Band-gap reference circuit

Abstract

The invention discloses a band-gap reference circuit with high precision and low temperature coefficient, which can achieve good curvature compensation in a wider temperature range, and the curvature correction is finer, so that the correction precision is greatly improved. And the curvature correction progress is not influenced by the leakage current of the transistor, so that the method can be suitable for the transistor with a thin gate oxide layer with relatively high leakage current.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of integrated circuit technology, and more particularly, to a bandgap reference circuit. BACKGROUND

[0002] The bandgap reference circuit is a kind of voltage reference source widely used in integrated circuits, which has excellent temperature stability, and is often used for high-precision voltage reference. The bandgap reference source is widely used in motor drive, dynamic storage, flash memory and other analog devices, as a voltage reference, outputting a temperature-independent reference voltage. The working principle of the traditional bandgap reference circuit is based on the weighted addition of a positive temperature coefficient current and a negative temperature coefficient current, to obtain a reference voltage quantity that hardly changes with temperature.

[0003] However, the voltage quantity with positive temperature coefficient is not first-order, but has certain high-order temperature characteristics. Therefore, the temperature characteristics of the traditional bandgap reference voltage source are poor, and it is difficult to meet the requirements of high-performance analog circuits, and this shortcoming needs to be calibrated. SUMMARY

[0004] Therefore, the present application provides a bandgap reference circuit with lower temperature coefficient.

[0005] In a first aspect, the present application provides a bandgap reference circuit, characterized in that it comprises:

[0006] A positive temperature coefficient current circuit for generating a positive temperature coefficient current;

[0007] A negative temperature coefficient current circuit for generating a negative temperature coefficient current;

[0008] A compensation current generating circuit for generating a third compensation current, the third compensation current corresponding to different current values in different low-temperature or high-temperature sub-regions;

[0009] A reference voltage generating circuit for generating a low-temperature coefficient reference voltage according to the positive temperature coefficient current, the negative temperature coefficient current and the third compensation current.

[0010] Preferably, the compensation current generating circuit generates a plurality of first compensation currents in the high-temperature region and a plurality of second compensation currents in the low-temperature region, and generates the third compensation current by superimposing the plurality of first compensation currents and the plurality of second compensation currents.

[0011] Preferably, the compensation current generating circuit generates a plurality of second compensation currents in different sub-regions of the low-temperature region, and generates a plurality of first compensation currents in different sub-regions of the high-temperature region.

[0012] Preferably, the more the number of the second compensation currents in the sub-interval is as the temperature decreases in the low-temperature temperature zone; the more the number of the first compensation currents in the sub-interval is as the temperature increases in the high-temperature temperature zone.

[0013] Preferably, each of the first compensation currents or the second compensation currents presents a piecewise linear characteristic and has different piecewise temperature thresholds, and on both sides of the respective piecewise temperature threshold, the first compensation current or the second compensation current has different slopes, the first compensation current is used to compensate the curvature of the reference voltage in the high-temperature temperature zone, and the second compensation current is used to compensate the curvature of the reference voltage in the low-temperature temperature zone.

[0014] Preferably, the compensation current generation circuit generates the first compensation current and the second compensation current based on the values of the positive temperature coefficient current and the negative temperature coefficient current and the respective weights.

[0015] Preferably, the compensation current generation circuit changes the piecewise temperature threshold of each of the first compensation currents or the second compensation currents by changing the proportion of the positive temperature coefficient current and the negative temperature coefficient weight, and on both sides of the respective piecewise temperature threshold, the first compensation current or the second compensation current has different slopes.

[0016] Preferably, the compensation current generation circuit includes a plurality of positive temperature coefficient compensation circuits to respectively generate the plurality of first compensation currents, wherein when the product of the positive temperature coefficient current and its own weight is greater than the product of the negative temperature coefficient current and its own weight, each of the positive temperature coefficient compensation circuits outputs the first compensation current with a first slope.

[0017] Preferably, when the product of the positive temperature coefficient current and its own weight is not greater than the product of the negative temperature coefficient current and its own weight, each of the positive temperature coefficient compensation circuits outputs the first compensation current with a second slope.

[0018] Preferably, the compensation current generation circuit includes a plurality of negative temperature coefficient compensation circuits to respectively generate the plurality of second compensation currents, wherein when the product of the negative temperature coefficient current and its own weight is greater than the product of the positive temperature coefficient current and its own weight, each of the negative temperature coefficient compensation circuits outputs the first compensation current with a third slope.

[0019] Preferably, when the product of the negative temperature coefficient current and its own weight is not greater than the product of the positive temperature coefficient current and its own weight, each of the negative temperature coefficient compensation circuits outputs the first compensation current with a second slope.

[0020] Preferably, the reference voltage generating circuit comprises a resistive voltage dividing circuit, which comprises a first resistor and a second resistor connected in series, the second resistor is coupled to a ground potential, and the third compensation current is injected into the reference voltage generating circuit at a common node of the first resistor and the second resistor.

[0021] Preferably, the positive temperature coefficient current and the negative temperature coefficient current are both injected into the reference voltage generating circuit at a first end of the first resistor, and the reference voltage is generated at the first end of the first resistor, wherein a second end of the first resistor is coupled to the second resistor.

[0022] Preferably, the resistance of the first resistor is much larger than the resistance of the second resistor.

[0023] Preferably, the positive temperature coefficient current circuit comprises a first transistor and a second transistor connected in common source and common gate, a first operational amplifier circuit, a first bipolar transistor and a second bipolar transistor connected in common base and common collector, and a third resistor, wherein the first transistor is connected in series with the first bipolar transistor, the second transistor, the third resistor and the second bipolar transistor are connected in series, two input terminals of the first operational amplifier circuit are connected to the drain of the first transistor and the drain of the second transistor respectively, an output terminal of the first operational amplifier circuit is connected to the common gate of the first transistor and the second transistor, and a current flowing through the third resistor is the positive temperature coefficient current.

