A low-power bandgap reference voltage source

Abstract

The present invention discloses a low-power bandgap reference voltage source, addressing the circuit complexity, high power consumption, and low precision inherent in existing technologies. The bandgap reference voltage source circuit comprises a bandgap reference core circuit and a temperature compensation circuit. The bandgap reference core circuit utilizes MOS transistor leakage current to generate a positive temperature coefficient voltage, eliminating the need for a startup circuit and significantly reducing power consumption. The temperature compensation circuit employs an exponential current for curvature correction. The advantages of this circuit lie in its novel bandgap reference voltage generation circuit, which significantly reduces power consumption and maintains a simple structure. The exponential temperature compensation circuit effectively improves the accuracy of the bandgap reference source.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a low-power bandgap reference voltage source. Background Art

[0002] In integrated circuits, stable reference voltages are crucial because many circuits and modules require an accurate voltage reference for proper operation. Bandgap references provide a stable voltage reference that is unaffected by variations in supply voltage, temperature, or manufacturing process variations.

[0003] A traditional bandgap reference circuit such as Figure 1 As shown, it contains two bipolar transistors, an operational amplifier and a resistor. Its basic principle is to use the voltage difference between the base and emitter of two bipolar transistors with different current densities to generate a positive temperature coefficient. , multiply this voltage by a certain coefficient and then add it to the base-emitter voltage of the bipolar transistor (with a negative temperature coefficient) to achieve first-order temperature compensation, thereby obtaining an output voltage with an approximate zero temperature coefficient , its formula can be expressed as:

[0004] (1)

[0005] in is the output reference voltage, is the base-emitter voltage of transistor Q1, is the thermal voltage, and N is the number of transistors Q2 connected in parallel.

[0006] Bipolar transistor base voltage The relationship with temperature is as follows:

[0007] (2)

[0008] in is the bandgap voltage, which is about 1.12V, is the reference temperature, The emitter junction is at the reference temperature The junction voltage at is a constant that is process-dependent and temperature-independent, is the coefficient related to the temperature characteristic of the collector current, is the Boltzmann constant, is the thermodynamic temperature, is the electron charge.

[0009] It can be seen that the traditional bandgap reference circuit only compensates the base-emitter voltage of the bipolar transistor. The first-order component in the bandgap reference is eliminated, while the higher-order components related to temperature still exist, severely affecting the temperature coefficient of the output voltage and failing to meet the requirements of high-precision circuits. Furthermore, traditional bandgap reference circuits generally have high power consumption, limited by two main factors: 1) Traditional bandgap reference circuits have a "degeneracy point," which requires a startup circuit to be designed to avoid it, and this startup circuit consumes quiescent current; 2) Traditional circuits use the base-emitter voltage difference of bipolar transistors to generate a positive temperature coefficient voltage, which requires a certain junction bias voltage. Summary of the Invention

[0010] To solve the technical problems existing in the above circuit, the present invention proposes a low-power bandgap reference voltage source circuit, which reduces the temperature coefficient of the reference source while achieving ultra-low power consumption. The detailed technical solution of the present invention is as follows:

[0011] A low-power bandgap reference voltage source, comprising a bandgap reference core circuit and a temperature compensation circuit;

[0012] The bandgap reference core circuit includes a first NMOS transistor MN1, L second NMOS transistors MN2, a third NMOS transistor MN3, a first PMOS transistor MP1, a transistor Q1, an operational amplifier A1, a first resistor R1, a second resistor R2 and a first adjustable resistor Rt1; wherein the drain of MN3 is connected to the power supply potential , its source is connected to the drains of all MN2, the gate of MN3, the drain and gate of MN1, the gate and source of all MN2, and the negative input of the operational amplifier; the source of MN1 is grounded; the output of the operational amplifier is connected to the gate of MP1; Q1 is connected in the form of a diode, with its anode connected to the drain of MP1; the first end of Rt1 is connected to the cathode of Q1, and the second end is connected to the first end of R2, the second end of R2, the first end of R1, and the positive input of the operational amplifier are connected in common, and the second end of R1 is connected to ground potential;

[0013] The temperature compensation circuit includes a fifth NMOS transistor MN5, a sixth NMOS transistor MN6, a second PMOS transistor MP2, a third PMOS transistor MP3, a fourth PMOS transistor MP4, a fifth PMOS transistor MP5, a sixth PMOS transistor MP6, a seventh PMOS transistor MP7, a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a second adjustable resistor Rt2; wherein the gates of MP2 and MP3 are connected to the gate of MP1, and the sources of MP2 and MP3 are connected to the power supply potential The sources of MP4 and MP5 are connected and connected to the drain of MP2; the sources of MP6 and MP7 are connected and connected to the drain of MP3; the gates of MP5 and MP6 are connected, the drains of MP5 and MP7 are connected and connected to the ground potential; the drains of MP4 and MP6 are connected and connected to the drain of MN6; the gates of MN5 and MN6 are connected and connected to the drain of MN6, and the sources of MN5 and MN6 are connected to the ground potential; Rt2, R3, R4, and R5 are connected in series in sequence, wherein the first terminal of Rt2 is connected to the positive electrode of the transistor Q1, the second terminal of Rt2 and the first terminal of R3 are both connected to the output signal , the second end of R3, the first end of R4, and the gate of MP4 are connected in common, the second end of R4, the first end of R5, and the gate of MP7 are connected in common, and the second end of R5 is connected to the ground potential; the drain of MN5 is connected to the first end of R2 and the second end of Rt1.

