Band-gap reference voltage source circuit with high-order compensation

Abstract

The invention relates to the technical field of integrated circuits, in particular to a band-gap reference voltage source circuit with high-order compensation, which comprises a PTAT (proportional to absolute temperature) generation circuit, a high-order compensation circuit and a pre-voltage-stabilizing circuit, wherein the PTAT generation circuit generates PTAT current, and the high-order compensation circuit performs second-order compensation on the PTAT current; the pre-voltage-stabilizing circuit is used for driving the PTAT generation circuit and the high-order compensation circuit and comprises a starting circuit, a positive feedback loop and a negative feedback loop; the gain of the positive feedback loop is lower than that of the negative feedback loop; according to the band-gap reference voltage source circuit, the temperature coefficient and the power supply rejection ratio of the circuit are remarkably optimized by integrating high-order temperature compensation, a pre-adjusting power supply and a high-gain feedback loop, and the designed band-gap reference voltage source circuit has the advantages of being extremely low in temperature drift and high in precision.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of integrated circuits, and particularly relates to a bandgap reference voltage source circuit with high-order compensation. BACKGROUND

[0002] A bandgap reference voltage source is obtained by weighting and superimposing two voltage signals with opposite temperature coefficients (usually a positive temperature coefficient thermal voltage and a negative temperature coefficient PN junction voltage drop) in a certain proportion, and finally a zero temperature coefficient reference voltage that remains stable in a wide temperature range is obtained.

[0003] In the prior art, the temperature coefficient of the Brokaw bandgap reference is affected by the VBE nonlinearity and high-order temperature effects, and it is difficult to achieve an extremely low temperature drift (<5ppm / ℃), and the power supply rejection ratio (PSRR) is dependent on the operational amplifier gain at low frequencies and is limited by parasitic parameters at high frequencies, and is easily disturbed by power supply noise.

[0004] Therefore, there is an urgent need for a bandgap reference voltage source circuit with extremely low temperature drift and high precision. SUMMARY

[0005] Therefore, the application discloses a bandgap reference voltage source circuit with high-order compensation to solve the above problems; comprising: a PTAT generation circuit, a high-order compensation circuit and a pre-stabilization circuit; wherein the PTAT generation circuit generates a PTAT current, and the high-order compensation circuit performs second-order compensation on the PTAT current; the pre-stabilization circuit is used to drive the PTAT generation circuit and the high-order compensation circuit; the pre-stabilization circuit comprises a start-up circuit, a positive feedback loop and a negative feedback loop; the gain of the positive feedback loop is lower than that of the negative feedback loop.

[0006] The PTAT generation circuit comprises three MOS transistors M1-M3, three triodes Q1-Q3 and one resistor R1; wherein the source of M3 is connected to the source of M4 and the source of M5, the gate of M3 is connected to the drain of M3, the collector of Q1, the gate of M4 and the gate of M5, respectively; the drain of M4 is connected to the base of Q1 and the collector of Q2, respectively; the drain of M5 is connected to the base of Q2, the base of Q3 and the collector of Q3, respectively; and the emitter of Q3 is connected to one end of R1.

[0007] The high-order compensation circuit comprises 5 MOS transistors M1, M2, M6, M7 and M8, 1 capacitor C1, 3 resistors R2, R3 and R4, and 5 triodes Q4, Q5, Q6, Q7 and Q8; wherein, the source electrode of M1 is connected with the collector electrode of Q1, the drain electrode of M1 is connected with the source electrode of M2, the gate electrode of M1 is connected with the gate electrode of M2, the drain electrode of M2, the emitter electrode of Q1, one end of C1, the emitter electrode of Q2, the other end of R1 and one end of R2 respectively; the other end of C1 is connected with the base electrode of Q1; the source electrode of M6 is connected with the source electrode of M7, the collector electrode of Q5 and the source electrode of M8 and serves as the power supply end of the high-order compensation circuit, the gate electrode of M6 is connected with the gate electrode of M7, the drain electrode of M7 and the collector electrode of Q4 respectively, and the drain electrode of M6 is connected with the other end of R2 and one end of R3 respectively; the drain electrode of M8 is connected with the base electrode of Q5, the base electrode of Q6 and the collector electrode of Q6 respectively; the other end of R3 is connected with the emitter electrode of Q4, one end of R4, the emitter electrode of Q7, the emitter electrode of Q8 and the ground respectively; the other end of R4 is connected with the base electrode of Q4, the emitter electrode of Q5 and the collector electrode of Q7 respectively; the emitter electrode of Q6 is connected with the base electrode of Q7, the base electrode of Q8 and the collector electrode of Q8 respectively.