[0024] Preferably, the negative temperature coefficient current circuit comprises a second operational amplifier circuit and a third transistor and a fourth resistor connected in series, wherein two input terminals of the second operational amplifier circuit are connected to the drain of the first transistor and the drain of the third transistor respectively, an output terminal of the second operational amplifier circuit is connected to the gate of the third transistor, and a current flowing through the fourth resistor is the negative temperature coefficient current.

[0025] Preferably, the reference voltage generating circuit comprises a fourth transistor and a fifth transistor connected in parallel, and a resistive voltage dividing circuit, wherein a common node of the fourth transistor and the fifth transistor is connected to the resistive voltage dividing circuit, the fourth transistor and the second transistor form a first current mirror, and the fifth transistor and the third transistor form a second current mirror.

[0026] Preferably, a plurality of the positive temperature coefficient compensation circuits are coupled in parallel, each of the positive temperature coefficient compensation circuits comprises a current replication circuit, a third current mirror, and a fourth current mirror.

[0027] The current copying circuit is used for copying the positive temperature coefficient current and the negative temperature coefficient current respectively in a proportion corresponding to the weight of itself, to obtain a first positive temperature coefficient current and a first negative temperature coefficient current respectively.

[0028] The third current mirror is used for mirroring the first positive temperature coefficient current.

[0029] The fourth current mirror is used for generating a difference current according to the difference between the first positive temperature coefficient current and the first negative temperature coefficient current, and mirroring the difference current to generate the first compensation current.

[0030] Preferably, a plurality of the negative temperature coefficient compensation circuits are coupled in parallel, each of the negative temperature coefficient compensation circuits comprising a current copying circuit, a fifth current mirror, a sixth current mirror.

[0031] The current copying circuit is used for copying the positive temperature coefficient current and the negative temperature coefficient current respectively in a proportion corresponding to the weight of itself, to obtain a second positive temperature coefficient current and a second negative temperature coefficient current respectively.

[0032] The third current mirror is used for mirroring the second negative temperature coefficient current.

[0033] The fourth current mirror is used for generating a difference current according to the difference between the second positive temperature coefficient current and the second negative temperature coefficient current, and mirroring the difference current to generate the second compensation current.

[0034] Preferably, a starting circuit is further included, which is used for providing a starting voltage for the positive temperature coefficient current circuit during starting, so that the bandgap reference circuit starts to start.

[0035] The present application aims to provide a bandgap reference circuit, by dividing the temperature range into more segments, compensating in a smaller temperature range, so that the temperature range of curvature correction is widened, and the correction accuracy is improved. And further injecting the sum of the multiple compensation currents into the resistance center, so that the compensation current is much larger than the leakage current, so that the curvature correction technology is not sensitive to the leakage current. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0037] Figure 1Waveform diagram for curvature compensation technique of comparative example of the present invention;

[0038] Figure 2 Waveform diagram for curvature compensation technique of embodiment of the present invention;

[0039] Figure 3 Schematic diagram of bandgap reference circuit of embodiment of the present invention;

[0040] Figure 4 Schematic diagram of compensation current generation circuit of embodiment of the present invention;

[0041] Figure 5 Circuit schematic diagram of positive temperature coefficient compensation circuit of embodiment of the present invention;

[0042] Figure 6 Circuit schematic diagram of negative temperature coefficient compensation circuit of embodiment of the present invention. DETAILED DESCRIPTION

[0043] The present invention is described in detail based on embodiments, but the present invention is not limited to only these embodiments. In the following detailed description of the present invention, some specific details are described in detail. The present invention can also be fully understood without the description of these details by those skilled in the art. In order to avoid confusion of the essence of the present invention, well-known methods, processes, procedures, elements and circuits are not described in detail.

[0044] In addition, those of ordinary skill in the art will understand that the drawings provided herein are for illustrative purposes only and are not necessarily drawn to scale.

[0045] At the same time, it should be understood that in the following description, "circuit" refers to a conductive loop composed of at least one element or sub-circuit through electrical or electromagnetic connection. When an element or circuit is said to be "connected to" another element or said to be "connected between" two nodes, it can be directly coupled or connected to another element or there can be intermediate elements, and the connection between elements can be physical, logical, or a combination thereof. On the contrary, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there is no intermediate element between the two.

[0046] Unless the context clearly requires otherwise, throughout the description and the claims, "comprise", "comprise", and similar words such as "comprise" should be interpreted as inclusive rather than exclusive or exhaustive; that is, in the sense of "including, but not limited to".

[0047] In the description of the present invention, it should be understood that the terms "first", "second", etc. are only for descriptive purposes and should not be interpreted or implied as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise stated, the meaning of "multiple" is two or more.

[0048] Figure 1 This is a waveform diagram of the curvature compensation technology of the comparative example of the present invention. Figure 1 As shown, in the curvature compensation scheme of the bandgap reference circuit of the comparative example, when the negative temperature coefficient current I CTAT The current (current inversely proportional to absolute temperature) is greater than the positive temperature coefficient current I PTAT When the current (current proportional to absolute temperature) is 0, the compensation current circuit generates a compensation current Icurv with a negative temperature coefficient, i.e., the ab segment; when the negative temperature coefficient current ICTAT is less than the positive temperature coefficient current IPTAT, the compensation current generating circuit generates a compensation current Icurv with a positive temperature coefficient, i.e., the cd segment; the bc segment has no temperature coefficient compensation current, and the compensation current Icurv is divided into three segments: ab segment, bc segment, and cd segment. Although such compensation current can offset part of the temperature coefficient of the bowl-shaped reference voltage, this method has at least several obvious disadvantages: 1. This curvature compensation scheme only divides the temperature range into three segments. The temperature range and accuracy of curvature compensation are limited, and the temperature segmentation threshold needs to be adjusted; 2. When the compensation current circuit used to generate the compensation current Icurv uses a thin-gate oxide transistor with high leakage current, its leakage current will seriously affect the curvature correction accuracy. This is because when the injected compensation current Icurv is comparable to the leakage current of the thin-gate oxide transistor, the leakage current has a greater impact on the compensation current Icurv, resulting in the failure of curvature correction. Therefore, this scheme is only suitable for thick-gate oxide transistors with very small leakage current.

