Reference voltage circuit

Abstract

This invention provides a reference voltage circuit that reduces the dependence of the reference voltage on temperature fluctuations. [Solution] The reference voltage generation unit 2 generates the thermal voltage V of the semiconductor. T The circuit generates a reference voltage V1 that is proportional to the temperature and a reference voltage V2 generated by the base-emitter voltage of transistor M1. The correction voltage generation unit 3 generates a distortion correction voltage V3 that has a temperature characteristic in which the normal temperature region is lower than the low temperature region and the high temperature region. The reference voltage circuit 1 outputs a reference voltage VREF1 which is the sum of the reference voltage V1, the reference voltage V2, and the distortion correction voltage V3.

Description

[Technical Field]

[0001] This invention relates to a reference voltage circuit. [Background technology]

[0002] With the rapid advancement of the information and communications society, improving the precision and stability of electronic devices has become a major challenge. To ensure stable operation of the circuits and systems that make up electronic devices, a stable reference voltage circuit is necessary to provide a constant voltage in all environments. Many semiconductor integrated circuits are used in electronic devices. This invention aims to reduce the dependence of the reference voltage on temperature fluctuations in reference voltage circuits, which are widely used to constitute a constant voltage source for semiconductor integrated circuits, and to contribute to improving the precision and stability of electronic devices.

[0003] Conventionally, a bandgap type reference voltage circuit, as shown in Figure 4, is known as a reference voltage circuit used in semiconductor integrated circuits (see, for example, Patent Documents 1 and 2). The reference voltage circuit 100 shown in Figure 4 consists of transistors M1 and M2 whose bases are commonly connected to the output terminal T3, transistors M3 and M4 which are current mirrored as active loads to the collectors of transistors M1 and M2, transistor M5 whose base is connected to the connection point between transistors M2 and M4, whose collector is connected to the bases of transistors M1 and M2, and whose emitter is connected to the positive power supply voltage VCC, and resistors R1 and R2 connected in series. Resistor R1 is connected between the emitter of transistor M1 and the emitter of transistor M2, and resistor R2 is connected between the emitter of transistor M1 and the negative power supply voltage GND.

[0004] Furthermore, as shown in Equation 1, the base-emitter voltage V of transistors M1 and M2 BE1 ,V BE2 The difference is between the resistance value R1 of resistor R1 and the collector current I of transistor M2. C2 It is equal to the product of the base-emitter voltages V of transistors M1 and M2. BE1 ,V BE2is represented by Formula 2 and Formula 3.

[0005] [[Numerical Formula]]

[0006] [[Numerical Formula]]

[0007] [[Numerical Formula]]

[0008] Here, V T is thermal voltage (kT / q), k is Boltzmann constant, T is absolute temperature, q is elementary charge of an electron, I C1 is the collector current of transistor M1, I S is the reverse saturation current of transistor M1, I S ·A M2 / A M1 is the reverse saturation current of transistor M2, A M1 is the emitter-base junction area of transistor M1, A M2 is the emitter-base junction area of transistor M2.

[0009] The reference voltage VREF output to the output terminal T3 is represented by Formula 4.

[0010] [[Numerical Formula]]

[0011] Here, R2 is the resistance value of resistor R2.

[0012] According to the above Formulas 1 to 4, the reference voltage VREF is represented by the following Formula 5. The ratio of the emitter-base junction areas of transistors M1 and M2 is A M1 :A M2 =1:N. Further, the ratio of the emitter-base junction areas of transistors M3 and M4 is A M3 :AM3 Assuming a ratio of 1:1, the collector current I C1 =Collector current I C2 That is what they say.

[0013]

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[0014] Thermal voltage V T It has a positive temperature coefficient of approximately +0.086 mV / °C. The base-emitter voltage V of transistor M1 BE1 It has a negative temperature coefficient of approximately -2mV / °C. The values ​​of N, R1, and R2 are set so that the temperature characteristics of the first and second terms of Equation 5 cancel each other out. This makes it possible to obtain a reference voltage VREF with reduced temperature dependence. The reference voltage VREF is approximately equal to the bandgap voltage and is called a bandgap type reference voltage circuit.