[0014] Furthermore, the bandgap reference core circuit is used to generate a positive temperature coefficient voltage The temperature compensation circuit generates an exponential compensation current to compensate for the temperature drift of the reference voltage source; the low power bandgap reference voltage source generates a positive temperature coefficient voltage generated by the bandgap reference core circuit The exponential compensation current generated by the temperature compensation circuit and the negative temperature coefficient voltage generated by a transistor The superposition produces a voltage with approximately zero temperature coefficient.

[0015] Furthermore, a positive temperature coefficient voltage is generated at the drain terminal of MN1. This voltage is clamped to the first end of R1 through operational amplifier A1, generating a positive temperature coefficient current on R1. , this current flows through R1, R2, Rt1, generating The positive temperature coefficient voltage and the negative temperature coefficient voltage generated by transistor Q1 Adding them together produces a zero temperature coefficient voltage, which is calculated as:

[0016] (3).

[0017] Furthermore, MP4 and MP5, as well as MP6 and MP7 form two pairs of MOS pairs working in the subthreshold region, which can generate two exponential currents. The two currents are added together and copied through the current mirror composed of MN5 and MN6 to form a positive temperature coefficient current generated on R1 in the bandgap reference source core circuit. Added together, this current compensates for the negative temperature coefficient voltage The higher-order terms in , ultimately achieve zero temperature coefficient bandgap voltage.

[0018] Furthermore, the first adjustable resistor Rt1 and the second adjustable resistor Rt2 are two trimming resistor networks, and the output voltage V is adjusted by modifying the resistance value of the second adjustable resistor.REF The absolute value of V is adjusted by modifying the resistance of the first adjustable resistor. REF The temperature coefficient is adjusted.

[0019] The advantages of the present invention compared to the prior art are as follows:

[0020] The function of the bandgap reference source core circuit of the present invention is to generate a voltage that is positively correlated with temperature and negative temperature coefficient voltage. The values ​​are weighted to produce a reference voltage that is approximately independent of temperature.

[0021] The function of the temperature compensation circuit of the present invention is to use the MOS tube working in the subthreshold region to generate a compensation current that is exponentially related to the temperature, thereby realizing the base-emitter voltage of the bipolar transistor. Compensation for medium and high order nonlinear terms.

[0022] The low-power bandgap voltage reference provided by this invention utilizes the leakage current of MOS transistors to construct a simple circuit to generate a positive temperature coefficient voltage, achieving ultra-low power consumption. Furthermore, an exponential compensation current is generated by a MOS pair operating in the subthreshold region, reducing the temperature coefficient of the reference circuit. This circuit has a simple structure, extremely low power consumption, and excellent temperature drift performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of a traditional bandgap reference voltage source circuit.

[0024] Figure 2 This is a schematic diagram of a temperature compensation circuit for a low-power bandgap reference voltage source circuit provided in the present invention.

[0025] Figure 3 This is a schematic diagram of a low-power bandgap reference voltage source circuit provided by the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described and illustrated below in conjunction with specific embodiments. The embodiments are merely illustrative of the present disclosure and do not limit its scope. The technical features of the various embodiments of the present invention may be combined accordingly, provided that there is no conflict between them.

[0027] In the embodiment of the present application, a circuit involved in a low-power bandgap reference voltage source includes a bandgap reference source core circuit 1 and a temperature compensation circuit 2 connected in sequence, such as Figure 3 The specific design process is as follows:

[0028] Reference Figure 3The bandgap reference source core circuit 1 includes NMOS transistors: MN1, MN2, MN3; PMOS transistor: MP1; resistors: R1, R2; first adjustable resistor Rt1; transistor: Q1; operational amplifier: A1. The drain of MN3 is connected to the power supply potential. , its source is connected to the drains of all MN2s, the gate of MN3, the drain and gate of MN1, the gate and source of all MN2s, and the negative input of the operational amplifier; the source of MN1 is grounded; the output of the operational amplifier is connected to the gate of MP1; Q1 is connected in diode form, with its anode connected to the drain of MP1; the first end of Rt1 is connected to the cathode of Q1, and the second end is connected to the first end of R2; the second end of R2, the first end of R1, and the positive input of the operational amplifier are connected in common, and the second end of R1 is connected to ground potential; MN1 and MN2 are identical MOS transistors, and the number of MN2s connected in parallel is L. The gate and source of MN2 are shorted, forming a reverse-biased diode connection, so only leakage current flows, which is:

[0029] (4)

[0030] in is the reverse saturation current of MN2.