[0049] Based on this, the present invention proposes a bandgap reference circuit with high precision and low temperature coefficient, which can achieve good curvature compensation within a wider temperature range. The curvature correction is more precise, which greatly improves the correction accuracy; and its curvature correction progress is not affected by the leakage current of the transistor, so it can be applied to transistors with thin gate oxide layers with very high leakage current.

[0050] Figure 2 4 is a waveform diagram of the curvature compensation technology according to an embodiment of the present invention. Figure 2 Where Vref1 is the reference voltage before curvature correction. Figure 2 As can be seen intuitively, the reference voltage Vref1 has a high temperature coefficient. The temperature coefficient indicates the degree to which the reference voltage varies with ambient temperature. The amplitude of the reference voltage Vref1 decreases with decreasing temperature in the low temperature range and decreases with increasing temperature in the high temperature range. Therefore, its waveform exhibits an inverted "bowl" shape over the entire temperature range.

[0051] The embodiment of the present application divides the high-temperature temperature range and the low-temperature temperature range in the temperature range into more and smaller subintervals respectively, adopts an independent compensation current injection strategy in each subinterval, allows fine adjustment of the nonlinear characteristics of different temperature ranges through segmented compensation, and avoids the lack of adaptability of a single compensation strategy in a wide temperature range. The bandgap reference circuit of the embodiment of the present application can more accurately offset the curvature error of different temperature ranges through the injection of multiple first compensation currents and second compensation currents, and finally widen the curvature correction temperature range and improve the accuracy.

[0052] Preferably, the bandgap reference circuit of the embodiment of the present application generates multiple first compensation currents in the high-temperature temperature range, generates multiple second compensation currents in the low-temperature temperature range, and generates a third compensation current by superimposing the multiple first compensation currents and the multiple second compensation currents, and the third compensation current is used to compensate the output reference voltage signal. Specifically, in different subintervals of the low-temperature temperature range, different numbers of second compensation currents are generated; in different subintervals of the high-temperature temperature range, different numbers of first compensation currents are generated; further, in the low-temperature temperature range, the more the number of second compensation currents in the subinterval as the temperature decreases; in the high-temperature temperature range, the more the number of first compensation currents in the subinterval as the temperature increases.

[0053] Continuing to refer to Figure 2 In a preferred embodiment, the low-temperature temperature range is divided into four subintervals by using temperature thresholds T0, TL1-TL4, wherein T0 can be the lower limit of the temperature range, TL1-TL4 are the set segmented temperature thresholds, and T0<TL1<TL2<TL3<TL4. In the subinterval T0-TL1, the curvature of the reference voltage Vref1 is corrected by the second compensation currents In1, In2, In3 and In4; in the subinterval TL1-TL2, the curvature of the reference voltage Vref1 is corrected by the second compensation currents In2, In3 and In4; in the subinterval TL2-TL3, the curvature of the reference voltage Vref1 is corrected by the second compensation currents In3 and In4; in the subinterval TL3-TL4, the curvature of the reference voltage Vref1 is corrected by the second compensation current In4; in this way, in different temperature ranges, different numbers of second compensation currents are superimposed to generate corresponding compensation currents, and the more the number of second compensation currents for compensating the reference voltage Vref1 as the temperature decreases, so that in different temperature ranges, different numbers of second compensation currents are respectively corresponded, and the nonlinear characteristics of different temperature ranges are fine adjusted, so that the reference voltage has an extremely low temperature coefficient in the low-temperature temperature range.

[0054] Similarly, in the high-temperature temperature zone, the high-temperature temperature zone is divided into four subintervals by using temperature thresholds T1, TH1-TH4, wherein T1 can be the upper limit of the temperature range, TH1-TH4 are the set segmented temperature thresholds, TH1< TH2< TH3< TH4< T1. In the subinterval T1-TH4, the curvature of the reference voltage Vref1 is corrected by the first compensation currents Ip1, Ip2, Ip3 and Ip4; in the subinterval TH3-TH4, the curvature of the reference voltage Vref1 is corrected by the first compensation currents Ip2, Ip3 and Ip4; in the subinterval TH2-TH3, the curvature of the reference voltage Vref1 is corrected by the first compensation currents Ip3 and Ip4; in the subinterval TH1-TH2, the curvature of the reference voltage Vref1 is corrected by the first compensation current Ip4; in this way, in different temperature zones, different numbers of first compensation currents are superimposed to generate corresponding compensation currents, and as the temperature rises, the number of first compensation currents for compensating the reference voltage Vref1 is more, so that in different temperature zones, different numbers of first compensation currents are respectively corresponding, and then the non-linear characteristics for different temperature zones are finely adjusted, so that the reference voltage has an extremely low temperature coefficient in the high-temperature zone. The bandgap reference circuit of the present application can make the reference voltage have an extremely low temperature coefficient in the whole temperature range by such current compensation strategy, as shown by the waveform Vref.

[0055] Here, it should be noted that in the embodiment of the present application, only the low-temperature temperature zone and the high-temperature temperature zone are divided into four subintervals as an example to explain the curvature correction principle, and in other embodiments, other numbers of subintervals can also be divided according to needs, which is not limited by the present application.