[0015] However, the collector current I of transistor M1 C1 and the base-emitter voltage V BE1 The relationship is as shown in Equation 2. Here, the reverse saturation current I S It is known that this can be expressed by Equation 6 (see, for example, Non-Patent Document 1). The collector current I of transistor M1 C1 Since it is expressed in Equation 7, substituting Equations 6 and 7 into Equation 2, the base-emitter voltage V BE1 This is expressed by Equation 8.

[0016]

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[0017]

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[0018]

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[0019] Here, B and C are proportionality constants, m is the temperature dependence coefficient, and E G V is the energy bandwidth. G0 This is a linear approximation of the bandgap voltage at absolute zero.

[0020] The reference voltage VREF is the base-emitter voltage V in the second term of Equation 5. BE1 The temperature characteristics are offset in the first term. However, as shown in Equation 8, the base-emitter voltage V BE1 The temperature dependence of includes a third term that is nonlinear. The nonlinear component cannot be canceled out by the first term of equation 5, which has a linear characteristic, alone. Therefore, the temperature characteristic of the reference voltage VREF is an upward-convex curved characteristic, with the temperature decreasing more in the high-temperature and low-temperature regions than in the room-temperature region.

[0021] The reference voltage VREF of the conventional reference voltage circuit 100 described above exhibits a curvature characteristic that depends on temperature changes. Therefore, for reference voltages in applications requiring stable operation and high accuracy over a wide temperature range, this slight temperature dependence poses a problem. [Prior art documents] [Patent Documents]

[0022] [Patent Document 1] Patent No. 6873827 [Patent Document 2] Japanese Patent Publication No. 2017-191557 [Non-patent literature]

[0023] [Non-Patent Document 1] Behzad Razavi, *Design of Analog CMOS Integrated Circuits (Applied Edition)*, Maruzen Publishing, 2003 (see p. 465, Equation 11.8). [Overview of the Initiative] [Problems that the invention aims to solve]

[0024] This invention has been made in view of the circumstances described above, and its purpose is to provide a reference voltage circuit that reduces the dependence of the reference voltage on temperature fluctuations. [Means for solving the problem]

[0025] To achieve the aforementioned objectives, the reference voltage circuit according to the present invention is characterized by the following [1] to [7]. [1] A reference voltage generation unit that generates a first voltage proportional to the thermal voltage of the semiconductor and a second voltage generated by the forward voltage of the semiconductor's PN junction, It includes a correction voltage generation unit that generates a third voltage having temperature characteristics in which the room temperature region is lower than the low temperature region and the high temperature region, The sum of the first voltage, the second voltage, and the third voltage is output as the reference voltage. It is a reference voltage circuit. [2] In the reference voltage circuit described in [1], The aforementioned reference voltage generating unit is A first bipolar transistor and a second bipolar transistor, whose bases are connected and which have different emitter-base junction area ratios, A first current source that supplies current to the first bipolar transistor and the second bipolar transistor, respectively, A first resistor connected between the emitter of the first bipolar transistor and the emitter of the second bipolar transistor, The device comprises the first bipolar transistor, the second bipolar transistor, and a second resistor connected in series with the first resistor. The correction voltage generating unit includes a third resistor connected in series with the first resistor and the second resistor, The device comprises a second current source that supplies current to the connection point of the second resistor and the third resistor, The second current source supplies a current inversely proportional to the current amplification factor of the bipolar transistor. It is a reference voltage circuit. [3] In the reference voltage circuit described in [2], The first current source is, A third transistor connected in series with the first bipolar transistor, The present invention comprises a fourth transistor that is current-mirror connected to the third transistor and in series with the second bipolar transistor, It is a reference voltage circuit. [4] In the reference voltage circuit described in [2], The aforementioned reference voltage generating unit is The device has a fifth transistor connected between the bases of the first bipolar transistor and the second bipolar transistor and a power supply terminal to which the power supply voltage is supplied. The second current source is, The fifth transistor is connected to a sixth transistor via a current mirror, which folds back the current flowing through the fifth transistor and supplies it to the third resistor. It is a reference voltage circuit. [5] In the reference voltage circuit described in [3], The second current source is, A seventh transistor is connected to the third transistor via a current mirror, and the current flowing through the third transistor is folded back. An eighth bipolar transistor connected in series with the seventh transistor, A ninth transistor, whose emitter or source is connected to the base of the eighth bipolar transistor, A tenth transistor connected in series with the ninth transistor, The device includes a 11th transistor that is current-mirror connected to the 10th transistor and folds back the current flowing through the 10th transistor to supply it to the 3rd resistor, It is a reference voltage circuit. [6] In the reference voltage circuit described in any one of items [1] to [5], At least one of the aforementioned transistors is composed of a bipolar transistor. It is a reference voltage circuit. [7] In the reference voltage circuit described in any one of items [1] to [5], At least one of the aforementioned transistors is composed of an electrolytic effect transistor. It is a reference voltage circuit. [Effects of the Invention]

