Current sensing amplifier and current testing equipment

Abstract

The present application discloses a current sense amplifier and a current test device, applied to the field of current detection, comprising: a common mode voltage output circuit for outputting a common mode voltage; the negative feedback loop comprises a first operational amplifier and a differential-mode signal shifting circuit and is used for expanding the input common-mode voltage range and enabling the expanded input common-mode voltage range to be equivalent to a second operational amplifier; wherein the power supply end of the first operational amplifier is connected with the output end of the common-mode voltage output circuit, and the equivalent ground end of the first operational amplifier is connected with the equivalent ground potential smaller than the common-mode voltage. The common-mode voltage and the equivalent ground potential are connected to the power supply end of the first operational amplifier, so that the input common-mode voltage range of the current sensing amplifier is expanded, and the current sensing amplifier can normally work under the high-voltage condition.

Description

Technical Field

[0001] The utility model relates to the field of current detection, in particular to a current sensing amplifier and a current testing device. Background Art

[0002] With the development of electronic technology, more electronic circuits require current sensing amplifiers to accurately measure current. Typically, a current sensing amplifier is an operational amplifier. Its specific operation involves inserting a sensing shunt resistor into the measurement current path. The voltage across the resistor is proportional to the current flowing through it. The current sensing amplifier's non-inverting and inverting inputs are connected to the resistor, respectively. The voltage difference across the resistor is amplified by a fixed factor. Based on the current sensing amplifier's amplification factor and the resistor value, the precise current magnitude can be calculated, achieving high-precision current measurement. As a high-performance amplifier, current sensing amplifiers integrate key components within the amplifier. They feature high common-mode rejection ratio, high input impedance, low noise, low linearity error, and low offset drift, making them highly sought after in various applications.

[0003] However, existing current sensing amplifiers are all powered by a power supply and can only detect the magnitude of the current flowing through the resistor when the input common-mode voltage is within the power supply voltage range.

[0004] Therefore, how to make the range of input common-mode voltage not limited by the power supply voltage is an urgent problem to be solved. Utility Model Content

[0005] In view of this, an object of the present invention is to provide a current sensing amplifier and a current testing device to solve the problem that the range of the input common-mode voltage is limited by the power supply voltage.

[0006] To solve the above technical problems, the present application provides a current sensing amplifier, comprising:

[0007] A common-mode voltage output circuit, a first resistor, a second resistor, a negative feedback loop, and a second operational amplifier; wherein the negative feedback loop includes the first operational amplifier and a differential-mode signal shift circuit;

[0008] A common mode voltage output circuit, used for outputting a common mode voltage;

[0009] A negative feedback loop is configured to clamp the voltage at the non-inverting input of the first operational amplifier to be equal to the voltage at the inverting input of the first operational amplifier, thereby expanding the input common-mode voltage range, and applying the expanded input common-mode voltage range to the second operational amplifier. The positive power supply terminal of the first operational amplifier is connected to the output of the common-mode voltage output circuit, and the equivalent ground terminal of the first operational amplifier is connected to an equivalent ground potential less than the common-mode voltage and is connected to the first terminal of the differential-mode signal shifting circuit. The non-inverting input of the first operational amplifier is connected to the first terminal of the sensing shunt resistor via the first resistor, the inverting input of the first operational amplifier is connected to the second terminal of the sensing shunt resistor via the second resistor, and the output of the first operational amplifier is connected to the second terminal of the differential-mode signal shifting circuit. The input of the differential-mode signal shifting circuit is connected to the input of the first operational amplifier, and the output of the differential-mode signal shifting circuit is connected to the input of the second operational amplifier. The differential-mode signal is the voltage difference between the first terminal and the second terminal of the sensing shunt resistor.

[0010] As an optional solution, in the above current sensing amplifier, the common-mode voltage output circuit includes: a third resistor and a fourth resistor; the resistance value of the third resistor is equal to the resistance value of the fourth resistor;

[0011] The first end of the third resistor is connected to the first end of the sensing shunt resistor, and the second end of the fourth resistor is connected to the second end of the sensing shunt resistor;

[0012] The second end of the third resistor is connected to the first end of the fourth resistor, and the common end thereof serves as the output end of the common-mode voltage output circuit.

[0013] As an optional solution, in the above-mentioned current sensing amplifier, the differential mode signal shifting circuit includes: a first switch tube, a second switch tube, a fifth resistor, and a sixth resistor; wherein the resistance value of the fifth resistor is equal to the resistance value of the sixth resistor;

[0014] The control terminal of the second switch tube is connected to the equivalent ground terminal of the first operational amplifier as the first terminal of the differential mode signal shift circuit;

[0015] The control end of the first switch tube is connected to the output end of the first operational amplifier as the second end of the differential mode signal shift circuit, and the second end of the first switch tube is connected to the first end of the second switch tube;

[0016] The first end of the first switch tube is connected to the non-inverting input end of the first operational amplifier as the input end of the differential mode signal shift circuit;

[0017] The second end of the second switch tube is connected to the first end of the fifth resistor, and the common end thereof is connected to the non-inverting input end of the second operational amplifier as the first output end of the differential mode signal shift circuit; the first end of the sixth resistor is connected to the inverting input end of the second operational amplifier as the second output end of the differential mode signal shift circuit; the output end of the differential mode signal shift circuit includes the first output end of the differential mode signal shift circuit and the second output end of the differential mode signal shift circuit;

[0018] The second end of the fifth resistor and the second end of the sixth resistor are grounded.