[0056] As shown in the formula (1), the reference voltage Vref is generated by the positive temperature coefficient current I Figure 3 and the negative temperature coefficient current I Figure 3 The schematic diagram of the bandgap reference circuit of the embodiment of the present application is shown in the formula (2).

[0057] The positive temperature coefficient current circuit 31 is used to generate a positive temperature coefficient current I PTAT The positive temperature coefficient current I PTAT is a current source proportional to absolute temperature, which has a positive temperature coefficient (i.e. the current increases when the temperature rises). The positive temperature coefficient current I PTAT is used to offset components with a negative temperature coefficient (such as diodes or transistors), thereby generating a more stable reference voltage Vref with smaller temperature drift.

[0058] In a preferred embodiment, the positive temperature coefficient current circuit 31 comprises a common-source common-gate connected first transistor M1 and second transistor M2, a first operational amplifier circuit OP1, a common-base common-collector connected first bipolar transistor B1 and second bipolar transistor B2, and a third resistor R3. Specifically, the first transistor M1 is connected in series with the first bipolar transistor B1, and the source of the first transistor M1 receives a supply voltage VCC, the drain of the first transistor M1 is connected to the emitter of the first bipolar transistor B1, and the collector of the first bipolar transistor B1 is connected to a ground terminal. The second transistor M2, the third resistor R3, and the second bipolar transistor B2 are connected in series, and the source of the second transistor M2 receives the supply voltage VCC, the drain of the second transistor M2 is connected to one end of the third resistor R3, the other end of the third resistor R3 is connected to the emitter of the second bipolar transistor B2, and the collector of the second bipolar transistor B2 is connected to the ground terminal. The gates of the first transistor M1 and the second transistor M2 are connected together, and the bases of the first bipolar transistor B1 and the second bipolar transistor B2 are connected together. The two input terminals of the first operational amplifier circuit OP1 are connected to the drain of the first transistor M1 and the drain of the second transistor M2, respectively, and the output terminal of the first operational amplifier circuit OP1 is connected to the common gate of the first transistor M1 and the second transistor M2. The current flowing through the third resistor R3 is the positive temperature coefficient current I PTAT .

[0059] The positive temperature coefficient current circuit 31 utilizes the first bipolar transistor B1 and the second bipolar transistor B2 to work at different current densities (for example, different areas, etc.), resulting in a voltage difference ΔV BE (ΔV BE = V BE2 -V BE1 , V BE1 and V BE2 are the voltage differences between the bases and emitters of the first bipolar transistor B1 and the second bipolar transistor B2, respectively) and the absolute temperature T has a positive temperature characteristic, and ΔV BE generates a current on the third resistor R3, thereby generating the positive temperature coefficient current I PTAT . In a preferred embodiment, the area of the second bipolar transistor B2 is greater than that of the first bipolar transistor B1.

[0060] The negative temperature coefficient current circuit 32 is used to generate a negative temperature coefficient current I CTAT . The negative temperature coefficient current I CTAT is a current source that is inversely proportional to the absolute temperature, and has a negative temperature coefficient (i.e., the current decreases as the temperature rises). The negative temperature coefficient current I CTATIt is used to offset components with positive temperature coefficients (such as diodes or transistors), thereby generating a more stable reference voltage Vref with smaller temperature drift.

[0061] In a preferred embodiment, the negative temperature coefficient current circuit 32 includes a second operational amplifier circuit OP2 and a third transistor M3 and a fourth resistor R4 connected in series, wherein the two input terminals of the second operational amplifier circuit OP2 are respectively connected to the drain of the first transistor M1 and the drain of the third transistor M3, and the output terminal is connected to the gate of the third transistor M3. The current flowing through the fourth resistor R4 is the current with a negative temperature coefficient I CTAT .

[0062] The negative temperature coefficient current circuit 32 utilizes the base-emitter voltage V BE1 Negative temperature characteristics, and V BE1 A current is generated on the fourth resistor R4, thereby generating a current with a negative temperature coefficient I CTAT .

[0063] The compensation current generating circuit 33 is used to generate multiple first compensation currents Ip1, Ip2...IpM and multiple second compensation currents In1, In2...InM, and superimpose the compensation currents of all the paths to generate a third compensation current Icomp, so that in different sub-intervals of low temperature zones or high temperature zones, different numbers of second compensation currents or first compensation currents correspond to each other, so as to generate compensation currents of different values.

[0064] Further, refer to Figure 2 As shown, each first compensation current exhibits a piecewise linear characteristic and has different segmented temperature thresholds TH. On either side of the segmented threshold TH, the first compensation current Ip has different slopes. The first compensation current Ip is used to compensate for the curvature of the reference voltage Vref1 in the high temperature zone. For example, the first compensation current Ip1 has a slope of zero when the temperature is less than the segmented temperature threshold TH4, and preferably, its amplitude is also zero. When the temperature is greater than the segmented temperature threshold TH4, its amplitude increases from zero at a predetermined slope. The first compensation current Ip2 has a slope of zero when the temperature is less than the segmented temperature threshold TH3, and preferably, its amplitude is also zero. When the temperature is greater than the segmented temperature threshold TH3, its amplitude increases from zero at a predetermined slope. The same applies to the first compensation currents Ip3…IpM, and no further description is given here.

[0065] Further, continue to refer to Figure 2, each of the second compensation currents presents a piecewise linear characteristic and has different piecewise temperature thresholds TL, on both sides of the corresponding piecewise temperature threshold TL, the second compensation current In has different slopes, and the second compensation current In is used to compensate the curvature of the reference voltage Vref1 in the low-temperature temperature zone. For example, the second compensation current In1 has a slope of zero when the temperature is greater than the piecewise temperature threshold TL1, and preferably, the amplitude is also zero, and the amplitude decreases at a certain slope when the temperature is less than the piecewise temperature threshold TL1; the second compensation current In2 has a slope of zero when the temperature is greater than the piecewise temperature threshold TL2, and preferably, the amplitude is also zero, and the amplitude decreases at a certain slope when the temperature is less than the piecewise temperature threshold TL2; the second compensation currents In3...InM are the same, and details are not repeated here.