[0026] The reference voltage circuit according to the present invention provides a reference voltage circuit that reduces the dependence of the reference voltage on temperature fluctuations.

[0027] The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by referring to the attached drawings and reading through the embodiments for carrying out the invention described below (hereinafter referred to as "embodiments"). [Brief explanation of the drawing]

[0028] [Figure 1] Figure 1 is a circuit diagram showing a reference voltage circuit in the first embodiment. [Figure 2] Figure 2 is a circuit diagram showing the reference voltage circuit in the second embodiment. [Figure 3] Figure 3 is a circuit diagram showing the reference voltage circuit in the third embodiment. [Figure 4] Figure 4 is a circuit diagram showing an example of a conventional reference voltage circuit. [Modes for carrying out the invention]

[0029] Specific embodiments of the present invention will be described below with reference to the figures.

[0030] (First Embodiment) First, the reference voltage circuit 1 of the first embodiment will be described with reference to Figure 1. As shown in the figure, the reference voltage circuit 1 includes a reference voltage generation unit 2 that generates a reference voltage V1 (= first voltage) and a reference voltage V2 (= second voltage), and a correction voltage generation unit 3 that generates a distortion correction voltage V3 (= third voltage). The reference voltage VREF1, which is the sum of the reference voltages V1, V2, and V3, is output from the output terminal T3.

[0031] The reference voltage generation unit 2 comprises transistor M1 (= first bipolar transistor), transistor M2 (= second bipolar transistor), current source 21 (= first current source), transistor M5 (= fifth transistor), resistor R1 (= first resistor), and resistor R21 (= second resistor). Transistors M1 and M2 are composed of NPN type bipolar transistors.

[0032] Transistors M1 and M2 have their bases connected to each other. Transistors M1 and M2 have different emitter-base junction area ratios.

[0033] The current source 21 supplies current to transistors M1 and M2. The current source 21 has transistors M3 (the third transistor) and M4 (the fourth transistor). Transistors M3 and M4 are made up of PNP-type bipolar transistors.

[0034] Transistor M3 is connected in series with transistor M1, with its emitter connected to the positive power supply terminal T21 and its collector connected to the collector of transistor M1. The positive power supply voltage VCC is supplied to the positive power supply terminal T21. Transistor M4 is connected in current mirror to transistor M3, with its base connected to the base and collector of transistor M3. Transistor M4 is connected in series with transistor M2, with its emitter connected to the positive power supply terminal T21 and its collector connected to the collector of transistor M2. Transistor M4 folds back the current flowing through transistor M3 and supplies it to transistor M2.

[0035] Transistor M5 has its emitter connected to the positive power supply terminal T21, its base connected to the junction point between transistors M2 and M4, and its collector connected to the bases of transistors M1 and M2. Output terminal T3 is connected to the junction point between the bases of transistors M1 and M2 and the collector of transistor M5. When transistor M5 is turned on, base current is supplied to transistors M1 and M2.

[0036] Resistor R1 is connected between the emitters of transistor M1 and transistor M2. Resistor R21 is connected in series with transistors M1, M2 and resistor R1.

[0037] The reference voltage V1 is expressed by the following equation 9.

[0038]

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[0039] Here, R 21 The resistance value of resistor R21 is I C1 The collector current of transistor M1 is I C2 is the collector current of transistor M2. According to equations 1 to 3 and 9 above, the reference voltage V1 is expressed by the following equation 10. Note that the emitter-base junction area ratio of transistors M1 and M2 is A. M1 :A M2 The ratio is set to =1:N (N>1). Also, the emitter-base junction area ratio of transistors M3 and M4 is A M3 :A M4 Assuming a ratio of 1:1, the collector current I C1 =Collector current I C2 Furthermore, the reference voltage V2 is expressed by the following equation 11.

