Buffer circuit, signal acquisition device and electronic equipment

Abstract

The present application relates to a buffer circuit, a signal acquisition device and an electronic device, wherein the buffer circuit includes a first power supply module, an operational amplifier module and a second power supply module. The first input end of the operational amplifier module is used to receive a bioelectric signal, and the output end of the operational amplifier module is respectively connected to the second input end of the operational amplifier module, the first power supply end of the operational amplifier module and the first power supply module. The difference between the first AC component output by the operational amplifier module according to the bioelectric signal and the voltage value of the bioelectric signal and the first power supply is within a first preset range; the input end of the second power supply module is connected to the output end of the operational amplifier module, and the output end of the second power supply module is connected to the second power supply end of the operational amplifier module. The difference between the second AC component output by the second power supply module to the operational amplifier module according to the first AC component and the voltage value of the bioelectric signal is within a second preset range. The first preset range and the second preset range are adjusted so that the first AC signal and the second AC signal are closer to the bioelectric signal and the input impedance is increased.

Description

Technical Field

[0001] The present application relates to the technical field of electronic equipment, and in particular to a buffer circuit, a signal acquisition device, and an electronic device. Background Art

[0002] With the rapid development of electronics and the internet, medical electronic devices are becoming increasingly intelligent and miniaturized. Wearable mobile medical devices are attracting increasing public attention. ECG signal acquisition devices are one such device that have garnered significant attention. ECG signal acquisition devices typically require a high front-end input impedance, which is achieved through the use of a buffer circuit.

[0003] However, in a conventional buffer circuit, due to the influence of the internal input capacitance of the operational amplifier within the buffer circuit, the increase in input impedance is limited, thereby affecting the acquisition of ECG signals. Summary of the Invention

[0004] The embodiments of the present application provide a buffer circuit, a signal acquisition device, and an electronic device, which can improve the input impedance and enhance the anti-interference capability and stability of the buffer circuit.

[0005] A buffer circuit comprising:

[0006] A first power supply module, configured to provide a first power supply;

[0007] an operational amplifier module, wherein a first input terminal of the operational amplifier module is used to receive a bioelectric signal, an output terminal of the operational amplifier module is respectively connected to a second input terminal of the operational amplifier module, a first power terminal of the operational amplifier module, and an output terminal of the first power supply module, the operational amplifier module is used to output a first voltage based on the bioelectric signal and the power supply, and a difference between a first AC component of the first voltage and a voltage value of the bioelectric signal is within a first preset range;

[0008] A second power supply module, the input end of the second power supply module is connected to the output end of the operational amplifier module, the output end of the second power supply module is connected to the second power supply end of the operational amplifier module, the second power supply module is used to provide a second power supply, and is also used to output a second voltage to the operational amplifier module according to the first AC component, and the difference between the second AC component of the second voltage and the voltage value of the bioelectric signal is within a second preset range.

[0009] A signal acquisition device, comprising:

[0010] A buffer circuit as described above; and

[0011] The acquisition module is connected to the first input terminal of the operational amplifier module, and is used to acquire bioelectric signals and output the bioelectric signals to the operational amplifier module.

[0012] An electronic device, comprising:

[0013] The signal acquisition device as described above.

[0014] The above-mentioned buffer circuit, signal acquisition device and electronic equipment, wherein the buffer circuit includes a first power supply module, an operational amplifier module and a second power supply module. The first power supply module provides a first power supply; the first input end of the operational amplifier module is used to receive the bioelectric signal, and the output end of the operational amplifier module is respectively connected to the second input end of the operational amplifier module, the first power supply end of the operational amplifier module and the output end of the first power supply module. The operational amplifier module is used to output a first voltage according to the bioelectric signal and the power supply, and the difference between the first AC component of the first voltage and the voltage value of the bioelectric signal is within a first preset range; the input end of the second power supply module is connected to the output end of the operational amplifier module, and the output end of the second power supply module is connected to the second power supply end of the operational amplifier module. The second power supply module is used to provide a second power supply and output a second voltage to the operational amplifier module according to the first AC component. The difference between the second AC component of the second voltage and the voltage value of the bioelectric signal is within a second preset range. Thus, the first power supply module, the operational amplifier module and the second power supply module constitute a buffer circuit for power bootstrapping. When the first AC signal and the second AC signal on the two power rails of the operational amplifier module are closer to the input bioelectric signal, the input capacitance inside the operational amplifier module is smaller, and thus the input impedance of the operational amplifier module is larger. Therefore, the input impedance of the buffer circuit can be improved by adjusting the first preset range and the second preset range, and the interference effects such as common-mode to differential-mode signal interference and base drift caused by impedance changes can be effectively suppressed, thereby improving the anti-interference ability, signal-to-noise ratio and stability of the buffer circuit, more effectively driving the subsequent circuit, and improving the reliability of signal acquisition. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application 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 only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0016] Figure 1 is a structural block diagram of a buffer circuit in one embodiment;