[0066] That is, each of the first compensation currents and the second compensation currents has a corresponding effective temperature interval, and the value of the corresponding first compensation current and the second compensation current is a non-zero value within the effective temperature interval, otherwise, the value of the corresponding first compensation current and the second compensation current is zero. And the effective temperature interval corresponding to each of the first compensation currents and the second compensation currents is different.

[0067] It should be noted that in the embodiment, the second compensation currents In1, In2, In3, and In4 have different piecewise thresholds but the same slope, and the first compensation currents Ip1, Ip2, Ip3, and Ip4 have different piecewise thresholds but the same slope are taken as examples for description, and in other embodiments, the slopes of each of the negative temperature coefficient compensation currents or the positive temperature coefficient compensation currents can also be different, which is not limited here.

[0068] Reference Figure 4 , the circuit schematic diagram of the compensation current generation circuit of the embodiment of the present application. The embodiment of the present application takes M positive temperature coefficient currents and M negative temperature coefficient currents as examples for description. The compensation current generation circuit 33 includes M positive temperature coefficient compensation circuits P1, P2...PM connected in parallel, and M negative temperature coefficient compensation circuits N1, N2...NM connected in parallel. They are respectively used to generate a plurality of first compensation currents Ip1, Ip2...IpM and a plurality of second compensation currents In1, In2...InM. Here, the sum of the plurality of first compensation currents Ip1, Ip2...IpM is denoted as Ip, the sum of the plurality of second compensation currents In1, In2...InM is denoted as In, and the sum of the plurality of first compensation currents Ip and the sum of the plurality of second compensation currents In are denoted as the third compensation current Icomp.

[0069] The compensation current generation circuit 33 generates the third compensation current Icomp based on the positive temperature coefficient current Ip and the negative temperature coefficient current In. PTAT And the negative temperature coefficient current In CTATThe values of the currents and the respective weights are used to generate the first compensation currents and the second compensation currents. Further, the compensation current generating circuit 33 changes the segment temperature threshold of each first compensation current or second compensation current by changing the proportion of the positive temperature coefficient current and the negative temperature coefficient weight.

[0070] Further, in each positive temperature coefficient compensation circuit Pi, when the product of the positive temperature coefficient current I PTAT and its own weight is greater than the product of the negative temperature coefficient current I CTAT and its own weight, the positive temperature coefficient compensation circuit Pi outputs a first compensation current Ipi with a first slope; when the product of the positive temperature coefficient current I PTAT and its own weight is not greater than the product of the negative temperature coefficient current I CTAT and its own weight, the positive temperature coefficient compensation circuit Pi outputs a first compensation current Ipi with a second slope, where the second slope is zero, and further, the amplitude of the first compensation current Ipi is also zero.

[0071] In each negative temperature coefficient compensation circuit Ni, when the product of the negative temperature coefficient current I CTAT and its own weight is greater than the product of the positive temperature coefficient current I PTAT and its own weight, the negative temperature coefficient compensation circuit Ni outputs a second compensation current Ini with a third slope; when the product of the negative temperature coefficient current I CTAT and its own weight is not greater than the product of the positive temperature coefficient current I PTAT and its own weight, the negative temperature coefficient compensation circuit Ni outputs a second compensation current Ini with a second slope, where the second slope is zero, and further, the amplitude of the second compensation current Ini is also zero.

[0072] Figure 5 Fig. 1 is a circuit schematic diagram of a positive temperature coefficient compensation circuit of an embodiment of the present application. Preferably, each positive temperature coefficient compensation circuit Pi comprises a current replication circuit 51, a third current mirror 52, and a fourth current mirror 53.

[0073] The current replication circuit 51 is used to replicate the positive temperature coefficient current I PTAT and the negative temperature coefficient current I CTAT in a proportion corresponding to their own weights, respectively, to obtain a first positive temperature coefficient current Ai*I PTAT and a first negative temperature coefficient current Bi*I CTATIn a preferred embodiment, the current copying circuit 51 comprises two transistors Mi2 and Mi1, which respectively form a current mirror with the second transistor M2 in the positive temperature coefficient current circuit 3, and form a current mirror with the third transistor M3 in the negative temperature coefficient current circuit 32, to respectively copy the positive temperature coefficient current I PTAT with a first proportion Ai, and copy the negative temperature coefficient current I CTAT with a second proportion Bi. The gate of the transistor Mi2 receives the output voltage Vop1 of the first operational amplifier circuit OP1, and the source receives the power supply voltage VCC; the gate of the transistor Mi1 receives the output voltage Vop2 of the second operational amplifier circuit OP2, and the source receives the power supply voltage VCC. The weight Bi is determined according to the size proportion of the transistor Mi1 and the third transistor M3, and the weight Ai is determined according to the size proportion of the transistor Mi2 and the second transistor M2.

[0074] Further, the current copying circuit 51 changes the segmented temperature threshold THi of the first compensation current Ipi by changing the weight proportion of the positive temperature coefficient current and the negative temperature coefficient current, i.e. changing the value of the first proportion Ai and the value of the second proportion Bi. Therefore, in different positive temperature coefficient compensation circuits, different values of the first proportion Ai and the second proportion Bi can be selected to make different positive temperature coefficient compensation circuits generate different first compensation currents Ipi.

