Electrocardiogram monitoring device

Abstract

The utility model discloses an electrocardiogram monitoring device, which belongs to the technical field of electrocardiogram monitoring and comprises a calibration voltage generating circuit, a plurality of analog switches, a pre-stage amplifying circuit, a post-stage amplifying circuit, a filter circuit and a controller. When the electrocardiogram monitoring device works in a calibration mode, a calibration signal is generated, the calibration signal is electrically connected with the pre-stage amplification circuit, the pre-stage amplification circuit is disconnected from the filter circuit, and an output signal of the post-stage amplification circuit is compared with the calibration signal to obtain an actual amplification factor; when the electrocardio monitoring device works in an electrocardio acquisition mode, the electrocardio input signal is electrically connected with the pre-stage amplification circuit, the pre-stage amplification circuit is electrically connected with the filter circuit, and an actually acquired electrocardio signal is obtained according to an output signal of the post-stage amplification circuit and an actual amplification factor. According to the scheme, the circuit is simple, the cost is low, and the electrocardiosignal acquisition error is effectively reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of electrocardiogram monitoring, in particular to an electrocardiogram monitoring device. Background Art

[0002] ECG monitoring products have a process of signal amplification from collecting ECG signals to outputting and displaying them. The amplification circuit is generally composed of an operational amplifier, a resistor, and a capacitor. Due to factors such as ambient temperature and usage time, the parameters of the electronic components of the amplification circuit will change, or the error in the resistance value of the resistor itself will cause the amplification factor to be different from the design value during use. If there is no calibration mechanism and the collected ECG waveform data is recorded or used directly according to the theoretical amplification factor, a large error will occur. Utility Model Content

[0003] In view of the above-mentioned problems in the background technology, the utility model provides an ECG monitoring device, which detects the actual amplification factor of the ECG monitoring device by calibrating the calibration signal generating circuit, and then processes the collected and amplified ECG signals in combination with the actual amplification factor to obtain accurate ECG signals.

[0004] The electrocardiogram monitoring device provided by the utility model comprises a calibration voltage generating circuit, a first analog switch, a second analog switch, a third analog switch, a front-stage amplifier circuit, a rear-stage amplifier circuit, a filter circuit, and a controller;

[0005] The first analog switch is a single-pole single-throw switch, the second analog switch is a double-pole double-throw switch, and the third analog switch is a single-pole double-throw switch;

[0006] The calibration voltage generating circuit is used to generate a calibration voltage signal, and the output end of the calibration voltage generating circuit is electrically connected to the fixed end of the first analog switch;

[0007] The control ends of the first analog switch, the second analog switch and the third analog switch are all electrically connected to the controller;

[0008] The active end of the first analog switch is electrically connected to the second fixed end of the second analog switch;

[0009] The first fixed end and the third fixed end of the second analog switch are electrically connected to the ECG input signal respectively; the first movable end and the second movable end of the second analog switch are electrically connected to the input end of the pre-amplifier circuit;

[0010] The active end of the third analog switch is electrically connected to the reference voltage end of the pre-amplifier circuit; the second fixed end of the third analog switch is grounded; the first fixed end of the third analog switch is electrically connected to the output end of the filter circuit;

[0011] The output end of the pre-stage amplifier circuit is electrically connected to the input end of the filter circuit and the input end of the post-stage amplifier circuit;

[0012] The output end of the post-stage amplifier circuit is electrically connected to the controller;

[0013] When the ECG monitoring device operates in the calibration mode, the controller:

[0014] Outputting a control level to the first analog switch to generate a calibration signal;

[0015] Outputting a control level to the second analog switch to connect the second fixed terminal of the second analog switch to the first active terminal, and the fourth fixed terminal to the second active terminal, so that the calibration signal is electrically connected to the pre-amplifier circuit;

[0016] Outputting a control level to the third analog switch to connect the active end of the third analog switch to the second fixed end, so as to disconnect the pre-amplifier circuit from the filter circuit;

[0017] When the ECG monitoring device operates in the ECG acquisition mode, the controller:

[0018] Outputting a control level to the first analog switch to disconnect the first analog switch from the calibration voltage generating circuit;

[0019] Outputting a control level to the second analog switch to connect the first fixed end and the third fixed end of the second analog switch to the first movable end and the second movable end respectively; so that the ECG input signal is electrically connected to the pre-amplifier circuit;

[0020] A control level is output to the third analog switch to connect the active end of the third analog switch to the first fixed end, so that the pre-amplifier circuit is electrically connected to the filter circuit.

