Signal amplification circuit, chip and electronic equipment

Abstract

The embodiment of the utility model provides a signal amplification circuit, a chip and electronic equipment, the signal amplification circuit comprises a first operational amplifier, a second operational amplifier, a first feedback resistor connected between a first input end and a first output end of the first operational amplifier, and a second feedback resistor connected between a second input end and a second output end of the first operational amplifier; the first end of the first resistor module is connected with the first input end of the first operational amplifier, and the second end of the first resistor module is connected with a common-mode voltage; the first end of the second resistor module is connected with the second input end of the first operational amplifier, and the second end of the second resistor module is connected with common-mode voltage. The input common-mode voltage of the first operational amplifier can be clamped into the output common-mode voltage through the first resistor module and the second resistor module, and finally the phenomenon of signal measurement errors caused by deviation of the input common-mode voltage is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of integrated circuits, in particular to a signal amplification circuit, a chip and an electronic device. BACKGROUND

[0002] At present, with the concern for health, wearable devices usually have the function of monitoring human body electrical signals, such as monitoring electrocardiogram (ECG) signals, electromyogram (EMG) signals and the like, so as to judge the health status of the human body. Since the human body electrical signal usually has the characteristics of low frequency, low amplitude and being easily disturbed, a trans-impedance amplifier (TIA) is generally required to amplify the electrical signal detected by the sensor.

[0003] However, due to the influence of factors such as signal input circuit, trans-impedance amplifier input end circuit and the like, the input common mode voltage of the trans-impedance amplifier and the output common mode voltage have deviation phenomenon, and the deviation of the input common mode voltage may cause the change of the differential voltage output by the trans-impedance amplifier, and finally cause the human body electrical signal measurement error phenomenon. SUMMARY

[0004] In view of the above problems, the embodiments of the present application provide a signal amplification circuit, a chip and an electronic device to solve the above technical problems.

[0005] In a first aspect, the embodiments of the present application provide a signal amplification circuit, comprising:

[0006] A first operational amplifier, a first feedback resistor is connected between the first input end and the first output end of the first operational amplifier, and a second feedback resistor is connected between the second input end and the second output end of the first operational amplifier;

[0007] A first resistance module, the first end of the first resistance module is connected with the first input end of the first operational amplifier, and the second end of the first resistance module is connected with the common mode voltage;

[0008] A second resistance module, the first end of the second resistance module is connected with the second input end of the first operational amplifier, and the second end of the second resistance module is connected with the common mode voltage;

[0009] Wherein, the common mode voltage is equal to the output common mode voltage of the first operational amplifier.

[0010] In a second aspect, the embodiments of the present application further provide a chip comprising the above signal amplification circuit.

[0011] In a third aspect, the embodiments of the present application further provide an electronic device comprising the above chip or signal amplification circuit.

[0012] The first feedback resistor and the second feedback resistor are arranged between the first input terminal and the first output terminal of the first operational amplifier, so that the first operational amplifier, the first feedback resistor and the second feedback resistor constitute a transimpedance amplifier. Therefore, the transimpedance amplifier can convert a current signal of a sensor (for example, a photodiode) into a voltage signal, so as to realize measurement of the current signal output by the sensor after the voltage signal is measured by an analog-to-digital converter.

[0013] The first input terminal of the first operational amplifier is connected with the first resistor module connected to the common-mode voltage, the second input terminal of the first operational amplifier is connected with the second resistor module connected to the common-mode voltage, and the common-mode voltage is equal to the output common-mode voltage of the first operational amplifier. Therefore, the input common-mode voltage of the first operational amplifier can be clamped to the output common-mode voltage through the first resistor module and the second resistor module, so as to reduce the deviation between the input common-mode voltage and the output common-mode voltage of the first operational amplifier, and finally reduce the measurement error of the human body electrical signal caused by the deviation of the input common-mode voltage.

[0014] These aspects or other aspects of the present application will be more apparent in the following description of the embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0016] Figure 1 A schematic diagram of a signal measurement circuit in the related art is shown.

[0017] Figure 2 A schematic diagram of a signal amplification circuit in an embodiment of the present application is shown.

[0018] Figure 3 Another schematic diagram of a signal amplification circuit in an embodiment of the present application is shown.

[0019] Figure 4 Another schematic diagram of a signal amplification circuit in an embodiment of the present application is shown.

[0020] Figure 5 Another schematic diagram of a signal amplification circuit in an embodiment of the present application is shown.

