Bandgap reference with high supply voltage rejection ratio, integrated circuit and electronic device

Abstract

The application provides a high power voltage rejection ratio band gap reference source, integrated circuit and electronic equipment, relates to the technical field of integrated circuits, and the first stage operational amplifier unit of the reference source comprises a first field effect tube, a second field effect tube, an input pair tube, a first resistor, a first node and a second node, the second stage operational amplifier unit is used for realizing that the potentials of the first node and the second node are equal, the input pair tube comprises a first triode, a second triode and a third triode. The output part comprises an output pair tube, a second resistor, a third node and a fourth node, the output pair tube comprises a third triode and a fourth triode, the third node and the fourth node are electrically connected with the base ends of the first triode and the second triode respectively. According to the resistance value of the first resistor, the current ratio of the third node and the first resistor is a first preset value. The reference source suppresses the input distortion of the operational amplifier part, and realizes that the current ratio of the operational amplifier part and the output part is a preset proportion through the first resistor with very small voltage drop, so that the application provides a feasible scheme for the band gap reference source with high PSR under the condition of low power voltage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of integrated circuits, and in particular to a bandgap reference source with high power supply rejection ratio, an integrated circuit and an electronic device. BACKGROUND

[0002] In the field of integrated circuit design, a bandgap reference source is a very important module. Its performance, especially the power supply rejection ratio (PSR), is a key parameter for measuring its ability to suppress power supply voltage fluctuations, and directly affects the output accuracy and stability. However, with the gradual development of integrated circuit technology, the design of the bandgap reference source is also facing more and more challenges, such as the power supply rejection ratio under low voltage conditions.

[0003] Due to the large gain of the operational amplifier in the bandgap reference source under low voltage conditions, it is difficult to achieve due to the dual constraints of voltage margin and loop stability, and there is also a possibility that the output voltage of the operational amplifier will not match the change in the power supply voltage, resulting in poor PSR. Therefore, it is inevitable that the bandgap reference source is applied under low voltage conditions, and how to achieve high power supply rejection ratio of the bandgap reference source under low voltage conditions has become an important problem for those skilled in the art. SUMMARY

[0004] Therefore, the present application provides a bandgap reference source with high power supply rejection ratio, an integrated circuit and an electronic device, and the scheme is as follows:

[0005] A bandgap reference source with high power supply rejection ratio, the reference source comprising: an operational amplifier part, an output part and a power supply end, the power supply end being used to provide a power supply voltage, the operational amplifier part comprising a first-stage operational amplifier unit and a second-stage operational amplifier unit;

[0006] The first-stage operational amplifier unit comprises a first field effect transistor, a second field effect transistor, an input pair transistor, a first resistor, a first node and a second node, the second-stage operational amplifier unit being electrically connected with the power supply end and the second node, and being used to realize that the potentials of the first node and the second node are equal; the control ends of the first field effect transistor and the second field effect transistor are electrically connected, the first ends thereof are respectively electrically connected with the power supply end, and the second ends thereof are respectively electrically connected with the first node and the second node, and the control end of the second field effect transistor is also electrically connected with the first node; the input pair transistor comprises a first triode and a second triode, the emitter ends of the first triode and the second triode are respectively electrically connected with the first node and the second node, the collector ends of the first triode and the second triode are electrically connected with the first resistor, and the base ends of the first triode and the second triode are respectively the positive and negative input ends of the operational amplifier part;

[0007] The output part comprises an output pair of transistors, a second resistor, a third node and a fourth node, the output pair of transistors comprises a third transistor and a fourth transistor; the emitter of the third transistor is electrically connected with the third node, and is also electrically connected with the base; the emitter of the fourth transistor is electrically connected with the fourth node through the second resistor, and is also electrically connected with the base, the collectors of the third transistor and the fourth transistor are grounded; the third node and the fourth node are also electrically connected with the bases of the first transistor and the second transistor respectively, and the third node and the fourth node are also electrically connected with the power supply end;

[0008] The ratio of the third node to the current of the first resistor is a first preset value according to the resistance of the first resistor.

[0009] Optionally, the ratio m of the number of the first transistor to the number of the third transistor, the resistance of the first resistor is R1, and the current I1 of the first resistor is V T × (lnm) / R1.

[0010] The ratio n of the number of the fourth transistor to the number of the third transistor, the resistance of the second resistor is R2, and the current I2 of the third node is V T × (lnn) / R2.

[0011] Wherein, V T =kT / q, k is the Boltzmann constant, T is the absolute temperature, and q is the unit charge.

[0012] Optionally, the number of the first transistor is m, the number of the third transistor is 1, and the number of the fourth transistor is n.

[0013] Optionally, the second-stage operational amplifier unit comprises a third field effect transistor;

[0014] The first end of the third field effect transistor is electrically connected with the power supply end, the control end of the third field effect transistor is electrically connected with the second node, and the second end of the third field effect transistor is electrically connected with the collector of the third transistor.

[0015] The width-length ratio of the third field effect transistor and the first field effect transistor is equal.