[0021] Preferably, the calibration voltage generating circuit includes a current source and a fourth resistor; the first end of the fourth resistor is connected to a working power supply via the current source, and the first end of the fourth resistor is also connected to a fixed end of the first analog switch; the second end of the fourth resistor is grounded.

[0022] Preferably, the controller outputs a square wave signal to the control end of the first analog switch.

[0023] Preferably, the current source is a 100 μA current source, the resistance value of the fourth resistor is 10Ω, and the frequency of the square wave signal is 1 Hz.

[0024] Preferably, the first fixed end of the second analog switch is electrically connected to the electrocardiogram signal LA, the third fixed end of the second analog switch is electrically connected to the electrocardiogram signal RA, and the fourth fixed end of the second analog switch is grounded.

[0025] Preferably, the pre-stage amplifier circuit includes an instrument amplifier, a first resistor, and a second resistor. The same-direction input pin and the reverse input pin of the instrument amplifier are electrically connected to the first active end and the second active end of the second analog switch, respectively. The output pin of the instrument amplifier is electrically connected to the input end of the post-stage amplifier circuit. The feedback pin of the instrument amplifier is electrically connected to the output pin via the first resistor. The feedback pin of the instrument amplifier is also electrically connected to the active end of the third analog switch via the second resistor. The reference voltage pin of the instrument amplifier is electrically connected to the active end of the third analog switch.

[0026] Preferably, the filtering circuit includes a high-pass filter composed of a first operational amplifier, a third resistor, and a first capacitor; the same-direction input pin of the first operational amplifier is grounded, the reverse input pin is electrically connected to the input end of the post-stage amplifier circuit via the third resistor, and the inverting input pin is also electrically connected to the first fixed end of the third analog switch via the first capacitor; the output pin is electrically connected to the first fixed end of the third analog switch.

[0027] Preferably, the post-stage amplifier circuit includes a second operational amplifier, a fifth resistor, a sixth resistor, and a seventh resistor; the same-direction input pin of the second operational amplifier is connected to the output end of the pre-stage amplifier circuit via the fifth resistor, the reverse input pin is grounded via the seventh resistor, the reverse input pin is also electrically connected to the output pin via the sixth resistor, and the output pin is electrically connected to the controller; the resistance value of the fifth resistor is set to the parallel resistance value of the sixth resistor and the seventh resistor.

[0028] The utility model has the following beneficial effects: the electrocardiogram monitoring device provided by the utility model comprises a calibration and calibration voltage generating circuit, a first analog switch, a second analog switch, a third analog switch, a front-stage amplifier circuit, a rear-stage amplifier circuit, a filter circuit, and a controller; when the electrocardiogram monitoring device works in a calibration mode, the controller outputs a control level to the first analog switch to generate a calibration and calibration signal, outputs a control level to the second analog switch to electrically connect the calibration and calibration signal to the front-stage amplifier circuit, and outputs a control level to the third analog switch to disconnect the front-stage amplifier circuit from the filter circuit, and compares the output signal of the rear-stage amplifier circuit with the calibration and calibration signal to obtain an actual amplification factor; when the electrocardiogram monitoring device works in an electrocardiogram acquisition mode, the controller outputs a control level to the first analog switch to disconnect the first analog switch from the calibration and calibration voltage generating circuit, outputs a control level to the second analog switch to electrically connect the electrocardiogram input signal to the front-stage amplifier circuit, and outputs a control level to the third analog switch to electrically connect the front-stage amplifier circuit to the filter circuit, and obtains an actually acquired electrocardiogram signal according to the output signal of the rear-stage amplifier circuit and the actual amplification factor. This scheme detects the actual amplification factor of the ECG monitoring device through a stable calibration voltage signal. The circuit is simple and low-cost, and the acquisition error of the ECG signal is effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a circuit block diagram of an electrocardiogram monitoring device provided in an embodiment of the utility model.

[0030] Figure 2 This is a circuit diagram of an electrocardiogram monitoring device provided in a preferred embodiment of the utility model.

[0031] Figure 3 This is a circuit diagram of an electrocardiogram monitoring device provided in a preferred embodiment of the utility model.

[0032] Figure 4 This is a waveform diagram of the amplified calibration signal provided in the preferred embodiment of the utility model. DETAILED DESCRIPTION

[0033] In order to have a clearer understanding of the technical features, purposes and effects of the present utility model, the specific implementation methods of the present utility model are now described in detail with reference to the accompanying drawings.