[0075] The third current mirror 52 is used to mirror the first positive temperature coefficient current Ai*I PTAT . In a preferred embodiment, the third current mirror 52 comprises a current mirror composed of transistors Mi4 and Mi3. Specifically, the transistor Mi4 is connected in series with the transistor Mi2, the transistor Mi3 is connected in series with the transistor Mi1, and the common end of the gates of the transistors Mi4 and Mi3 is connected to the drain of the transistor Mi2, so that the first positive temperature coefficient current Ai*I PTAT is mirrored to the transistor Mi3.

[0076] The fourth current mirror 53 is used to generate a difference current Ic1 according to the difference between the first positive temperature coefficient current Ai*I PTAT and the first negative temperature coefficient current Bi*I CTAT , and mirror and amplify the difference current Ic1 by n times to generate a positive temperature coefficient compensation current Ipi=n*Ic1. The fourth current mirror 53 comprises a current mirror composed of transistors Mi5 and Mi6. When the first positive temperature coefficient current Ai*I PTAT is greater than the first negative temperature coefficient current Bi*I CTAT , a difference current Ic1=Ai*I PTAT -Bi*I CTATWhen the first positive temperature coefficient current Ai*I PTAT is less than or equal to the first negative temperature coefficient current Bi*I CTAT , Ic1=0, no current flows through the transistor Mi6, and thus no current flows through the transistor Mi5, Ipi=0.

[0077] Further, the transistors Mi5 and Mi6 are configured to have different areas, and the area of the transistor Mi5 is greater than the area of the transistor Mi6, so as to amplify the difference current Ic by a certain multiple to generate the first compensation current Ipi.

[0078] Figure 6 Fig. 1 is a circuit schematic diagram of a negative temperature coefficient compensation circuit according to an embodiment of the present application. Preferably, each negative temperature coefficient compensation circuit Ni comprises a current replication circuit 61, a fifth current mirror 62, and a sixth current mirror 63.

[0079] The current replication circuit 61 is used to replicate the positive temperature coefficient current I PTAT and the negative temperature coefficient current I CTAT in a ratio corresponding to their respective weights, to obtain a second positive temperature coefficient current Di*I PTAT and a second negative temperature coefficient current Ci*I CTAT , respectively. In a preferred embodiment, the current replication circuit 61 comprises two transistors Mi1 and Mi2, which respectively form a current mirror with the second transistor M2 in the positive temperature coefficient current circuit 3, and form a current mirror with the third transistor M3 in the negative temperature coefficient current circuit 32, to respectively replicate the positive temperature coefficient current I PTAT in a third ratio Di, and replicate the negative temperature coefficient current I CTAT in a fourth ratio Ci. The gate of the transistor Mi1 receives the output voltage Vop1 of the first operational amplifier circuit OP1, and the gate of the transistor Mi2 receives the output voltage Vop2 of the second operational amplifier circuit OP2. The weight Di is determined according to the size ratio of the transistor Mi1 and the second transistor M2, and the weight Ci is determined according to the size ratio of the transistor Mi2 and the third transistor M3.

[0080] Further, the current replication circuit 61 changes the segment temperature threshold TLi of the first compensation current Ini by changing the weight ratios of the positive temperature coefficient current and the negative temperature coefficient current, i.e., changing the value of the third ratio Di and the value of the fourth ratio Ci. It can be understood that in different negative temperature coefficient compensation circuits, different values of the third ratio Di and the fourth ratio Ci can be selected, so that different negative temperature coefficient compensation circuits generate different second compensation currents Ini.

[0081] The fifth current mirror 62 is configured to mirror the second negative temperature coefficient current Ci*I CTAT The fifth current mirror 62 is configured to mirror the second negative temperature coefficient current Ci*I CTAT to the transistor Mi3.

[0082] The sixth current mirror 63 is configured to generate a difference current Ic2 according to a difference between the second positive temperature coefficient current Di*I PTAT and the second negative temperature coefficient current Ci*I CTAT , and mirror the difference current Ic2 n times to generate a negative temperature coefficient compensation current Ini. The sixth current mirror 63 includes a current mirror composed of transistors Mi5 and Mi6. When the second negative temperature coefficient current Ci*ICTAT is greater than the second positive temperature coefficient current Di*I PTAT , the difference current Ic2=Ci*I CTAT -Di*I PTAT , the second negative temperature coefficient current Ci*ICTAT is less than or equal to the second positive temperature coefficient current Di*I PTAT , Ic2=0, no current flows through the transistor Mi6, and thus no current flows through the transistor Mi5, Ini=0.

[0083] Further, the transistors Mi5 and Mi6 are configured to have different areas, and the area of the transistor Mi5 is greater than the area of the transistor Mi6, to achieve the generation of the second compensation current Ini after the difference current Ic2 is amplified by a certain multiple. As shown in Figure 5 and Figure 6 , the area of the transistor Mi5 is set to be n times the area of the transistor Mi6, and in other examples, Figure 5 and Figure 6 , different multiples can be set.

[0084] Continuing to refer to Figure 3 , the reference voltage generation circuit 34 is configured to receive the positive temperature coefficient current I PTAT , the negative temperature coefficient current I CTAT , and the third compensation current Icomp to generate a low-temperature coefficient reference voltage Vref.

[0085] In a preferred embodiment, the reference voltage generating circuit 34 comprises a fourth transistor M4 and a fifth transistor M5 connected in parallel, and a resistive voltage dividing circuit. The common node of the fourth transistor M4 and the fifth transistor M5 is connected to the resistive voltage dividing circuit, the fourth transistor M4 and the second transistor M2 form a first current mirror to mirror a positive temperature coefficient current I PTAT to the fourth transistor M4, and the fifth transistor M5 and the third transistor M3 form a second current mirror to mirror a negative temperature coefficient current I CTAT to the fifth transistor M5.

