CN107478890A - A kind of current sensing means for integrated circuit - Google Patents

本发明提供了一种用于集成电路的电流检测装置，包括电流检测模块、反馈模块、电流复制模块；电流检测模块，用于检测负载电流，并将检测到的负载电流转换为避负载电流小的参考电流，将参考电流提供给电流复制模块；反馈模块，用于对电流检测模块的电压进行反馈，使电流检测模块输出的参考电流与负载电流保持同步变化；电流复制模块，对电流检测模块检测大的参考电流进行复制，并输出电流信号。该装置将低损耗、高精度的电流检测和共源共栅的场效应管进行结合，实现了电流侦测的精确高效快捷，实用价值高。

The invention provides a current detection device for integrated circuits, including a current detection module, a feedback module, and a current replication module; the current detection module is used to detect the load current, and convert the detected load current into The reference current is used to provide the reference current to the current replication module; the feedback module is used to feed back the voltage of the current detection module, so that the reference current output by the current detection module and the load current can be changed synchronously; the current replication module is for the current detection module Detect a large reference current for replication, and output a current signal. The device combines low-loss, high-precision current detection with cascode field effect transistors to achieve accurate, efficient and fast current detection with high practical value.

一种用于集成电路的电流检测装置A current detection device for integrated circuits

技术领域technical field

本发明涉及的是集成电路领域，尤其是一种用于集成电路的电流检测装置。The invention relates to the field of integrated circuits, in particular to a current detection device for integrated circuits.

背景技术Background technique

在现有技术中，公知的技术是在高速超大规模集成电路中，负载具有工作电压较低、电流较大、各种工作状态相互转换时对应的电流变化率较高等特点，所以电流检测电路在高效率电流模式电源管理芯片或者其他功率电子等模拟应用中有着无法比拟的作用。当前学术界、工业界都投入了大量的精力研究电流检测方法以及相对应的高性能电流检测电路。其中有些电路虽然检测精度比较高，但是存在外加电路过于复杂以及功耗大、速度慢和稳定性不够等多种问题，使用效果并不是很理想。In the prior art, the known technology is that in high-speed ultra-large-scale integrated circuits, the load has the characteristics of low operating voltage, large current, and high corresponding current change rate when various operating states are converted to each other, so the current detection circuit is in It plays an incomparable role in analog applications such as high-efficiency current-mode power management chips or other power electronics. At present, academia and industry have invested a lot of energy in researching current detection methods and corresponding high-performance current detection circuits. Although some of these circuits have relatively high detection accuracy, there are many problems such as the external circuit is too complicated, the power consumption is large, the speed is slow, and the stability is not enough, so the use effect is not very ideal.

现在采用的技术大致分为三类：1、传统的SENSE电阻技术，2、R_DS检测技术，3、电感电流检测技术，The technologies currently used are roughly divided into three categories: 1. Traditional SENSE resistance technology, 2. R _DS detection technology, 3. Inductive current detection technology,

传统的SENSE电阻技术是放置一个已知阻值的sense电阻耦合在电感末端，如图1，这样只需要设计一个基本的电流检测电路检测出电阻两端的电压就能间接的检测出电感上流过的电流，技术虽然简单，但是电阻上流过的电流相当大消耗的功耗也大，影响了电源转换器的转换效率。The traditional SENSE resistor technology is to place a sense resistor of known resistance coupled at the end of the inductor, as shown in Figure 1, so that only a basic current detection circuit needs to be designed to detect the voltage at both ends of the resistor to indirectly detect the current flowing through the inductor. Current, although the technology is simple, the current flowing through the resistor is quite large and consumes a lot of power consumption, which affects the conversion efficiency of the power converter.

R_DS检测技术，利用MOS管处于线性区可以作为电阻的特点，如图2，检测功率管两端的电压从而检测出功率管的电流。但是这种技术的精度不高，功率管的RDS是非线性的，其值随工艺的变化而变化，随温度的变化也会导致50%的浮动，所以电流检测出来并不精确。The R _DS detection technology uses the characteristic that the MOS tube can be used as a resistor in the linear region, as shown in Figure 2, to detect the voltage at both ends of the power tube to detect the current of the power tube. However, the accuracy of this technology is not high. The RDS of the power tube is nonlinear, and its value changes with the process, and the temperature will also cause a 50% fluctuation, so the current detection is not accurate.

