CN101042590A

CN101042590A - Fiducial reference source with gap

Info

Publication number: CN101042590A
Application number: CN 200710039655
Authority: CN
Inventors: 詹陈长; 周晓方
Original assignee: Fudan University
Current assignee: Fudan University
Priority date: 2007-04-19
Filing date: 2007-04-19
Publication date: 2007-09-26
Anticipated expiration: 2027-04-19
Also published as: CN100465851C

Abstract

本发明属于集成电路技术领域，具体为一种针对模拟电路应用的低温度系数、低噪声的新型带隙基准参考源。电误差放大器、PMOS控制管、PMOS输出管、控制电阻、输出电阻和带隙电流产生电路组成。该带隙基准参考源可以产生稳定的电压和电流，并且它的核心控制部分只采用一个PMOS管，而不是传统的两个PMOS管，因而避免了控制管的失配而造成的误差，同时与传统结构相比，在输出管与控制管1∶1镜像的情况下，产生同样的参考电压可以采用一半阻值的输出电阻，因而降低了输出端的电阻热噪声。另外，由于是零温度系数电流而非电压用于产生参考值，因此该带隙基准源能够在低电压下工作。仿真结果表明该带隙基准源能产生低温度系数的参考电压和参考电流。The invention belongs to the technical field of integrated circuits, in particular to a novel bandgap reference source with low temperature coefficient and low noise for analog circuit applications. It is composed of electric error amplifier, PMOS control tube, PMOS output tube, control resistor, output resistor and bandgap current generating circuit. The bandgap reference source can generate stable voltage and current, and its core control part only uses one PMOS transistor instead of the traditional two PMOS transistors, thus avoiding the error caused by the mismatch of the control transistors, and at the same time with Compared with the traditional structure, in the case of a 1:1 mirror image between the output tube and the control tube, an output resistor with half the resistance can be used to generate the same reference voltage, thus reducing the resistance thermal noise at the output end. In addition, this bandgap reference is capable of operating at low voltages because a zero-temperature-coefficient current is used to generate the reference instead of a voltage. Simulation results show that the bandgap reference source can generate reference voltage and reference current with low temperature coefficient.

Description

A Bandgap Reference Source

技术领域technical field

本发明属于集成电路设计领域，具体涉及一种给模拟电路提供低温度系数参考电压和参考电流的新型带隙基准参考源(Bandgap Reference)。The invention belongs to the field of integrated circuit design, and in particular relates to a novel bandgap reference source (Bandgap Reference) which provides low temperature coefficient reference voltage and reference current for analog circuits.

背景技术Background technique

带隙基准参考源通常是模拟和混合信号处理系统中重要的组成模块，它们用来提供高稳定度的参考电平和参考电压，对于系统的性能起着至关重要的作用。随着半导体技术的发展，人们越来越多地将带隙基准源集成到整个系统中，而不是做为分立电路或单一芯片工作。而在深亚微米工艺中，电路元器件的失配以及电路的噪声都是高性能模拟电路设计的阻碍因素。因此，带隙基准源的设计中，如何降低失配和噪声的影响成为人们需要解决的问题。Bandgap reference sources are usually important building blocks in analog and mixed-signal processing systems. They are used to provide high-stability reference levels and reference voltages, which play a vital role in system performance. With the development of semiconductor technology, more and more people integrate the bandgap reference source into the whole system instead of working as a discrete circuit or a single chip. However, in deep submicron technology, the mismatch of circuit components and circuit noise are the hindering factors of high-performance analog circuit design. Therefore, in the design of the bandgap reference source, how to reduce the impact of mismatch and noise has become a problem that people need to solve.