[0034] like Figure 1-3 As shown, an embodiment of the utility model provides an electrocardiogram monitoring device, which includes a calibration voltage generating circuit, a first analog switch S1, a second analog switch S2, a third analog switch S3, a pre-stage amplifier circuit, a post-stage amplifier circuit, a filter circuit, and a controller.

[0035] The first analog switch S1 is a single-pole single-throw switch, the second analog switch S2 is a double-pole double-throw switch, and the third analog switch S3 is a single-pole double-throw switch.

[0036] The calibration voltage generating circuit is used to generate a calibration voltage signal, and the output end of the calibration voltage generating circuit is electrically connected to the fixed end of the first analog switch S1.

[0037] The control ends of the first analog switch S1 , the second analog switch S2 , and the third analog switch S3 are all electrically connected to the controller.

[0038] The ECG signals collected by the electrodes of the ECG monitoring device are very weak, and the voltage is usually several hundred microvolts to several millivolts. The amplification factor of the amplifier circuit of the ECG monitoring device needs to be set to a large value so that the controller such as the single-chip microcomputer can recognize the amplified ECG signal. A slight deviation in the resistance value in the amplifier circuit may cause a large change in the amplification factor. In order to know the amplification factor of the amplifier circuit in real time, a known standard signal is input at the input end of the amplifier circuit. As long as the signal voltage at the output end is measured, the accurate amplification factor of the amplifier circuit can be obtained. In order to make the final output signal unsaturated, the input standard signal voltage cannot be too large, and it is better to be close to the voltage amplitude of the ECG signal.

[0039] The present invention has no particular restrictions on the circuit structure of the calibration voltage generating circuit. Figure 2-3 As shown, in some embodiments of the utility model, the calibration voltage generating circuit is a 1mV voltage generating circuit, including a current source U4 and a fourth resistor R4; the first end of the fourth resistor R4 is connected to the working power supply through the current source U4, and the first end of the fourth resistor R4 is also electrically connected to the first end of the first analog switch S1; the second end of the fourth resistor R4 is grounded. The controller outputs a square wave signal to the control end of the first analog switch S1. The current source is a 100μA current source, the resistance value of the fourth resistor R4 is 10Ω, and the frequency of the square wave signal is 1Hz. The 1mV voltage generating circuit outputs a DC voltage of 1mV. When the controller controls the first analog switch S1 to switch at a frequency of 1Hz, a square wave of 1mV / 1Hz is obtained, that is, a calibration signal.

[0040] The active end of the first analog switch is electrically connected to the second fixed end of the second analog switch.

[0041] The first fixed end and the third fixed end of the second analog switch are electrically connected to the ECG input signal respectively; the first movable end and the second movable end of the second analog switch are electrically connected to the input end of the pre-amplifier circuit.

[0042] The active end of the third analog switch is electrically connected to the reference voltage end of the pre-amplifier circuit; the second fixed end of the third analog switch is grounded; and the first fixed end of the third analog switch is electrically connected to the output end of the filter circuit.

[0043] The output end of the pre-stage amplifier circuit is electrically connected to the input end of the filter circuit and the input end of the post-stage amplifier circuit.

[0044] The output end of the post-stage amplifier circuit is electrically connected to the controller.

[0045] The front-stage amplifier circuit preliminarily amplifies the ECG signals LA and RA, and the rear-stage amplifier circuit further amplifies the output signal of the front-stage amplifier circuit. The overall amplification factor is the product of the amplification factors of the two-stage amplifier circuits.

[0046] In the embodiment of the utility model, the first analog switch S1 is a single-pole single-throw switch. When the controller gives a high level, the first analog switch S1 is closed. The second analog switch S3 is a single-pole double-throw switch. When it is normally closed, the filter circuit is connected to the signal path.

[0047] The working principle of the ECG monitoring device is as follows:

[0048] When the ECG monitoring device operates in the calibration mode, the controller:

[0049] (1) outputting a control level to the first analog switch to generate a calibration signal;

[0050] (2) outputting a control level to the second analog switch to connect the second fixed terminal of the second analog switch to the first active terminal, and connect the fourth fixed terminal to the second active terminal, so that the calibration signal is electrically connected to the pre-amplifier circuit;

[0051] (3) Outputting a control level to the third analog switch to connect the active end of the third analog switch to the second fixed end, so as to disconnect the pre-amplifier circuit from the filter circuit.