[0008] The pre-stabilization circuit comprises 6 MOS transistors M9-M14, 5 triodes Q9-Q13 and 1 resistor R5; wherein, the gate electrode of M9 is connected with the drain electrode of M9, the drain electrode of M10, the emitter electrode of Q9, one end of R5 and the emitter electrode of Q11 and grounded, the source electrode of M9 is connected with the gate electrode of M10 and the drain electrode of M11 respectively; the source electrode of M10 is connected with the drain electrode of M13, the collector electrode of Q10 and the gate electrode of M14 respectively; the gate electrode of M11 is connected with the gate electrode of M12, the drain electrode of M12, the collector electrode of Q9 and the gate electrode of M13 respectively, and the source electrode of M11 is connected with the source electrode of M12, the source electrode of M13 and the source electrode of M14 and serves as the power supply end of the pre-stabilization circuit; the drain electrode of M14 is connected with the collector electrode of Q13 and the base electrode of Q13 and serves as the output end of the pre-stabilization circuit; the emitter electrode of Q13 is connected with the collector electrode of Q12 and the base electrode of Q12 respectively; the emitter electrode of Q12 is connected with the collector electrode of Q11, the base electrode of Q11, the base electrode of Q10 and the base electrode of Q9 respectively; the emitter electrode of Q10 is connected with the other end of R5;

[0009] Further, the sizes of M3, M4, M5, M6, M7 and M8 are the same, and the sizes of M11, M12, M13 and M14 are the same.

[0010] The emitter electrode area of Q3 is 8 times of the emitter electrode area of Q2.

[0011] The sizes of Q9, Q11, Q12 and Q13 are the minimum unit sizes allowed by the process, and the size of Q10 is 4 times of the unit size.

[0012] The beneficial effects of the present application include:

[0013] A high-order compensation circuit is designed to generate I PTAT 2 The current is used to offset the nonlinear temperature coefficient in the base-emitter voltage, so that the bandgap reference voltage source circuit with high-order compensation has a low temperature coefficient of 3.8ppm / ℃;

[0014] The design of the pre-regulator circuit is used to improve the power supply rejection ratio of the bandgap reference by generating a pseudo power supply voltage. The bandgap reference voltage source circuit with high-order compensation obtained based on the design has a power supply rejection ratio of 73dB at low frequency, 72.8dB at 1kHz, and 35.2dB at 1MHz;

[0015] By integrating high-order temperature compensation, pre-regulated power supply, and high-gain feedback loop, the temperature coefficient and power supply rejection ratio of the circuit are significantly optimized, thereby meeting the stringent requirements of high-precision reference sources in complex application scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The influence of the first-order compensation on the forward-biased diode reference source in the prior art;

[0017] Figure 2 The circuit structure diagram of the traditional Brokaw structure bandgap reference voltage source in the prior art;

[0018] Figure 3 The circuit structure diagram of the PTAT generation circuit and the high-order compensation circuit in the embodiment of the present application;

[0019] Figure 4 The circuit structure diagram of the pre-regulator circuit in the embodiment of the present application;

[0020] Figure 5 The temperature drift characteristic curve of the bandgap reference voltage source circuit with high-order compensation in the embodiment of the present application;

[0021] Figure 6 The power supply rejection ratio characteristic curve of the bandgap reference voltage source circuit with high-order compensation in the embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme, characteristics and advantages of the present application more clear and explicit, and to make the technical personnel in the art better understand the technical scheme of the present application, the present application will be further described in detail in combination with the drawings and embodiments.