[0017] Figure 2 is a structural block diagram of a buffer circuit in one embodiment;

[0018] Figure 3is a structural block diagram of a buffer circuit in one embodiment;

[0019] Figure 4 is a circuit model of the input impedance of the third operational amplifier in one embodiment;

[0020] Figure 5 This is a structural block diagram of a signal acquisition device in one embodiment;

[0021] Figure 6 1 is a structural block diagram of a signal acquisition device in one embodiment. DETAILED DESCRIPTION

[0022] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of the present application.

[0023] It is understood that the terms "first," "second," etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0025] Bioelectric signals are generally weak, low-frequency signals and can include electrocardiogram (ECG), electroencephalogram (EEG), and myoelectric signals. For example, the amplitude of an ECG signal is approximately 0.1mV to 5mV, and the frequency range is approximately 0.05Hz to 100Hz. ECG signals are high-impedance, low-frequency, and weak signals.

[0026] Traditional bioelectric signal acquisition devices generally use electrodes in contact with the skin to obtain corresponding electrical signals. For example, ECG signal acquisition devices usually use wet electrodes in contact with the skin to obtain ECG signals. The impedance of the wet electrodes in contact with the skin is relatively small, and the front-end input impedance of the ECG signal acquisition device is generally required to be greater than 10M to meet this requirement. With the development of wearable devices, wet electrodes cannot be used for a long time and are disposable consumables. At the same time, their size and other factors cannot meet the use and appearance requirements of wearable devices. Therefore, wearable devices, especially smart bracelets and smart watches, all use contact dry electrodes to collect ECG signals. The impedance of the dry electrodes in contact with the skin can reach several megohms or even hundreds of megohms. The impedance change is more likely to affect the signal-to-noise ratio of the signal acquisition system, so the front-end input impedance of the ECG signal acquisition device is required to be larger.

[0027] To increase input impedance, a buffer circuit is typically added after the ECG electrodes to achieve this. However, in traditional buffer circuits, the increase in input impedance is limited due to the input capacitance of the operational amplifier within the buffer circuit, thus affecting ECG signal acquisition.

[0028] In order to solve the above problems, embodiments of the present application provide a buffer circuit, a signal acquisition device, and an electronic device.

[0029] Figure 1 FIG. 1 is a block diagram of a buffer circuit in one embodiment. Figure 1 As shown, the buffer circuit 100 includes a first power supply module 101 , an operational amplifier module 102 and a second power supply module 103 .

[0030] In this embodiment, the first power supply module 101 is used to provide a first power supply.

[0031] The first power supply module 101 is connected to the first power supply terminal of the operational amplifier module 102, the second input terminal of the operational amplifier module 102, and the output terminal of the operational amplifier module 102, respectively. The first power supply is input to the first power supply terminal of the operational amplifier module 102 to start the operation of the operational amplifier module 102, so that the operational amplifier module 102 outputs a first voltage based on the first power supply and the bioelectric signal. Optionally, the first power supply module 101 can be a DC current source, so that the first power supply is a DC power supply. When the DC power supply supplies power to the first power supply terminal of the operational amplifier module 102, it will not affect the first AC component of the first voltage output by the operational amplifier module 102. At the same time, in other embodiments, for example, when the buffer circuit 100 is specifically applied to a signal acquisition device, a resistor-capacitor coupling circuit can be provided between the buffer circuit 100 and the subsequent circuit to isolate the DC component brought by the DC power supply, thereby preventing the DC component from interfering with the subsequent circuit.