[0021] Figure 6 Another schematic diagram of a signal amplification circuit in an embodiment of the present application is shown.

[0022] The first resistance module 10, the second resistance module 20, the signal amplification circuit 100, the first operational amplifier OP, the first feedback resistance RF1, the second feedback resistance RF2, the first resistance R1, the second resistance R2, the first switch S1, the second switch S2, the common-mode voltage Vcm, the input common-mode voltage Vcmin, the output common-mode voltage Vcmout, the first control voltage Vc1, and the second control voltage Vc2. DETAILED DESCRIPTION

[0023] The embodiments of the present application will be described in detail below with reference to the drawings, in which the same or similar components are denoted by the same or similar reference numerals, and therefore the description will be given only once. The embodiments described below are merely exemplary of the present application, and are not intended to limit the present application.

[0024] In order to make the technical personnel in the art better understand the scheme of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0025] In the embodiments of the present application, it should be noted that, in this document, relational terms such as first and second and the like are used solely to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between or among the entities or actions.

[0026] Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusions, so that processes, methods, articles or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed, or further include elements inherent to such processes, methods, articles or devices. Without more limitations, the element defined by the statement "including a" does not exclude the presence of additional identical elements in the process, method, article or device including the element.

[0027] In the description of the embodiments of the present application, the words "example" or "for example" are used to mean example, illustration or description. Any embodiment or design scheme described as "example" or "for example" in the embodiments of the present application is not interpreted as more preferred or having more advantages than another embodiment or design scheme. The words "example" or "for example" are intended to present the relative concept in a clear manner.

[0028] In addition, "multiple" in the embodiments of the present application refers to two or more, and therefore, "multiple" in the embodiments of the present application can also be understood as "at least two". "At least one" can be understood as one or more, for example, understood as one, two or more. For example, "including at least one" refers to including one, two or more, and does not limit which ones are included, for example, including at least one of A, B and C, and the included can be A, B, C, A and B, A and C, B and C, or A and B and C.

[0029] It should be noted that "connection" in the embodiments of the present application can be understood as electrical connection, and the connection between two electrical elements can be direct or indirect connection between the two electrical elements. For example, A and B are connected, which can be direct connection between A and B, or indirect connection between A and B through one or more other electrical elements.

[0030] The first pole / first end of each transistor used in the embodiments of the present application is one of the source and the drain, and the second pole / second end of each transistor is the other of the source and the drain. Since the source and the drain of the transistor can be symmetrical in structure, the source and the drain can be indistinguishable in structure, that is, the first pole / first end and the second pole / second end of the transistor in the embodiments of the present application can be indistinguishable in structure. Illustratively, in the case of a P-type transistor, the first pole / first end of the transistor is the source and the second pole / second end of the transistor is the drain; illustratively, in the case of an N-type transistor, the first pole / first end of the transistor is the drain and the second pole / second end of the transistor is the source.

[0031] In the circuit structure provided by the embodiments of the present application, the nodes such as the first node and the second node do not represent actual components, but represent the convergence points of relevant couplings in the circuit diagram, that is, these nodes are nodes equivalent to the convergence points of relevant couplings in the circuit diagram.

[0032] At present, since the human body electrical signal usually has the characteristics of low frequency, low amplitude and easy to be disturbed, it is generally necessary to use a transimpedance amplifier to amplify the electrical signal detected by the sensor, so as to Figure 1 For example, Figure 1 A schematic diagram of a signal measurement circuit in the related art is shown, which includes a photodiode PD, a first current source IDAC1, a second current source IDAC2, an operational amplifier OP, a feedback resistor RF and an analog-to-digital converter ADC.

[0033] The photodiode PD can receive light transmitted by the light source through the target site, so as to generate photo-generated current IP and IN related to electrocardiogram (ECG), electromyogram (EMG) and the like; the first current source IDAC1 and the second current source IDAC2 can reduce the direct current signal in the input current signal IP and IN, so as to improve the dynamic range of the trans-impedance amplifier output signal; the trans-impedance amplifier composed of the operational amplifier OP and the feedback resistor RF can convert the current signal into a voltage signal, and finally the measurement process of the electrocardiogram and the electromyogram can be realized after the voltage signal is converted into a digital signal by the analog-to-digital converter ADC.