传统的带隙基准参考源常常使用误差放大器控制两个PMOS管的电流，然后采用输出镜像管和输出电阻来生成需要的参考电流和参考电压。因此，受控管的失配会产生误差，不仅是参考电平的绝对误差，还会产生温度系数的漂移，使得产生的参考不够稳定。另外，当输出镜像管与受控管是1∶1的镜像关系时——这是人们比较倾向于采取的比例，输出管的电流就与单个受控管的电流相等，也就是受控总电流的一半，因此，产生一定的参考电压需要更大的输出电阻，从而输出端口产生了更大的电阻热噪声。Traditional bandgap reference sources often use error amplifiers to control the currents of two PMOS transistors, and then use output mirror transistors and output resistors to generate the required reference current and reference voltage. Therefore, the mismatch of the controlled tube will produce errors, not only the absolute error of the reference level, but also the drift of the temperature coefficient, making the generated reference not stable enough. In addition, when the output mirror tube and the controlled tube have a 1:1 mirror image relationship—this is the ratio that people tend to adopt, the current of the output tube is equal to the current of a single controlled tube, that is, the total controlled current Therefore, a larger output resistance is required to generate a certain reference voltage, and thus a larger resistance thermal noise is generated at the output port.

随着便携式设备的发展，延长电池使用寿命也成为人们追求的一个目标。因此，低功耗设计是现在的集成电路设计中主流研究方向之一。在低功耗设计中，降低电源电压是一个常常采用的手段，也是随着半导体器件尺寸缩小所需要采取的一种技术。在片上系统中，不仅数字电路的电源电压降低，模拟电路也需要降低工作电压。因此，带隙基准源如何保持低电压工作也是设计中的一个难点。With the development of portable devices, prolonging battery life has also become a goal pursued by people. Therefore, low power consumption design is one of the mainstream research directions in current integrated circuit design. In low power consumption design, lowering the power supply voltage is a commonly used method, and it is also a technology that needs to be adopted as the size of semiconductor devices shrinks. In the system on chip, not only the power supply voltage of the digital circuit is lowered, but also the operating voltage of the analog circuit needs to be lowered. Therefore, how to maintain the low voltage operation of the bandgap reference source is also a difficult point in the design.

发明内容Contents of the invention

本发明的目的在于提供一种可降低失配和噪声影响，并可保持低电压工作的高性能带隙基准参考源。The purpose of the present invention is to provide a high-performance bandgap reference source that can reduce mismatch and noise effects and maintain low-voltage operation.

本发明提出的新型带隙基准参考源，其电路如图1所示。它由误差放大器A、PMOS控制管M1、PMOS输出管M2、控制电阻、输出电阻以及带隙电流产生电路组成；其中，控制管M1与输出管M2的栅极接在一起，并与误差放大器A的输出端连接，它们的源极和衬底都接在电源VDD上，输出管M2的漏极接在输出电阻R6的一端；控制电阻R4和R5的公共端与控制管M1漏极连接，另一端分别接在误差放大器A的正、负输入端VB和VA；控制管M1的电流通过两个控制电阻R4和R5输送给带隙电流产生电路；带隙电流产生电路由3个电阻R1、R2、R3以及2个三极管Q1和Q2构成，其中，电阻R1和R2有一公共端，都接地；另一端分别接误差放大器A的负输入端VA、正输入端VB，电阻R3一端接在误差放大器A的正输入端VB，另一端接在三极管Q2的发射极上；三极管Q1和Q2都接成二极管连接方式，即它们的基极和集电极接在一起，并接地。The circuit of the novel bandgap reference source proposed by the present invention is shown in FIG. 1 . It consists of an error amplifier A, a PMOS control tube M1, a PMOS output tube M2, a control resistor, an output resistor, and a bandgap current generation circuit. The output terminal of the control resistors R4 and R5 is connected to the drain of the control tube M1, and the drain of the output tube M2 is connected to the output terminal of the output resistor R6. One end is respectively connected to the positive and negative input terminals VB and VA of the error amplifier A; the current of the control tube M1 is sent to the bandgap current generation circuit through two control resistors R4 and R5; the bandgap current generation circuit consists of three resistors R1, R2 , R3 and two triodes Q1 and Q2, wherein, resistors R1 and R2 have a common end, both of which are grounded; the other end is respectively connected to the negative input terminal VA and positive input terminal VB of the error amplifier A, and one end of the resistor R3 is connected to the error amplifier A The positive input terminal VB of the transistor is connected to the emitter of the transistor Q2; the transistors Q1 and Q2 are connected in a diode connection mode, that is, their bases and collectors are connected together and grounded.