电感电流检测技术，如图3，这种技术使用低通滤波电路过滤电感上的电压，再检测流过电感等效串联电阻的电流。电感电流检测技术必须事先知道电感的电感值和ESR值，然后相应地选择R和C的大小，分立元件较多。对于集成电路来说，因为要集成电容电阻，这种技术并不特别适用。这种技术检测精度取决于电感的大小通常比较高，但是使用技术相对复杂的多。Inductor current detection technology, as shown in Figure 3, this technology uses a low-pass filter circuit to filter the voltage on the inductor, and then detects the current flowing through the equivalent series resistance of the inductor. Inductive current detection technology must know the inductance value and ESR value of the inductor in advance, and then select the size of R and C accordingly, and there are many discrete components. For integrated circuits, this technique is not particularly applicable because of the integration of capacitors and resistors. The detection accuracy of this technology depends on the size of the inductance, which is usually relatively high, but the technology used is relatively complicated.

发明内容Contents of the invention

本发明的目的就是针对现有技术所存在的不足，而提供一种用于集成电路的电流检测装置，该装置将低损耗、高精度的电流检测和共源共栅的场效应管进行结合，实现了电流侦测的精确高效快捷，实用价值高。The purpose of the present invention is to provide a current detection device for integrated circuits, which combines low-loss, high-precision current detection and cascode field effect transistors to address the shortcomings of the prior art. Accurate, efficient and quick current detection is realized, and the practical value is high.

本方案是通过如下技术措施来实现的：一种用于集成电路的电流检测装置，包括电流检测模块、反馈模块、电流复制模块；电流检测模块，用于检测负载电流，并将检测到的负载电流转换为避负载电流小的参考电流，将参考电流提供给电流复制模块；反馈模块，用于对电流检测模块的电压进行反馈，使电流检测模块输出的参考电流与负载电流保持同步变化；电流复制模块，对电流检测模块检测大的参考电流进行复制，并输出电流信号。This solution is realized through the following technical measures: a current detection device for integrated circuits, including a current detection module, a feedback module, and a current replication module; the current detection module is used to detect the load current, and the detected load The current is converted into a reference current that avoids the small load current, and the reference current is provided to the current replication module; the feedback module is used to feed back the voltage of the current detection module, so that the reference current output by the current detection module and the load current keep changing synchronously; the current The copy module copies the large reference current detected by the current detection module and outputs a current signal.

所述的电流检测模块包括第一场效应管M1和第二场效应管M2,第一场效应管 M1的源极S接地，第一场效应管M1的漏极D与负载电流Iload连接，第一场效应管的栅极G与第二场效应管M2的栅极G连接，第二场效应管M2的源极S接地。第二场效应管M2比第一场效应管M1尺寸小10⁵倍。The current detection module includes a first field effect transistor M1 and a second field effect transistor M2, the source S of the first field effect transistor M1 is grounded, the drain D of the first field effect transistor M1 is connected to the load current Iload, and the second field effect transistor M1 is connected to the load current Iload. The gate G of the field effect transistor is connected to the gate G of the second field effect transistor M2, and the source S of the second field effect transistor M2 is grounded. The size of the second field effect transistor M2 is 10 ⁵ times smaller than that of the first field effect transistor M1.

所述反馈模块包括运算放大器1C1，运算放大器1C1的同相输入端与第一场效应管M1的漏极D连接，运算放大器1C1的反相输入端与第二场效应管M2的漏极D连接，运算放大器1C1的输出端与第三场效应管M3的栅极G连接，第三场效应管M3的源极S与第二场效应管M2的漏极D连接。用于对构成电流检测电路的第一场效应管M1（PowerFET）和第二场效应管M2（Sense FET）的漏极电压进行钳位，应用其正输入端和负输入端电压相等的特性，确保两个MOS管的漏极电压相等。运算放大器的输出端接到第三场效应管M3的栅极，负反馈特性使得放大器输出电压信号会自动调整，以保证运算放大器正输入端和负输入端的电压相等，M3的栅极电压恰好使M3维持电流I_S。第一场效应管M1（功率管）和第二场效应管M2（电流侦测管）的源极都接地，所以功率管和电流侦测管对应的漏极和源极电压是相等的，且它们的栅极互连，驱动电压也相等。功率管和侦测管相匹配，且侦测管比功率管尺寸小10⁵倍，可知流过侦测管的电流为Is=Iload/10⁵。The feedback module includes an operational amplifier 1C1, the non-inverting input terminal of the operational amplifier 1C1 is connected to the drain D of the first field effect transistor M1, the inverting input terminal of the operational amplifier 1C1 is connected to the drain D of the second field effect transistor M2, The output terminal of the operational amplifier 1C1 is connected to the gate G of the third field effect transistor M3, and the source S of the third field effect transistor M3 is connected to the drain D of the second field effect transistor M2. It is used to clamp the drain voltage of the first field effect transistor M1 (PowerFET) and the second field effect transistor M2 (Sense FET) constituting the current detection circuit, and apply the characteristic that the voltage of the positive input terminal and the negative input terminal are equal, Make sure that the drain voltages of the two MOS transistors are equal. The output terminal of the operational amplifier is connected to the gate of the third field effect transistor M3, and the negative feedback characteristic makes the output voltage signal of the amplifier automatically adjusted to ensure that the voltages of the positive input terminal and the negative input terminal of the operational amplifier are equal, and the gate voltage of M3 just makes M3 maintains current I _S . The sources of the first FET M1 (power tube) and the second FET M2 (current detection tube) are both grounded, so the corresponding drain and source voltages of the power tube and the current detection tube are equal, and Their gates are interconnected and their drive voltages are also equal. The power tube and the detection tube are matched, and the size of the detection tube is 10 ⁵ times smaller than that of the power tube. It can be seen that the current flowing through the detection tube is Is=Iload/10 ⁵ .