[0034] Specifically, in Figure 1 According to the characteristics of the operational amplifier OP, the voltage VOP at the non-inverting output end of the operational amplifier OP and the voltage VON at the inverting output end satisfy the following relationship:

[0035] VOP = VB + (IN + IDAC2) * RF

[0036] VON = VA - (IP + IDAC1) * RF

[0037] wherein VA is the voltage at node A, and VB is the voltage at node B.

[0038] Then, the input common-mode voltage Vcmin and the output common-mode voltage Vcmout of the operational amplifier OP can be calculated according to the following formula:

[0039] Vcmin = 0.5 * (VA + VB)

[0040] Vcmout = 0.5 * (VOP + VON)

[0041] Vcmout = 0.5 * (VA + VB) + 0.5 * [(IN - IP) + (IDAC2 - IDAC1)] * RF

[0042] Since the two ends of the photodiode PD are connected to the non-inverting input end and the inverting input end of the operational amplifier OP respectively, IP = IN, and it can be known that the input common-mode voltage Vcmin and the output common-mode voltage Vcmout of the operational amplifier OP satisfy the following formula:

[0043] Vcmout = Vcmin + 0.5 * (IDAC2 - IDAC1) * RF

[0044] Since the output common-mode voltage of the operational amplifier is equal to the common-mode voltage Vcmout = Vcm, the deviation between the input common-mode voltage Vcmin and the common-mode voltage Vcm can be calculated according to the following formula:

[0045] Vcm-Vcmin=0.5*(IDAC2-IDAC1)*RF

[0046] It can be seen that the deviation of the input common-mode voltage is mainly caused by the unequal output current of the first current source IDAC1 and the second current source IDAC2.

[0047] It can be understood that, Figure 1 The circuit structure at the input end of the transimpedance amplifier is exemplarily described to illustrate the reason for the deviation between the input common-mode voltage and the output common-mode voltage of the transimpedance amplifier. In some possible embodiments, when the inverting input end and the non-inverting input end of the operational amplifier are simultaneously connected to two photodiodes, the deviation between the input common-mode voltage and the output common-mode voltage can also be caused by the unequal current signal IP and the current signal IN.

[0048] Therefore, due to the influence of the signal input circuit, the circuit at the input end of the transimpedance amplifier, and the like, the input common-mode voltage and the output common-mode voltage of the transimpedance amplifier currently have a deviation phenomenon. The deviation of the input common-mode voltage can cause the change of the differential voltage output by the transimpedance amplifier, and finally cause the measurement error of the human body electrical signal.

[0049] To this end, the present application provides a signal amplification circuit, a chip, and an electronic device, which are described in detail below.

[0050] First, refer to Figure 2 , Figure 2 A schematic diagram of a signal amplification circuit 100 in an embodiment of the present application is shown, wherein the signal amplification circuit 100 includes a first operational amplifier OP, a first feedback resistor RF1, a second feedback resistor RF2, a first resistance module 10, and a second resistance module 20.

[0051] Specifically, the first feedback resistor RF1 is connected between the first input end and the first output end of the first operational amplifier OP, and the second feedback resistor RF2 is connected between the second input end and the second output end of the first operational amplifier OP, so that the first operational amplifier OP, the first feedback resistor RF1, and the second feedback resistor RF2 constitute a transimpedance amplifier. Thus, the current signal input from the first input end and the second input end is converted into a voltage signal by the transimpedance amplifier, so that the analog-to-digital converter converts the digital signal according to the voltage signal.

[0052] It should be noted that one of the first input terminal and the second input terminal of the first operational amplifier OP is a non-inverting input terminal, and the other is an inverting input terminal. One of the first output terminal and the second output terminal of the first operational amplifier OP is a non-inverting output terminal, and the other is an inverting output terminal. For example, the first input terminal of the first operational amplifier OP can be referred to as a non-inverting input terminal, the second input terminal can be referred to as an inverting input terminal, the first output terminal can be referred to as an inverting output terminal, and the second output terminal can be referred to as a non-inverting output terminal. For another example, the first input terminal of the first operational amplifier OP can be referred to as an inverting input terminal, the second input terminal can be referred to as a non-inverting input terminal, the first output terminal can be referred to as a non-inverting output terminal, and the second output terminal can be referred to as an inverting output terminal.