[0023] The application comprises a bandgap reference voltage source circuit with high-order compensation, comprising: a PTAT generation circuit, a high-order compensation circuit, and a pre-stabilization circuit; wherein the PTAT generation circuit generates a PTAT current, and the high-order compensation circuit performs second-order compensation on the PTAT current; and the pre-stabilization circuit is used to drive the PTAT generation circuit and the high-order compensation circuit.

[0024] The PTAT generation circuit comprises: three MOS transistors M1-M3, three triodes Q1-Q3, and one resistor R1; wherein the source of M3 is connected to the source of M4 and the source of M5, the gate of M3 is connected to the drain of M3, the collector of Q1, the gate of M4, and the gate of M5; the drain of M4 is connected to the base of Q1 and the collector of Q2; the drain of M5 is connected to the base of Q2, the base of Q3, and the collector of Q3; and the emitter of Q3 is connected to one end of R1.

[0025] The high-order compensation circuit comprises: five MOS transistors M1, M2, M6, M7, and M8, one capacitor C1, three resistors R2, R3, and R4, and five triodes Q4, Q5, Q6, Q7, and Q8; wherein the source of M1 is connected to the collector of Q1, the drain of M1 is connected to the source of M2, the gate of M1 is connected to the gate of M2, the drain of M2, the emitter of Q1, one end of C1, the emitter of Q2, the other end of R1, and one end of R2; the other end of C1 is connected to the base of Q1; the source of M6 is connected to the source of M7, the collector of Q5, and the source of M8, and serves as a power supply end of the high-order compensation circuit, the gate of M6 is connected to the gate of M7, the drain of M7, and the collector of Q4, and the drain of M6 is connected to the other end of R2 and one end of R3; the drain of M8 is connected to the base of Q5, the base of Q6, and the collector of Q6; the other end of R3 is connected to the emitter of Q4, one end of R4, the emitter of Q7, the emitter of Q8, and the ground; the other end of R4 is connected to the base of Q4, the emitter of Q5, and the collector of Q7; and the emitter of Q6 is connected to the base of Q7, the base of Q8, and the collector of Q8.

[0026] Further, the sizes of M3, M4, M5, M6, M7, and M8 are the same, and cross matching is realized on the layout to reduce the performance difference between devices caused by uncontrollable factors in the manufacturing process as much as possible. The triodes designed in the application are all bipolar transistors (BJT).

[0027] In the PTAT generation circuit, the emitter area of ​​Q3 is 8 times that of Q2. In this embodiment, the emitter area of ​​Q2 is 4 times the smallest unit size allowed by the process, in order to improve the matching performance between Q2 and Q3 as much as possible. Q3 and Q2 can be implemented by parallel transistors, with the number of parallel Q3 transistors being 8 times the number of parallel Q2 transistors. In this case, Q2 is placed in the middle of the 8 bipolar transistors Q3, forming an array structure.

[0028] In existing technologies, first-order or zero-order compensated forward-biased diode reference sources are often referred to as bandgap reference sources, with a typical output voltage of approximately 1.2V, roughly the diode voltage at 0K. By adding the PTAT (Proportional To Absolute Temperature) voltage to a base-emitter voltage, the negative temperature coefficient of the base-emitter voltage can be effectively offset, thus achieving first-order temperature compensation. The resulting reference voltage exhibits better temperature drift performance than a zero-order reference voltage, typically 20~50ppm / ℃. However, due to the presence of the logarithmic component in the diode voltage-temperature characteristic, the improvement achieved by first-order compensation is quite limited. Figure 1 The diagram illustrates the effect of first-order compensation on a forward-biased diode reference source. It can be seen that the PTAT voltage source only effectively cancels the CTAT (Complementary to Absolute Temperature) characteristic of the reference source. The output voltage still exhibits the logarithmic characteristics of the diode voltage and is not a completely zero-temperature coefficient.