[0032] In this embodiment, the first input end of the operational amplifier module 102 is used to receive the bioelectric signal, and the output end of the operational amplifier module 102 is respectively connected to the second input end of the operational amplifier module 102, the first power supply end of the operational amplifier module 102 and the output end of the first power supply module 101. The operational amplifier module 102 is used to output a first voltage according to the bioelectric signal and the first power supply, and the difference between the first AC component of the first voltage and the voltage value of the bioelectric signal is within a first preset range; the input end of the second power supply module 103 is connected to the output end of the operational amplifier module 102, and the output end of the second power supply module 103 is connected to the second power supply end of the operational amplifier module 102. The second power supply module 103 is used to provide a second power supply, and is also used to output a second voltage to the operational amplifier module 102 according to the first AC component, and the difference between the second AC component of the second voltage and the voltage value of the bioelectric signal is within a second preset range.

[0033] It can be understood that the first preset range and the second preset range can be ranges close to zero or equal to zero.

[0034] The second power supply may be a DC power supply. When the DC power supply supplies power to the second power supply terminal of the operational amplifier module 102, the first AC component of the first voltage and the second AC component of the second voltage are not affected. Furthermore, in other embodiments, for example, when the buffer circuit 100 is applied to a signal acquisition device, a resistor-capacitor coupling circuit may be provided between the buffer circuit 100 and subsequent circuits to isolate the DC component from the DC power supply, thereby preventing the DC component from interfering with the subsequent circuits.

[0035] Among them, the first input end of the operational amplifier module 102 is used to receive the bioelectric signal, and the second input end of the operational amplifier module 102 is connected to the output end of the operational amplifier module 102, so that the operational amplifier module 102 constitutes a follower module, and the buffer circuit 100 constitutes a voltage follower circuit. The buffer circuit 100 can output the weak bioelectric signal of the input bioelectric signal to the subsequent circuit through the output end of the operational amplifier module 102 to drive the subsequent circuit in the signal acquisition device, play a buffering role for the previous and subsequent circuits, and have an isolation effect on the previous and next circuits, reducing the impact between the previous and next circuits.

[0036] The first power supply terminal of the operational amplifier module 102 is a positive power supply terminal, and the second power supply terminal of the operational amplifier module 102 is a negative power supply terminal. The output terminal of the operational amplifier module 102 is respectively connected to the second input terminal of the operational amplifier module 102, the first power supply terminal of the operational amplifier module 102, the output terminal of the first power supply module 101, and the input terminal of the second power supply terminal. The second power supply terminal of the operational amplifier module 102 is connected to the output terminal of the second power supply terminal, so that the first power supply module 101 and the second power supply module 103 form a power bootstrap mode to supply power to the operational amplifier module 102, and the power signal of the first power supply terminal of the operational amplifier module 102 is equal to the output signal of the output terminal of the operational amplifier module 102.

[0037] Among them, the first input end of the operational amplifier module 102 is used to receive the bioelectric signal, and the output end of the operational amplifier module 102 outputs a first voltage according to the bioelectric signal and the first power supply, and the first voltage includes a first AC component, so that the first power supply end of the operational amplifier module 102 correspondingly inputs the first voltage, and the difference between the voltage value of the first AC component and the bioelectric signal is within a first preset range; because the second power supply module 103 outputs a second voltage to the second power supply end of the operational amplifier module 102 according to the first AC component, the second voltage includes a second AC component, so that the second power supply end of the operational amplifier module 102 correspondingly inputs the second voltage, and the difference between the voltage value of the second AC component and the bioelectric signal is within a second preset range.

[0038] The first AC component of the first power supply terminal and the second AC component of the second power supply terminal each affect the input capacitance within the operational amplifier module 102. In the buffer circuit 100 powered by the power supply bootstrap, as the first preset range and the second preset range approach zero, the first AC signal and the second AC signal on the two power rails of the operational amplifier module 102 become closer to the input bioelectric signal, thereby reducing the input capacitance within the operational amplifier module 102 and increasing the input impedance of the operational amplifier module 102. This further improves the input impedance of the buffer circuit 100, allowing the buffer circuit 100 to better suppress the effects of common-mode noise and the effects of baseline offset caused by the impedance transformation between the skin and the acquisition module, thereby more effectively driving the subsequent circuits and improving the anti-interference capability and reliability of signal acquisition.