[0086] In particular, the resistive voltage dividing circuit comprises a first resistor R1 and a second resistor R2 connected in series, the second resistor R2 is coupled to the ground potential, the sum of the positive temperature coefficient current I PTAT and the negative temperature coefficient current I CTAT is injected into the resistive voltage dividing circuit at the first resistor R1 and the common node of the fourth transistor M4 and the fifth transistor M5, and the third compensation current Icomp is injected into the resistive voltage dividing circuit at the common node of the first resistor R1 and the second resistor R2, and generates a reference voltage Vref = (I PTAT + I CTAT )*(R1+R2)+Icomp*(R1+R2) / R2 at the first resistor R1 and the common node of the fourth transistor M4 and the fifth transistor M5. In the embodiment of the present application, the first resistor R1 is configured to be much larger than the second resistor R2, so that the third compensation current actually injected into the resistive voltage dividing circuit is significantly increased.

[0087] The reference voltage generating circuit 34 of the embodiment of the present application, by injecting the sum of the multiple compensation currents in the compensation current generating circuit 33, i.e. the third compensation current Icomp, into the resistance center of the resistive voltage dividing circuit, so that the third compensation current actually injected into the resistive voltage dividing circuit is significantly increased, and the compensation current is much larger than the leakage current, so that the curvature correction technique is not sensitive to the leakage current.

[0088] The bandgap reference circuit further comprises a start-up circuit 35 for providing a start-up voltage for the positive temperature coefficient current circuit during start-up, so that the bandgap reference circuit starts to start up. The start-up circuit 35 is used to provide a start-up voltage for the positive temperature coefficient current circuit during start-up, so that the bandgap reference circuit starts to start up. In a preferred embodiment, the start-up circuit 35 comprises a first P-type transistor MP1 and a first N-type transistor MN1 connected in series, and a second P-type transistor MP2, a second N-type transistor MN2 and a second N-type transistor MN2 connected in series.

[0089] The source of the first P-type transistor MP1 is connected to a power supply end of a power supply voltage VCC through a resistor, the drain is connected to the drain of the first N-type transistor MN1, the source of the first N-type transistor MN1 is connected to a ground potential, the gates of the first P-type transistor MP1 and the first N-type transistor MN1 are connected together, and the common gate receives a reference voltage Vref. The source of the second P-type transistor MP2 is connected to the power supply end of the power supply voltage VCC, the drain is connected to the drain of the second N-type transistor MN2, the source of the second N-type transistor MN2 is connected to the drain of the third N-type transistor MN3, the source of the third N-type transistor MN3 is connected to the ground potential and the gate is connected to the common drain of the first P-type transistor MP1 and the first N-type transistor MN1, and the gates of the second P-type transistor MP2 and the second N-type transistor MN2 are connected together, the common gate receives the power supply voltage VCC, and the start-up voltage Vst is output at the common drain of the second P-type transistor MP2 and the second N-type transistor MN2 and injected into the output end of the first operational amplifier circuit OP1 of the positive temperature coefficient current circuit to start up the bandgap reference circuit.

[0090] When the system starts to start up, the reference voltage Vref is 0, at this time, the first P-type transistor MP1 is turned on, so that the gate of the third N-type transistor MN3 is pulled up to the power supply voltage VCC and turned on, and then the source of the second N-type transistor MN2 is pulled to the ground potential and turned on, at this time, the start-up voltage Vst is 0.

[0091] When the reference voltage Vref is established, at this time, the first N-type transistor MN1 is turned on, so that the gate of the third N-type transistor MN3 is pulled to the ground potential and turned off, and the second P-type transistor MP2 is turned on, at this time, the start-up voltage Vst is high, which does not affect the normal work.

[0092] It can be seen that the bandgap reference circuit of the embodiment of the present application generates corresponding compensation currents by superimposing different paths of first compensation currents in different temperature zones, so that different values of compensation currents are respectively corresponding to different temperature zones, and then the nonlinear characteristics for different temperature zones are finely adjusted, so that the reference voltage has an extremely low temperature coefficient in the high temperature zone. Further, the sum of the multiple compensation currents is injected into the resistance center of the resistance voltage dividing circuit, so that the compensation current actually injected into the resistance voltage dividing circuit is significantly increased, and then the compensation current is much larger than the leakage current, so that the curvature correction technology is not sensitive to the leakage current.

[0093] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A bandgap reference circuit, characterized in that: include; Positive temperature coefficient current circuit, used to generate current with positive temperature coefficient; Negative temperature coefficient current circuit, used to generate current with negative temperature coefficient; a compensation current generating circuit, configured to generate a third compensation current, wherein the third compensation current corresponds to currents of different values ​​in different sub-intervals of the low temperature zone or the high temperature zone; The reference voltage generating circuit generates a reference voltage with a low temperature coefficient according to the current with the positive temperature coefficient, the current with the negative temperature coefficient and the third compensation current.

2. The bandgap reference circuit according to claim 1, wherein: The compensation current generating circuit generates multiple first compensation currents in a high temperature zone and multiple second compensation currents in a low temperature zone, and generates the third compensation current by superimposing the multiple first compensation currents and the multiple second compensation currents.

3. The bandgap reference circuit according to claim 2, wherein: The compensation current generating circuit generates different numbers of second compensation currents in different sub-intervals of the low temperature zone; and generates different numbers of first compensation currents in different sub-intervals of the high temperature zone.

4. The bandgap reference circuit according to claim 2, wherein: In the low temperature range, as the temperature decreases, the number of paths of the second compensation current in the sub-range increases; in the high temperature range, as the temperature increases, the number of paths of the first compensation current in the sub-range increases.

5. The bandgap reference circuit according to claim 2, wherein: Each of the first compensation current or the second compensation current exhibits a piecewise linear characteristic and has different piecewise temperature thresholds. On both sides of the corresponding piecewise temperature threshold, the first compensation current or the second compensation current has different slopes. The first compensation current is used to compensate for the curvature of the reference voltage in the high temperature zone, and the second compensation current is used to compensate for the curvature of the reference voltage in the low temperature zone.