[0040]

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[0041]

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[0042] Here, R1 is the resistance value of resistor R1, R 21 The resistance value of resistor R21 is V. T is the thermal voltage (kT / q), k is the Boltzmann constant, T is the absolute temperature, q is the unit charge of an electron, and N is the emitter-base junction area ratio (A) of transistors M1 and M2. M2 / A M1 ), A M1 The emitter-base junction area of ​​transistor M1 is A M2 The emitter-base junction area of ​​transistor M2 is I S This is the reverse saturation current of transistor M1.

[0043] The correction voltage generation unit 3 includes a current source 31 (= second current source) and a resistor R22 (= third resistor). Resistor R22 is connected in series with resistor R21 and is connected between resistor R21 and the negative power supply terminal T22. The negative power supply terminal T22 is supplied with the negative power supply voltage GND. The current source 31 is connected between the power supply terminal T21 and the connection point of resistors R21 and R22, and the current amplification factor h of the transistor FE It generates a current inversely proportional to [the given value].

[0044] The current I generated by the current source 31 at the connection point between resistors R21 and R22 31 When current I is introduced, the curvature correction voltage V3 of the correction voltage generation unit 3 is supplied with current I 31 and the voltage drop across resistor R22 (=I 31 ×R 22 ) is added. The curvature correction voltage V3 is expressed by equation 12. According to equations 10 to 12, the reference voltage VREF1 is expressed by equations 13 and 14.

[0045]

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[0046]

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[0047]

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[0048] Here, K G V is the thermal voltage T R is a constant that represents the amplification factor. 22 This is the resistance value of resistor R22.

[0049] Next, in the reference voltage VREF1 generated by the reference voltage circuit 1 described above, the current I generated by the current source 31 31 Let's explain the behavior when the value is zero.

[0050] Reference voltage circuit 1 outputs a reference voltage VREF1 from output terminal T3, which is the sum of reference voltage V1, reference voltage V2, and distortion correction voltage V3. Current I generated by current source 31 31 The curvature correction voltage when is zero is V3 Z , the reference voltage is VREF1 Z Therefore, the reference voltage VREF1 Z This is expressed by Equation 15.

[0051]

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[0052] Reference voltage V1 + Curvature correction voltage V3 Z (=K G ×V T ) is set by the emitter-base junction area ratio of transistors M1 and M2 and the resistance ratio of resistors R1 and (R21 + R22), as shown in equations 15 and 14, and the thermal voltage V T It is proportional to (+0.086mV / ℃×K) G The positive temperature characteristic is approximately ). The reference voltage V2 is the base-emitter voltage V of transistor M1. BE1 Therefore, it exhibits a negative temperature characteristic of approximately -2mV / °C. The base-emitter voltage of transistor M1 is V BE1 This is the voltage generated by the forward voltage of a semiconductor PN junction.

[0053] Therefore, as shown in Equation 16, the reference voltage V1 and the curvature correction voltage V3 Z The added voltage (=K G ×V T The ratio of the temperature characteristic of () to the absolute value of the temperature characteristic of the reference voltage V2 is made equal. This makes the base-emitter voltage V of transistor M1, which is the second term of equation 15, equal. BE1 The temperature characteristics are canceled out in the first term, and the reference voltage VREF1 Z This can reduce the temperature dependence of the product.

[0054]

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[0055] However, the current I generated by the current source 31 31 When V is zero, the base-emitter voltage of transistor M1 is V BE1 This includes a nonlinear component. The first term of Equation 15 alone cannot completely cancel out the temperature characteristics. Therefore, the reference voltage VREF1 Z The temperature characteristics exhibit an upward-convex curve, with the curve decreasing in both the high-temperature and low-temperature regions compared to the room-temperature region.

[0056] Next, in the reference voltage VREF1 generated by the reference voltage circuit 1 described above, the current I generated by the current source 31 31 This section explains how the bending due to temperature changes is reduced by flowing the current through resistor R22.