[0039] The adjustment of the first preset range and the second preset range can be achieved by adjusting the internal parameters of the first power supply module 101 and the second power supply module 103. In some embodiments, the first preset range and the second preset range are respectively zero, that is, the difference between the voltage value of the first AC component and the bioelectric signal is zero, and the difference between the voltage value of the second AC component and the bioelectric signal is zero. As a result, the first AC signal and the second AC signal on the two power rails of the operational amplifier module 102 are respectively equal to the input bioelectric signal, thereby improving the input AC impedance.

[0040] It should be noted that, in some embodiments, the first voltage and the second voltage may further include a DC component, but the DC component has no effect on the input capacitance inside the operational amplifier module 102 , and thus the DC component may be ignored.

[0041] The buffer circuit 100 provided in this embodiment includes a first power supply module 101, an operational amplifier module 102, and a second power supply module 103. The first power supply module 101 provides a first power supply; the first input terminal of the operational amplifier module 102 is used to receive a bioelectric signal, and the output terminal of the operational amplifier module 102 is respectively connected to the second input terminal of the operational amplifier module 102, the first power supply terminal of the operational amplifier module 102, and the output terminal of the first power supply module 101. The operational amplifier module 102 is used to output a first voltage based on the bioelectric signal and the first power supply, and the difference between the first AC component of the first voltage and the voltage value of the bioelectric signal is within a first preset range; the input terminal of the second power supply module 103 is connected to the output terminal of the operational amplifier module 102, and the output terminal of the second power supply module 103 is connected to the second power supply terminal of the operational amplifier module 102. The second power supply module 103 is used to provide a second power supply and is also used to output a second voltage to the operational amplifier module 102 based on the first AC component, and the difference between the second AC component of the second voltage and the voltage value of the bioelectric signal is within a second preset range. Thus, the first power supply module 101, the operational amplifier module 102 and the second power supply module 103 constitute a buffer circuit 100 with bootstrap power supply. When the first AC signal and the second AC signal on the two power rails of the operational amplifier module 102 are closer to the input bioelectric signal, the input capacitance inside the operational amplifier module 102 is smaller, and thus the input impedance of the operational amplifier module 102 is larger. Therefore, the input impedance of the buffer circuit 100 can be improved by adjusting the first preset range and the second preset range, and the interference effects such as common-mode to differential-mode signal interference and base drift caused by impedance changes can be effectively suppressed, thereby improving the anti-interference ability, signal-to-noise ratio and stability of the buffer circuit 100, more effectively driving the subsequent circuit, and improving the reliability of signal acquisition.

[0042] In some embodiments, as Figure 2 As shown, the second power supply module 103 includes a first operational amplifier unit 201 and a second operational amplifier unit 202. The input end of the first operational amplifier unit 201 serves as the input end of the second power supply module 103. The first operational amplifier unit 201 is configured to output a third voltage from the output end of the first operational amplifier unit 201 based on the first AC component. The input end of the second operational amplifier unit 202 is connected to the output end of the first operational amplifier unit 201. The output end of the second operational amplifier unit 202 serves as the output end of the second power supply module 103. The second operational amplifier unit 202 is configured to output a second voltage based on the third voltage. Thus, the first operational amplifier unit 201 and the second operational amplifier unit 202 constitute the second power supply module 103 to provide a second power supply to the second power supply end of the operational amplifier module 102 and input a second AC component to the second power supply end of the operational amplifier module 102.

[0043] In some embodiments, as Figure 3 As shown, the first operational amplifier unit 201 includes: a first operational amplifier A1 and a voltage divider component 301, wherein the non-inverting input terminal of the first operational amplifier A1 is the input terminal of the first operational amplifier unit 201, the inverting input terminal of the first operational amplifier A1, the output terminal of the first operational amplifier A1 and the first terminal of the voltage divider component 301 are connected in common, and the second terminal of the voltage divider component 301 is the output terminal of the first operational amplifier unit 201.