电流复制模块包括第四场效应管M4和第五场效应管M5, 第四场效应管M4的源极S与第三场效应管M3的漏极D连接，第四场效应管M4的漏极D与供电电压VDD连接，第四场效应管M4的栅极G与第四场效应管M4的源极S连接，第四场效应管M4的栅极G与第五场效应管M5的栅极连接，第五场效应管M5的漏极D与供电电源VDD连接。第四场效应管M4和第五场效应管M5，构成电流镜，对参考电流进行复制。第四场效应管和第五场效应管的源极与供电电压VDD相连，其栅极相互连接，并接到第四场效应管M4的漏极，栅极电压是第四场效应管的漏极提供的偏置电压。第四场效应管的漏极与电流检测电路相连，第五场效应管的漏极作为复制电流信号的输出端，通过外接电阻，可将电流信号I_CS转化为电压信号。The current replication module includes a fourth field effect transistor M4 and a fifth field effect transistor M5, the source S of the fourth field effect transistor M4 is connected to the drain D of the third field effect transistor M3, and the drain of the fourth field effect transistor M4 D is connected to the power supply voltage VDD, the gate G of the fourth field effect transistor M4 is connected to the source S of the fourth field effect transistor M4, the gate G of the fourth field effect transistor M4 is connected to the gate of the fifth field effect transistor M5 The drain D of the fifth field effect transistor M5 is connected to the power supply VDD. The fourth field effect transistor M4 and the fifth field effect transistor M5 constitute a current mirror to replicate the reference current. The sources of the fourth field effect transistor and the fifth field effect transistor are connected to the power supply voltage VDD, and their gates are connected to each other and connected to the drain of the fourth field effect transistor M4, and the gate voltage is the drain of the fourth field effect transistor. The bias voltage provided by the pole. The drain of the fourth field effect transistor is connected to the current detection circuit, and the drain of the fifth field effect transistor is used as an output end of the copied current signal, and the current signal I _CS can be converted into a voltage signal through an external resistor.

本方案的有益效果可根据对上述方案的叙述得知，在该方案中过功率管的电流发生变化时，电流侦测管流过的电流也能够相应地立刻改变，按尺寸的比例精确减小为功率管的很小的比例值，小电流使得电路损耗很小，同时共源共栅电流镜能够精确实时地采集并输出电流检测电路发出的电流信号。整个电流侦测电路核心电路只有几个MOS管和运算放大器，不需要额外的部件例如电流检测电阻，结构简单，节省了面积和额外电路组件带来的功耗问题，实现了电流侦测的精确高效快捷，实用价值高。由此可见，本发明与现有技术相比，具有突出的实质性特点和显著的进步，其实施的有益效果也是显而易见的。The beneficial effect of this solution can be known from the description of the above-mentioned solution. In this solution, when the current of the overpower tube changes, the current flowing through the current detection tube can also be changed immediately, and the size can be accurately reduced in proportion It is a very small proportional value of the power tube, and the small current makes the circuit loss very small. At the same time, the cascode current mirror can accurately collect and output the current signal sent by the current detection circuit in real time. The core circuit of the entire current detection circuit has only a few MOS transistors and operational amplifiers, and does not require additional components such as current detection resistors. The structure is simple, saving area and power consumption caused by additional circuit components, and achieving accurate current detection. Efficient and quick, high practical value. It can be seen that, compared with the prior art, the present invention has outstanding substantive features and remarkable progress, and the beneficial effects of its implementation are also obvious.

附图说明Description of drawings

图1为传统的SENSE电阻技术电路图。Figure 1 is a circuit diagram of traditional SENSE resistor technology.

图2为R_DS检测技术电路图。Figure 2 is a circuit diagram of R _DS detection technology.

图3为电感电流检测技术电路图。Figure 3 is a circuit diagram of the inductor current detection technology.