[0029] Traditional Brokaw bandgap reference voltage sources utilize the base-emitter voltage of a bipolar transistor (NPN) and the voltage obtained by the positive temperature coefficient current flowing through a resistor to obtain a zero-temperature coefficient bandgap reference voltage. The circuit structure is as follows: Figure 2 As shown. The formula for the output voltage of a traditional Brokaw bandgap reference voltage source is:

[0030]

[0031] in, This represents the output voltage of a traditional Brokaw bandgap reference voltage source. Indicates reference temperature The silicon bandgap voltage at that point, This represents the base-emitter voltage of a bipolar transistor. Represents absolute temperature. Coefficients representing the relationship between process technology and transistor physical characteristics. This is a coefficient related to the transistor's operating current characteristics. Indicates thermal voltage. This represents the ratio of the emitter junction area of ​​Q2 to that of Q1. It is 300k, which shows that With temperature The relationship between them is a first-order linear one. By adjusting the ratio of the resistance values ​​of R1 and R0 through first-order compensation, the second and fourth terms can cancel each other out, achieving the effect of temperature compensation. However, due to the existence of a non-linear term with respect to temperature... In order to obtain a smaller temperature coefficient, high-order curvature compensation techniques must be used to eliminate nonlinear terms.

[0032] This application designs a high-order compensation circuit to solve the above problems, specifically:

[0033] The loop formed by transistors Q2 and Q3 and resistor R1 generates a PTAT current, which flows through resistors R2 and R3. If the PTAT2 current is ignored, this circuit is a first-order bandgap reference source circuit, and the reference voltage is the simple sum of the base-emitter voltage of transistor Q2 and the PTAT voltage across resistors R2 and R3. When the PTAT2 current is forced to flow through resistor R3, the circuit achieves second-order correction, and the reference voltage is expressed as:

[0034]

[0035] in, This indicates the output voltage of the bandgap reference voltage source circuit with high-order compensation designed in this application. This represents the base-emitter voltage of transistor Q2. This indicates the current generated by the PTAT generation module. This indicates the current in PTAT2.

[0036] Furthermore, Q4, Q5, Q6, and Q8 form an intrinsic voltage loop. By summing the voltages in the loop and substituting each base-emitter voltage into the formula for the reference voltage based on KVL's law, we obtain... Derivation formula for the current generation process:

[0037]

[0038] in, express The output current of the generating circuit, i.e. Figure 3 The drain current of M6, This represents the current that is positively correlated with temperature. All are constants.

[0039] Furthermore, the temperature characteristics of a bipolar transistor are as follows:

[0040]

[0041] in, This represents the base-emitter voltage of a bipolar transistor. This represents the voltage of the transistor at 0K. Represents a linear term. Represents nonlinear terms, and Let represent constants that are independent of temperature. Indicates temperature.

[0042] This application designs a high-order compensation circuit to generate a current I with a nonlinear positive temperature coefficient. PTAT 2 , will I PTAT 2 With a current I having a linear positive temperature coefficient PTAT The base-emitter voltages are added together to compensate for the difference, using the following formula:

[0043]

[0044] Among them, voltage Through PTAT generation circuit and PTAT 2 Generating circuit, constant Approximately , Representing the nonlinear term, it is approximated as: ;like Figure 3 As shown, this application uses PTAT 2 Component compensation method , PTAT 2 The voltage, PTAT voltage, and diode voltage (i.e., base-emitter voltage) are added together to obtain the reference voltage for curvature correction higher-order compensation.

[0045] Furthermore, the pre-regulator circuit includes a startup circuit, a positive feedback loop, and a negative feedback loop; the gain of the positive feedback loop is lower than the gain of the negative feedback loop; the pre-regulator circuit constitutes a pseudo power supply voltage structure to improve the power supply rejection ratio of the bandgap reference circuit.