[0016] Optionally, the second-stage operational amplifier unit comprises a third field effect transistor and a fifth node, and the output part further comprises a fourth field effect transistor;

[0017] The first end of the third field effect tube and the fourth field effect tube is electrically connected with the power supply end, the control end of the third field effect tube is electrically connected with the second node, the second end of the third field effect tube is electrically connected with the fifth node, and the fifth node is also electrically connected with the collector end of the third triode; the control end of the fourth field effect tube is electrically connected with the fifth node, and the second end of the fourth field effect tube is electrically connected with the third node and the fourth node respectively.

[0018] The current of the fifth node is equal to the current of the third node, the width-length ratio of the first field effect tube is a second preset value, the width-length ratio of the third field effect tube is a third preset value, and the ratio of the third preset value to the second preset value is 2 times the first preset value.

[0019] Optionally, the second-stage operational amplifier unit further comprises a current mirror, and the second end of the third field effect tube is electrically connected with the collector end of the third triode through the current mirror.

[0020] Optionally, the output part further comprises a third resistor and a fourth resistor, and the third node is electrically connected with the power supply end through the third resistor, and the fourth node is electrically connected with the power supply end through the fourth resistor.

[0021] The resistance values of the third resistor and the fourth resistor are equal.

[0022] Optionally, the field effect tubes in the reference source are all P-type field effect tubes, and the triodes in the reference source are all NPN-type triodes.

[0023] An integrated circuit comprising the bandgap reference source with a high power supply voltage rejection ratio as described in any of the above embodiments.

[0024] An electronic device comprising the integrated circuit.

[0025] Compared with the related art, the technical scheme of the present application has the following advantages:

[0026] The reference source comprises an operational amplifier part and an output part, the first stage operational amplifier unit of the operational amplifier part comprises a first field effect tube, a second field effect tube, an input pair tube, a first resistor, a first node and a second node, the potentials of the first node and the second node are equal. The control ends of the first field effect tube and the second field effect tube are electrically connected, the first end is electrically connected with the power supply end of the reference source, the second end is electrically connected with the first node and the second node respectively, and the control end of the first field effect tube is also electrically connected with the second end. The emitter ends of the first triode and the second triode in the input pair tube are electrically connected with the first node and the second node respectively, the collector end is electrically connected with the first resistor, and the base ends are the positive and negative input ends of the operational amplifier part respectively. The output part comprises an output pair tube, a second resistor, a third node and a fourth node, the emitter end of the third triode in the output pair tube is electrically connected with the third node, and also electrically connected with the base end, the emitter end of the fourth triode is electrically connected with the fourth node through the second resistor, and also electrically connected with the base end, and the collector ends of the third triode and the fourth triode are grounded. The third node and the fourth node are also electrically connected with the base ends of the first triode and the second triode respectively, and also electrically connected with the power supply end. Among them, according to the resistance value of the first resistor, the ratio of the current of the third node and the first resistor is a preset ratio, that is, by adjusting the resistance value of the first resistor, the ratio of the output current of the operational amplifier part and the current of the output part can meet the requirements. As can be seen, the bandgap reference source not only maintains the same potential of the first node and the second node, but also suppresses the input offset of the operational amplifier part. Through the first resistor with very small voltage drop, the bias current of the operational amplifier part and the bias current of the output part are in the desired preset ratio, thereby the bandgap reference source has the feasibility under low power voltage, and realizes high power voltage rejection ratio, which provides a feasible scheme for realizing the bandgap reference source under low power voltage. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments or the related art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only belong to the 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.

[0028] The structures, proportions, sizes and the like shown in the drawings of the specification are only used to cooperate with the content disclosed in the specification, so that those skilled in the art can understand and read, and are not used to limit the defined conditions that can be implemented by the present application, so they do not have technical significance. Any modification of structure, change of proportion relationship or adjustment of size, without affecting the effect and purpose that can be achieved by the present application, should still fall within the scope of the technical content disclosed by the present application.

[0029] Figure 1A structure diagram of a bandgap reference source with high power supply rejection ratio provided by the application is shown in the figure;

[0030] Figure 2 A circuit structure diagram of a bandgap reference source with high power supply rejection ratio provided by the application is shown in the figure;

[0031] Figure 3 A circuit structure diagram of a bandgap reference source provided by the application is shown in the figure. DETAILED DESCRIPTION

[0032] The embodiments in the application will be described in detail below with the accompanying drawings of the embodiments in the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0033] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the application will be further described in detail below with the accompanying drawings and specific embodiments.

[0034] As described in the background section, due to the difficulty in realizing large gain and the mismatch between the output voltage of the operational amplifier and the power supply voltage under low voltage condition, it is difficult to realize high power supply rejection ratio (i.e. high PSR) of the bandgap reference source under low voltage condition.

[0035] Specifically, the conventional operational amplifier usually needs sufficient voltage margin to ensure that the transistor works in the saturation region. However, under low voltage condition, the voltage margin will be insufficient, and the transistor will easily exit the saturation region and enter the linear region, at which time the gain of the operational amplifier will be reduced, resulting in poor PSR. If the large gain of the operational amplifier is realized by more gain stages (3 stages and above), more poles will be generated due to too many gain stages, which greatly affects the loop stability and results in poor PSR. In addition, if the output voltage of the operational amplifier and the power supply voltage do not match, the input pair transistor will be subjected to different channel length modulation effects, resulting in poor PSR.