[0057] Reverse saturation current I of transistor M1 S This is expressed by Equation 17. The collector current I of transistor M1 C1 This is expressed in equation 18. Therefore, substituting equations 17 and 18 into equation 11, we get the base-emitter voltage V of transistor M1. BE1 The temperature dependence of is expressed by Equation 19. Equation 19 includes a nonlinear third term, resulting in an upwardly curved characteristic where the change increases with increasing temperature, rather than a linear one. Furthermore, the collector current I of transistor M1 is also expressed. C1, the resistor R1 is arranged such that the thermal voltage V of the semiconductor T is a resistor having a temperature coefficient of about +3300 ppm / °C, which is equal to the temperature coefficient of , thereby obtaining a current with suppressed temperature dependence.

[0058] [Math.]]

[0059] [Math.]]

[0060] [Math.]]

[0061] Here, B and C are proportionality constants, m is a temperature dependence coefficient, E G is the energy bandwidth, V G0 is the linear approximation of the bandgap voltage at absolute zero.

[0062] The current amplification factor h of a transistor FE is known to be represented by the relational expression of Formula 20 if the recombination current is sufficiently small. Further, as shown in Formula 21, the current I generated by the current source 31 31 is set as a current inversely proportional to the current amplification factor h FE , whereby a voltage component inversely proportional to the current amplification factor h FE is added to the curvature correction voltage V3. Further, even when the current I 31 is supplied, compared to the reference voltage V1, the voltage drop caused by the current I 31 and the resistor R22 (= curvature correction voltage V3 - curvature correction voltage V3 Z ) is sufficiently small, so the thermal voltage V T has an amplification factor K G has only a negligible influence on .

[0063] [Math.]]

[0064]

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[0065] Here, ΔE G is the reduction width resulting from the bandgap narrowing effect in the emitter.

[0066] In Formula 20, the reduction width ΔE resulting from the bandgap narrowing effect G and Boltzmann constant k are constants that do not depend on temperature changes. For this reason, the current I, which is inversely proportional to the current amplification factor h of the transistor FE is inversely proportional to the current amplification factor h of the transistor, the current I 31 exhibits a downward-convex curvature characteristic according to Formula 21, where the value in the normal temperature region is lower than that in the low-temperature region and the high-temperature region. The curvature correction voltage V3 also exhibits a downward-convex curvature characteristic similarly according to Formula 12.

[0067] That is, if the current I generated by the current source 31 31 is zero or a constant current, the curvature correction voltage V3 will have linear characteristics. Accordingly, the temperature characteristic of the reference voltage VREF1 will have an upward-convex curvature characteristic. However, by setting the current I generated by the current source 31 31 to be a current inversely proportional to the current amplification factor h of the transistor M1 FE , the curvature correction voltage V3 exhibits a downward-convex curvature characteristic. Accordingly, the curvature characteristic of the reference voltage VREF1 is reduced.

[0068] In other words, the curvature correction voltage V3 of the reference voltage circuit 1 in the first embodiment acts in a direction that cancels out the upward-convex curvature characteristic of the reference voltage V2, which is the base-emitter voltage V of the transistor M1 BE1 and acts to cancel the upward-convex curvature characteristic of the reference voltage V2. Therefore, by adjusting the resistance ratio of the resistors R21, R22 and the current I generated by the current source 31 31 , the curvature caused by the temperature change of the reference voltage VREF1 is reduced.

[0069] Accordingly, the effect of reducing the dependence of the reference voltage on temperature fluctuations can be obtained.

[0070] (Second Embodiment) Next, the reference voltage circuit 1B of the second embodiment will be described with reference to Figure 2. In Figure 2, components identical to those in the circuit shown in Figure 1 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0071] As shown in the figure, the reference voltage circuit 1B, similar to the first embodiment, includes a reference voltage generation unit 2 that generates reference voltages V1 and V2, and a correction voltage generation unit 3B that generates a curvature correction voltage V3B. The reference voltage VREF2, which is the sum of the reference voltages V1, V2, and V3B, is output from the output terminal T3. The reference voltage generation unit 2 is the same as in the first embodiment described above, so a detailed explanation is omitted here.

[0072] The difference between the first and second embodiments lies in the configuration of the correction voltage generation unit 3B. The correction voltage generation unit 3B comprises a current source 31B (= second current source) and a resistor R22. The current source 31B is composed of a transistor M6 (= sixth transistor). The transistor M6 is composed of a PNP type bipolar transistor.