[0019] As an optional solution, in the above-mentioned current sensing amplifier, the differential-mode signal shifting circuit includes: a first switching tube, a second switching tube, a fifth resistor, a sixth resistor, and a charge pump; wherein the resistance value of the fifth resistor is equal to the resistance value of the sixth resistor;

[0020] The control terminal of the second switch tube is connected to the equivalent ground terminal of the first operational amplifier as the first terminal of the differential mode signal shift circuit;

[0021] The control end of the first switch tube is connected to the output end of the first operational amplifier as the second end of the differential mode signal shift circuit; the second end of the first switch tube is connected to the first end of the second switch tube;

[0022] The first end of the first switch tube is connected to the non-inverting input end of the first operational amplifier as the first input end of the differential mode signal shift circuit;

[0023] The second end of the second switch tube is connected to the first end of the fifth resistor, and the common end thereof is connected to the non-inverting input end of the second operational amplifier as the first output end of the differential mode signal shift circuit; the first end of the sixth resistor is connected to the inverting input end of the second operational amplifier as the second output end of the differential mode signal shift circuit; the output end of the differential mode signal shift circuit includes the first output end of the differential mode signal shift circuit and the second output end of the differential mode signal shift circuit;

[0024] The second end of the fifth resistor and the second end of the sixth resistor are connected to the output end of the charge pump.

[0025] As an optional solution, in the above current sensing amplifier, the differential mode signal shift circuit further includes: a seventh resistor, a third switch tube;

[0026] A first end of the seventh resistor is connected to the inverting input terminal of the first operational amplifier, and a second end of the seventh resistor is connected to the first end of the third switch tube;

[0027] The control terminal of the third switch tube is connected to the equivalent ground terminal of the first operational amplifier, and the second terminal of the third switch tube is connected to the inverting input terminal of the second operational amplifier.

[0028] As an optional solution, in the above-mentioned current sensing amplifier, the equivalent ground potential is provided by an equivalent ground potential generating circuit, and the equivalent ground potential generating circuit is provided in the first operational amplifier; the input end of the equivalent ground potential generating circuit is connected to the output end of the common-mode voltage output circuit, and the output end of the equivalent ground potential generating circuit is connected to the equivalent ground end of the first operational amplifier.

[0029] As an optional solution, in the above-mentioned current sensing amplifier, the equivalent ground potential generating circuit includes: an eighth resistor, a ninth resistor, a fourth switch tube, a fifth switch tube, and a constant current source;

[0030] A first end of the eighth resistor is connected to the output end of the common mode voltage output circuit;

[0031] The second end of the eighth resistor and the control end of the fourth switch tube are both connected to the first end of the ninth resistor; the control end of the fifth switch tube and the first end of the fourth switch tube are both connected to the second end of the ninth resistor;

[0032] The fifth switch tube is used to output an equivalent ground potential, wherein the first end of the fifth switch tube is connected to the second end of the fourth switch tube; and the second end of the fifth switch tube is connected to the positive electrode of the constant current source;

[0033] The negative electrode of the constant current source is grounded.

[0034] As an optional solution, in the above-mentioned current sensing amplifier, the equivalent ground potential generating circuit includes a plurality of diodes;

[0035] The multiple diodes are connected in series in the same direction; the cathode ports of the multiple diodes connected in series are the input terminals of the equivalent ground potential generating circuit, and the anode ports of the multiple diodes connected in series are the output terminals of the equivalent ground potential generating circuit.

[0036] As an optional solution, the current sensing amplifier further includes: a tenth resistor and an eleventh resistor; the resistance value of the tenth resistor is equal to the resistance value of the eleventh resistor;

[0037] The second end of the tenth resistor is connected to the inverting input terminal of the second operational amplifier, the first end of the eleventh resistor is connected to the non-inverting input terminal of the second operational amplifier, and the first end of the tenth resistor is connected to the output terminal of the second operational amplifier;

[0038] A second end of the eleventh resistor is grounded.

[0039] To solve the above technical problems, the present application also provides a current testing device, including the above current sensing amplifier.

[0040] The current sensing amplifier provided in the present application includes: a common-mode voltage output circuit, a first resistor, a second resistor, a negative feedback loop, and a second operational amplifier; wherein the negative feedback loop includes the first operational amplifier and a differential-mode signal shifting circuit; the common-mode voltage output circuit is directly connected to the power supply terminal of the first operational amplifier as the equivalent power supply voltage of the first operational amplifier, and the equivalent ground terminal of the first operational amplifier is connected to an equivalent ground potential smaller than the common-mode voltage; the negative feedback loop composed of the first operational amplifier and the differential-mode signal shifting circuit clamps the input voltage of the first operational amplifier to be equal, and at the same time transmits the input common-mode voltage range and the differential-mode voltage amplified by the first operational amplifier to the input terminal of the second operational amplifier connected to the output terminal of the differential-mode signal shifting circuit. As can be seen from the above, the common-mode voltage output circuit is directly connected to the power supply terminal of the first operational amplifier to provide the common-mode voltage as the equivalent power supply voltage for the first operational amplifier. At the same time, the equivalent ground terminal of the first operational amplifier is connected to an equivalent ground potential that is less than the common-mode voltage, so that the equivalent power supply voltage and the equivalent ground potential of the first operational amplifier can adapt to changes in the common-mode voltage, thereby expanding the input common-mode voltage range of the first operational amplifier. When the common-mode voltage is high, the first operational amplifier can also operate in the high-voltage range. At the same time, the differential-mode signal shift circuit amplifies the differential-mode signal at both ends of the measuring resistor and transmits it to the input terminal of the second operational amplifier, and the expanded input common-mode voltage range is equivalent to the second operational amplifier. The second operational amplifier amplifies the received differential-mode signal, ensuring that the input common-mode voltage range of the current sensing amplifier is not limited by the power supply voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0042] Figure 1 A circuit diagram of a current sensing amplifier provided in this embodiment;

[0043] Figure 2 A circuit diagram of a specific equivalent ground potential generating circuit provided in this embodiment;

[0044] Figure 3 A schematic diagram of a specific application provided by this embodiment;

[0045] Figure 4 This is a circuit diagram of a specific current sensing amplifier provided in this embodiment. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0047] The core of this application is to provide a current sensing amplifier.