[0052] Figure 2-Figure 3 In the embodiment shown, when calibration is required, the second analog switch S2 is connected to the calibration signal, and the 1mV / 1Hz square wave is connected to the amplifier circuit. The third analog switch S3 disconnects the filter circuit, and the calibration signal can directly pass through the two-stage amplifier circuit, and finally the amplified 1Hz square wave is output to the A / D sampling circuit of the controller. The amplitude of the output signal = the amplitude of the calibration signal × the amplification factor; after the controller performs A / D conversion on the output signal, the amplification factor can be obtained. Disconnecting the high-pass filter is to prevent the square wave from being distorted and affecting the accuracy of A / D sampling.

[0053] like Figure 4The waveform of the calibration signal collected by the embodiment of the utility model after amplification is shown. The amplification factor of the front-stage amplifier circuit is 10.09, the amplification factor of the rear-stage amplifier circuit is 52, and the overall amplification factor is 524.68. The voltage of the calibration signal of the embodiment of the utility model is 1mV, and the voltage value after amplification is 524.68mV in theory. Figure 4 The amplified voltage value measured in the embodiment of the utility model is 525mV. It can be seen that the accuracy of the amplification factor measured by the embodiment of the utility model is very high. Therefore, after the collected ECG signal is processed using the calibrated amplification factor, the collection error of the ECG signal can be significantly reduced.

[0054] When the ECG monitoring device operates in the ECG acquisition mode, the controller:

[0055] (1) outputting a control level to the first analog switch so that the first analog switch is disconnected from the calibration voltage generating circuit;

[0056] (2) outputting a control level to the second analog switch to connect the first fixed terminal and the third fixed terminal of the second analog switch to the first movable terminal and the second movable terminal respectively; so that the ECG input signal is electrically connected to the pre-amplifier circuit;

[0057] (3) Outputting a control level to the third analog switch to connect the active end of the third analog switch to the first fixed end, so that the pre-amplifier circuit is electrically connected to the filter circuit.

[0058] Figure 2-Figure 3 In the illustrated embodiment, the second analog switch S2 switches to the ECG signal for ECG waveform acquisition, and the third analog switch S3 adds a filter circuit to the signal path. The controller acquires the amplified ECG signal and divides it by the amplification factor obtained in the calibration mode to obtain the original ECG signal amplitude.

[0059] In the embodiment of the utility model, the first fixed end of the second analog switch S2 is electrically connected to the ECG signal LA, the third fixed end of the second analog switch S2 is electrically connected to the ECG signal RA, and the fourth fixed end of the second analog switch S2 is grounded. The second analog switch S2 includes two active ends, the first active end is conductively connected to the first fixed end or the second fixed end, and the second active end is conductively connected to the third fixed end or the fourth fixed end.

[0060] In the embodiment of the utility model, the pre-amplification circuit includes an instrumentation amplifier U1, a first resistor R1, and a second resistor R2. The same-direction input pin and the reverse input pin of the instrumentation amplifier U1 are electrically connected to the first active end and the second active end of the second analog switch, respectively. The output pin of the instrumentation amplifier U1 is electrically connected to the input end of the post-amplification circuit. The feedback pin of the instrumentation amplifier U1 is electrically connected to the output pin via the first resistor R1. The feedback pin of the instrumentation amplifier U1 is also electrically connected to the active end of the third analog switch S3 via the second resistor R2. The reference voltage pin of the instrumentation amplifier U1 is electrically connected to the active end of the third analog switch S3. The resistance values ​​of the first resistor R1 and the second resistor R2 determine the amplification factor of the instrumentation amplifier U1.

[0061] The instrumentation amplifier U1 cooperates with the first resistor R1 and the second resistor R2 to preliminarily amplify the ECG signal. The amplification factor of the instrumentation amplifier is determined by the voltage of the input signal, the characteristics of the instrumentation amplifier chip, the working power supply voltage, and the amplification factor of the subsequent amplifier circuit. In practical applications, the amplification factor can be determined in conjunction with the operational amplifier in the subsequent amplifier circuit.

[0062] In an embodiment of the utility model, the filtering circuit includes a high-pass filter composed of a first operational amplifier U2, a third resistor R3, and a first capacitor C1; the same-direction input pin of the first operational amplifier U2 is grounded, the reverse input pin is electrically connected to the input end of the post-stage amplifier circuit via the third resistor R3, and the inverting input pin is also electrically connected to the first fixed end of the third analog switch S3 via the first capacitor C1; the output pin is electrically connected to the first fixed end of the third analog switch S3.