本发明中，输出管M2和控制管M1构成镜像电源流，其电流本身构成低温度系数的带隙电流源，且该电流通过不同的输出电阻组合能够产生不同的低温度系统的输出参考电压。In the present invention, the output tube M2 and the control tube M1 constitute a mirrored power supply current, and the current itself constitutes a bandgap current source with a low temperature coefficient, and the current can generate different output reference voltages for low-temperature systems through different combinations of output resistors.

本发明中，可通过调整控制电阻R4和R5的阻值，使本参考源能够工作在不同的电源电压下。降低阻值，则在低电源电压下也能够正常工作；提高阻值，则提高了误差放大器A的控制能力，使得误差放大器A的正负输入端电压差更接近于零。In the present invention, the reference source can work under different power supply voltages by adjusting the resistance values of the control resistors R4 and R5. If the resistance value is reduced, it can work normally under low power supply voltage; if the resistance value is increased, the control capability of the error amplifier A is improved, so that the voltage difference between the positive and negative input terminals of the error amplifier A is closer to zero.

本发明中，带隙电流产生电路中，电阻R1和R2的阻值相等，但与电阻R3的阻值不相等。In the present invention, in the bandgap current generating circuit, the resistance values of the resistors R1 and R2 are equal, but not equal to the resistance value of the resistor R3.

为了消除传统带隙基准参考源电路中的控制管失配带来的误差，本发明采用单一PMOS控制管M1，由该控制管给两个控制电阻R4和R5提供两路电流。电阻R4与R5阻值大小相等。误差放大器A连接成负反馈方式，使得VA和VB两点的电压相等，因此流过控制电阻R4和R5的电流也相等，都是IR4。电阻R1和R2大小相等，因此它们流过的电流也相等。从而，双极型晶体管Q1流过的电流与Q2或电阻R3流过的电流也相等。电阻R1或R2的电流IR2等于Q1的发射极-基极电压VEB1除以它们的阻值。由于VEB1具有负温度系数，因此电流IR2也具有负温度系数；电阻R3的电流IR3等于R3两端的电压，即Q1与Q2的发射极-基极电压之差dVEB，除以电阻R3阻值。由于dVEB具有正温度系数，因此，只要适当调整电阻比值和晶体管饱和电流比值，电流IR2与IR3的和即电流IR4或IR5就可以具有零温度系数。控制管M1的电流等于IR4与IR5之和，也相应地具有零温度系数，输出管M2的电流以及输出电压也是如此。In order to eliminate the error caused by the mismatch of control tubes in the traditional bandgap reference source circuit, the present invention adopts a single PMOS control tube M1, which provides two currents to two control resistors R4 and R5. The resistors R4 and R5 have the same resistance value. The error amplifier A is connected in a negative feedback mode, so that the voltages of VA and VB are equal, so the currents flowing through the control resistors R4 and R5 are also equal, both of which are IR4. Resistors R1 and R2 are equal in size, so the currents flowing through them are also equal. Therefore, the current flowing through the bipolar transistor Q1 is also equal to the current flowing through Q2 or the resistor R3. The current IR2 across resistor R1 or R2 is equal to the emitter-base voltage VEB1 of Q1 divided by their resistance. Since VEB1 has a negative temperature coefficient, the current IR2 also has a negative temperature coefficient; the current IR3 of the resistor R3 is equal to the voltage across R3, that is, the difference between the emitter-base voltages of Q1 and Q2, dVEB, divided by the resistance of resistor R3. Since dVEB has a positive temperature coefficient, as long as the resistance ratio and transistor saturation current ratio are properly adjusted, the sum of current IR2 and IR3, that is, current IR4 or IR5, can have a zero temperature coefficient. The current of the control tube M1 is equal to the sum of IR4 and IR5, and correspondingly has a zero temperature coefficient, and the same is true for the current and output voltage of the output tube M2.