[0048] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0049] With the development of electronic technology, more electronic circuits require current sensing amplifiers to accurately measure current. Typically, a current sensing amplifier is an operational amplifier. Its specific operation involves inserting a sensing shunt resistor into the measurement current path. The voltage across the resistor is proportional to the current flowing through it. The current sensing amplifier's non-inverting and inverting inputs are connected to the resistor, respectively. The voltage difference across the resistor is amplified by a fixed factor. Based on the current sensing amplifier's amplification factor and the resistor value, the precise current magnitude can be calculated, achieving high-precision current measurement. As a high-performance amplifier, current sensing amplifiers integrate key components within the amplifier. They feature high common-mode rejection ratio, high input impedance, low noise, low linearity error, and low offset drift, making them highly sought after in various applications.

[0050] However, existing current sensing amplifiers are all powered by a power supply and can only detect the magnitude of the current flowing through the resistor when the input common-mode voltage is within the power supply voltage range.

[0051] Therefore, how to make the range of input common-mode voltage not limited by the power supply voltage is an urgent problem to be solved.

[0052] To solve the above problems, see Figure 1 As shown in FIG2 , an embodiment of the present utility model discloses a current sensing amplifier, comprising: a common-mode voltage output circuit, a first resistor R1, a second resistor R2, a negative feedback loop and a second operational amplifier A1; wherein the negative feedback loop comprises a first operational amplifier A0 and a differential-mode signal shifting circuit.

[0053] The common-mode voltage output circuit is used to output a common-mode voltage. Figure 1In the embodiment, the common mode voltage output circuit can be composed of a third resistor and a fourth resistor, but it is understood that Figure 1 This is just one specific implementation method, and it does not mean that there is only this one implementation method.

[0054] A negative feedback loop is used to clamp the voltage at the non-inverting input terminal of the first operational amplifier A0 to be equal to the voltage at the inverting input terminal of the first operational amplifier A0, expand the input common-mode voltage range, and make the expanded input common-mode voltage range equivalent to the second operational amplifier A1; wherein, the power supply terminal of the first operational amplifier A0 is connected to the output terminal of the common-mode voltage output circuit, and the equivalent ground terminal of the first operational amplifier A0 is connected to the first terminal of the differential-mode signal shift circuit; the non-inverting input terminal of the first operational amplifier A0 is connected to the first terminal of the sensing shunt resistor through the first resistor R1, the inverting input terminal of the first operational amplifier A0 is connected to the second terminal of the sensing shunt resistor through the second resistor R2, and the output terminal of the first operational amplifier A0 is connected to the second terminal of the differential-mode signal shift circuit; the input terminal of the differential-mode signal shift circuit is connected to the input terminal of the first operational amplifier A0, and the output terminal of the differential-mode signal shift circuit is connected to the input terminal of the second operational amplifier A1; the differential-mode signal is the voltage difference between the first terminal and the second terminal of the sensing shunt resistor. Figure 1 In the differential mode signal shift circuit, the differential mode signal shift circuit may be composed of a first switch tube, a second switch tube, a third switch tube, a fifth resistor, a sixth resistor and a seventh resistor, but it is understandable that Figure 1 This is just one specific implementation method, and it does not mean that there is only this one implementation method.

[0055] Figure 1 in is the common mode voltage, is the equivalent ground potential output by the equivalent ground potential generation circuit. The common-mode voltage is the same voltage component across the sensing shunt resistor, that is, the average value of the voltage across the sensing shunt resistor. The specific formula is:

[0056]

[0057] Among them, V CM is the common mode voltage, V INP is the voltage value of the first terminal of the sensing shunt resistor, V INN is a voltage value at the second end of the sensing shunt resistor.

[0058] In a specific embodiment, the common-mode voltage output circuit may be two resistors of equal magnitude connected in series. According to the characteristics of resistor voltage division, the common end of the two resistors is the output end of the common-mode voltage output circuit.

[0059] It should be noted that to ensure that the input common-mode voltage remains within the input common-mode voltage range, the voltage at the equivalent ground terminal of the first operational amplifier A0 also needs to adaptively change with changes in the common-mode voltage. The above-mentioned equivalent ground potential generation circuit can provide a corresponding equivalent ground potential for the first operational amplifier A0 based on the magnitude of the common-mode voltage.

[0060] In this embodiment, the current sensing amplifier needs to amplify the differential mode voltage, which is the differential mode signal mentioned above. The differential mode voltage is the difference between the voltages across the sensing shunt resistor, and the specific formula is:

[0061] ;

[0062] Where V AC is the differential mode voltage, V INP is the voltage value of the first terminal of the sensing shunt resistor, V INN is used to sense the voltage value at the second end of the shunt resistor.

[0063] In this embodiment, the equivalent ground potential connected to the equivalent ground terminal of the first operational amplifier A0 can be generated by an equivalent ground potential generation circuit, and the equivalent ground potential generation circuit can adjust the output equivalent ground potential as the common-mode voltage changes. In one specific embodiment, the equivalent ground potential generation circuit is composed of a diode. In another specific embodiment, the equivalent ground potential generation circuit includes a resistor, a switch, and a constant current source. The voltage difference between the equivalent ground potential and the common-mode voltage can be adjusted by adjusting the constant current source.

[0064] It can be understood that since the specific circuits of the differential mode signal shift circuit have many different situations, in a specific embodiment, the differential mode signal shift circuit has only one input end, which is connected to the non-inverting input end of the first operational amplifier A0. At this time, the input end of the above-mentioned first operational amplifier A0 is the non-inverting input end of the first operational amplifier A0; in another specific embodiment, the input end of the differential mode signal shift circuit includes the first input end of the differential mode signal shift circuit and the second input end of the differential mode signal shift circuit, which are respectively connected to the non-inverting input end and the inverting input end of the first operational amplifier A0. At this time, the input end of the above-mentioned first operational amplifier includes the non-inverting input end of the first operational amplifier A0 and the inverting input end of the first operational amplifier A0.

