the MOSFET. DS This is the drain-source voltage of the MOSFET.

[0032] When V DS >>V T At that time, there were:

[0033]

[0034]

[0035] Where μ0 is the carrier mobility at absolute zero.

[0036] The measured value of m is approximately 2, therefore the temperature coefficient in the logarithmic term... We can ignore this and approximate that the logarithmic term is independent of temperature. Assuming the argument of the logarithmic term is M, then we have:

[0037]

[0038] Where q is the elementary charge, KB is the Boltzmann constant.

[0039] because and Therefore V GS It has a negative temperature coefficient.

[0040] The NMOS transistors M5 and M6, connected in series by two diodes, form a stacked structure. Since M5 and M6 have the same width-to-length ratio, the temperature coefficient of the gate-source voltage of M5 is:

[0041]

[0042] Therefore, the first-order temperature coefficient of the CTAT voltage was doubled.

[0043] Similarly, the PTAT temperature sensing voltage generation circuit includes two PMOS transistors M7 and M8 and a second current mirror M3 and M4. The drain of the second current mirror M3 is connected to the reference current generation circuit, and the drain of M4 is connected to the PMOS transistor.

[0044] The second current mirror replicates the reference current to the branch containing M4 through M3, making the current I in the branch containing M4... REF2 =I, therefore I REF2 It is also the reference current, and provides bias current for the NMOS transistors M7 and M8 in the diode-connected PTAT temperature sensing voltage generation circuit, so that M7 and M8 operate in the subthreshold region. Among them, M3 and M4 are NMOS transistors, and the leakage current is calculated as follows:

[0045]

[0046] Where K is the aspect ratio of the MOS transistor, μ is the carrier mobility, and C... ox To remove the oxide layer capacitance, V T For thermal voltage, V GS V is the gate-source voltage of the MOSFET, η is the subthreshold coefficient, and V th V is the threshold voltage of the MOSFET. DS This refers to the drain-source voltage of the MOSFET.

[0047] When V DS >>V T At that time, there were:

[0048]

[0049]

[0050] Where μ0 is the carrier mobility at absolute zero.

[0051] The measured value of m is approximately 2, therefore the temperature coefficient in the logarithmic term can be ignored, meaning the logarithmic term can be approximated as independent of temperature. Assuming the argument of the logarithmic term is M, then:

[0052]

[0053] Where q is the elementary charge, K B is the Boltzmann constant.

[0054] V PTAT =VDD-|V GS7 |-|V GS8 |

[0055] =VDD+V GS7 +V GS8

[0056] Due to V GS7 V GS8 It is negative, and V GS Having the above temperature characteristics, as the temperature increases, V GS The absolute value of V decreases linearly, therefore V PTAT It has a positive temperature coefficient.

[0057] The NMOS transistors M7 and M8, connected in series by two diodes, form a stacked structure. Since M7 and M8 have the same width-to-length ratio, the temperature coefficient of the gate-source voltage of M8 is:

[0058]

[0059] Therefore, the first-order temperature coefficient of the PTAT voltage is doubled.

[0060] The beneficial effects of this invention are as follows:

[0061] The reference voltage generation circuit uses a diode stacked structure, ensuring that the generated reference voltage remains almost unchanged with temperature. The reference current generation circuit generates a reference current through a dual-loop clamping structure, requiring fewer branches, resulting in lower power consumption and better temperature stability of the reference current. The high-gain operational amplifier in the dual-loop current reference circuit clamps the voltage across the resistor to the reference voltage, reducing the voltage drop across the resistor in this type of structure and thus reducing the overall power consumption of the circuit. The reference current is used to bias the temperature-sensing MOSFET, giving the output voltage good first-order temperature characteristics. Through MOSFET stacking, the voltage temperature coefficient is doubled, improving the resolution of the temperature sensing circuit. The entire circuit completes temperature-independent current and multi-temperature sensing signal output on only four branches, reducing the required circuit area and providing high process compatibility.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A temperature sensing circuit based on a dual-loop clamping structure, characterized in that, The circuit includes a reference voltage generation circuit, a reference current generation circuit, and a temperature sensing voltage generation circuit. The reference voltage generation circuit includes multiple PMOS transistors connected in series. The reference voltage generation circuit is used to generate two reference voltages. and Reference voltage and Each voltage is connected to one of the input terminals of an operational amplifier, serving as the input voltage for the operational amplifier. , The reference voltage generation circuit is connected to the reference current generation circuit and is used to generate a reference voltage, which serves as the input voltage of the reference current generation circuit. The reference current generation circuit is a dual-loop clamping structure, including two operational amplifiers (op-amps). Each op-amp forms a feedback loop, and the two op-amps are respectively connected across a resistor to clamp the voltage across the resistor. The reference current generation circuit uses the clamping action of the two op-amps to control the voltage across the resistor. , These are respectively equal to the input voltages of the operational amplifiers connected across the resistors. , Voltage is input across the resistor. , The difference is used to calculate the reference current. The temperature-sensing voltage generation circuit includes a positive temperature coefficient (PTAT) temperature-sensing voltage generation circuit and a negative temperature coefficient (CTAT) temperature-sensing voltage generation circuit. Both the PTAT and CTAT temperature-sensing voltage generation circuits are biased by a reference current and connected to the two operational amplifiers. The PTAT and CTAT temperature-sensing voltage generation circuits employ a diode stacking structure to double the first-order temperature coefficient of the PTAT and CTAT voltages, respectively. The CTAT temperature-sensing voltage generation circuit includes two NMOS transistors M5 and M6 and a first current mirror M1 and M2. The drain of the first current mirror M1 is connected to the reference current generation circuit, and the drain of M2 is connected to the NMOS transistor. The NMOS transistors M5 and M6 of the CTAT temperature-sensing voltage generation circuit are connected in series. The PTAT temperature-sensing voltage generation circuit includes two PMOS transistors M7 and M8 and a second current mirror M3 and M4. The drain of the second current mirror M3 is connected to the reference current generation circuit, and the drain of M4 is connected to the PMOS transistor. The PMOS transistors M7 and M8 of the PTAT temperature-sensing voltage generation circuit are connected in series.

2. The temperature sensing circuit according to claim 1, characterized in that, The operational amplifier is a two-stage operational amplifier.

3. The temperature sensing circuit according to claim 1, characterized in that, The first current mirror is used to copy the reference current to the branch where M2 is located through M1, and to provide bias current for the NMOS transistors M5 and M6 of the CTAT temperature sensing voltage generation circuit, so that M5 and M6 operate in the subthreshold region, and M1 and M2 are PMOS transistors.

4. The temperature sensing circuit according to claim 1, characterized in that, The second current mirror is used to copy the reference current to the branch where M4 is located through M3, and to provide bias current for the PMOS transistors M7 and M8 of the PTAT temperature sensing voltage generation circuit, so that M7 and M8 operate in the subthreshold region, and M3 and M4 are NMOS transistors.

5. The temperature sensing circuit according to claim 3, characterized in that, The NMOS transistors M5 and M6 in the CTAT temperature sensing voltage generation circuit have the same width-to-length ratio.

6. The temperature sensing circuit according to claim 4, characterized in that, The PMOS transistors M7 and M8 in the PTAT temperature sensing voltage generation circuit have the same width-to-length ratio.

Images