从以上分析中可以看出，由于控制电流仅仅由控制管M1提供，因此消除了传统结构中的两个PMOS管失配而带来的误差，这种误差可能会导致整个带隙基准源的温度系数大的漂移。本发明中，仅一个控制管M1，输出管M2与控制管M1匹配，在实际制造过程中，输出管M2与控制管M1的失配也会造成输出电压和电流的误差，但是不会产生温度系数的漂移。It can be seen from the above analysis that since the control current is only provided by the control tube M1, the error caused by the mismatch of the two PMOS tubes in the traditional structure is eliminated. This error may cause the temperature of the entire bandgap reference source to Drift with a large coefficient. In the present invention, there is only one control tube M1, and the output tube M2 matches the control tube M1. In the actual manufacturing process, the mismatch between the output tube M2 and the control tube M1 will also cause errors in output voltage and current, but will not cause temperature Coefficient drift.

从以上分析中还可以看出，本发明中当输出管M2与控制管M1采取1∶1的尺寸比例时，输出管M2的电流IM2等于控制管M1的电流IM1，都是两个控制电阻的支路电流IR4与IR5之和。与传统结构相比，输出电流增大了一倍，这样，产生相同大小的输出电压，就可以采用一半阻值的输出电阻R6，因此输出电压会具有更小的电阻热噪声。From the above analysis, it can also be seen that when the output tube M2 and the control tube M1 have a size ratio of 1:1 in the present invention, the current IM2 of the output tube M2 is equal to the current IM1 of the control tube M1, which is the result of two control resistors. The sum of the branch currents IR4 and IR5. Compared with the traditional structure, the output current is doubled. In this way, to generate the same output voltage, the output resistor R6 with half the resistance can be used, so the output voltage will have smaller resistance thermal noise.

本发明采用单个PMOS控制管提供两路控制电流，从而避免了晶体管的失配带来的误差，并且，当输出管与控制管镜像时，输出电流等于两路控制电流的总和，因此，产生一定的参考输出电压所需要的输出电阻阻值降低一半，使得输出电阻热噪声降低，有利于高精度模拟和混合信号处理系统的应用，另外，采用零温度系数电流而非电压产生输出参考，使得它在低电压下也能够工作。The present invention uses a single PMOS control transistor to provide two control currents, thereby avoiding the error caused by the mismatch of the transistors, and when the output transistor and the control transistor are mirrored, the output current is equal to the sum of the two control currents, therefore, a certain The output resistor resistance value required for the reference output voltage is reduced by half, which reduces the thermal noise of the output resistor, which is beneficial to the application of high-precision analog and mixed signal processing systems. In addition, the zero temperature coefficient current is used instead of voltage to generate the output reference, making it It can also work under low voltage.

附图说明Description of drawings

图1为本发明的电原理图Fig. 1 is the electrical schematic diagram of the present invention

具体实施方式Detailed ways

新型带隙基准参考源的电原理图见图1所示，做出如下两点假设：The electrical schematic diagram of the new bandgap reference source is shown in Figure 1, and the following two assumptions are made:

1.误差放大器A增益足够大并且输入无失调，因此负反馈使得VA和VB点电压相等。1. The error amplifier A gain is large enough and the input has no offset, so the negative feedback makes the voltages at VA and VB points equal.

2.输出管M2和控制管M1的失配以及电阻失配均可以忽略不计。2. The mismatch between the output tube M2 and the control tube M1 as well as the resistance mismatch can be ignored.