[0044] The inverting input terminal of the first operational amplifier A1 is connected to the output terminal of the first operational amplifier A1, and the first operational amplifier A1 constitutes a voltage follower amplifier. The voltage follower has an extremely high input impedance, which can reduce the impact on the signal source, thereby ensuring that the first voltage is input to the first operational amplifier A1 while reducing the impact on the first voltage. The voltage output from the output terminal of the first operational amplifier A1 is equal to the voltage input to the non-inverting input terminal of the first operational amplifier A1, so that the first terminal voltage of the voltage divider component 301 is the first AC component. The first AC component is divided by the voltage divider component 301 so that the first operational amplifier unit 201 obtains the target third voltage. Optionally, as Figure 3 As shown, the voltage divider component 301 includes: a first resistor R1, a second resistor R2 and a first capacitor C1, wherein the first end of the first resistor R1 serves as the first end of the voltage divider component 301, the second end of the first resistor R1, the first end of the second resistor R2, and the first end of the first capacitor C1 are commonly connected as the second end of the voltage divider component 301 to output a third voltage, and the second end of the second resistor R2 and the second end of the first capacitor C1 are commonly connected to ground.

[0045] In some embodiments, as Figure 3 As shown, the second operational amplifier unit 202 includes: a second operational amplifier A2, a third resistor R3 and a fourth resistor R4, wherein the non-inverting input terminal of the second operational amplifier A2 is the input terminal of the second operational amplifier unit 202, the inverting input terminal of the second operational amplifier A2, the first terminal of the third resistor R3, and the first terminal of the fourth resistor R4 are connected in common, the output terminal of the second operational amplifier A2 and the second terminal of the third resistor R3 are connected in common as the output terminal of the second operational amplifier unit 202, and the second terminal of the fourth resistor R4 is used to receive the reference voltage Vref. The reference voltage Vref is a DC reference voltage, and the DC reference voltage will not affect the AC signal in the second power supply module 103. In some embodiments, as Figure 3As shown, the first power supply includes an operating current, and the first power supply module 101 includes a current source Iso. The input end of the current source Iso is connected to the power supply voltage Vcc, and the output end of the current source Iso is the output end of the first power supply module 101. The current source Iso is used to provide the operating current Iin. Optionally, the current source Iso is an adjustable current source, such as an LM234 adjustable current source.

[0046] In some embodiments, as Figure 3 As shown, the operational amplifier module 102 includes: a third operational amplifier A3, a non-inverting input terminal of the third operational amplifier A3 is the first input terminal of the operational amplifier module 102, an inverting input terminal of the third operational amplifier A3 is the second input terminal of the operational amplifier module 102, a positive power supply terminal of the third operational amplifier A3 is the first power supply terminal of the operational amplifier module 102, a negative power supply terminal of the third operational amplifier A3 is the second power supply terminal of the operational amplifier module 102, and an output terminal of the third operational amplifier A3 is the output terminal of the operational amplifier module 102.

[0047] The non-inverting input of the third operational amplifier A3 receives the bioelectric signal Vi, and the inverting input of the third operational amplifier A3 is connected to the output. Thus, the third operational amplifier A3 forms a voltage follower, which can output the weak bioelectric signal Vi to the subsequent circuit through the output of the operational amplifier module 102 to drive the subsequent circuit in the signal acquisition device, acting as a buffer between the previous and subsequent circuits, and has an isolation effect on the previous and subsequent circuits, reducing the impact between the previous and subsequent circuits. The third operational amplifier A3 has the characteristics of high input impedance and low output impedance.

[0048] The bioelectric signal Vi is introduced into the non-inverting input terminal of the third operational amplifier A3. The positive power supply terminal V+ and the negative power supply terminal V- of the third operational amplifier A3 provide power to the third operational amplifier A3. The output terminal of the third operational amplifier A3 is respectively connected to the inverting input terminal, the positive power supply terminal, the output terminal of the current source Iso, and the input terminal of the second power supply terminal. The negative power supply terminal of the third operational amplifier A3 is connected to the output terminal of the second power supply terminal. Thus, the current source Iso and the second power supply module 103 form a power supply bootstrap method to power the third operational amplifier A3.