[0053] The first end of the first resistance module 10 is connected to the first input terminal of the first operational amplifier OP, and the second end of the first resistance module 10 is connected to the common-mode voltage Vcm. The first end of the second resistance module 20 is connected to the second input terminal of the first operational amplifier OP, and the second end of the second resistance module 20 is connected to the common-mode voltage Vcm. The common-mode voltage Vcm is equal to the output common-mode voltage Vcmout of the first operational amplifier OP. The first resistance module 10 and the second resistance module 20 connected to the common-mode voltage Vcm can clamp the input common-mode voltage Vcmin of the first operational amplifier OP to the output common-mode voltage Vcmout, thereby avoiding the measurement error phenomenon caused by the input common-mode voltage Vcmin commutation mode.

[0054] For example, the resistance values of the first resistance module 10 and the second resistance module 20 are equal, and the resistance values of the first feedback resistor RF1 and the second feedback resistor RF2 are equal. The voltages of the node A and the node B can be calculated according to the following formula:

[0055]

[0056] Wherein, VA is the voltage of the node A, VB is the voltage of the node B, R1 is the resistance value of the first resistance module 10 and the second resistance module 20, RF is the resistance value of the first feedback resistor RF1 and the second feedback resistor RF2, VON is the voltage of the first output terminal of the first operational amplifier OP, VOP is the voltage of the second output terminal of the first operational amplifier OP, Vcm is the common-mode voltage of the first operational amplifier OP, IDAC1 is the current size of the first current source output, IDAC2 is the current size of the second current source output, IP is the current size of the first input terminal of the first operational amplifier OP, and IN is the current size of the second input terminal of the first operational amplifier OP.

[0057] According to the above formula, the input common-mode voltage Vcmin and the output common-mode voltage Vcmout of the first operational amplifier OP can be calculated according to the following formula:

[0058] Vcmin = 0.5 * (VA+VB)

[0059]

[0060] Vcmout = (VOP+VON) * 0.5 = Vcm

[0061] Assuming IP = IN, the input common-mode voltage Vcmin of the first operational amplifier OP can be calculated as follows:

[0062]

[0063] That is:

[0064]

[0065] As can be seen, when the currents output by the first current source IDAC1 and the second current source IDAC2 are not equal, compared with the scheme in which the input common-mode voltage Vcmin deviates by 0.5 * (IDAC2-IDAC1) * RF due to the absence of the first resistance module 10 and the second resistance module 20, the term in the above formula is less than 1, so the first resistance module 10 and the second resistance module 20 configured to access the common-mode voltage Vcm can effectively reduce the deviation of the input common-mode voltage Vcmin of the first operational amplifier OP, and ultimately help to improve the accuracy of signal measurement.

[0066] It should be noted that the signal amplification circuit in the above exemplary embodiments further includes a first current source IDAC1 and a second current source IDAC2, the input end of the first current source IDAC1 is connected to the power supply end, the output end of the first current source IDAC1 is connected to the first input end of the first operational amplifier, so that the first current source IDAC1 inputs current to node A to increase the current flowing through the first feedback resistor RF1, thereby increasing the voltage VON at the first output end of the first operational amplifier OP; the input end of the second current source IDAC2 is connected to the second input end of the first operational amplifier, the output end of the second current source IDAC2 is connected to the ground, and the second current source IDAC2 extracts the current of node B to increase the current flowing through the second feedback resistor RF2, thereby increasing the voltage VOP at the second output end of the first operational amplifier OP, and ultimately improving the dynamic range of the voltage VON at the first output end and the voltage VOP at the second output end of the first operational amplifier OP.

[0067] ​Meanwhile, it should be noted that the first current source IDAC1 and the second current source IDAC2 are only one possible factor that causes the input common-mode voltage Vcmin of the trans-impedance amplifier to deviate from the output common-mode voltage Vcmout, and are not essential parts of the signal amplification circuit of the present application. The factor that causes the input common-mode voltage Vcmin to deviate from the output common-mode voltage Vcmout is not limited to this, for example, the current signal IP not being equal to the current signal IN can also cause the input common-mode voltage Vcmin of the trans-impedance amplifier to deviate from the output common-mode voltage Vcmout.

[0068] In summary, in the embodiments of the present application, the first feedback resistor RF1 is arranged between the first input terminal and the first output terminal of the first operational amplifier OP, and the second feedback resistor RF2 is arranged between the second input terminal and the second output terminal of the first operational amplifier OP, so that the first operational amplifier OP, the first feedback resistor RF1 and the second feedback resistor RF2 constitute a trans-impedance amplifier. Therefore, the trans-impedance amplifier can convert the current signal of the sensor (for example, a photodiode) into a voltage signal, so as to facilitate the measurement of the voltage signal by the analog-to-digital converter, thereby realizing the measurement of the output current signal of the sensor.