[0046] like Figure 4As shown, the pre-stabilization circuit is composed of 6 MOS transistors M9-M14, 5 triodes Q9-Q13 and 1 resistor R5; wherein the gate of M9 is connected to the drain of M9, the drain of M10, the emitter of Q9, one end of R5, the emitter of Q11 and the ground, the source of M9 is connected to the gate of M10 and the drain of M11; the source of M10 is connected to the drain of M13, the collector of Q10 and the gate of M14; the gate of M11 is connected to the gate of M12, the drain of M12, the collector of Q9 and the gate of M13, the source of M11 is connected to the source of M12, the source of M13 and the source of M14 and serves as the power supply end of the pre-stabilization circuit; the drain of M14 is connected to the collector of Q13 and the base of Q13 and serves as the output end of the pre-stabilization circuit; the emitter of Q13 is connected to the collector of Q12 and the base of Q12; the emitter of Q12 is connected to the collector of Q11, the base of Q11, the base of Q10 and the base of Q9; the emitter of Q10 is connected to the other end of R5.

[0047] Wherein M9, M10 and M11 constitute a starting circuit, Q9, Q11, Q12, Q13, M12, M13 and M14 constitute a positive feedback loop, and Q10 and R5 constitute a negative feedback loop. In the negative feedback loop, Q10 serves as a current source of M13 and simultaneously provides a positive feedback path for the output of the circuit. In the positive feedback loop, a negative feedback resistor is arranged on the emitter of Q10, and no feedback resistor is arranged on the emitter of Q9 in the negative feedback loop, so that the gain of the positive feedback loop is relatively low.

[0048] When the pre-stabilization circuit is working, M10 compares the current passing through Q9 with the current passing through M9. If the current passing through Q9 is smaller, M10 will pull down the gate voltage of M14 and forcibly change the current of Q11, thereby changing the current of Q9. If the current passing through Q9 is larger, M10 will be turned off and the circuit will work normally.

[0049] Further, Q9, Q10 and R5 constitute a PTAT current source generation circuit. Since for the pre-stabilization circuit, the accuracy is not the most important factor affecting the output, except that Q10 needs a larger size to generate the PTAT current, all other NPN devices can select the smallest size. In the present application, the sizes of Q9, Q11, Q12 and Q13 are selected to be the smallest unit size allowed by the process, and the size of Q10 is selected to be 4 times the unit size to save the chip area. In addition, Q10 and Q9 can also be realized by parallel triodes respectively, and the number of parallel Q10 is 4 times the number of parallel Q9.

[0050] Further, in the present application, M11, M12, M13 and M14 have the same size.

[0051] Further, the bandgap reference circuit designed in the application is simulated and tested, and the test results are shown in Figs. 6-8. Figure 5 , Figure 6 Figure 5 The temperature drift characteristic curve of the bandgap reference circuit in the embodiment is shown in Fig. 6. It can be seen from the figure that the maximum and minimum difference of the bandgap reference output voltage of the design is 0.8mV, which has extremely low temperature drift, and the temperature coefficient is 3.8ppm / ℃. Figure 6 The power supply rejection ratio characteristic curve of the bandgap reference circuit in the embodiment is shown in Fig. 7. It can be seen from the figure that the power supply rejection ratio of the bandgap reference of the design is 73dB at low frequency, 72.8dB at 1kHz, and 35.2dB at 1MHz.

[0052] The above only describes some embodiments of the application, and those skilled in the art can think of various changes, modifications, replacements and deformations of the embodiments without departing from the principles and spirits of the application. The protection scope of the application is defined by the appended claims and their equivalents, and the above behaviors should be covered in the protection scope of the application.​

Claims

1. A bandgap reference voltage source circuit with high order compensation, characterized by, The application relates to a PTAT generating circuit, a high-order compensation circuit and a pre-stabilization circuit. The pre-stabilization circuit is used for driving the PTAT generating circuit and the high-order compensation circuit. The PTAT generating circuit comprises three MOS transistors M1-M3, three triodes Q1-Q3 and one resistor R1; the source of the M3 is connected with the source of the M4 and the source of the M5, the gate of the M3 is connected with the drain of the M3, the collector of the Q1, the gate of the M4 and the gate of the M5, the drain of the M4 is connected with the base of the Q1 and the collector of the Q2, the drain of the M5 is connected with the base of the Q2, the base of the Q3 and the collector of the Q3, and the emitter of the Q3 is connected with one end of the R1.