[0031] The drain-source short circuit of MN1 also forms a diode. The middle node between MN1 and MN2 is , the current flowing through MN1 is:

[0032] (5)

[0033] According to equations (4) and (5), the positive temperature coefficient voltage expression can be obtained as follows:

[0034] (6)

[0035] The voltage across resistor R1 is , a positive temperature coefficient current flows through R1, and its value is:

[0036] (7)

[0037] Reference Figure 3 The temperature compensation circuit 2 includes NMOS transistors: MN5, MN6; PMOS transistors: MP2, MP3, MP4, MP5, MP6, MP7; resistors: R3, R4, R5, Rt2. The gates of MP2 and MP3 are connected to the gate of MP1, and the sources of MP2 and MP3 are connected to the power supply potential. The sources of MP4 and MP5 are connected and connected to the drain of MP2; the sources of MP6 and MP7 are connected and connected to the drain of MP3; the gates of MP5 and MP6 are connected, the drains of MP5 and MP7 are connected and connected to the ground potential; the drains of MP4 and MP6 are connected and connected to the drain of MN6; the gates of MN5 and MN6 are connected and connected to the drain of MN6, and the sources of MN5 and MN6 are connected to the ground potential; Rt2, R3, R4, and R5 are connected in series in sequence, wherein the first terminal of Rt2 is connected to the positive electrode of the transistor Q1, the second terminal of Rt2 and the first terminal of R3 are both connected to the output signal , the second end of R3, the first end of R4, and the gate of MP4 are connected in common, the second end of R4, the first end of R5, and the gate of MP7 are connected in common, and the second end of R5 is connected to the ground potential; the drain of MN5 is connected to the first end of R2 and the second end of Rt1.

[0038] In the present invention, the bandgap reference core circuit (1) is used to generate a positive temperature coefficient voltage The temperature compensation circuit (2) generates an exponential compensation current to compensate for the temperature drift of the reference voltage source; the low-power bandgap reference voltage source converts the positive temperature coefficient voltage generated by the bandgap reference core circuit (1) into The exponential compensation current generated by the temperature compensation circuit (2) and the negative temperature coefficient voltage generated by a transistor The superposition generates a voltage with an approximate zero temperature coefficient. Specifically, a positive temperature coefficient voltage is generated at the drain end of MN1. This voltage is clamped to the first end of R1 through operational amplifier A1, generating a positive temperature coefficient current on R1. , this current flows through R1, R2, Rt1, generating The positive temperature coefficient voltage and the negative temperature coefficient voltage generated by transistor Q1 Added together, they produce a zero temperature coefficient voltage.

[0039] Figure 2 (a) is the schematic diagram of the temperature compensation circuit, which is used to generate exponential current to compensate The high-order terms that change with temperature. From formula (2), we can know that The temperature change curve is a downward-opening curve, so the goal of the temperature compensation module is to generate a curve that opens upward with temperature changes to compensate for its temperature coefficient. Therefore, two pairs of MOS pairs working in the subthreshold region are used, namely MP4 and MP5, and MP6 and MP7, which can generate two exponential currents. The sum of these two currents is copied through the current mirror composed of MN5 and MN6, and the positive temperature coefficient current is generated on R1 in the bandgap reference source core circuit. Added together, this current compensates for the negative temperature coefficient voltage The high-order terms in , ultimately achieve zero temperature coefficient bandgap voltage. Figure 2 As shown, the compensation current generated by one of the MOS pairs is:

[0040] (8)

[0041] Where V X Is a voltage that does not change with temperature, V PTAT It is a voltage that is positively correlated with temperature.

[0042] when hour:

[0043] (9)

[0044] In the above formula, γ is the positive temperature coefficient. is the reference temperature.

[0045] Then when When , the compensation current generated by the MOS pair composed of MP4 and MP5 is:

[0046] (10)

[0047] Similarly, the compensation current generated by another pair of MOS pairs working in the subthreshold region, MP6 and MP7, is:

[0048] (11)

[0049] The two compensation currents are added together to generate the compensation current I through the current mirror composed of MN5 and MN6. COMP , compensate V BE The high-order terms in (9) vary with temperature, and V X In the two pairs of subthreshold MOS tubes, the voltage divider network of Rt2, R3, R4, and R5 generates two different voltages that do not change with temperature. Figure 3 In the figure, they are represented as V h and V l , Rt2 can adjust V h and V l voltage value.