[0036] Based on this, the application provides a bandgap reference source with high power supply rejection ratio, as shown in the figure. Figure 1 Figure 1 A structure diagram of a bandgap reference source with high power supply rejection ratio provided by the application is shown in the figure, which includes an operational amplifier part 100, an output part 200 and a power supply end VDD, and vbg represents the output port. The output part 200 and the operational amplifier part 100 can output the expected bias signal (current / voltage) in cooperation with each other, and the operational amplifier part 100 is the operational amplifier part. The operational amplifier part 100 includes a first-stage operational amplifier unit 120 and a second-stage operational amplifier unit 140. ​

[0037] As Figure 2 shown, Figure 2 A circuit structure schematic diagram of a high power voltage rejection ratio bandgap reference source provided by the present application, the first stage operational amplifier unit 120 includes a first field effect transistor M1, a second field effect transistor M2, an input pair of transistors (Q1 and Q2), a first resistor R1, a first node 1 and a second node 2. The second stage operational amplifier unit 140 is electrically connected with the power supply end VDD, and also electrically connected with the second node 2. The second stage operational amplifier unit 140 is used to realize that the potential of the first node is equal to the potential of the second node. Specifically, based on the first field effect transistor M1, the second field effect transistor M2 and the second stage operational amplifier unit 140, the potential of the first node is equal to the potential of the second node.

[0038] The control ends of the first field effect transistor M1 and the second field effect transistor M2 are electrically connected, the first ends are respectively electrically connected with the power supply end VDD of the reference source, the second ends are respectively electrically connected with the first node 1 and the second node 2, and the control end of the first field effect transistor M1 is also electrically connected with the first node 1. That is, the control end of the first field effect transistor M1 and the control end of the second field effect transistor M2 are electrically connected, the first end of the first field effect transistor M1 is electrically connected with the power supply end VDD of the reference source, and the second end of the first field effect transistor M1 is electrically connected with the first node 1. The first end of the second field effect transistor M2 is electrically connected with the power supply end VDD of the reference source, and the second end of the second field effect transistor M2 is electrically connected with the second node 2.

[0039] The input pair of transistors includes a first transistor Q1 and a second transistor Q2, the emitter ends of the first transistor Q1 and the second transistor Q2 are respectively electrically connected with the first node 1 and the second node 2, the collector ends of the first transistor Q1 and the second transistor Q2 are electrically connected with the first resistor R1, and the base ends of the first transistor Q1 and the second transistor Q2 are respectively the positive and negative input ends Vin / Vip of the operational amplifier part. Specifically, the emitter end of the first transistor Q1 is electrically connected with the first node 1, and the collector end of the first transistor Q1 is electrically connected with the first end of the first resistor R1. The emitter end of the second transistor Q2 is electrically connected with the second node 2, and the collector end of the second transistor Q2 is electrically connected with the first end of the first resistor R1. The base end of the first transistor Q1 is the positive input end Vin of the operational amplifier part 100, and the base end of the second transistor Q2 is the negative input end Vip of the operational amplifier part 100, wherein the voltage of the positive and negative input ends Vin / Vip of the operational amplifier part 100 is provided based on the first stage operational amplifier unit 120. It should be noted that the above-mentioned first transistor Q1 and second transistor Q2 can also be referred to as bipolar transistors (abbreviated as BJT), and the following-described transistors can also be referred to as bipolar transistors, which will not be described again.

[0040] The output part 200 comprises an output pair of transistors (Q3 and Q4), a second resistor R2, a third node 3 and a fourth node 4, wherein the output pair of transistors comprises a third transistor Q3 and a fourth transistor Q4. The emitter terminal of the third transistor Q3 is electrically connected to the third node 3 and also electrically connected to the base terminal of the third transistor Q3. The emitter terminal of the fourth transistor Q4 is electrically connected to the fourth node 4 through the second resistor R2 and also electrically connected to the base terminal of the fourth transistor Q4, and the collector terminals of the third transistor Q3 and the fourth transistor Q4 are grounded. Specifically, the emitter terminal of the third transistor Q3 is electrically connected to the third node 3, the collector terminal of the third transistor Q3 is grounded, and the emitter terminal and the base terminal of the third transistor Q3 are electrically connected. The emitter terminal of the fourth transistor Q4 is electrically connected to the fourth node 4 through the second resistor R2, the collector terminal of the fourth transistor Q4 is grounded, and the emitter terminal and the base terminal of the fourth transistor Q4 are electrically connected.

[0041] The third node 3 and the fourth node 4 are also electrically connected to the base terminals of the first transistor Q1 and the second transistor Q2, respectively, and the third node 3 and the fourth node 4 are also electrically connected to the power terminal VDD of the reference source. Specifically, the third node 3 is electrically connected to the base terminal of the first transistor Q1, i.e., the third node 3 is electrically connected to the positive input terminal Vin of the operational amplifier part 100, and the third node 3 is also electrically connected to the power terminal VDD of the reference source. The fourth node 4 is electrically connected to the base terminal of the second transistor Q2, i.e., the fourth node 4 is electrically connected to the negative input terminal Vip of the operational amplifier part 100, and the fourth node 4 is also electrically connected to the power terminal VDD of the reference source.