[0065] In this embodiment, the common-mode voltage output by the common-mode voltage output circuit serves as the equivalent power supply for first operational amplifier A0, while the potential generated by the equivalent ground potential generation circuit serves as the equivalent ground potential for first operational amplifier A0. In this case, first operational amplifier A0 can operate within a voltage range between the equivalent common-mode voltage and the equivalent ground potential, independent of the actual power supply voltage. Therefore, the common-mode voltage acting as the equivalent power supply and the equivalent ground potential output by the equivalent ground potential generation circuit expand the input common-mode voltage range of first operational amplifier A0. The negative feedback loop then transmits this expanded input common-mode voltage range to second operational amplifier A1, ensuring that second operational amplifier A1 can further amplify the differential-mode voltage output by first operational amplifier A0.

[0066] It is understood that to eliminate the effects of bias current on the second operational amplifier A1, the current sensing amplifier may further include a balancing resistor. In one specific embodiment, the non-inverting input of the second operational amplifier A1 is grounded via the balancing resistor. In another embodiment, the non-inverting input of the second operational amplifier A1 is connected to a power supply voltage via the balancing resistor.

[0067] like Figure 3 As shown in the figure, this circuit is a specific application scenario of the current sensing amplifier. SENSE The sensing shunt resistor R is connected to the measuring end of the current sensing amplifier. SENSE The output of the current sensing amplifier flows through the sensing shunt resistor R SENSE The current size is input into the controller's ADC (Analog-to-Digital Converter). The controller controls the on and off of the switch tube based on the converted current size. V CM The sensing shunt resistor R SENSE Common-mode voltage across the board.

[0068] The current sensing amplifier provided by the present application includes: a common-mode voltage output circuit, a first resistor R1, a second resistor R2, a negative feedback loop, and a second operational amplifier A1; wherein the negative feedback loop includes a first operational amplifier A0 and a differential-mode signal shifting circuit; a common-mode voltage output circuit for outputting a common-mode voltage; a negative feedback loop for clamping the voltage of the non-inverting input terminal of the first operational amplifier A0 to be equal to the voltage of the inverting input terminal of the first operational amplifier A0, thereby expanding the input common-mode voltage range, and making the expanded input common-mode voltage range equivalent to the second operational amplifier A1; wherein the power supply terminal of the first operational amplifier A0 is connected to the output terminal of the common-mode voltage output circuit, The equivalent ground terminal of the first operational amplifier A0 is connected to the first terminal of the differential mode signal shift circuit; the non-inverting input terminal of the first operational amplifier A0 is connected to the first terminal of the sensing shunt resistor through the first resistor R1, the inverting input terminal of the first operational amplifier A0 is connected to the second terminal of the sensing shunt resistor through the second resistor R2, and the output terminal of the first operational amplifier A0 is connected to the second terminal of the differential mode signal shift circuit; the input terminal of the differential mode signal shift circuit is connected to the input terminal of the first operational amplifier A0, and the output terminal of the differential mode signal shift circuit is connected to the input terminal of the second operational amplifier A1; the differential mode signal is the voltage difference between the first terminal of the sensing shunt resistor and the second terminal of the sensing shunt resistor. As can be seen from the above, the common-mode voltage output circuit is directly connected to the power supply terminal of the first operational amplifier A0 to provide the common-mode voltage as the equivalent power supply voltage for the first operational amplifier A0. At the same time, the equivalent ground terminal of the first operational amplifier A0 is connected to an equivalent ground potential that is lower than the common-mode voltage. This allows the equivalent power supply voltage and the equivalent ground potential of the first operational amplifier A0 to adapt to changes in the common-mode voltage, thereby expanding the input common-mode voltage range of the first operational amplifier A0. When the common-mode voltage is high, the first operational amplifier A0 can also operate in a high-voltage range. At the same time, the differential-mode signal shifting circuit amplifies the differential-mode signal across the measuring resistor and transmits it to the input terminal of the second operational amplifier A1, and equates the expanded input common-mode voltage range to the second operational amplifier A1. The second operational amplifier A1 amplifies the received differential-mode signal, ensuring that the input common-mode voltage range of the current sensing amplifier is not limited by the power supply voltage.

[0069] In order to obtain the common-mode voltage, the embodiment of the present utility model discloses a specific current sensing amplifier. Compared with the previous embodiment, this embodiment further explains and optimizes the technical solution. Specifically:

[0070] The common mode voltage output circuit includes: a third resistor R3 and a fourth resistor R4; the resistance value of the third resistor R3 is equal to the resistance value of the fourth resistor R4;

[0071] A first end of the third resistor R3 is connected to the first end of the sensing shunt resistor, and a second end of the fourth resistor R4 is connected to the second end of the sensing shunt resistor;

[0072] The second end of the third resistor R3 is connected to the first end of the fourth resistor R4, and the common end thereof serves as the output end of the common mode voltage output circuit.

[0073] In this embodiment, the third resistor R3 and the fourth resistor R4 are connected in series and connected to both ends of the sensing shunt resistor, and are connected in parallel with the above-mentioned sensing shunt resistor. Therefore, the voltage value of the first end of the third resistor R3 is V INP The voltage value of the second terminal of the fourth resistor R4 is V INN Since the resistance of the third resistor R3 is equal to that of the fourth resistor R4, the voltage at the common terminal is the average of the voltage at the first terminal of the third resistor R3 and the voltage at the second terminal of the fourth resistor R4, that is, V INP With V INN The average value of , is equal to the common-mode voltage across the sense shunt resistor.