图1中，双极型晶体管的电流与其发射极-基极电压之间关系为：In Figure 1, the relationship between the current of a bipolar transistor and its emitter-base voltage is:

${I I}_{Q Q} = = {I I}_{S S} (({e e}^{q q {V V}_{EB EB} / / kT kT} - - 11)) \approx \approx {I I}_{S S} {e e}^{q q {V V}_{EB EB} / / kT kT} - - - - - - ((11))$

其中，I_S为晶体管饱和电流，q为电子电荷量，V_EB为晶体管的发射极-基极电压，k为波尔兹曼常数，T是绝对温度。因此，从公式(1)可以推导出晶体管的发射极-基极电压为：Among them, I _S is the saturation current of the transistor, q is the electronic charge, V _EB is the emitter-base voltage of the transistor, k is Boltzmann's constant, and T is the absolute temperature. Therefore, from equation (1), the emitter-base voltage of the transistor can be deduced as:

${V V}_{EB EB} = = \frac{kT kT}{q q} ln ln \frac{{I I}_{Q Q}}{{I I}_{S S}} = = {V V}_{T T} ln ln \frac{{I I}_{Q Q}}{{I I}_{S S}} - - - - - - ((22))$

由于R4与R5阻值相等，VA与VB电压相等，因此R4和R5电流相等；另外，R1和R2阻值相等，从而它们的电流也相等；因此，晶体管Q1与Q2的电流I_Q1与I_Q2相等，它们的发射极-基极电压之差为：Since the resistance values of R4 and R5 are equal, the voltages of VA and VB are equal, so the currents of R4 and R5 are equal; in addition, the resistance values of R1 and R2 are equal, so their currents are also equal; therefore, the currents I _Q1 and I Q2 of transistors Q1 and _Q2 equal, their emitter-base voltage difference is:

${dV dV}_{EB EB} = = {V V}_{EB EB 11} - - {V V}_{EB EB 22} = = {V V}_{T T} ln ln \frac{{I I}_{Q Q 11}}{{I I}_{S S 11}} \frac{{I I}_{S S 22}}{{I I}_{Q Q 22}} = = {V V}_{T T} ln ln \frac{{I I}_{S S 22}}{{I I}_{S S 11}} - - - - - - ((33))$

从图1看出，上式所表示的电压差正是电阻R3两端电压V_R3。假设Q1与Q2管的发射极面积之比为1∶N，N为一整数，从而它们的饱和电流之比也为1∶N。因此，上式成为：It can be seen from Fig. 1 that the voltage difference represented by the above formula is exactly the voltage V _R3 at both ends of the resistor R3. Assume that the ratio of the emitter areas of Q1 and Q2 is 1:N, and N is an integer, so the ratio of their saturation currents is also 1:N. Therefore, the above formula becomes:

dV_EB＝V_R3＝V_T ln N (4)dV _EB ＝V _R3 ＝V _T ln N (4)

因此，流过Q2管的电流，即电阻R3的电流为：Therefore, the current flowing through the Q2 tube, that is, the current of the resistor R3 is:

${I I}_{Q Q 22} = = {I I}_{R R 33} = = \frac{{V V}_{T T} ln ln N N}{R R 33} - - - - - - ((55))$

另一方面，电阻R2两端的电压为VB点电压，等于VA点电压，也即等于Q1管的发射极-基极电压V_EB1，因此，电阻R2的电流为：On the other hand, the voltage across the resistor R2 is the voltage at point VB, which is equal to the voltage at point VA, that is, equal to the emitter-base voltage V _EB1 of the Q1 tube. Therefore, the current of the resistor R2 is:

${I I}_{R R 22} = = \frac{{V V}_{EB EB 11}}{{R R}_{22}} - - - - - - ((66))$

电阻R4的电流等于R2与R3电流之和：The current of resistor R4 is equal to the sum of the currents of R2 and R3:

${I I}_{R R 44} = = {I I}_{R R 22} + + {I I}_{R R 33} = = \frac{{V V}_{EB EB 11}}{{R R}_{22}} + + \frac{{V V}_{T T} ln ln N N}{R R 33} = = \frac{11}{{R R}_{22}} (({V V}_{EB EB 11} + + {V V}_{T T} \frac{{R R}_{22}}{R R 33} ln ln N N)) - - - - - - ((77))$