[0042] Based on the above, for the bandgap reference source provided in the present application, according to the resistance value of the first resistor R1, the ratio of the current at the third node 3 to the current of the first resistor R1 is a first preset value. That is, according to the resistance value of the first resistor R1, the ratio of the current at the third node 3 to the current of the first resistor R1 can be realized as a first preset value.

[0043] Firstly, since the bandgap reference source is based on the first field effect transistor M1 and the second field effect transistor M2 and the second-stage operational amplifier unit 140, the potentials of the first node 1 and the second node 2 are equal, so the input pair of transistors (the first transistor Q1 and the second transistor Q2) is subjected to the same channel length modulation effect, i.e., the influence is the same, which suppresses the input offset of the operational amplifier part 100, thereby effectively improving the power supply voltage rejection ratio of the bandgap reference source and helping to realize a high power supply voltage rejection ratio of the bandgap reference source.

[0044] Secondly, the potentials of the first node 1 and the second node 2 are equal, the first transistor Q1 and the second transistor Q2 are affected in the same way, so the potentials of the positive input terminal and the negative input terminal of the operational amplifier part 100 are equal, that is, the operational amplifier part 100 is virtually shorted. Since the third node 3 and the fourth node 4 of the output part 200 are electrically connected to the positive input terminal and the negative input terminal of the operational amplifier part 100, the potential of the third node 3 is also equal to the potentials of the first node 1 and the second node 2. However, since the potentials of the positive input terminal and the negative input terminal of the operational amplifier part 100 are low, the potential of the third node 3 is also low, and the output part 200 cannot use the current mirror. At this time, the current of the first resistor R1 is generated by the first transistor Q1, the third transistor Q3, and the first resistor R1. That is, the bias current output by the first-stage operational amplifier unit 120 is generated by the first transistor Q1, the third transistor Q3, and the first resistor R1. Specifically, the bias current of the first-stage operational amplifier unit 120 is denoted as a first current I1. The first current I1 can be obtained according to the difference ΔVBE1 between the base-emitter voltage VBE1 of the first transistor Q1 and the base-emitter voltage VBE3 of the third transistor Q3, and the resistance value of the first resistor R1. It should be noted that the bias current output by the first-stage operational amplifier unit 120 is the bias current output by the operational amplifier part 100.

[0045] The current at the third node 3 is denoted as a second current I2. The second current I2 can be obtained according to the difference ΔVBE2 between the base-emitter voltage VBE3 of the third transistor Q3 and the base-emitter voltage VBE4 of the fourth transistor Q4, and the resistance value of the second resistor R2. Therefore, the size of the second current I2 mainly depends on the resistance value of the second resistor R2. Since the size of the second current I2 mainly determines the size of the bias current output by the output part 200, that is, the second current I2 mainly determines the size of the current that can be output by the bandgap reference source, and the bias current output by the bandgap reference source is usually a known value, the resistance value of the second resistor R2 is also a known value that is set in advance based on the bias current output by the bandgap reference source.

[0046] Based on the above, for the bandgap reference source provided by the application, the ratio of the current of the third node 3 to the current of the first resistor R1 can be adjusted by adjusting the resistance value of the first resistor R1, and then the ratio of the current of the third node 3 to the bias current of the first-stage operational amplifier unit 120 is adjusted, and the ratio of the bias current of the output part 200 to the bias current of the first-stage operational amplifier unit 120 is adjusted, so that the bias current of the bandgap reference source and the bias current of the operational amplifier part 100 can be the desired preset ratio. Therefore, the bandgap reference source can adjust the bias current of the operational amplifier part 100 and the bias current of the output part 200 to the desired preset ratio by adjusting the resistance value of the first resistor R1 in the first-stage operational amplifier unit 120, and then the bandgap reference source can output the desired bias current. As can be seen, the bandgap reference source provided by the application adjusts the ratio of the bias current of the operational amplifier part 100 to the bias current of the output part 200 by adjusting the resistance value of the first resistor R1, rather than using a current mirror as in related art. Since the current mirror requires sufficient source-drain voltage to make VDS>VGS-VTH so that the mirror tube works in a reasonable working interval, it will occupy a part of the power supply voltage margin. The resistance does not need to limit the size of the voltage across it, so the voltage drop generated by the first resistor R1 is much smaller than the voltage drop generated by the current mirror, which does not affect the voltage margin of the bandgap reference source, or the impact is small and can be ignored, thereby realizing the feasibility of the bandgap reference source under low power supply voltage.

