A circuit for suppressing temperature drift of NPN bandgap reference source

Abstract

The present invention discloses a circuit for suppressing the temperature drift of an NPN-type bandgap reference source, and relates to the technical field of analog integrated circuits, including: a third resistor, whose input end is connected to the output end of the NPN-type bandgap reference source; a current generating module, whose input end is connected to the output end of the third resistor, and is used to generate a compensation current; the current generating module includes a third NPN-type triode and a fourth NPN-type triode, a fourth resistor and a fifth resistor, and a first P-type MOS tube and a first P-type MOS tube; the ratio of the fourth resistor and the fifth resistor can be adjusted, and the compensation current value is 0 below medium and high temperatures, and drifts up at the same time as the original bandgap reference voltage at high temperatures, and the high-order temperature drift voltage of the original bandgap reference voltage at high temperatures is well suppressed by the third resistor. The compensation current flows through R The compensated bandgap reference voltage generated after 3 is output as a new bandgap voltage.

Description

Technical Field

[0001] The invention relates to the technical field of analog integrated circuits, and in particular to a circuit for suppressing temperature drift of an NPN type bandgap reference source. Background Art

[0002] The bandgap reference source can provide a reference voltage source that is independent of voltage fluctuations and temperature changes. It is the core module of analog, digital and mixed analog and digital circuits. Many electrical systems are designed to work under various physical conditions, so the stability of the reference voltage is crucial. For example, in power management circuits, the ever-changing load conditions bring different degrees of heat, requiring the circuit to work within a wide temperature range. However, the base-emitter voltage of bipolar transistors usually contains multi-order components, resulting in the temperature coefficient of the bandgap reference source using first-order temperature compensation technology being limited to 15×10 -6 / ℃. It is difficult to meet the design requirements of high-precision systems. Therefore, for high-precision bandgap reference voltage sources, additional compensation must be used to improve accuracy. Summary of the invention

[0003] The present invention provides a circuit for suppressing the temperature drift of an NPN type bandgap reference source, which solves the problem that the base-emitter voltage of an existing bipolar transistor usually contains multi-order components, resulting in the temperature coefficient of the bandgap reference source being limited to 15×10 -6 / ℃, which makes it difficult to meet the design requirements of high-precision systems.

[0004] The present invention provides a circuit for suppressing temperature drift of an NPN type bandgap reference source, comprising:

[0005] A third resistor, one end of which is connected to the output end of an NPN type bandgap reference source, and the output end of the NPN type bandgap reference source outputs an original bandgap reference voltage;

[0006] A current generating module, whose input end is connected to the other end of the third resistor, is used to generate a compensation current; the current generating module includes a third NPN transistor and a fourth NPN transistor, a fourth resistor 、The fifth resistor and the sixth resistor and the first P-type MOS tube and the second P-type MOS tube; the collector of the third NPN-type triode is connected to the power supply, the base is connected to the other end of the third resistor, and the emitter is connected to one end of the fourth resistor; the collector of the fourth NPN-type triode is connected to the gate and drain of the first P-type MOS tube and the gate of the second P-type MOS tube, the base is connected to the other end of the fourth resistor and one end of the fifth resistor, and the emitter is connected to one end of the sixth resistor; the gate of the first P-type MOS tube is connected to the gate of the second P-type MOS tube, the source of the first P-type MOS tube and the second P-type MOS tube are both connected to the power supply, and the drain of the second P-type MOS tube is connected to the input end of the third resistor;

[0007] The compensation current flows through the third resistor to generate a compensation voltage, and the compensation voltage is combined with the original bandgap reference voltage to output the compensated bandgap reference voltage from the other end of the third resistor.

[0008] Preferably, the other ends of the fifth resistor and the sixth resistor are both grounded.

[0009] Preferably, the NPN bandgap reference source includes a first NPN transistor and a second NPN transistor, a first resistor and a second resistor, and negative feedback; the collectors of the first NPN transistor and the second NPN transistor are connected to the output of the negative feedback, the bases are connected to one end of the third resistor, the drain of the second P-type MOS tube and the input of the negative feedback, the emitter of the first NPN transistor is connected to one end of the first resistor, the emitter of the second NPN transistor is connected to one end of the first resistor and one end of the second resistor, and the other end of the second resistor is grounded.

[0010] Preferably, the method for generating the compensation current is specifically as follows:

[0011] ;

[0012] In the formula, I 4 is the current flowing through the sixth resistor, V BG2 To compensate the bandgap reference voltage, V be3 is the base-emitter voltage of the third NPN transistor, V be4 is the base-emitter voltage of the fourth NPN transistor; I 4 The compensation current is obtained by the 1:1 mirror image of the first P-type MOS tube and the second P-type MOS tube. I 3.