[0069] Since the first input terminal of the first operational amplifier OP is connected to the first resistance module 10 connected to the common-mode voltage Vcm, the second input terminal of the first operational amplifier OP is connected to the second resistance module 20 connected to the common-mode voltage Vcm, and the common-mode voltage Vcm is equal to the output common-mode voltage Vcmout of the first operational amplifier OP, the input common-mode voltage Vcmin of the first operational amplifier OP can be clamped to the output common-mode voltage Vcmout by the first resistance module 10 and the second resistance module 20. Therefore, the present application can reduce the deviation of the input common-mode voltage Vcmin and the output common-mode voltage Vcmout of the first operational amplifier OP, and ultimately reduce the measurement error of the human body electrical signal caused by the deviation of the input common-mode voltage Vcmin.

[0070] In some embodiments of the present application, for example, for embodiments in which the resistance values of the first resistance module 10 and the second resistance module 20 are equal, and the resistance values of the first feedback resistor RF1 and the second feedback resistor RF2 are equal, the resistance values of the first resistance module 10 and the second resistance module 20 are equal to a first preset value, and the resistance values of the first feedback resistor RF1 and the second feedback resistor RF2 are equal to a second preset value; wherein the first preset value is less than the second preset value.

[0071] It should be noted that, in combination with the input common-mode voltage Vcmin calculation formula of the first operational amplifier OP It can be known that, when the resistance values of the first resistance module 10 and the second resistance module 20 are less than the resistance values of the first feedback resistor RF1 and the second feedback resistor RF2, the term The term will be less than 1, for example, when R1 = 0.5RF, The value of the term is 1 / 3; when R1 = 0.25RF, The value of the term is 1 / 5; it can be seen that when the resistance values of the first resistance module 10 and the second resistance module 20 are much smaller than the resistance values of the first feedback resistance RF1 and the second feedback resistance RF2, it is beneficial to further reduce the deviation of the input common-mode voltage Vcmin and the output common-mode voltage Vcmout of the first operational amplifier OP.

[0072] In some embodiments of the present application, referring to Figure 3 , Figure 3 Another schematic diagram of the signal amplification circuit 100 in the embodiments of the present application is shown, wherein the first resistance module 10 includes a first resistance R1, and the second resistance module 20 includes a second resistance R2; the first end of the first resistance R1 is connected with the first input end of the first operational amplifier OP, and the second end of the first resistance R1 is connected with the common-mode voltage Vcm; the first end of the second resistance R2 is connected with the second input end of the first operational amplifier OP, and the second end of the second resistance R2 is connected with the common-mode voltage Vcm. That is, the first resistance module 10 and the second resistance module 20 can be composed of a single resistance, and the input common-mode voltage Vcmin of the first operational amplifier OP can be clamped to the output common-mode voltage Vcmout through the first resistance R1 and the second resistance R2 connected with the common-mode voltage Vcm, so as to reduce the human body electric signal measurement error caused by the deviation of the input common-mode voltage Vcmin.

[0073] In some embodiments of the present application, referring to Figure 4 , Figure 4 Another schematic diagram of the signal amplification circuit 100 in the embodiments of the present application is shown, wherein the first resistance module 10 includes a plurality of first switches S1 and a plurality of first resistances R1, and the first switch S1 corresponds to the first resistance R1 one by one; the first end of the first switch S1 is connected with the first input end of the first operational amplifier OP, the second end of the first switch S1 is connected with the first end of the first resistance R1, and the second end of the first resistance R1 is connected with the common-mode voltage Vcm. Specifically, when the number of the first switches S1 controlled to be closed is controlled, the resistance value of the first resistance module 10 can be changed, for example, when the number of two first switches S1 is controlled, the two first resistances R1 are connected in parallel, and therefore the resistance value of the first resistance module 10 is 1 / 2*R1; for another example, when the number of three first switches S1 is controlled, the three first resistances R1 are connected in parallel, and therefore the resistance value of the first resistance module 10 is 1 / 3*R1, and so on. In this way, in actual application, the resistance value of the different first resistance modules 10 can be selected according to the requirement of noise, so as to realize better noise performance of the system.