[0047] At the same time, the input pair of the bandgap reference source uses BJT tubes, which are the first transistor Q1 and the second transistor Q2, rather than the first field effect transistor M1 and the second field effect transistor M2. If a PMOS tube is used as the input pair, considering that the base B-emitter E voltage VBE of the third transistor Q3 is maximum 800-900mv, the voltage of the gate of the PMOS input pair plus the gate-source voltage VGS of the PMOS in the SS process angle will make the VDS of the operational amplifier tail current source PMOS tube very small, resulting in the circuit cannot work normally. If an NMOS tube is used as the input pair, then there will be a situation that the VGS of the input pair is less than the threshold voltage, which will also make the circuit cannot work normally. Therefore, the bandgap reference source realizes the feasibility under low power supply voltage while ensuring the normal operation of the circuit, and has high reliability. In addition, the input pair uses BJT tubes, which have better matching characteristics and larger transconductance than field effect transistors (also known as field effect tubes), which can reduce input offset and help achieve high power supply rejection ratio.

[0048] In summary, the bandgap reference source realizes the potential equality of the first node 1 and the second node 2 through the first field effect transistor M1 and the second field effect transistor M2 and the second stage operational amplifier unit 140, suppresses the input offset of the operational amplifier part 100, and effectively improves the power supply voltage rejection ratio. Moreover, the bandgap reference source realizes the desired preset ratio of the bias current of the operational amplifier part 100 and the bias current of the output part 200 through the first resistor R1 with a small voltage drop, and then realizes the feasibility of the bandgap reference source under low power supply voltage. That is, the bandgap reference source has both the feasibility under low power supply voltage and the high power supply voltage rejection ratio, thereby providing a feasible scheme for realizing the bandgap reference source under low power supply voltage.

[0049] In an embodiment of the present application, the ratio m of the number of the first transistor Q1 to the number of the third transistor Q3, and the resistance value of the first resistor R1 is also denoted as R1, then the current I1 (i.e. the first current I1) of the first resistor R1 = V T ×(lnm) / R1. Specifically, ΔVBE1=VBE3-VBE1=(V T ×ln(IC / IS)-V T ×ln(IC / mIS)) / R1=V T ×(lnm) / R1, wherein IC is the current of the collector of the first transistor Q1 and the third transistor Q3, IS is the reverse saturation current of the collector of the first transistor Q1 and the third transistor Q3, V T =kT / q, k is the Boltzmann constant (1.38×10 -23 J / K), T is the absolute temperature (unit: Kelvin K), and q is the unit charge (1.6×10 -19 C).

[0050] The ratio n of the number of the fourth transistor Q4 to the number of the third transistor Q3, and the resistance value of the second resistor R2 is R2, the current I2 (i.e. the second current I2) of the third node 3 = V T ×(lnn) / R2. Specifically, ΔVBE2=VBE3-VBE4=(V T ×ln(IC / IS)-V T ×ln(IC / nIS)) / R2=V T ×(lnn) / R2, wherein IC is the current of the collector of the third transistor Q3 and the fourth transistor Q4, IS is the reverse saturation current of the collector of the third transistor Q3 and the fourth transistor Q4, V T =kT / q, k is the Boltzmann constant (1.38×10 -23 J / K), T is the absolute temperature (unit: Kelvin K), and q is the unit charge (1.6×10 -19 C).

[0051] From the above, if the second current I2 is equal to x times the first current I1, i.e. I1 = xI2, V T x(lnn) / R2 = xV T x(lnm) / R1, since V T is a known constant, R2 is the set resistance value of the second resistor, and m and n are respectively the known quantity ratios of the first transistor Q1 and the third transistor Q3 and the fourth transistor Q4 and the third transistor Q3, so that the second current I2 can be equal to x times the first current I1 by adjusting the resistance value of the first resistor R1. It can be seen that the bandgap reference source can realize the proportional adjustment of the bias current of the operational amplifier part 100 and the bias current of the output part 200 by adjusting the resistance value of the first resistor R1, so as to realize the bias current of the operational amplifier part 100 and the bias current of the output part 200 in the desired preset proportion.

[0052] It should be noted that if the number of the first transistor Q1 and the third transistor Q3 is multiple, it should be understood that multiple first transistors Q1 are connected in parallel between the first node 1 and the first resistor R1. If the number of the third transistor Q3 and the fourth transistor Q4 is multiple, it should be understood that multiple third transistors Q3 are connected in parallel between the third node 3 and the ground terminal GND, and multiple fourth transistors Q4 are connected in parallel between the second resistor R2 and the ground terminal GND. Figure 2 For the sake of simplicity of illustration, only one first transistor Q1 and one third transistor Q3 are shown, and only one third transistor Q3 and one fourth transistor Q4 are shown.

[0053] Based on the above, in an embodiment of the present application, the number of the first transistor Q1 and the second transistor Q2 is equal, the number of the first transistor Q1 can be m, the number of the third transistor Q3 can be 1, and the number of the fourth transistor Q4 can be n. However, on the basis of meeting the above quantity ratio, the present application does not limit the number of the first transistor Q1, the second transistor Q2, the third transistor Q3 and the fourth transistor Q4, which is determined according to the specific situation.