6. The bandgap reference circuit according to claim 2, wherein: The compensation current generating circuit generates the first compensation current and the second compensation current based on the values ​​of the positive temperature coefficient current and the negative temperature coefficient current and their respective weights.

7. The bandgap reference circuit according to claim 6, wherein: The compensation current generating circuit changes the segmented temperature threshold of each first compensation current or second compensation current by changing the weight ratio of the current of the positive temperature coefficient and the negative temperature coefficient. On both sides of the corresponding segmented temperature threshold, the first compensation current or the second compensation current has different slopes.

8. The bandgap reference circuit according to claim 6, wherein: The compensation current generating circuit includes a plurality of positive temperature coefficient compensation circuits to respectively generate the plurality of first compensation currents, wherein when the product of the current with the positive temperature coefficient and its own weight is greater than the product of the current with the negative temperature coefficient and its own weight, each of the positive temperature coefficient compensation circuits outputs the first compensation current with a first slope.

9. The bandgap reference circuit according to claim 8, wherein: When the product of the current with the positive temperature coefficient and its own weight is not greater than the product of the current with the negative temperature coefficient and its own weight, each of the positive temperature coefficient compensation circuits outputs the first compensation current with a second slope.

10. The bandgap reference circuit according to claim 6, wherein: The compensation current generating circuit includes a plurality of negative temperature coefficient compensation circuits to respectively generate the plurality of second compensation currents, wherein when the product of the current with the negative temperature coefficient and its own weight is greater than the product of the current with the positive temperature coefficient and its own weight, each of the negative temperature coefficient compensation circuits outputs the first compensation current with a third slope.

11. The bandgap reference circuit according to claim 10, wherein: When the product of the current with the negative temperature coefficient and its own weight is not greater than the product of the current with the positive temperature coefficient and its own weight, each of the negative temperature coefficient compensation circuits outputs the first compensation current with a second slope.

12. The bandgap reference circuit according to claim 1, wherein: The reference voltage generating circuit includes a resistor divider circuit, which includes a first resistor and a second resistor connected in series, the second resistor is coupled to the ground potential, and the third compensation current is injected into the reference voltage generating circuit at a common node between the first resistor and the second resistor.

13. The bandgap reference circuit according to claim 12, wherein: The current with the positive temperature coefficient and the current with the negative temperature coefficient are both injected into the reference voltage generating circuit at the first end of the first resistor, and the reference voltage is generated at the first end of the first resistor, wherein the second end of the first resistor is coupled to the second resistor.

14. The bandgap reference circuit according to claim 12, wherein: The resistance of the first resistor is much greater than the resistance of the second resistor.

15. The bandgap reference circuit according to claim 1, wherein: The positive temperature coefficient current circuit includes a first transistor and a second transistor connected with a common source and a common gate, a first operational amplifier circuit, a first bipolar transistor and a second bipolar transistor connected with a common base and a common collector, and a third resistor, wherein the first transistor is connected in series with the first bipolar transistor, the second transistor, the third resistor and the second bipolar transistor are connected in series in sequence, the two input terminals of the first operational amplifier circuit are respectively connected to the drain of the first transistor and the drain of the second transistor, and the output terminal is connected to the common gate of the first transistor and the second transistor, and the current flowing through the third resistor is the current with the positive temperature coefficient.

16. The bandgap reference circuit according to claim 15, wherein: The negative temperature coefficient current circuit includes a second operational amplifier circuit and a third transistor and a fourth resistor connected in series, wherein the two input terminals of the second operational amplifier circuit are respectively connected to the drain of the first transistor and the drain of the third transistor, and the output terminal is connected to the gate of the third transistor, and the current flowing through the fourth resistor is the current with the negative temperature coefficient.

17. The bandgap reference circuit according to claim 16, wherein: The reference voltage generating circuit includes a fourth transistor and a fifth transistor connected in parallel, and a resistor voltage divider circuit, wherein a common node of the fourth transistor and the fifth transistor is connected to the resistor voltage divider circuit, the fourth transistor and the second transistor constitute a first current mirror, and the fifth transistor and the third transistor constitute a second current mirror.

18. The bandgap reference circuit according to claim 8, wherein: A plurality of positive temperature coefficient compensation circuits are coupled in parallel, each of the positive temperature coefficient compensation circuits comprising a current replication circuit, a third current mirror, and a fourth current mirror; The current replication circuit is used to replicate the current with the positive temperature coefficient and the current with the negative temperature coefficient in proportions corresponding to their own weights, so as to obtain a current with a first positive temperature coefficient and a current with a first negative temperature coefficient, respectively; The third current mirror is used to mirror the current of the first positive temperature coefficient; The fourth current mirror is configured to generate a difference current according to a difference between the first positive temperature coefficient current and the first negative temperature coefficient current, and mirror the difference current to generate the first compensation current.

19. The bandgap reference circuit according to claim 10, wherein: A plurality of the negative temperature coefficient compensation circuits are coupled in parallel, each of the negative temperature coefficient compensation circuits comprising a current replication circuit, a fifth current mirror, and a sixth current mirror; The current replication circuit is used to replicate the current with the positive temperature coefficient and the current with the negative temperature coefficient in proportions corresponding to their own weights, so as to obtain a current with a second positive temperature coefficient and a current with a second negative temperature coefficient, respectively; The third current mirror is used to mirror the current of the second negative temperature coefficient; The fourth current mirror is configured to generate a difference current according to a difference between the second positive temperature coefficient current and the second negative temperature coefficient current, and mirror the difference current to generate the second compensation current.

20. The bandgap reference circuit according to claim 1, wherein: The invention also includes a startup circuit for providing a startup voltage to the positive temperature coefficient current circuit at startup, so that the bandgap reference circuit starts to start.

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