[0063] The function of the high-pass filter is to filter out signals below the cutoff frequency. In the ECG acquisition circuit, the cutoff frequency is set relatively low. The function of the high-pass filter is to filter out DC signals and pass AC signals.

[0064] In the embodiment of the utility model, the post-stage amplifier circuit includes a second operational amplifier U3, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7; the same-direction input pin of the second operational amplifier U3 is connected to the output end of the pre-stage amplifier circuit via the fifth resistor R5, the reverse input pin is grounded via the seventh resistor R7, the reverse input pin is also electrically connected to the output pin via the sixth resistor R6, and the output pin is electrically connected to the controller; the resistance value of the fifth resistor R5 is set to the parallel resistance value of the sixth resistor R6 and the seventh resistor R7. Among them, the resistance values ​​of the sixth resistor R6 and the seventh resistor R7 determine the amplification factor of the second operational amplifier U3.

[0065] Operational amplifier U3, resistor R5, resistor R6 and resistor R7 form an amplifier circuit to amplify the initially amplified ECG signal again. The input ECG signal is amplified twice by instrument amplifier U1 and operational amplifier U3, and the total amplification factor is the product of the two amplification factors, which is determined by the voltage of the input ECG signal and the power supply voltage. In practical applications, after determining the total amplification factor, the characteristics of the selected instrument amplifier U1 and operational amplifier U3 chips are combined to determine the amplification factor of each stage and design the resistance value.

[0066] The utility model has the following beneficial effects: the electrocardiogram monitoring device provided by the utility model comprises a calibration and calibration voltage generating circuit, a first analog switch, a second analog switch, a third analog switch, a front-stage amplifier circuit, a rear-stage amplifier circuit, a filter circuit, and a controller; when the electrocardiogram monitoring device works in a calibration mode, the controller outputs a control level to the first analog switch to generate a calibration and calibration signal, outputs a control level to the second analog switch to electrically connect the calibration and calibration signal to the front-stage amplifier circuit, and outputs a control level to the third analog switch to disconnect the front-stage amplifier circuit from the filter circuit, and compares the output signal of the rear-stage amplifier circuit with the calibration and calibration signal to obtain an actual amplification factor; when the electrocardiogram monitoring device works in an electrocardiogram acquisition mode, the controller outputs a control level to the first analog switch to disconnect the first analog switch from the calibration and calibration voltage generating circuit, outputs a control level to the second analog switch to electrically connect the electrocardiogram input signal to the front-stage amplifier circuit, and outputs a control level to the third analog switch to electrically connect the front-stage amplifier circuit to the filter circuit, and obtains an actually acquired electrocardiogram signal according to the output signal of the rear-stage amplifier circuit and the actual amplification factor. This scheme detects the actual amplification factor of the ECG monitoring device through a stable calibration voltage signal. The circuit is simple and low-cost, and the acquisition error of the ECG signal is effectively reduced.

[0067] The embodiments of the utility model are described above in conjunction with the accompanying drawings, but the utility model is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the utility model, ordinary technicians in this field can also make many forms of deformation without departing from the scope of protection of the utility model and the claims, which all fall within the protection of the utility model.