[0074] As can be seen from the above, the resistance values ​​of the third resistor R3 and the fourth resistor R4 are equal, and due to the voltage dividing effect of the resistors, the third resistor R3 and the fourth resistor R4 divide the total voltage equally, so that the voltage at the output end of the common-mode voltage output circuit is equal to the common-mode voltage across the sensing shunt resistor.

[0075] In order to simultaneously expand the input common-mode voltage range of the second operational amplifier A1, the present embodiment of the utility model discloses a specific current sensing amplifier. Compared with the previous embodiment, this embodiment further illustrates and optimizes the technical solution. Specifically:

[0076] The differential mode signal shift circuit includes: a first switch tube M1, a second switch tube M2, a fifth resistor R5, and a sixth resistor R6; wherein the resistance value of the fifth resistor R5 is equal to the resistance value of the sixth resistor R6;

[0077] The control terminal of the second switch tube M2 is connected to the equivalent ground terminal of the first operational amplifier A0 as the first terminal of the differential mode signal shift circuit;

[0078] The control end of the first switch tube M1 is connected to the output end of the first operational amplifier A0 as the second end of the differential signal shift circuit, and the second end of the first switch tube M1 is connected to the first end of the second switch tube M2;

[0079] The first end of the first switch tube M1 is connected to the non-inverting input end of the first operational amplifier A0 as the input end of the differential mode signal shift circuit;

[0080] The second end of the second switch tube M2 is connected to the first end of the fifth resistor R5, and the common end thereof is connected to the non-inverting input end of the second operational amplifier A1 as the first output end of the differential mode signal shift circuit; the first end of the sixth resistor R6 is connected to the inverting input end of the second operational amplifier A1 as the second output end of the differential mode signal shift circuit; the output end of the differential mode signal shift circuit includes the first output end of the differential mode signal shift circuit and the second output end of the differential mode signal shift circuit;

[0081] A second end of the fifth resistor R5 and a second end of the sixth resistor R6 are grounded.

[0082] In this embodiment, the first operational amplifier A0 uses the common-mode voltage as the equivalent power supply voltage and the potential output by the equivalent ground potential generating circuit as the equivalent ground potential, thereby expanding its input common-mode voltage range. Through the differential-mode signal shifting circuit, the input common-mode voltage range of the first operational amplifier A0 can be equivalent to that of the second operational amplifier A1. At the same time, the differential-mode voltage amplified by the first operational amplifier A0 is transmitted to the input terminal of the second operational amplifier A1, so that the second operational amplifier A1 can further amplify the amplified differential-mode voltage transmitted by the differential-mode signal shifting circuit within the operating range.

[0083] It is understandable that the first switch tube M1 and the second switch tube M2 can be IGBT transistors. The gate and channel of the IGBT transistor are isolated by an insulating layer, which makes its input impedance very high. Therefore, the current required to drive the IGBT transistor is relatively small, the requirements for the control circuit are low, and the circuit complexity and cost can be reduced.

[0084] As can be seen from the above, by using the differential mode signal shift circuit to make the input common mode voltage range of the first operational amplifier A0 equivalent to that of the second operational amplifier A1, the input common mode voltage range of the second operational amplifier A1 can be expanded while expanding the input common mode voltage range of the first operational amplifier A0.

[0085] like Figure 4 As shown, in order to expand the negative pressure detection range, the embodiment of the present utility model discloses a specific current sensing amplifier. Compared with the previous embodiment, this embodiment further explains and optimizes the technical solution. Specifically:

[0086] The differential mode signal shift circuit includes: a first switch tube M1, a second switch tube M2, a fifth resistor R5, a sixth resistor R6, and a charge pump; wherein the resistance value of the fifth resistor R5 is equal to the resistance value of the sixth resistor R6;

[0087] The control terminal of the second switch tube M2 is connected to the equivalent ground terminal of the first operational amplifier A0 as the first terminal of the differential mode signal shift circuit;

[0088] The control end of the first switch tube M1 is connected to the output end of the first operational amplifier A0 as the second end of the differential signal shift circuit; the second end of the first switch tube M1 is connected to the first end of the second switch tube M2;

[0089] The first end of the first switch tube M1 is connected to the non-inverting input end of the first operational amplifier A0 as the input end of the differential mode signal shift circuit;

[0090] The second end of the second switch tube M2 is connected to the first end of the fifth resistor R5, and the common end thereof is connected to the non-inverting input end of the second operational amplifier A1 as the first output end of the differential mode signal shift circuit; the first end of the sixth resistor R6 is connected to the inverting input end of the second operational amplifier A1 as the second output end of the differential mode signal shift circuit; the output end of the differential mode signal shift circuit includes the first output end of the differential mode signal shift circuit and the second output end of the differential mode signal shift circuit;

[0091] The second end of the fifth resistor R5 and the second end of the sixth resistor R6 are connected to the output end of the charge pump.

[0092] In this embodiment, when the input common-mode voltage is negative, a negative voltage NEG_V needs to be generated by a charge pump. The equivalent ground potential generating circuit generated by the equivalent ground potential generating circuit and the charge pump work together to obtain the maximum negative voltage input common-mode range. The specific derivation process is as follows:

[0093]

[0094] ;

[0095] ;

[0096] ;

[0097] ;

[0098] in, is the source voltage of the second switch tube M2, is the equivalent ground potential, is the voltage difference between the common mode voltage and the equivalent ground potential, is the gate-source voltage of the second switch tube M2, is the drain-source voltage of the second switch tube M2, is the current flowing through the fifth resistor R5, is the resistance of the fifth resistor R5, This is the negative voltage input common mode range.

[0099] As can be seen from the above, as long as the negative voltage output by the charge pump is large enough, the allowable negative input common-mode range will also be larger. This design method effectively replaces the limitation of ground potential on the input common-mode voltage range and can expand the input common-mode voltage range below ground potential.