[0074] In some embodiments of the present application, continuing to refer to Figure 4 The second resistance module 20 includes a plurality of second switches S2 and a plurality of second resistors R2, and the second switches S2 correspond to the second resistors R2 one by one. The first end of the second switch S2 is connected to the second input end of the first operational amplifier OP, the second end of the second switch S2 is connected to the first end of the second resistor R2, and the second end of the second resistor R2 is connected to the common-mode voltage Vcm. Similarly, when the number of the second switches S2 that are controlled to be closed is changed, the resistance value of the second resistance module 20 can be changed. For example, when the number of two second switches S2 is controlled to be closed, the resistance value of the second resistance module 20 is 1 / 2*R2; for another example, when the number of three second switches S2 is controlled to be closed, the resistance value of the second resistance module 20 is 1 / 3*R2, and so on. In this way, the resistance value of the second resistance module 20 is controlled, so that in actual application, the resistance value of the second resistance module 20 can be selected according to the requirement of noise.

[0075] In some embodiments of the present application, referring to Figure 5 , Figure 5 Another schematic diagram of the signal amplification circuit 100 in the embodiments of the present application is shown, wherein the first resistance module 10 includes a first transistor M1. The first end of the first transistor M1 is connected to the first input end of the first operational amplifier OP, the second end of the first transistor M1 is connected to the common-mode voltage Vcm, and the control end of the first transistor M1 is connected to the first control voltage Vc1.

[0076] Specifically, the impedance of the first transistor M1 can be calculated according to the following formula:

[0077]

[0078] Wherein μ is the mobility of the transistor, Cox is the specific capacitance of the transistor, W1 is the channel width of the first transistor M1, L1 is the channel length of the first transistor M1, VGS1 is the voltage difference between the gate and the source of the first transistor M1, and VTH1 is the threshold voltage of the first transistor M1.

[0079] Since the first end of the first transistor M1 is connected to the first input end of the first operational amplifier OP, and the control end of the first transistor M1 is connected to the first control voltage Vc1, the voltage difference between the gate and the source of the first transistor M1 is:

[0080] VGS1 = Vc1 - VA

[0081] It can be seen from the above formula that the size of the first control voltage Vc1 is changed, the voltage difference between the gate and the source of the first transistor M1 is changed, and thus the impedance of the first transistor M1 is changed, so that in actual application, the resistance value of the first resistance module 10 can be selected according to the requirement of noise.

[0082] In some embodiments of the present application, continuing to refer to Figure 5 The second resistance module 20 comprises a second transistor M2. The first end of the second transistor M2 is connected to the second input end of the first operational amplifier OP, the second end of the second transistor M2 is connected to the common-mode voltage Vcm, and the control end of the second transistor M2 is connected to the second control voltage Vc2.

[0083] Similarly, the impedance of the second transistor M2 can be calculated as follows:

[0084]

[0085] Wherein, W2 is the channel width of the second transistor M2, L2 is the channel length of the second transistor M2, VGS2 is the voltage difference between the gate and the source of the second transistor M2, and VTH2 is the threshold voltage of the second transistor M2.

[0086] Since the first end of the second transistor M2 is connected to the second input end of the first operational amplifier OP, and the control end of the second transistor M2 is connected to the second control voltage Vc2, the voltage difference between the gate and the source of the second transistor M2 satisfies the following formula:

[0087] VGS2 = Vc - VB

[0088] It can be seen from the above formula that changing the size of the second control voltage Vc2 can change the voltage difference between the gate and the source of the second transistor M2, thereby changing the impedance of the second transistor M2, so that in actual application, different resistance values of the second resistance module 20 can be selected according to the requirements of noise.

[0089] It is worth noting that the above content about the signal amplification circuit 100 is intended to clearly explain that the person skilled in the art can make equivalent modifications or further designs under the guidance of the present application during the implementation and verification process of the present application. For example, a group of resistors in series or in parallel is used as the first resistance module 10, and another group of resistors in series or in parallel is used as the second resistance module 20; for example, referring to Figure 6 , Figure 6 Another schematic diagram of the signal amplification circuit 100 in the embodiment of the present application is shown, and the first capacitor C1 can be connected in parallel across the first feedback resistor RF1, and the second capacitor C2 can be connected in parallel across the second feedback resistor RF2.

[0090] The embodiment of the present application further provides a chip, which comprises the signal amplification circuit 100 described above. The chip (IC) is also called a chip, which can be but is not limited to a SOC (System on Chip) chip, a SIP (system in package) chip. Since the chip of the present application is provided with the signal amplification circuit 100 described in the above embodiment, it has all the beneficial effects of the signal amplification circuit 100 in the above embodiment, which will not be repeated here.