[0013] Preferably, the compensation voltage is combined with the original bandgap reference voltage, as shown below:

[0014] ;

[0015] In the formula, V BG1 is the original bandgap reference voltage, V BG2 is the compensated bandgap reference voltage.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention proposes a circuit for suppressing the temperature drift of an NPN-type bandgap reference, and introduces an additional third resistor and a compensation current into a traditional NPN-type bandgap reference circuit. The compensation current is a temperature-related current, which is generated by a current generation module. The current generation module includes a third NPN-type triode and a fourth NPN-type triode, a fourth resistor and a fifth resistor, and a first P-type MOS tube and a second P-type MOS tube. Through this module, the ratio of the fourth resistor and the fifth resistor can be adjusted. The compensation current value is 0 below medium and high temperatures, and drifts high at the same time as the original bandgap reference voltage at high temperatures. The high-order temperature drift voltage of the original bandgap reference voltage at high temperatures is well suppressed by the third resistor. The compensated bandgap reference voltage generated after the compensation current flows through the third resistor is output as a new bandgap voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is the circuit structure diagram of the traditional NPN bandgap reference source;

[0020] Figure 2 For traditional V BG1 Voltage variation curve diagram;

[0021] Figure 3 A schematic diagram of the structure of a circuit for suppressing temperature drift of an NPN-type bandgap reference source according to the present invention;

[0022] Figure 4 It is a voltage temperature drift suppression curve diagram of the present invention;

[0023] Figure 5 It is a current temperature drift suppression curve diagram of the present invention.

[0024] In the figure: R 1-First resistor, R 2- Second resistor, R3- The third resistor, R 4- The fourth resistor, R 5-Fifth resistor, R 6-sixth resistor, Q1-first NPN transistor, Q2-second NPN transistor, Q3-third NPN transistor, Q4-fourth NPN transistor, PM1-first P-type MOS transistor, PM2-second P-type MOS transistor. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The traditional NPN (Negative-Positive-Negative) bandgap reference source circuit is as follows: Figure 1 As shown, the circuit uses the relationship that the base-emitter voltage difference between the first NPN transistor Q1 and the second NPN transistor Q2 is proportional to the thermodynamic temperature to generate a current that is proportional to the temperature. I 1, I 1 is injected into the second resistor R 2 generates a voltage with a positive temperature coefficient, which is equal to the base-emitter voltage of the second NPN transistor Q2 with a compensation temperature coefficient. V be2 Adding them together, we get a reference output voltage with a low temperature coefficient.

[0027] In the clamping of the high gain negative feedback loop, I 1 and I 2 The currents are equal. The emitter area ratio of the first NPN transistor Q1 and the second NPN transistor Q2 is N:1, so the current flows through the first resistor R 1 current I 1 can be expressed as:

[0028] (1);

[0029] in, V be1 is the base-emitter voltage of the first NPN transistor Q1, V be2 is the base-emitter voltage of the second NPN transistor Q2, V T represents the thermal voltage, which is proportional to the absolute temperature. kis the Boltzmann constant, T is the thermodynamic temperature, q The charge carried by a single electron. The current flowing through Q1 and Q2 is equal, so it flows through the second resistor R The current of 2 is 2* I 1. The final reference voltage can be expressed as:

[0030] (2).

[0031] According to formula (2), the second term on the right side of the equation has a positive temperature coefficient, and the first term has a negative temperature coefficient. R 2 and the first resistor R The ratio of 1 cancels the temperature coefficients of the two terms, resulting in a bandgap reference output voltage with a low temperature coefficient.

[0032] However, the calculation formula of this model only contains the first-order component. V BG1 The high-order components of the voltage will quickly drift up at high temperatures. Figure 2 shown.

[0033] Based on the above defects, the present invention provides an NPN type bandgap reference source temperature drift compensation circuit, such as Figure 3 As shown in the figure, an additional third resistor is introduced into the traditional NPN bandgap reference circuit. R 3 and current I 3. Electric current I 3 is a temperature-dependent current given by Figure 3 The right part of the circuit is generated, including the third NPN transistor Q3 and the fourth NPN transistor Q4, the fourth resistor R 4. Fifth resistor R 5 and 6 resistors R 6 and the first P-type MOS transistor PM1 and the second P-type MOS transistor PM2. The collectors of the first NPN-type transistor Q1 and the second NPN-type transistor Q2 are connected to the output of the negative feedback. The bases of the first NPN-type transistor Q1 and the second NPN-type transistor Q2 are connected to the third resistor R 3. The drain of the second P-type MOS tube PM2 is connected to the input of the negative feedback, and the emitter of the first NPN transistor Q1 is connected to the first resistor R 1, the emitter of the second NPN transistor Q2 is connected to the first resistor R 1 and the second resistor R 2. The collector of the third NPN transistor Q3 is connected to the power supply VDD, and the base of the third NPN transistor Q3 is connected to the third resistor R 3 connected and used as output V BG2, the emitter of the third NPN transistor Q3 and the fourth resistor R 4, the collector of the fourth NPN transistor Q4 is connected to the gate of the first P-type MOS transistor PM1, the gate of the second P-type MOS transistor PM2 and the drain of the first P-type MOS transistor PM1, and the base of the fourth NPN transistor Q4 is connected to the fourth resistor R 4 is connected to the fifth resistor R5, and the emitter of the fourth NPN transistor Q4 is connected to the sixth resistor R 6, the sources of the first P-type MOS transistor PM1 and the second P-type MOS transistor PM2 are both connected to the power supply VDD. R 5 and 6 resistors R The other ends of 6 are grounded GND.