图4为本发明具体实施方式电路图。Fig. 4 is a circuit diagram of a specific embodiment of the present invention.

具体实施方式detailed description

为能清楚说明本方案的技术特点，下面通过一个具体实施方式，并结合其附图，对本方案进行阐述。In order to clearly illustrate the technical features of the solution, the solution will be described below through a specific implementation mode combined with the accompanying drawings.

通过附图可以看出，本方案的1. 一种用于集成电路的电流检测装置，其特征是：包括电流检测模块、反馈模块、电流复制模块；As can be seen from the accompanying drawings, 1. a current detection device for integrated circuits of the program is characterized in that: it includes a current detection module, a feedback module, and a current replication module;

电流检测模块，用于检测负载电流，并将检测到的负载电流转换为避负载电流小的参考电流，将参考电流提供给电流复制模块；电流检测模块包括第一场效应管M1和第二场效应管M2,第一场效应管 M1的源极S接地，第一场效应管M1的漏极D与负载电流Iload连接，第一场效应管的栅极G与第二场效应管M2的栅极G连接，第二场效应管M2的源极S接地。第二场效应管M2比第一场效应管M1尺寸小10⁵倍。The current detection module is used to detect the load current, and convert the detected load current into a reference current that avoids the small load current, and provides the reference current to the current replication module; the current detection module includes a first field effect transistor M1 and a second field effect transistor Effect transistor M2, the source S of the first field effect transistor M1 is grounded, the drain D of the first field effect transistor M1 is connected to the load current Iload, the gate G of the first field effect transistor is connected to the gate of the second field effect transistor M2 The pole G is connected, and the source S of the second field effect transistor M2 is grounded. The size of the second field effect transistor M2 is 10 ⁵ times smaller than that of the first field effect transistor M1.

反馈模块，用于对电流检测模块的电压进行反馈，使电流检测模块输出的参考电流与负载电流保持同步变化；所述反馈模块包括运算放大器1C1，运算放大器1C1的同相输入端与第一场效应管M1的漏极D连接，运算放大器1C1的反相输入端与第二场效应管M2的漏极D连接，运算放大器1C1的输出端与第三场效应管M3的栅极G连接，第三场效应管M3的源极S与第二场效应管M2的漏极D连接。The feedback module is used to feed back the voltage of the current detection module, so that the reference current output by the current detection module and the load current change synchronously; the feedback module includes an operational amplifier 1C1, the non-inverting input terminal of the operational amplifier 1C1 and the first field effect The drain D of the transistor M1 is connected, the inverting input terminal of the operational amplifier 1C1 is connected with the drain D of the second field effect transistor M2, the output terminal of the operational amplifier 1C1 is connected with the gate G of the third field effect transistor M3, and the third The source S of the field effect transistor M3 is connected to the drain D of the second field effect transistor M2.

电流复制模块，对电流检测模块检测大的参考电流进行复制，并输出电流信号。电流复制模块包括第四场效应管M4和第五场效应管M5, 第四场效应管M4的源极S与第三场效应管M3的漏极D连接，第四场效应管M4的漏极D与供电电压VDD连接，第四场效应管M4的栅极G与第四场效应管M4的源极S连接，第四场效应管M4的栅极G与第五场效应管M5的栅极连接，第五场效应管M5的漏极D与供电电源VDD连接。电流复制模块的输出电流信号I_CS能够根据控制MOS管开关信号LG精确追踪并等于M2导通时流过的电流I_S，I_CS通过外接电阻可将电流信号转化为电压信号。The current replication module replicates the large reference current detected by the current detection module and outputs a current signal. The current replication module includes a fourth field effect transistor M4 and a fifth field effect transistor M5, the source S of the fourth field effect transistor M4 is connected to the drain D of the third field effect transistor M3, and the drain of the fourth field effect transistor M4 D is connected to the power supply voltage VDD, the gate G of the fourth field effect transistor M4 is connected to the source S of the fourth field effect transistor M4, the gate G of the fourth field effect transistor M4 is connected to the gate of the fifth field effect transistor M5 The drain D of the fifth field effect transistor M5 is connected to the power supply VDD. The output current signal I _CS of the current replication module can accurately track and be equal to the current I _S flowing when M2 is turned on according to the control MOS tube switching signal LG. I _CS can convert the current signal into a voltage signal through an external resistor.

本发明并不仅限于上述具体实施方式，本领域普通技术人员在本发明的实质范围内做出的变化、改型、添加或替换，也应属于本发明的保护范围。The present invention is not limited to the above-mentioned specific implementation methods, and changes, modifications, additions or substitutions made by those skilled in the art within the essential scope of the present invention should also fall within the protection scope of the present invention.