[0091] The embodiment of the present application further provides an electronic device, which comprises a device main body and a chip as described above arranged in the device main body. The electronic device can be but is not limited to a body weight scale, a body fat scale, a nutrition scale, an infrared electronic thermometer, a pulse oximeter, a human body composition analyzer, a mobile power supply, a wireless charger, a fast charger, a vehicle charger, an adapter, a display, a USB (Universal Serial Bus) docking station, a touch pen, a true wireless earphone, a car central control screen, a car, a smart wearable device, a mobile terminal, a smart home device. The smart wearable device includes but is not limited to a smart watch, a smart bracelet, a cervical vertebra massage instrument. The mobile terminal includes but is not limited to a smart phone, a notebook computer, a tablet computer, a POS (point of sales terminal) machine. The smart home device includes but is not limited to a smart socket, a smart rice cooker, a smart sweeper, a smart lamp.

[0092] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as the above preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present application. Any modification, change and modification of the above embodiment according to the technical essence of the present application, which does not depart from the technical solution of the present application, is still within the scope of the technical solution of the present application.

Claims

1. A signal amplification circuit, characterized by, The signal amplification circuit comprises: a first operational amplifier, a first input end of the first operational amplifier is connected with a first output end through a first feedback resistor, and a second input end of the first operational amplifier is connected with a second output end through a second feedback resistor; a first resistance module, a first end of the first resistance module is connected with the first input end of the first operational amplifier, and a second end of the first resistance module is connected with a common-mode voltage; a second resistance module, a first end of the second resistance module is connected with the second input end of the first operational amplifier, and a second end of the second resistance module is connected with the common-mode voltage; wherein the common-mode voltage is equal to an output common-mode voltage of the first operational amplifier.

2. The signal amplification circuit of claim 1, wherein, The resistance values of the first resistance module and the second resistance module are equal, and the resistance values of the first feedback resistor and the second feedback resistor are equal.

3. The signal amplification circuit of claim 2, wherein, The resistance values of the first resistance module and the second resistance module are equal to a first preset value, and the resistance values of the first feedback resistor and the second feedback resistor are equal to a second preset value; wherein the first preset value is less than the second preset value.

4. The signal amplification circuit of claim 1, wherein, The first resistance module comprises a first resistor, and the second resistance module comprises a second resistor; a first end of the first resistor is connected with the first input end of the first operational amplifier, and a second end of the first resistor is connected with the common-mode voltage; a first end of the second resistor is connected with the second input end of the first operational amplifier, and a second end of the second resistor is connected with the common-mode voltage.

5. The signal amplification circuit of claim 1, wherein, The first resistance module comprises a plurality of first switches and a plurality of first resistors, and the first switches correspond to the first resistors one by one; a first end of the first switch is connected with the first input end of the first operational amplifier, a second end of the first switch is connected with a first end of the first resistor, and a second end of the first resistor is connected with the common-mode voltage.

6. The signal amplification circuit of claim 5, wherein, The second resistance module comprises a plurality of second switches and a plurality of second resistors, and the second switches correspond to the second resistors one by one; a first end of the second switch is connected with the second input end of the first operational amplifier, a second end of the second switch is connected with a first end of the second resistor, and a second end of the second resistor is connected with the common-mode voltage.

7. The signal amplification circuit of claim 1, wherein, The first resistance module comprises a first transistor, and the second resistance module comprises a second transistor; a first end of the first transistor is connected with the first input end of the first operational amplifier, a second end of the first transistor is connected with the common-mode voltage, and a control end of the first transistor is connected with a first control voltage; a first end of the second transistor is connected with the second input end of the first operational amplifier, a second end of the second transistor is connected with the common-mode voltage, and a control end of the second transistor is connected with a second control voltage.

8. The signal amplification circuit according to any one of claims 1 to 7, wherein The signal amplification circuit further comprises a first current source and a second current source; an input end of the first current source is connected with a power supply end, and an output end of the first current source is connected with the first input end of the first operational amplifier; an input end of the second current source is connected with the second input end of the first operational amplifier, and an output end of the second current source is connected with a ground end.

9. A chip, characterized by The signal amplification circuit according to any one of claims 1 to 8.

10. An electronic device, comprising: The device body and the chip according to claim 9 are arranged in the device body.

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