[0034] V BG2 Connected to the base of the third NPN transistor Q3 to reduce the voltage V be3 After that, the fourth resistor R 4 and 5th resistor R 5 divided voltage is connected to the base of the fourth NPN transistor Q4, and then reduced by one V be4 Through the sixth resistor R 6Generate current I 4. I 4 by V be4 The negative temperature coefficient is generated by adjusting the fourth resistor R 4 and 5th resistor R 5 ratios can be adjusted I 4 generates a temperature threshold, adjust the sixth resistor R 6 The size can be changed I 4The slope of the temperature curve.

[0035] This current can be expressed as:

[0036] (3).

[0037] I 4 is obtained by 1:1 mirroring of the first P-type MOS tube PM1 and the second P-type MOS tube PM2. I 3. I 3 flows through the third resistor R 3 Produce high temperature compensation pressure drop, V BG1 Voltage after adding compensation V BG2 It can be expressed as:

[0038] (4).

[0039] According to the calculation results, the voltage and current temperature drift suppression curve using this structure can be drawn, such as Figure 4 and Figure 5 As shown, it can be seen I 3 is added at high temperature, V BG2 Perfectly suppressed V BG1 The high-end drift is high.

[0040] By adjusting the fourth resistor R 4 and 5th resistor R 5, the current value is 0 below medium and high temperatures, and at high temperatures V BG1 The voltage drifts high at the same time. I 3 flows through the third resistor R 3 The voltage generated after V BG2 As the new bandgap voltage output, through the third resistor R 3. Make V BG1 High-order temperature drift voltage at high temperatures is well suppressed.

[0041] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0042] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A circuit for suppressing temperature drift of an NPN type bandgap reference source, characterized in that: include: A third resistor (R3), one end of which is connected to an output end of an NPN type bandgap reference source, and the output end of the NPN type bandgap reference source outputs an original bandgap reference voltage; A current generating module, whose input end is connected to the other end of a third resistor (R3) and is used to generate a compensation current; the current generating module comprises a third NPN-type triode (Q3) and a fourth NPN-type triode (Q4), a fourth resistor (R4), a fifth resistor (R5) and a sixth resistor (R6), and a first P-type MOS transistor (PM1) and a second P-type MOS transistor (PM2); the collector of the third NPN-type triode (Q3) is connected to a power supply, the base is connected to the other end of the third resistor (R3), and the emitter is connected to one end of the fourth resistor (R4); the fourth NPN-type triode (Q4) ) is connected to the gate and drain of the first P-type MOS transistor (PM1) and the gate of the second P-type MOS transistor (PM2), the base is connected to the other end of the fourth resistor (R4) and one end of the fifth resistor (R5), and the emitter is connected to one end of the sixth resistor (R6); the gate of the first P-type MOS transistor (PM1) is connected to the gate of the second P-type MOS transistor (PM2), the source of the first P-type MOS transistor (PM1) and the source of the second P-type MOS transistor (PM2) are both connected to the power supply, and the drain of the second P-type MOS transistor (PM2) is connected to the input end of the third resistor (R3); The compensation current flows through the third resistor (R3) to generate a compensation voltage, the compensation voltage is combined with the original bandgap reference voltage, and the compensated bandgap reference voltage is output from the other end of the third resistor (R3); The method is used to generate a compensation current, which is specifically as follows: Where I4 is the current flowing through the sixth resistor (R6), V BG2 To compensate the bandgap reference voltage, V be3 is the base-emitter voltage of the third NPN transistor (Q3), V be4 is the base-emitter voltage of the fourth NPN transistor (Q4); I4 is a compensation current I3 through the 1:1 mirroring of the first P-type MOS transistor (PM1) and the second P-type MOS transistor (PM2); The compensation voltage is combined with the original bandgap reference voltage as follows: V BG2 =V BG1 -I3·R3; Where V BG1 is the original bandgap reference voltage, V BG2 is the compensated bandgap reference voltage.

2. A circuit for suppressing temperature drift of an NPN type bandgap reference source as claimed in claim 1, characterized in that: The other ends of the fifth resistor (R5) and the sixth resistor (R6) are both grounded.

3. A circuit for suppressing temperature drift of an NPN type bandgap reference source as claimed in claim 1, characterized in that: The NPN type bandgap reference source comprises a first NPN type triode (Q1) and a second NPN type triode (Q2), a first resistor (R1) and a second resistor (R2) and negative feedback; the collectors of the first NPN type triode (Q1) and the second NPN type triode (Q2) are connected to the output of the negative feedback, the bases are connected to one end of the third resistor (R3), the drain of the second P-type MOS tube (PM2) and the input of the negative feedback, the emitter of the first NPN type triode (Q1) is connected to one end of the first resistor (R1), the emitter of the second NPN type triode (Q2) is connected to one end of the first resistor (R1) and one end of the second resistor (R2), and the other end of the second resistor (R2) is grounded.

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