在室温下，V_EB1的温度系数约为-1.5mV/℃，而V_T的温度系数约为+0.087mV/℃，因此，当 $\frac{R_{2}}{R 3} \ln N \approx 17.2$ 时，电阻R4的电流温度系数约为零，产生了零温度系数电流。输出管M2与M1镜像，它们的电流相等，都为电阻R4和R5的电流之和：At room temperature, the temperature coefficient of V _EB1 is about -1.5mV/℃, and the temperature coefficient of V _T is about +0.087mV/℃, so when $\frac{R_{2}}{R 3} \ln N \approx 17.2$ , the current temperature coefficient of resistor R4 is about zero, resulting in a zero temperature coefficient current. The output tube M2 is mirrored to M1, and their currents are equal, which is the sum of the currents of resistors R4 and R5:

${I I}_{M m 22} = = {I I}_{M m 11} = = {I I}_{R R 44} + + {I I}_{R R 55} = = {22 I I}_{R R 44} = = 22 \frac{11}{{R R}_{22}} (({V V}_{EB EB 11} + + {V V}_{T T} \frac{{R R}_{22}}{R R 33} ln ln N N)) - - - - - - ((88))$

因此，输出电压即电阻R6两端电压为：Therefore, the output voltage, that is, the voltage across the resistor R6 is:

${V V}_{BG BG} = = {V V}_{R R 66} = = 22 \frac{R R 66}{{R R}_{22}} (({V V}_{EB EB 11} + + {V V}_{T T} \frac{{R R}_{22}}{R R 33} ln ln N N)) - - - - - - ((99))$

由上式可看出，产生的带隙基准电压由电阻R6与R2的阻值之比决定，从而可以产生很低的参考电压；并且，系数2说明电阻R6可以取一半的阻值用于产生一定的电压。It can be seen from the above formula that the generated bandgap reference voltage is determined by the ratio of the resistances of resistors R6 and R2, so that a very low reference voltage can be generated; and the coefficient 2 shows that resistor R6 can take half of the resistance value to generate certain voltage.

仿真结果表明，本发明的带隙基准参考源能够产生低温度系数的参考电压和参考电流，并且可以降低输出端的电阻热噪声。Simulation results show that the bandgap reference source of the invention can generate reference voltage and reference current with low temperature coefficient, and can reduce resistance thermal noise at the output end.

Claims

1. A bandgap reference source is characterized in that it is made up of error amplifier (A), PMOS control transistor (M1), PMOS output transistor (M2), control resistor, output resistor and bandgap current generation circuit; Wherein, The gate of the control tube (M1) and the output tube (M2) are connected together, and connected to the output terminal of the error amplifier (A), their source and substrate are connected to the power supply VDD, and the output tube (M2) The drain is connected to one end of the output resistor R6; the common end of the control resistors R4 and R5 is connected to the drain of the control tube (M1), and the other end is respectively connected to the positive and negative input terminals VB and VA of the error amplifier (A); the control tube The current of (M1) is delivered to the bandgap current generation circuit through two control resistors R4 and R5; the bandgap current generation circuit is composed of three resistors R1, R2, R3 and two transistors Q1 and Q2, among them, the resistors R1 and R2 There is a common terminal, both of which are grounded; the other terminal is respectively connected to the negative input terminal VA and the positive input terminal VB of the error amplifier (A), and one terminal of the resistor R3 is connected to the positive input terminal VB of the error amplifier (A), and the other terminal is connected to the transistor Q2. On the emitter; Transistors Q1 and Q2 are connected into a diode connection and grounded.

2. The bandgap reference source according to claim 1, characterized in that the ratio of the output tube (M1) and the control tube (M2) is 1:1.

3. The bandgap reference source according to claim 1, characterized in that the resistance values of the controlled resistors R4 and R5 are equal.

4. The bandgap reference source according to claim 1, characterized in that the resistance values of the resistors R1 and R2 in the bandgap current generating circuit are equal, and they are not equal to the resistance value of the resistor R3.