[0073] Transistor M6 has its emitter connected to the positive power supply terminal T21, its base connected to the base of transistor M5, and its collector connected to the junction of resistors R21 and R22. In other words, transistor M6 is current-mirror connected to transistor M5, copying and folding back the current flowing through transistor M5.

[0074] Since the collector of transistor M5 is connected to the bases of transistors M1 and M2, the collector current of transistor M5 is I C5 This is expressed in Equation 22.

[0075]

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[0076] Here, I B1 The base current of transistor M1 is I B2This is the base current of transistor M2.

[0077] Since transistor M6 is in current mirror connection with transistor M5, the collector current I of transistor M6 C6 The emitter-base junction area ratio of transistors M5 and M6 is A M5 :A M6 If we set =1:M, it can be expressed in equation 23.

[0078]

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[0079] Here, M is the emitter-base junction area ratio of transistors M5 and M6 (A M6 / A M5 ), A M5 This is the emitter-base junction area of ​​transistor M5, A M6 This is the emitter-base junction area of ​​transistor M6.

[0080] The distortion correction voltage V3B of the correction voltage generation unit 3B is the collector current I of transistor M6 at the connection point between resistors R21 and R22. C6 By flowing in the collector current I C6 and the voltage drop across resistor R22 (=I C6 ×R 22 The following is added: The curvature correction voltage V3B is expressed by equation 24, and the reference voltage VREF2 is expressed by equation 25.

[0081]

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[0082]

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[0083] In Equation 20, the reduction in band gap due to the band gap reduction effect ΔE GThe Boltzmann constant k is a constant that does not depend on temperature. Therefore, the current amplification factor h FE The collector current I of transistor M6 is inversely proportional to I. C6 From Equation 23, the curve characteristic is convex downwards, with the curve decreasing more in the room temperature region than in the low temperature and high temperature regions. Similarly, from Equation 24, the curve correction voltage V3B also exhibits a convex downwards curve characteristic.

[0084] Also, the collector current I of transistor M6 C6 The current amplification factor h FE Although it fluctuates depending on manufacturing variations, the amount of fluctuation can be corrected by trimming resistors R21 and R22.

[0085] In other words, the collector current I of transistor M6 C6 However, if the current is zero or constant, the curvature correction voltage V3B will have a linear characteristic. Therefore, the temperature characteristic of the reference voltage VREF2 will have an upward-convex curvature. However, the collector current I of transistor M6 C6 Current amplification factor h FE By setting the current to be inversely proportional, the curvature correction voltage V3B will have a downward-convex curvature characteristic, thus reducing the curvature characteristic of the reference voltage VREF2.

[0086] In other words, the curvature correction voltage V3B of the reference voltage circuit 1B in this second embodiment is equal to the base-emitter voltage V of transistor M1. BE1 The reference voltage V2 acts in a direction that cancels out the upward-convex curvature characteristic. Therefore, the resistance ratio of resistors R21 and R22 and the collector current I of transistor M6 C6 By adjusting this setting, the curvature caused by temperature changes in the reference voltage VREF2 is reduced.

[0087] Therefore, this method has the effect of reducing the dependence of the reference voltage on temperature fluctuations.

[0088] (Third embodiment) Next, the reference voltage circuit 1C of the third embodiment will be described with reference to Figure 3. In Figure 3, components identical to those in the circuit shown in Figure 1 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0089] As shown in the figure, the reference voltage circuit 1C, similar to the first embodiment, includes a reference voltage generation unit 2 that generates reference voltages V1 and V2, and a correction voltage generation unit 3C that generates a curvature correction voltage V3C. The reference voltage VREF3, which is the sum of the reference voltages V1, V2, and V3C, is output from the output terminal T3. The reference voltage generation unit 2 is the same as in the first embodiment described above, so a detailed explanation is omitted here.

[0090] The difference between the first and third embodiments lies in the configuration of the correction voltage generation unit 3C. The correction voltage generation unit 3C comprises a current source 31C and a resistor R22. The current source 31C includes transistors M7 (=7th transistor), M8 (=8th bipolar transistor), M9 (=9th transistor), M10 (=10th transistor), and M11 (=11th transistor). Transistors M8 and M9 are composed of NPN type bipolar transistors. Transistors M7, M10, and M11 are composed of PNP type bipolar transistors.