[0054] In an embodiment of the present application, the second-stage operational amplifier unit 140 comprises a third field effect transistor M3, a first end of the third field effect transistor M3 is electrically connected with the power supply end VDD, a control end of the third field effect transistor M3 is electrically connected with the second node 2, and a second end of the third field effect transistor M3 is electrically connected with a collector end of the third transistor Q3. Wherein, a width-length ratio of the third field effect transistor M3 is equal to that of the first field effect transistor M1, that is, the third field effect transistor M3 and the first field effect transistor M1 are the same field effect transistor, so when the third field effect transistor M3 is in the saturation region, the first field effect transistor M1 is also in the saturation region, at this time, VGS of the third field effect transistor M3 and the first field effect transistor M1 are equal, the third field effect transistor M3 can be used to clamp the potential of the second node 2 to be equal to the potential of the first node 1, and the potential of the first node 1 and the potential of the second node 2 are equal. It should be noted that the first field effect transistor M1 and the second field effect transistor M2 are the same field effect transistor, that is, in the embodiment, the first field effect transistor M1, the second field effect transistor M2 and the third field effect transistor M3 can be the same field effect transistor.

[0055] It should be noted that the above embodiment is under the premise that the second-stage channel length modulation effect is not considered, the first field effect transistor M1, the second field effect transistor M2 and the third field effect transistor M3 are collectively in the saturation region, and VGS of the third field effect transistor M3 and the first field effect transistor M1 are equal. Based on this, in an embodiment of the present application, the second-stage operational amplifier unit 140 comprises a third field effect transistor M3 and a fifth node, and the output part 200 further comprises a fourth field effect transistor M4. A first end of the third field effect transistor M3 and the fourth field effect transistor M4 is electrically connected with the power supply end VDD, a control end of the third field effect transistor M3 is electrically connected with the second node 2, a second end of the third field effect transistor M3 is electrically connected with the fifth node 5, and the fifth node 5 is further electrically connected with a collector end of the third transistor Q3. A control end of the fourth field effect transistor M4 is electrically connected with the fifth node 5, and a second end of the fourth field effect transistor M4 is electrically connected with the third node 3 and the fourth node 4 respectively.

[0056] Specifically, the control end of the third field effect transistor M3 is electrically connected with the second node 2, the first end of the third field effect transistor M3 is electrically connected with the power supply end VDD, the second end of the third field effect transistor M3 is electrically connected with the fifth node 5, and the fifth node 5 is further electrically connected with the collector end of the third transistor Q3. The control end of the fourth field effect transistor M4 is electrically connected with the fifth node 5, the first end of the fourth field effect transistor M4 is electrically connected with the power supply end VDD of the bandgap reference source, and the second end of the fourth field effect transistor M4 is electrically connected with the third node 3 and the fourth node 4 respectively, that is, the third node 3 and the fourth node 4 are both electrically connected with the second end of the fourth field effect transistor M4.

[0057] The current of the fifth node 5 is equal to the current of the third node 3, and the width-length ratio of the first field effect transistor M1 is the second preset value, the width-length ratio of the third field effect transistor M3 is the third preset value, and the ratio of the third preset value to the second preset value is 2 times the first preset value.

[0058] Based on the above, the current of the fifth node 5 (denoted as the third current I3) comes from the fourth field effect transistor M4 mirror, so the current of the fifth node is equal to the current of the third node 3. Based on this, if the first preset value is x, the current of the fifth node 5 is x times the current of the first resistor R1, which is 2x times the current of the first node 1. Since the width-length ratio of the third field effect transistor M3 is 2x times the width-length ratio of the first field effect transistor M1, the ratio of the bias current of the third field effect transistor M3 to the bias current of the first field effect transistor M1 is equal to 2x, and the ratio of the width-length ratio of the third field effect transistor M3 to the width-length ratio of the first field effect transistor M1 is also equal to 2x. That is, the ratio of the width-length ratio of the third field effect transistor M3 to the width-length ratio of the first field effect transistor M1 is equal to the ratio of the current of the third node 3 to the current of the first node 1, that is, on the basis of the bias currents of the operational amplifier part 100 and the output part 200 satisfying the desired preset ratio, the current matching of the first-stage operational amplifier unit 120 and the second-stage operational amplifier unit 140 is realized. Based on this, the potentials of the first node 1 and the third node 3 are almost equal, and the secondary channel length modulation effect of the first field effect transistor M1 and the third field effect transistor M3 is also very close, so the potential of the second node 2 can be clamped to the same as the potential of the first node by using the third field effect transistor M3, and the potentials of the first node 1 and the second node 2 are equal.

[0059] It should be noted that due to the existence of the Early effect, when the VCE of the triode increases, the reverse bias voltage of the collector increases, causing the collector junction depletion layer to expand towards the base region, reducing the effective width of the base region. After the base region width is reduced, the recombination probability of the carriers in the base region is reduced, and more carriers can reach the collector, causing the collector current IC to increase slightly with the increase of VCE. Since IB is constant, β = IC / IB, the increase of IC directly shows that the value of β increases slightly with the increase of VCE. This phenomenon will cause the input pair of the first triode Q1 and the second triode Q2 of the transistor to be affected differently by the channel length modulation effect, thereby causing the input imbalance of the input pair, resulting in insufficient power supply voltage rejection ratio of the bandgap reference source. In the embodiment, the fifth node 5 is electrically connected to the control end of the fourth field effect transistor M4, and the fourth field effect transistor M4 is also electrically connected to the power supply end VDD, so that the potential of the fifth node 5 can change with the voltage change of the power supply end VDD, thereby realizing that the potentials of the first node 1 and the second node 2 are equal, and can change with the change of the power supply voltage. As can be seen, the bandgap reference source can suppress the input imbalance of the operational amplifier part 100 caused by the potential change of the first node 1 and the second node 2 with the power supply voltage, and can effectively improve the power supply voltage rejection ratio of the bandgap reference source, thereby helping to realize the high power supply voltage rejection ratio of the bandgap reference source.