[0049] like Figure 4 The figure shows a circuit model of the input impedance of the third operational amplifier A3 in one embodiment. The input impedance affects both the positive power supply terminal V+ and the negative power supply terminal V- of the third operational amplifier A3. Due to the presence of the internal input capacitance of the third operational amplifier A3, the input impedance decreases when the signal frequency is high. Alternatively, when the input capacitance is relatively large, the input impedance also decreases at the same frequency. Vi is the bioelectric signal input to the first input terminal of the third operational amplifier A3, Ii is the working power output by the current source Iso, and Zi is the input impedance. According to (1) and (2), we can obtain

[0050] When the first AC component of the first voltage V+ and the second AC component of the second voltage V- on the two power rails of the third operational amplifier A3 respectively approach the potential of the bioelectric signal Vi, the input impedance Zi of the third operational amplifier A3 will tend to infinity. Therefore, when the first AC component and the second AC component respectively approach the potential of the bioelectric signal Vi, the input AC impedance of the buffer circuit 100 increases.

[0051] Among them, the first AC component R is the output impedance of the third operational amplifier A3 and is generally small. Ao is the open-loop gain of the third operational amplifier A3 and is a large value. Therefore, V+=Vo≈Vi.

[0052] The first operational amplifier unit 201 composed of the first operational amplifier A1, the first resistor R1, the second resistor R2 and the first capacitor C1 can realize the voltage division processing of the first AC component to obtain the third voltage The second operational amplifier unit 202 composed of the second operational amplifier A2, the third resistor R3 and the fourth resistor R4 can obtain the second voltage Vo1 and the reference voltage Vref. in, is the second AC component of the second voltage, is the DC component, and by adjusting the parameters of the resistors and capacitors, Approaching 1, the second AC component approaches Vo. Actually, at low frequencies, the value close to 1 can be achieved by setting the parameters of the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4. The function of the first capacitor C1 is to stabilize the bootstrap circuit at high frequencies, thereby achieving V-≈Vi.

[0053] Thus, by using the bootstrap power supply of the third operational amplifier A3, the AC signal on the power supply rail of the third operational amplifier A3 is brought close to the input signal, thereby reducing the influence of the input capacitance. The input capacitance of the buffer circuit is reduced from the pF level to the femtofarad level, thereby reducing the influence of the input capacitance and improving the input impedance. This effectively suppresses interference such as common-mode to differential-mode signal interference and base drift caused by impedance changes, thereby improving the anti-interference capability, signal-to-noise ratio, and stability of the buffer circuit 100, more effectively driving the subsequent circuit, and improving the reliability of signal acquisition.

[0054] Optionally, the first operational amplifier A1 and the second operational amplifier A2 can be op amps with high cost performance and good performance; the third operational amplifier A3 can be an operational amplifier with rail-to-rail output, large open-loop gain, high power supply rejection ratio, low noise, and a small package. The parameters of the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 can be adjusted according to actual needs. For example, the first resistor R1 can be 1.5K-2.5K ohms, the second resistor R2 can be 1K-2K ohms, the third resistor R3 can be 3K-4K ohms, and the fourth resistor R4 can be 4.5K-5.5K ohms. Furthermore, for example, the first resistor R1 = 2K ohms, the second resistor R2 = 1.5K ohms, the third resistor R3 = 3.6K ohms, and the fourth resistor R4 = 5.1K ohms.

[0055] Figure 5 FIG. 1 is a structural block diagram of a signal acquisition device in one embodiment. Figure 5 As shown, the signal acquisition device 10 includes the buffer circuit 100 and the acquisition module 200 as described in the above embodiment.

[0056] The buffer circuit 100 is connected to the acquisition module 200 and is used to input bioelectric signals and output the bioelectric signals to the subsequent circuit through the output terminal of the operational amplifier module, thereby increasing the input impedance and ensuring that the output impedance is sufficiently small to effectively drive the subsequent circuit in the signal acquisition device. The detailed description of the buffer circuit 100 is based on the relevant description of the above embodiment and is not repeated here.