[0091] Transistor M7 has its emitter connected to the positive power supply terminal T21, its base connected to the base and collector of transistor M3, and its collector connected to the collector of transistor M8 and the base of transistor M9. In other words, transistor M7 is current mirrored to transistor M3, and the collector current I of transistor M3 C3 Copy this and supply it to transistor M8. Transistor M8 has its emitter connected to the negative power supply terminal T22 and its base connected to the emitter of transistor M9.

[0092] Transistor M10 has its emitter connected to the positive power supply terminal T21, and its base and collector connected to the collector of transistor M9. Transistors M9 and M10 receive the base current I from transistor M8. B8 The following is supplied. Transistor M11 has its emitter connected to the positive power supply terminal T21, its base connected to the base and collector of transistor M10, and its collector connected to the connection point of resistors R21 and R22. In other words, transistor M11 is current mirrored to transistor M10, and the base current I flowing through transistor M8 is supplied. B8 Copy and wrap.

[0093] Collector current I of transistor M10 C10 The emitter-base junction area ratio of transistors M3 and M7 is A M3 :A M7 If we set the ratio to 1:1, it can be expressed in equation 26.

[0094]

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[0095] Here, I C8 This is the collector current of transistor M8.

[0096] Since transistor M11 is in current mirror connection with transistor M10, the collector current I of transistor M11 C11 The emitter-base junction area ratio of transistors M10 and M11 is A M10 :A M11 If we set =1:U, it can be expressed in equation 27.

[0097]

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[0098] Here, U is the emitter-base junction area ratio of transistors M10 and M11 (A M11 / A M10 ), A M10This is the emitter-base junction area of ​​transistor M10, A M11 This is the emitter-base junction area of ​​transistor M11.

[0099] The distortion correction voltage V3C of the correction voltage generation unit 3C is the collector current I of transistor M11 at the connection point between resistors R21 and R22. C11 By flowing in the collector current I C11 and the voltage drop across resistor R22 (=I C11 ×R 22 The following is added: The curvature correction voltage V3C is expressed by equation 28, and the reference voltage VREF3 is expressed by equation 29.

[0100]

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[0101]

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[0102] In Equation 20, the reduction in band gap due to the band gap reduction effect ΔE G The Boltzmann constant k is a constant that does not depend on temperature. Therefore, the current amplification factor h FE The collector current I of transistor M11 is inversely proportional to I. C11 From Equation 27, the curve characteristic is convex downwards, with the curve decreasing more in the room temperature region than in the low temperature and high temperature regions. Similarly, from Equation 28, the curve correction voltage V3C also exhibits a convex downwards curve characteristic.

[0103] Also, the collector current I of transistor M11 C11 The current amplification factor h FE Although it fluctuates depending on manufacturing variations, the amount of fluctuation can be corrected by trimming resistors R21 and R22.

[0104] In other words, the collector current I of transistor M11 C11However, if the current is zero or constant, the curvature correction voltage V3C will have a linear characteristic. Therefore, the temperature characteristic of the reference voltage VREF3 will have an upward-convex curvature. However, the collector current I of transistor M11 C11 Current amplification factor h FE By making the current inversely proportional to the curve correction voltage V3C, the curve correction voltage V3C will have a downward convex curve characteristic, thus reducing the curve characteristic of the reference voltage VREF3.

[0105] In other words, the curvature correction voltage V3C of the reference voltage circuit 1C in this third embodiment is equal to the base-emitter voltage V of transistor M1. BE1 The reference voltage V2 acts in a direction that cancels out the upward-convex curvature characteristic. Therefore, the resistance ratio of resistors R21 and R22 and the collector current I of transistor M11 C11 By adjusting this setting, the curvature caused by temperature changes in the reference voltage VREF3 is reduced.

[0106] Therefore, this method has the effect of reducing the dependence of the reference voltage on temperature fluctuations.

[0107] In the correction voltage generation unit 3C of the third embodiment described above, a current mirror circuit was configured using transistors M10 and M11, but this is not the only option. Other well-known current mirror circuits may also be used.

[0108] (Other embodiments) The present invention is not limited to the embodiments described above, and can be modified, improved, etc., as appropriate. Furthermore, the material, shape, dimensions, number, placement, etc., of each component in the embodiments described above are arbitrary and not limited, as long as they can achieve the present invention.