[0100] In order to ensure that the bandwidth is not affected when the differential mode voltage is very small, the embodiment of the utility model discloses a specific current sensing amplifier. Compared with the previous embodiment, this embodiment further explains and optimizes the technical solution. Specifically:

[0101] The differential mode signal shift circuit further includes: a seventh resistor R7 and a third switch tube M3;

[0102] A first end of the seventh resistor R7 is connected to the inverting input terminal of the first operational amplifier A0, and a second end of the seventh resistor R7 is connected to the first end of the third switch tube M3;

[0103] The control terminal of the third switch tube M3 is connected to the equivalent ground terminal of the first operational amplifier A0 , and the second terminal of the third switch tube M3 is connected to the inverting input terminal of the second operational amplifier A1 .

[0104] When there is no voltage difference at the input of the current sensing amplifier, the currents flowing through the first resistor R1 and the second resistor R2 are equal in magnitude and are determined by the seventh resistor R7. The specific formula is as follows:

[0105] ;

[0106] in, 、 are the magnitudes of the current flowing through the first resistor R1 and the second resistor R2 respectively, is the gate-source voltage of the third switch tube M3, is the resistance of the seventh resistor R7.

[0107] As can be seen from the above, when the differential mode voltage across the sensing shunt resistor is very small, the first switch M1 can still be turned on due to the presence of the seventh resistor R7 and the third switch M3, ensuring that the bandwidth is not affected when the differential mode signal is very small.

[0108] In order to provide an equivalent ground potential for the first operational amplifier A0, the embodiment of the present utility model discloses a specific current sensing amplifier. Compared with the previous embodiment, this embodiment further illustrates and optimizes the technical solution. Specifically:

[0109] The equivalent ground potential is provided by an equivalent ground potential generating circuit, and the first operational amplifier A0 is provided with an equivalent ground potential generating circuit;

[0110] An input terminal of the equivalent ground potential generating circuit is connected to an output terminal of the common mode voltage output circuit, and an output terminal of the equivalent ground potential generating circuit is connected to an equivalent ground terminal of the first operational amplifier A0.

[0111] It should be noted that the input and output ends of the above-mentioned equivalent ground potential generating circuit are respectively connected to the output end of the common-mode voltage output circuit and the equivalent ground end of the first operational amplifier A0. The equivalent ground voltage input to the equivalent ground end of the first operational amplifier A0 can be adjusted based on the change of the common-mode voltage to ensure that the equivalent ground voltage is less than the common-mode voltage.

[0112] From the above, it can be seen that the output common-mode voltage value of the common-mode voltage output circuit is equivalent to the ground potential generating circuit. The equivalent ground potential generating circuit can generate an equivalent ground potential smaller than the common-mode voltage and provide it to the equivalent ground terminal of the first operational amplifier A0.

[0113] like Figure 2 As shown, in order to enable the equivalent ground potential to be adaptively changed based on the common-mode voltage, the embodiment of the present utility model discloses a specific current sensing amplifier. Compared with the previous embodiment, this embodiment further explains and optimizes the technical solution. Specifically:

[0114] The equivalent ground potential generating circuit includes: an eighth resistor R8, a ninth resistor R9, a fourth switch tube M4, a fifth switch tube M5, and a constant current source;

[0115] A first end of the eighth resistor R8 is connected to the output end of the common mode voltage output circuit;

[0116] The second end of the eighth resistor R8 and the control end of the fourth switch tube M4 are both connected to the first end of the ninth resistor R9; the control end of the fifth switch tube M5 and the first end of the fourth switch tube M4 are both connected to the second end of the ninth resistor R9;

[0117] The first end of the fifth switch tube M5 is connected to the second end of the fourth switch tube M4; the second end of the fifth switch tube M5 is connected to the positive electrode of the constant current source; the voltage output by the second end of the fifth switch tube M5 is equivalent to the ground potential;

[0118] The negative pole of the constant current source is grounded.

[0119] In this embodiment, based on the common mode voltage, the equivalent ground potential generating circuit can output a corresponding equivalent ground potential, and the specific formula is:

[0120] ;

[0121] in, Generate an equivalent ground potential for the equivalent ground potential generating circuit, The current provided by the constant current source is is the resistance of the eighth resistor R8, is the resistance of the ninth resistor R9, is the gate-source voltage of the fifth switch tube M5.

[0122] At this time, the voltage difference between the common mode voltage and the equivalent ground potential is .

[0123] As can be seen from the above, the equivalent ground potential generation circuit generates an equivalent ground potential based on the above formula. The equivalent ground potential can not only adaptively change with the common-mode voltage, but also adjust the current provided by the constant current source according to the specific application scenario to adjust the voltage difference between the common-mode voltage and the above equivalent ground potential.

[0124] In order to adaptively change the equivalent ground potential based on the common-mode voltage, the embodiment of the present utility model discloses a specific current sensing amplifier. Compared with the previous embodiment, this embodiment further explains and optimizes the technical solution. Specifically:

[0125] The equivalent ground potential generating circuit includes a plurality of diodes;

[0126] Multiple diodes are connected in series in the same direction; the cathode ports of the multiple diodes connected in series are the input ports of the equivalent ground potential generating circuit, and the anode ports of the multiple diodes connected in series are the output ports of the equivalent ground potential generating circuit.

[0127] In this embodiment, based on the common mode voltage, the equivalent ground potential generating circuit can output a corresponding equivalent ground potential, and the specific formula is:

[0128] ;

[0129] in, is the voltage difference of a diode, and n is the number of diodes.

[0130] At this time, the voltage difference between the common mode voltage and the equivalent ground potential is .

[0131] As can be seen from the above, the equivalent ground potential generation circuit generates an equivalent ground potential based on the above formula. The equivalent ground potential can not only adaptively change with the common-mode voltage, but also adjust the number of diodes according to the specific application scenario to adjust the voltage difference between the common-mode voltage and the above equivalent ground potential.