2. The bandgap reference voltage source circuit with high order compensation of claim 1, wherein, The high-order compensation circuit comprises five MOS transistors M1, M2, M6, M7 and M8, one capacitor C1, three resistors R2, R3 and R4, and five triodes Q4, Q5, Q6, Q7 and Q8; the source of the M1 is connected with the collector of the Q1, the drain of the M1 is connected with the source of the M2, the gate of the M1 is connected with the gate of the M2, the drain of the M2, the emitter of the Q1, one end of the C1, the emitter of the Q2, the other end of the R1 and one end of the R2, the other end of the C1 is connected with the base of the Q1, the source of the M6 is connected with the source of the M7, the collector of the Q5 and the source of the M8 and is used as the power supply end of the high-order compensation circuit, the gate of the M6 is connected with the gate of the M7, the drain of the M7 and the collector of the Q4, the drain of the M6 is connected with the other end of the R2 and one end of the R3, the drain of the M8 is connected with the base of the Q5, the base of the Q6 and the collector of the Q6, the other end of the R3 is connected with the emitter of the Q4, one end of the R4, the emitter of the Q7, the emitter of the Q8 and the ground, and the other end of the R4 is connected with the base of the Q4, the emitter of the Q5 and the collector of the Q7; the emitter of the Q6 is connected with the base of the Q7, the base of the Q8 and the collector of the Q8. The triode is a bipolar transistor.

3. The bandgap reference voltage source circuit with high order compensation of claim 2, wherein, The sizes of the M3, M4, M5, M6, M7 and M8 are the same.

4. The bandgap reference voltage source circuit with high order compensation of claim 2, wherein, The emitter area of the Q3 is 8 times of the emitter area of the Q2.

5. The bandgap reference voltage source circuit with high order compensation of claim 2, wherein, The pre-stabilization circuit comprises a starting circuit, a positive feedback loop and a negative feedback loop; the gain of the positive feedback loop is lower than the gain of the negative feedback loop.

6. The bandgap reference voltage source circuit with high order compensation of claim 1, wherein, ​ 7. The bandgap reference voltage source circuit with high order compensation of claim 6, wherein, The pre-stabilization circuit is composed of 6 MOS transistors M9-M14, 5 triodes Q9-Q13 and 1 resistor R5; wherein the gate of M9 is connected with the drain of M9, the drain of M10, the emitter of Q9, one end of R5, the emitter of Q11 and the ground, the source of M9 is connected with the gate of M10 and the drain of M11; the source of M10 is connected with the drain of M13, the collector of Q10 and the gate of M14; the gate of M11 is connected with the gate of M12, the drain of M12, the collector of Q9 and the gate of M13, the source of M11 is connected with the source of M12, the source of M13 and the source of M14 and serves as the power supply end of the pre-stabilization circuit; the drain of M14 is connected with the collector of Q13 and the base of Q13 and serves as the output end of the pre-stabilization circuit; the emitter of Q13 is connected with the collector of Q12 and the base of Q12; the emitter of Q12 is connected with the collector of Q11, the base of Q11, the base of Q10 and the base of Q9; the emitter of Q10 is connected with the other end of R5.

8. The bandgap reference voltage source circuit with high order compensation of claim 7, wherein, The triode is a bipolar transistor.

9. The bandgap reference voltage source circuit with high order compensation of claim 7, wherein, The sizes of M11, M12, M13 and M14 are the same.

10. The bandgap reference voltage source circuit with high order compensation of claim 7, wherein, The sizes of Q9, Q11, Q12 and Q13 are the minimum unit sizes allowed by the process, and the size of Q10 is 4 times the unit size.

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