[0109] For example, in the first to third embodiments described above, the transistors were composed of bipolar transistors, but the invention is not limited to this. At least one of the transistors, excluding transistors M1, M2, and M8, may be replaced with field-effect transistors. In this case, "PNP type" can be read as "P channel," "NPN type" as "N channel," "base" as "gate," "emitter" as "source," "collector" as "drain," and "emitter-base junction area ratio" as "aspect ratio."

[0110] Furthermore, while the first to third embodiments described above used a reference voltage generation unit 2 as shown in Figures 1 to 3, the invention is not limited to this. Thermal voltage V T Other embodiments are possible as long as the circuit generates a voltage proportional to the given value. [Explanation of symbols]

[0111] 1,1B,1C Reference Voltage Circuit 2. Reference voltage generation unit 3,3B,3C Correction voltage generation section 21 Current source (first current source) 31, 31B, 31C Current source (second current source) M1 transistor (first bipolar transistor) M2 transistor (second bipolar transistor) M3 transistor (third transistor) M4 transistor (fourth transistor) M5 transistor (the fifth transistor) M6 transistor (the sixth transistor) M7 transistor (the seventh transistor) M8 transistor (8th bipolar transistor) M9 transistor (9th transistor) M10 transistor (10th transistor) M11 transistor (11th transistor) R1 Resistor (First resistor) R2 Resistor (Second resistor) T21 Positive power terminal (power terminal) V1 Reference voltage (first voltage) V2 Reference voltage (second voltage) V3 Curvature correction voltage (third voltage) VREF1~VREF3 Reference Voltage

Claims

1. A reference voltage generating unit that generates a first voltage proportional to the thermal voltage of the semiconductor and a second voltage generated by the forward voltage of the semiconductor's PN junction, It includes a correction voltage generation unit that generates a third voltage having temperature characteristics in which the room temperature region is lower than the low temperature region and the high temperature region, The sum of the first voltage, the second voltage, and the third voltage is output as the reference voltage. Reference voltage circuit.

2. In the reference voltage circuit described in claim 1, The aforementioned reference voltage generating unit is A first bipolar transistor and a second bipolar transistor, whose bases are connected and which have different emitter-base junction area ratios, A first current source that supplies current to the first bipolar transistor and the second bipolar transistor, A first resistor connected between the emitter of the first bipolar transistor and the emitter of the second bipolar transistor, The device comprises the first bipolar transistor, the second bipolar transistor, and a second resistor connected in series with the first resistor. The correction voltage generating unit includes a third resistor connected in series with the first resistor and the second resistor, The device comprises a second current source that supplies current to the connection point of the second resistor and the third resistor, The second current source supplies a current inversely proportional to the current amplification factor of the bipolar transistor. Reference voltage circuit.

3. In the reference voltage circuit described in claim 2, The first current source is, A third transistor connected in series with the first bipolar transistor, The third transistor is currently mirrored to a fourth transistor, and the second bipolar transistor is connected in series with the third transistor. Reference voltage circuit.

4. In the reference voltage circuit described in claim 2, The aforementioned reference voltage generating unit is The device has a fifth transistor connected between the bases of the first bipolar transistor and the second bipolar transistor and a power supply terminal to which the power supply voltage is supplied. The second current source is, The fifth transistor is connected to a sixth transistor via a current mirror, which folds back the current flowing through the fifth transistor and supplies it to the third resistor. Reference voltage circuit.

5. In the reference voltage circuit described in claim 3, The second current source is, A seventh transistor is connected to the third transistor via a current mirror, and the current flowing through the third transistor is folded back. An eighth bipolar transistor connected in series with the seventh transistor, A ninth transistor, whose emitter or source is connected to the base of the eighth bipolar transistor, A tenth transistor connected in series with the ninth transistor, The system includes a 11th transistor that is current-mirror connected to the 10th transistor and folds back the current flowing through the 10th transistor to supply it to the 3rd resistor, Reference voltage circuit.

6. In the reference voltage circuit according to any one of claims 1 to 5, At least one of the aforementioned transistors is composed of a bipolar transistor. Reference voltage circuit.

7. In the reference voltage circuit according to any one of claims 1 to 5, At least one of the aforementioned transistors is composed of an electrolytic effect transistor. Reference voltage circuit.

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