[0132] In order to ensure that the second operational amplifier A1 can operate normally, the embodiment of the present utility model discloses a specific current sensing amplifier. Compared with the previous embodiment, this embodiment further explains and optimizes the technical solution. Specifically:

[0133] The current sensing amplifier further includes: a tenth resistor R10 and an eleventh resistor R11; the resistance value of the tenth resistor R10 is equal to the resistance value of the eleventh resistor R11;

[0134] A second end of the tenth resistor R10 is connected to the inverting input terminal of the second operational amplifier A1, a first end of the eleventh resistor R11 is connected to the non-inverting input terminal of the second operational amplifier A1, and a first end of the tenth resistor R10 is connected to the output terminal of the second operational amplifier A1;

[0135] A second terminal of the eleventh resistor R11 is grounded.

[0136] In this embodiment, the tenth resistor R10 serves as the feedback resistor for the second operational amplifier A1. Connected between the inverting input and output of the second operational amplifier A1, it stabilizes the gain and controls the bandwidth. The bandwidth of the current sensing amplifier decreases as the value of the tenth resistor R10 increases. Furthermore, the tenth resistor R10 further enhances the output linearity of the second operational amplifier A1, reducing output signal distortion.

[0137] The eleventh resistor R11 can serve as a balancing resistor for the second operational amplifier A1. Since bias currents are prone to flowing at the input terminals of operational amplifiers, these currents can generate offset voltages at the input terminals of the operational amplifiers, affecting the accuracy of the current sensing amplifier. Therefore, the eleventh resistor R11 is connected between the non-inverting input terminal of the second operational amplifier A1 and ground. This can make the DC potentials of the two input terminals of the second operational amplifier A1 the same, thereby reducing the offset voltage generated by the bias current at the input terminals and improving the accuracy of the current sensing amplifier.

[0138] It should be noted that the fixed gain of the current sensing amplifier is determined by the first resistor R1 and the tenth resistor R10. When a differential-mode voltage exists across the sensing shunt resistor, the negative feedback loop clamps the voltage at the input of the first operational amplifier circuit to be equal. At this time, the currents flowing through the first resistor R1 and the second resistor R2 are:

[0139] ;

[0140] ;

[0141] in, 、 are the magnitudes of the current flowing through the first resistor R1 and the second resistor R2 respectively, is the resistance of the first resistor R1, is the resistance of the second resistor R2, is the voltage at the non-inverting input of the first operational amplifier A0, is the voltage at the inverting input terminal of the first operational amplifier A0.

[0142] Also because , ,therefore

[0143] ;

[0144] The non-inverting input terminal and the inverting input terminal of the first operational amplifier circuit are connected to the first switch tube M1 and the third switch tube M3 respectively, so the current flowing through the first resistor R1 and the second resistor R2 all flows out from the first switch tube M1 and the seventh resistor R7, that is, , ;in, is the current flowing through the second switch tube M2, is the current flowing through the third switch tube M3.

[0145] Since the second operational amplifier A1 is in a negative feedback connection, the voltages at its non-inverting input terminal and its inverting input terminal are equal, and the current flowing through the fifth resistor R5 and the sixth resistor R6 is:

[0146] ;

[0147] ;

[0148] in, 、 are the magnitudes of the current flowing through the fifth resistor R5 and the sixth resistor R6 respectively, is the voltage at the non-inverting input of the second operational amplifier A1, is the voltage at the inverting input of the second operational amplifier A1, is the resistance of the fifth resistor R5, is the resistance of the sixth resistor R6, is the voltage at the common end of the fifth resistor R5 and the sixth resistor R6.

[0149] It can be understood that when the common end of the fifth resistor and the sixth resistor is grounded, , when the common end of the fifth resistor and the sixth resistor is connected to the charge pump, .

[0150] because , , according to Kirchhoff's law:

[0151] ;

[0152] ;

[0153] Conclusion ;

[0154] because , and , the voltage at the output of the second operational amplifier A1 is:

[0155] ;

[0156] in, 、 are the currents flowing through the tenth resistor R10 and the eleventh resistor R11, is the voltage at the output of the second operational amplifier A1, is the resistance of the tenth resistor R10, is the resistance value of the eleventh resistor R11.

[0157] Therefore, the fixed gain of the current sensing amplifier is determined by the first resistor R1 and the tenth resistor R10, which is .

[0158] As can be seen from the above, adding the tenth resistor R10 and the eleventh resistor R11 can stabilize the gain, control the bandwidth, reduce the distortion of the output signal, and simultaneously reduce the offset voltage generated by the bias current at the input end of the second operational amplifier A1, thereby ensuring that the second operational amplifier A1 can operate normally.

[0159] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A current sensing amplifier, characterized in that: include: A common-mode voltage output circuit, a first resistor, a second resistor, a negative feedback loop, and a second operational amplifier; wherein the negative feedback loop includes the first operational amplifier and a differential-mode signal shift circuit; A common mode voltage output circuit, used for outputting a common mode voltage; A negative feedback loop is configured to clamp the voltage at the non-inverting input of the first operational amplifier to be equal to the voltage at the inverting input of the first operational amplifier, thereby expanding the input common-mode voltage range, and applying the expanded input common-mode voltage range to the second operational amplifier. The power supply terminal of the first operational amplifier is connected to the output terminal of the common-mode voltage output circuit, and the equivalent ground terminal of the first operational amplifier is connected to an equivalent ground potential less than the common-mode voltage and is connected to the first terminal of the differential-mode signal shifting circuit. The non-inverting input terminal of the first operational amplifier is connected to the first terminal of the sensing shunt resistor via the first resistor, the inverting input terminal of the first operational amplifier is connected to the second terminal of the sensing shunt resistor via the second resistor, and the output terminal of the first operational amplifier is connected to the second terminal of the differential-mode signal shifting circuit. The input terminal of the differential-mode signal shifting circuit is connected to the input terminal of the first operational amplifier, and the output terminal of the differential-mode signal shifting circuit is connected to the input terminal of the second operational amplifier. The differential-mode signal is the voltage difference between the first terminal and the second terminal of the sensing shunt resistor.