[0057] The acquisition module 200 is connected to the first input terminal of the operational amplifier module, and is used to acquire the ECG signal and output the ECG signal to the operational amplifier module. Optionally, the acquisition module 200 includes an electrode, one end of which is used to contact the skin of the acquisition subject to acquire the bioelectrical signal, and one end of the electrode is connected to the first input terminal of the operational amplifier module to output the acquired bioelectrical signal to the buffer circuit 100. Tissues and body fluids in a living body can conduct electricity through ionic conduction. For example, when the bioelectrical signal is an ECG signal, the tissues and body fluids around the heart can conduct electricity. The sum of the changes in the action potentials of countless myocardial cells can be conducted and reflected to the body surface, thereby forming a potential difference or equipotential between many points on the body surface. By contacting the skin of the acquisition subject, the electrode can detect the bioelectrical signal in the human body that relies on ionic conduction, convert the ionic bioelectrical signal into a bioelectrical signal that relies on electronic conduction in the buffer circuit 100, and output the bioelectrical signal to the buffer circuit 100.

[0058] It should be noted that the signal acquisition device 10 can also be provided with other functional circuits according to actual needs to realize corresponding functions. For example, the signal acquisition device 10 can also include an amplification circuit, the input end of the amplification circuit is connected to the output end of the operational amplifier module in the buffer circuit 100, and is used to amplify the bioelectric signal output by the buffer circuit 100 to meet the application requirements of the biomedical field for low noise, ultra-low frequency, high impedance, high precision and low power consumption of physiological electrical signals.

[0059] In some embodiments, as Figure 6 As shown, the signal acquisition device 10 further includes a first circuit board 300 and a second circuit board 400. The acquisition module 200 and the operational amplifier module 102 are located on the first circuit board, and the first power supply module 101 and the second power supply module 103 are located on the second circuit board.

[0060] When traditional signal acquisition devices are used in wearable devices, the structures in wearable devices are usually stacked compactly and the electrodes are generally exposed. Usually, the circuit boards where the electrodes are located are separated from the circuit boards of the buffer circuits. Therefore, an adapter is required between the electrodes and the buffer circuits. Therefore, the corresponding buffer circuit requires at least three signal lines (the V+ signal line that provides positive power to the operational amplifier, the V- signal line that provides negative power to the operational amplifier, and the output signal line of the operational amplifier). However, the number of pins of connectors that generally implement the adapter is often very limited. If a connector with a large number of pins is selected, the structure stacking space is often affected.

[0061] In this embodiment, the acquisition module 200 and the operational amplifier module 102 can be arranged on the first circuit board to place the buffer circuit 100 closer to the electrode. At the same time, the first power supply module 101 and the second power supply module 103 are located on the second circuit board. Therefore, only two signal traces are required, namely the V- signal line 1 that provides a negative power supply to the operational amplifier module 102 and the output signal line 2 of the operational amplifier, to achieve the connection of the buffer circuit 100. Therefore, the PCB layout is optimized, and better stacking is provided for the wearable acquisition device, while ensuring the performance of the signal acquisition device.

[0062] The signal acquisition device 10 provided in this embodiment includes a buffer circuit 100 and an acquisition device 200. Since the buffer circuit 100 has a high input impedance, it can effectively suppress interference effects such as common-mode to differential-mode signal interference and base drift caused by impedance changes. Therefore, the signal acquisition device 10 has high anti-interference capability, signal-to-noise ratio, stability, and reliability.

[0063] This embodiment also provides an electronic device including the signal acquisition device described in the above embodiment. In one embodiment, the electronic device can include a wearable device (such as a smart watch, smart bracelet, pedometer, etc.), a mobile phone, a tablet computer, a laptop computer, a PDA, a mobile internet device (MID), or other bioelectric signal detection device that can be equipped with a signal acquisition device.