Claims

1. An electrocardiogram monitoring device, characterized in that: The device comprises a calibration voltage generating circuit, a first analog switch (S1), a second analog switch (S2), a third analog switch (S3), a front-stage amplifier circuit, a rear-stage amplifier circuit, a filter circuit, and a controller; The first analog switch (S1) is a single-pole single-throw switch, the second analog switch (S2) is a double-pole double-throw switch, and the third analog switch is a single-pole double-throw switch; The calibration voltage generating circuit is used to generate a calibration voltage signal, and the output end of the calibration voltage generating circuit is electrically connected to the fixed end of the first analog switch (S1); The control ends of the first analog switch (S1), the second analog switch (S2), and the third analog switch (S3) are all electrically connected to the controller; The active end of the first analog switch (S1) is electrically connected to the second fixed end of the second analog switch (S2); The first fixed end and the third fixed end of the second analog switch (S2) are electrically connected to the ECG input signal respectively; the first movable end and the second movable end of the second analog switch (S2) are electrically connected to the input end of the pre-amplifier circuit; The active end of the third analog switch (S3) is electrically connected to the reference voltage end of the pre-amplifier circuit; the second fixed end of the third analog switch (S3) is grounded; the first fixed end of the third analog switch (S3) is electrically connected to the output end of the filter circuit; The output end of the pre-stage amplifier circuit is electrically connected to the input end of the filter circuit and the input end of the post-stage amplifier circuit; The output end of the post-stage amplifier circuit is electrically connected to the controller; When the ECG monitoring device operates in the calibration mode, the controller: Outputting a control level to the first analog switch (S1) to generate a calibration signal; Outputting a control level to the second analog switch (S2) to connect the second fixed end of the second analog switch (S2) to the first active end, and the fourth fixed end to the second active end, so that the calibration signal is electrically connected to the pre-amplifier circuit; Outputting a control level to the third analog switch (S3) to connect the active end of the third analog switch (S3) to the second fixed end, so as to disconnect the pre-amplifier circuit from the filter circuit; When the ECG monitoring device operates in the ECG acquisition mode, the controller: Outputting a control level to the first analog switch (S1) so that the first analog switch (S1) is disconnected from the calibration voltage generating circuit; Outputting a control level to the second analog switch (S2) to connect the first fixed end and the third fixed end of the second analog switch (S2) to the first movable end and the second movable end respectively; so that the ECG input signal is electrically connected to the pre-amplifier circuit; A control level is output to the third analog switch (S3) to connect the active end of the third analog switch (S3) to the first fixed end, so that the pre-amplifier circuit is electrically connected to the filter circuit.

2. The electrocardiogram monitoring device according to claim 1, characterized in that: The calibration voltage generating circuit comprises a current source (U4) and a fourth resistor (R4); the first end of the fourth resistor (R4) is connected to a working power supply via the current source (U4), and the first end of the fourth resistor (R4) is also connected to a fixed end of the first analog switch (S1); and the second end of the fourth resistor (R4) is grounded.

3. The electrocardiogram monitoring device according to claim 2, characterized in that: The controller outputs a square wave signal to a control end of the first analog switch (S1).

4. The electrocardiogram monitoring device according to claim 3, characterized in that: The current source is a 100 μA current source, the resistance value of the fourth resistor ( R4 ) is 10Ω, and the frequency of the square wave signal is 1 Hz.

5. The electrocardiogram monitoring device according to claim 1, characterized in that: The first fixed end of the second analog switch (S2) is electrically connected to the electrocardiogram signal LA, the third fixed end of the second analog switch (S2) is electrically connected to the electrocardiogram signal RA, and the fourth fixed end of the second analog switch (S2) is grounded.

6. The electrocardiogram monitoring device according to claim 1, characterized in that: The front-stage amplifier circuit comprises an instrument amplifier (U1), a first resistor (R1), and a second resistor (R2); a non-inverting input pin and a reverse input pin of the instrument amplifier (U1) are respectively electrically connected to a first active end and a second active end of the second analog switch (S2); an output pin of the instrument amplifier (U1) is electrically connected to an input end of a rear-stage amplifier circuit; a feedback pin of the instrument amplifier (U1) is electrically connected to the output pin via the first resistor (R1); the feedback pin of the instrument amplifier (U1) is also electrically connected to an active end of the third analog switch (S3) via the second resistor (R2); and a reference voltage pin of the instrument amplifier (U1) is electrically connected to an active end of the third analog switch (S3).

7. The electrocardiogram monitoring device according to claim 1, characterized in that: The filter circuit comprises a high-pass filter composed of a first operational amplifier (U2), a third resistor (R3), and a first capacitor (C1); the same-direction input pin of the first operational amplifier (U2) is grounded, the reverse input pin is electrically connected to the input end of the post-stage amplifier circuit via the third resistor (R3), and the inverting input pin is also electrically connected to the first fixed end of the third analog switch (S3) via the first capacitor (C1); and the output pin is electrically connected to the first fixed end of the third analog switch (S3).

8. The electrocardiogram monitoring device according to claim 1, characterized in that: The post-stage amplifier circuit comprises a second operational amplifier (U3), a fifth resistor (R5), a sixth resistor (R6), and a seventh resistor (R7); the same-direction input pin of the second operational amplifier (U3) is connected to the output end of the pre-stage amplifier circuit via the fifth resistor (R5), the reverse input pin is grounded via the seventh resistor (R7), the reverse input pin is also electrically connected to the output pin via the sixth resistor (R6), and the output pin is electrically connected to the controller; the resistance value of the fifth resistor (R5) is set to the parallel resistance value of the sixth resistor (R6) and the seventh resistor (R7).

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