[0060] In an embodiment of the present application, the second-stage operational amplifier unit 140 further includes a current mirror 142, and the second end of the third field effect transistor M3 is electrically connected to the collector end of the third triode Q3 through the current mirror 142. Specifically, the second end of the third field effect transistor M3 can be electrically connected to the current mirror 142 through the fifth node 5, and the current mirror 142 is also electrically connected to the collector end of the third triode Q3. It should be noted that the second-stage operational amplifier unit 140 is equivalent to a common source amplifier, and the load of the common source amplifier is the current mirror 142, so the second-stage operational amplifier unit 140 can have a relatively large output impedance, that is, a relatively large second-stage gain, compared with the common source amplifier with a "diode connection" load in the prior art, as shown in the dashed box in FIG. 1, which can provide a larger gain, thereby improving the power supply voltage rejection ratio of the bandgap reference source while meeting the desired gain. Figure 3

[0061] In addition, as can be seen from the above, the bandgap reference source provided by the present application can realize a high power supply voltage rejection ratio under low voltage conditions under the condition of two-stage operational amplification. Compared with the related art which adopts at least three-stage operational amplification, the circuit structure can be simplified and the circuit area can be reduced.

[0062] ​In an embodiment of the present application, the output part 200 further comprises a third resistor R3 and a fourth resistor R4, the third node 3 is electrically connected to the power terminal VDD through the third resistor R3, and the fourth node 4 is electrically connected to the power terminal VDD through the fourth resistor R4. Specifically, the third node 3 is electrically connected to the second terminal of the fourth field effect transistor M4 through the third resistor R3, and the fourth node 4 is electrically connected to the second terminal of the fourth field effect transistor M4 through the fourth resistor R4. Wherein, the third resistor R3 and the fourth resistor R4 have the same resistance value, and the second current I2 of the third node 3 can be obtained according to the difference ΔVBE4 between the base-emitter voltage VBE3 of the third transistor Q3 and the base-emitter voltage VBE4 of the fourth transistor Q4, and the resistance value of the second resistor R2.

[0063] In an embodiment of the present application, for the bandgap reference source provided by the present application, the field effect transistors in the reference source are all P-type field effect transistors, and the transistors are all NPN type transistors. That is, the input pair of the operational amplifier part 100 of the bandgap reference source adopts the NPN type transistor with greater current gain, and the load adopts the P-type field effect transistor with greater output impedance. Therefore, high gain of the operational amplifier part 100 can be realized, and then the bandgap reference source can realize greater gain of the operational amplifier part 100 without increasing the gain stage, and the loop stability can be considered, and then the power supply voltage rejection ratio of the bandgap reference source can be improved.

[0064] The present application further provides an integrated circuit, which comprises the bandgap reference source described in any of the above embodiments.

[0065] The present application further provides an electronic device, which comprises the integrated circuit described above.

[0066] In summary, the application provides a bandgap reference source with high power voltage rejection ratio, an integrated circuit and an electronic device. The bandgap reference source comprises an operational amplifier part, an output part and a power supply end. The first-stage operational amplifier unit of the operational amplifier part comprises a first field effect transistor, a second field effect transistor, an input pair transistor, a first resistor, a first node and a second node. The second-stage operational amplifier unit is configured to equalize the potentials of the first node and the second node. The control terminals of the first field effect transistor and the second field effect transistor are electrically connected. The first terminal is electrically connected to the power supply end. The second terminal is electrically connected to the first node and the second node, respectively. The control terminal of the first field effect transistor is also electrically connected to the second terminal. The emitter terminals of the first transistor and the second transistor of the input pair transistor are electrically connected to the first node and the second node, respectively. The collector terminal is electrically connected to the first resistor. The base terminals are the positive and negative input terminals of the operational amplifier part, respectively. The output part comprises an output pair transistor, a second resistor, a third node and a fourth node. The emitter terminal of the third transistor of the output pair transistor is electrically connected to the third node and the base terminal. The emitter terminal of the fourth transistor is electrically connected to the fourth node through the second resistor and the base terminal. The collector terminals of the third transistor and the fourth transistor are grounded. The third node and the fourth node are also electrically connected to the base terminals of the first transistor and the second transistor, respectively, and are also electrically connected to the power supply end. The ratio of the current of the third node to the first resistor is a first preset value according to the resistance value of the first resistor. Thus, the bandgap reference source not only maintains the same potentials of the first node and the second node and suppresses the input offset of the operational amplifier part, but also realizes the desired preset ratio of the bias current of the operational amplifier part to the bias current of the output part through the first resistor with small voltage drop. Thus, the bandgap reference source has the feasibility under low power voltage and realizes high power voltage rejection ratio, thereby providing a feasible scheme for realizing the bandgap reference source under low power voltage.