[0064] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0065] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A buffer circuit, characterized in that: include: A first power supply module, configured to provide a first power supply; an operational amplifier module, wherein a first input terminal of the operational amplifier module is used to receive a bioelectric signal, an output terminal of the operational amplifier module is respectively connected to a second input terminal of the operational amplifier module, a positive power terminal of the operational amplifier module, and an output terminal of the first power supply module, the operational amplifier module is used to output a first voltage based on the bioelectric signal and the power supply, and a difference between a first AC component of the first voltage and a voltage value of the bioelectric signal is within a first preset range; A second power supply module, the input end of the second power supply module is connected to the output end of the operational amplifier module, the output end of the second power supply module is connected to the negative power supply end of the operational amplifier module, the second power supply module is used to provide a second power supply, and is also used to output a second voltage to the operational amplifier module according to the first AC component, and the difference between the second AC component of the second voltage and the voltage value of the bioelectric signal is within a second preset range.

2. The buffer circuit according to claim 1, wherein: The second power supply module includes: a first operational amplifier unit, wherein the input end of the first operational amplifier unit is the input end of the second power supply module, and the first operational amplifier unit is configured to output a third voltage from the output end of the first operational amplifier unit according to the first AC component; A second operational amplifier unit, wherein the input end of the second operational amplifier unit is connected to the output end of the first operational amplifier unit, the output end of the second operational amplifier unit is the output end of the second power supply module, and the second operational amplifier unit is used to output the second voltage according to the third voltage.

3. The buffer circuit according to claim 2, wherein: The first operational amplifier unit includes: A first operational amplifier and a voltage divider component, wherein the non-inverting input terminal of the first operational amplifier is the input terminal of the first operational amplifier unit, the inverting input terminal of the first operational amplifier, the output terminal of the first operational amplifier and the first terminal of the voltage divider component are connected in common, and the second terminal of the voltage divider component is the output terminal of the first operational amplifier unit.

4. The buffer circuit according to claim 3, wherein: The voltage divider assembly includes: a first resistor, a second resistor, and a first capacitor, wherein the first end of the first resistor serves as the first end of the voltage divider component, the second end of the first resistor, the first end of the second resistor, and the first end of the first capacitor are connected together as the second end of the voltage divider component, and the second end of the second resistor and the second end of the first capacitor are connected together to ground.

5. The buffer circuit according to claim 2, wherein: The second operational amplifier unit includes: A second operational amplifier, a third resistor and a fourth resistor, wherein the non-inverting input terminal of the second operational amplifier is the input terminal of the second operational amplifier unit, the inverting input terminal of the second operational amplifier, the first terminal of the third resistor, and the first terminal of the fourth resistor are connected in common, the output terminal of the second operational amplifier and the second terminal of the third resistor are connected in common as the output terminal of the second operational amplifier unit, and the second terminal of the fourth resistor is used to receive a reference voltage.

6. The buffer circuit according to claim 1, wherein: The operational amplifier module includes: A third operational amplifier, wherein the non-inverting input terminal of the third operational amplifier is the first input terminal of the operational amplifier module, the inverting input terminal of the third operational amplifier is the second input terminal of the operational amplifier module, the positive power supply terminal of the third operational amplifier is the positive power supply terminal of the operational amplifier module, the negative power supply terminal of the third operational amplifier is the negative power supply terminal of the operational amplifier module, and the output terminal of the third operational amplifier is the output terminal of the operational amplifier module.

7. The buffer circuit according to claim 1, wherein: The power supply includes a working current, and the first power supply module includes: A current source, wherein the input end of the current source is used to access the power supply voltage, the output end of the current source is the output end of the first power supply module, and the current source is used to provide the working current.

8. A signal acquisition device, characterized in that: include: The buffer circuit according to any one of claims 1 to 7; as well as The acquisition module is connected to the first input terminal of the operational amplifier module, and is used to acquire bioelectric signals and output the bioelectric signals to the operational amplifier module.

9. The device according to claim 8, characterized in that Also included are a first circuit board and a second circuit board; The acquisition module and the operational amplifier module are located on the first circuit board, and the first power supply module and the second power supply module are located on the second circuit board.

10. The device according to claim 8, characterized in that The acquisition module includes: An electrode, one end of which is used to contact the skin of the subject being collected, and one end of which is connected to the first input end of the operational amplifier module.

11. An electronic device, characterized in that: include: The signal acquisition device according to any one of claims 8 to 10.

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