2. The current sensing amplifier according to claim 1, wherein: The common mode voltage output circuit includes: a third resistor and a fourth resistor; the resistance value of the third resistor is equal to the resistance value of the fourth resistor; The first end of the third resistor is connected to the first end of the sensing shunt resistor, and the second end of the fourth resistor is connected to the second end of the sensing shunt resistor; The second end of the third resistor is connected to the first end of the fourth resistor, and the common end thereof serves as the output end of the common-mode voltage output circuit.

3. The current sensing amplifier according to claim 1, wherein: The differential mode signal shift circuit includes: a first switch tube, a second switch tube, a fifth resistor, and a sixth resistor; wherein the resistance value of the fifth resistor is equal to the resistance value of the sixth resistor; The control terminal of the second switch tube is connected to the equivalent ground terminal of the first operational amplifier as the first terminal of the differential mode signal shift circuit; The control end of the first switch tube is connected to the output end of the first operational amplifier as the second end of the differential mode signal shift circuit, and the second end of the first switch tube is connected to the first end of the second switch tube; The first end of the first switch tube is connected to the non-inverting input end of the first operational amplifier as the input end of the differential mode signal shift circuit; The second end of the second switch tube is connected to the first end of the fifth resistor, and the common end thereof is connected to the non-inverting input end of the second operational amplifier as the first output end of the differential mode signal shift circuit; the first end of the sixth resistor is connected to the inverting input end of the second operational amplifier as the second output end of the differential mode signal shift circuit; the output end of the differential mode signal shift circuit includes the first output end of the differential mode signal shift circuit and the second output end of the differential mode signal shift circuit; The second end of the fifth resistor and the second end of the sixth resistor are grounded.

4. The current sensing amplifier according to claim 1, wherein: The differential mode signal shift circuit includes: a first switch tube, a second switch tube, a fifth resistor, a sixth resistor, and a charge pump; wherein the resistance value of the fifth resistor is equal to the resistance value of the sixth resistor; The control terminal of the second switch tube is connected to the equivalent ground terminal of the first operational amplifier as the first terminal of the differential mode signal shift circuit; The control end of the first switch tube is connected to the output end of the first operational amplifier as the second end of the differential mode signal shift circuit; the second end of the first switch tube is connected to the first end of the second switch tube; The first end of the first switch tube is connected to the non-inverting input end of the first operational amplifier as the first input end of the differential mode signal shift circuit; The second end of the second switch tube is connected to the first end of the fifth resistor, and the common end thereof is connected to the non-inverting input end of the second operational amplifier as the first output end of the differential mode signal shift circuit; the first end of the sixth resistor is connected to the inverting input end of the second operational amplifier as the second output end of the differential mode signal shift circuit; the output end of the differential mode signal shift circuit includes the first output end of the differential mode signal shift circuit and the second output end of the differential mode signal shift circuit; The second end of the fifth resistor and the second end of the sixth resistor are connected to the output end of the charge pump.

5. The current sensing amplifier according to claim 3 or 4, characterized in that: The differential mode signal shift circuit further includes: a seventh resistor and a third switch tube; A first end of the seventh resistor is connected to the inverting input terminal of the first operational amplifier, and a second end of the seventh resistor is connected to the first end of the third switch tube; The control terminal of the third switch tube is connected to the equivalent ground terminal of the first operational amplifier, and the second terminal of the third switch tube is connected to the inverting input terminal of the second operational amplifier.

6. The current sensing amplifier according to claim 1, wherein: The equivalent ground potential is provided by an equivalent ground potential generating circuit, and the equivalent ground potential generating circuit is provided in the first operational amplifier; An input terminal of the equivalent ground potential generating circuit is connected to an output terminal of the common-mode voltage output circuit, and an output terminal of the equivalent ground potential generating circuit is connected to an equivalent ground terminal of the first operational amplifier.

7. The current sensing amplifier according to claim 6, wherein: The equivalent ground potential generating circuit includes: an eighth resistor, a ninth resistor, a fourth switch tube, a fifth switch tube, and a constant current source; The first end of the eighth resistor is connected to the power supply end; and connected to the output end of the common mode voltage output circuit; The second end of the eighth resistor and the control end of the fourth switch tube are both connected to the first end of the ninth resistor; the control end of the fifth switch tube and the first end of the fourth switch tube are both connected to the second end of the ninth resistor; The fifth switch tube is used to output an equivalent ground potential, and the first end of the fifth switch tube is connected to the second end of the fourth switch tube; the second end of the fifth switch tube is also connected to the positive electrode of the constant current source; The negative electrode of the constant current source is grounded.

8. The current sensing amplifier according to claim 6, wherein: The equivalent ground potential generating circuit includes a plurality of diodes; The multiple diodes are connected in series in the same direction; the cathode ports of the multiple diodes connected in series are the input terminals of the equivalent ground potential generating circuit, and the anode ports of the multiple diodes connected in series are the output terminals of the equivalent ground potential generating circuit.

9. The current sensing amplifier according to claim 5, wherein: Also includes: a tenth resistor and an eleventh resistor; the resistance of the tenth resistor is equal to the resistance of the eleventh resistor; The second end of the tenth resistor is connected to the inverting input terminal of the second operational amplifier, the first end of the eleventh resistor is connected to the non-inverting input terminal of the second operational amplifier, and the first end of the tenth resistor is connected to the output terminal of the second operational amplifier; A second end of the eleventh resistor is grounded.

10. A current testing device, characterized in that: The invention comprises a controller and the current sensing amplifier according to any one of claims 1 to 9.

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