[0067] In the description of each embodiment in the specification, the differences between each embodiment are emphasized, and the same or similar parts of each embodiment can be referred to each other.

[0068] It should be noted that in the description of the present application, it should be understood that the terms "upper", "lower", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there can be a component disposed therebetween.

[0069] It is also noted that the relational terms herein, such as first and second, and the like, are used solely to distinguish one from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a vesicle or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such vesicle or apparatus. An element proceeded by "comprises a... " does not, without more constraints, preclude the existence of additional identical elements in the vesicle or apparatus that comprises the recited element.

[0070] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A bandgap reference with high supply voltage rejection ratio, characterized by, The application relates to an operational amplifier, which comprises an operational amplifier part, an output part and a power supply end, wherein the power supply end provides a power supply voltage, the operational amplifier part comprises a first-stage operational amplifier unit and a second-stage operational amplifier unit, the first-stage operational amplifier unit is electrically connected with the power supply end, the first-stage operational amplifier unit comprises a first field effect tube and a second field effect tube, the control end of the first field effect tube is electrically connected with the control end of the second field effect tube, the first end of the first field effect tube is electrically connected with the power supply end, the second end of the first field effect tube is electrically connected with a first node and a second node respectively, the control end of the second field effect tube is also electrically connected with the first node, the emitter end of a first triode and a second triode of an input pair is electrically connected with the first node and the second node respectively, the collector end of the first triode and the second triode is electrically connected with a first resistor, and the base end of the first triode and the second triode is the positive input end and the negative input end of the operational amplifier part respectively, the second-stage operational amplifier unit is electrically connected with the power supply end and the second node, the potential of the first node is equal to the potential of the second node, the output part comprises a third triode and a fourth triode, the emitter end of the third triode is electrically connected with a third node and the base end of the third triode, the collector end of the third triode is grounded, the emitter end of the fourth triode is electrically connected with a fourth node through a second resistor and the base end of the fourth triode, the collector end of the fourth triode is grounded, the third node and the fourth node are electrically connected with the base end of the first triode and the second triode respectively, and the third node and the fourth node are electrically connected with the power supply end, the ratio of the third node to the current of the first resistor is a first preset value, the number of the first triode is m, the number of the third triode is 1, and the number of the fourth triode is n, the second-stage operational amplifier unit comprises a third field effect tube, the first end of the third field effect tube is electrically connected with the power supply end, the control end of the third field effect tube is electrically connected with the second node, the second end of the third field effect tube is electrically connected with the collector end of the third triode, the width-length ratio of the third field effect tube is equal to the width-length ratio of the first field effect tube, the second-stage operational amplifier unit comprises a third field effect tube and a fifth node, the output part further comprises a fourth field effect tube, the first end of the third field effect tube and the fourth field effect tube is electrically connected with the power supply end, the control end of the third field effect tube is electrically connected with the second node, the second end of the third field effect tube is electrically connected with the fifth node, the fifth node is also electrically connected with the collector end of the third triode, the control end of the fourth field effect tube is electrically connected with the fifth node, the second end of the fourth field effect tube is electrically connected with the third node and the fourth node respectively, the current of the fifth node is equal to the current of the third node, the width-length ratio of the first field effect tube is a second preset value, the width-length ratio of the third field effect tube is a third preset value, the ratio of the third preset value to the second preset value is 2 times the first preset value, the second-stage operational amplifier unit further comprises a current mirror, the second end of the third field effect tube is electrically connected with the collector end of the third triode through the current mirror, the third node is electrically connected with the power supply end through a third resistor, and the fourth node is electrically connected with the power supply end through a fourth resistor. ​ ​ ​ ​ 2. The high power supply rejection ratio bandgap reference source of claim 1, wherein, The ratio m of the number of the first triode and the third triode, the resistance value of the first resistance is R1, the current I1 of the first resistance = V T ×(lnm) / R1; The ratio n of the number of the fourth triode to the third triode, the resistance of the second resistance is R2, the current of the third node I2= V T ×(lnn) / R2; where V T =kT / q, k is the Boltzmann constant, T is the absolute temperature, and q is the unit charge.

3. The high power supply rejection ratio bandgap reference source of claim 2, wherein, ​ 4. The high power supply rejection ratio bandgap reference source of claim 1, wherein, ​ ​ ​ 5. The high power supply rejection ratio bandgap reference source of claim 1, wherein, ​ ​ ​ 6. The high power supply rejection ratio bandgap reference source of claim 4 or 5, wherein, ​ 7. The high power supply rejection ratio bandgap reference source of claim 1 or 2, wherein, ​ The third resistor and the fourth resistor have equal resistance values.

8. The high power supply rejection ratio bandgap reference source of claim 1, wherein, The field effect tubes in the reference source are P-type field effect tubes, and the triodes in the reference source are NPN-type triodes.

9. An integrated circuit, characterized by A bandgap reference source comprising the high supply voltage rejection ratio of any one of claims 1-8.

10. An electronic device, comprising: An integrated circuit comprising the reference source of claim 9.

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