[0050] The compensated reference voltage is expressed as:

[0051]

[0052] The first adjustable resistor Rt1 and the second adjustable resistor Rt2 are two trimming resistor networks. By modifying the resistance value of the second adjustable resistor, the I COMP value, thus the output voltage V REF By modifying the absolute value of the first adjustable resistor, V REF The temperature coefficient is adjusted.

[0053] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. Persons skilled in the art will readily appreciate that variations and modifications may be made without departing from the scope of the present invention, all of which fall within the scope of protection of the present invention.

Claims

1. A low-power bandgap reference voltage source, characterized in that: include: A bandgap reference core circuit (1) and a temperature compensation circuit (2); The bandgap reference core circuit (1) comprises a first NMOS transistor MN1, L second NMOS transistors MN2, a third NMOS transistor MN3, a first PMOS transistor MP1, a transistor Q1, an operational amplifier, a first resistor R1, a second resistor R2 and a first adjustable resistor Rt1; wherein the drain of MN3 is connected to the power supply potential The source of MN3 is connected to the drains of all MN2s; the gate of MN3, the drain and gate of MN1, the gates and sources of all MN2s, and the negative input of the operational amplifier are connected in common; the source of MN1 is grounded; the output of the operational amplifier is connected to the gate of MP1; Q1 is connected in diode form, with its anode connected to the drain of MP1; its cathode is connected to the first end of Rt1, the second end of Rt1 is connected to the first end of R2, the second end of R2, the first end of R1, and the positive input of the operational amplifier are connected in common, and the second end of R1 is connected to ground potential; The temperature compensation circuit (2) comprises a fifth NMOS transistor MN5, a sixth NMOS transistor MN6, a second PMOS transistor MP2, a third PMOS transistor MP3, a fourth PMOS transistor MP4, a fifth PMOS transistor MP5, a sixth PMOS transistor MP6, a seventh PMOS transistor MP7, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a second adjustable resistor Rt2; wherein the gates of MP2 and MP3 are both connected to the gate of MP1, and the sources of MP2 and MP3 are both connected to the power supply potential The sources of MP4 and MP5 are connected and connected to the drain of MP2; the sources of MP6 and MP7 are connected and connected to the drain of MP3; the gates of MP5 and MP6 are connected, the drains of MP5 and MP7 are connected and connected to the ground potential; the drains of MP4 and MP6 are connected and connected to the drain of MN6; the gates of MN5 and MN6 are connected and connected to the drain of MN6, and the sources of MN5 and MN6 are connected to the ground potential; Rt2, R3, R4, and R5 are connected in series in sequence, wherein the first terminal of Rt2 is connected to the positive electrode of the transistor Q1, the second terminal of Rt2 and the first terminal of R3 are both connected to the output signal , the second end of R3, the first end of R4, and the gate of MP4 are connected in common, the second end of R4, the first end of R5, and the gate of MP7 are connected in common, and the second end of R5 is connected to the ground potential; the drain of MN5 is connected to the first end of R2 and the second end of Rt1.

2. A low-power bandgap reference voltage source according to claim 1, characterized in that: The bandgap reference core circuit (1) is used to generate a positive temperature coefficient voltage The temperature compensation circuit (2) generates an exponential compensation current to compensate for the temperature drift of the reference voltage source; the low-power bandgap reference voltage source converts the positive temperature coefficient voltage generated by the bandgap reference core circuit (1) into The exponential compensation current generated by the temperature compensation circuit (2) and the negative temperature coefficient voltage generated by a transistor The superposition produces a voltage with approximately zero temperature coefficient.

3. The low-power bandgap reference voltage source according to claim 1, wherein: Generates a positive temperature coefficient voltage at the drain end of MN1 This voltage is clamped to the first end of R1 through the operational amplifier, generating a positive temperature coefficient current on R1. , this current flows through R1, R2, Rt1, generating The positive temperature coefficient voltage and the negative temperature coefficient voltage generated by transistor Q1 Adding them together produces a zero temperature coefficient voltage, which is calculated as: 。 4. The low-power bandgap reference voltage source according to claim 1, wherein: MP4 and MP5, as well as MP6 and MP7 form two pairs of MOS pairs working in the subthreshold region, which can generate two exponential currents. The two currents are added together and copied through the current mirror composed of MN5 and MN6 to generate a positive temperature coefficient current on R1 in the bandgap reference core circuit. Add to compensate for negative temperature coefficient voltage The higher-order terms in , ultimately achieve zero temperature coefficient bandgap voltage.

5. The low-power bandgap reference voltage source according to claim 1, wherein: The first adjustable resistor Rt1 and the second adjustable resistor Rt2 are two trimming resistor networks. By modifying the resistance value of the second adjustable resistor, the output voltage V REF The absolute value of V is adjusted by modifying the resistance of the first adjustable resistor. REF The temperature coefficient is adjusted.

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