CN216090508U - High-voltage-resistance instrument amplifier for bioelectricity signals - Google Patents
High-voltage-resistance instrument amplifier for bioelectricity signals Download PDFInfo
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- CN216090508U CN216090508U CN202023009577.9U CN202023009577U CN216090508U CN 216090508 U CN216090508 U CN 216090508U CN 202023009577 U CN202023009577 U CN 202023009577U CN 216090508 U CN216090508 U CN 216090508U
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Abstract
The utility model discloses a high-voltage-resistance instrument amplifier for bioelectricity signals, which comprises a signal amplification module; the modulation circuit module is used for processing the low-impedance signal by the anti-aliasing circuit so as to prevent the low-impedance signal from being interfered by high-frequency waves; the isolation power supply module forms a voltage-multiplying rectification circuit for supplying power to the signal amplification module and the modulation circuit module; and the signal isolation module is used for reducing the common-mode current in the isolation power supply module, and synchronously receiving and outputting the high-frequency chopping signal. By adopting high-frequency chopping and increasing the use mode of the amplifier structure, the utility model achieves very small noise level and increases common-mode voltage, realizes the elimination of output ripples of the coupling chopping amplifier, ensures that the output of the instrumentation amplifier is not interfered by ripple signals, obtains larger signal swing amplitude, and has the advantages of reducing the number of original components and reducing the volume of an application circuit.
Description
Technical Field
The utility model relates to the technical field of biomedical electronics, in particular to a high-voltage-resistance instrument amplifier for bioelectricity signals.
Background
At present, an electrocardiogram monitoring system, an electroencephalogram monitoring system and a nerve signal recording system are a research hotspot in the field of biomedical electronics at home and abroad. The recording research of the electrocardiosignals, the electroencephalogram signals and the neural signals has wide application value, the electrocardiosignals have great significance for detecting the physiological and pathological changes of the heart, the electroencephalogram signals and the neural signals have high value for detecting and diagnosing the neural diseases such as epilepsy and the like, and the research progress of the electrocardiosignals, the electroencephalogram signals and the neural signals has great significance for future neural prosthesis and curing the neural diseases. A high performance instrumentation amplifier is a crucial module for electronic systems that record and detect the above mentioned biological signals.
The bioelectric signals are distributed in a low frequency band, typically below 10kHz, and the amplitude of the signals is weak, typically between a few microvolts to a few millivolts. For example, the EEG signal is generally distributed between 0.5Hz and 100Hz, and the amplitude is generally between 1 μ V and 100 μ V; the electrocardiosignals are generally distributed between 0.5Hz and 500Hz, and the amplitude is between 1 mu V and 500 mu V; neural signals are typically divided into action potential signals and local potential signals, with frequencies between 200Hz and 10kHz and 0.1Hz and 200Hz, respectively, and amplitudes also typically in the order of hundreds of microvolts to millivolts. Meanwhile, in a recording system of electroencephalogram, electrocardio and neural signals, an electrode for detecting signals can cause output impedance to be up to thousands of ohms due to attachment of peripheral neurons or cells. Due to the characteristics of the bioelectrical signal, the instrumentation amplifier applied to the bioelectrical signal is required to have low noise, high common mode rejection ratio, high input impedance, and high amplification factor.
The existing common instrument amplifying circuits are divided into two types: the first is a common three-operational amplifier structure, which is characterized by simple structure and convenient application; the second is a chopping operational amplifier structure, and is characterized in that the structure is complex, but noise and common mode are superior to those of a common three-operational amplifier structure.
However, the low-noise high-common-mode instrument of the existing common triple-operational amplifier structure has higher price, and is mainly characterized in that the matching resistance of the third pole is required to be higher and difficult to match, and the voltage of CMRR (common mode rejection ratio) withstand voltage is generally tens of volts to twenty volts; meanwhile, the chopping operational amplifier structure is applied to more analog switches, is complex in circuit, difficult to integrate and difficult to realize in application, and meanwhile, the voltage resistance of the CMRR (common mode rejection ratio) is generally dozens of volts to twenty volts.
Therefore, the utility model is urgently needed to create a circuit which can build a high common mode ratio by realizing a common operational amplifier through a charge transfer principle, reduce the number of original parts, is easier to realize practical application, reduce the volume of an application circuit, reduce the application cost and expand the bioelectricity signals of the single operational amplifier applied to an instrument circuit space.
SUMMERY OF THE UTILITY MODEL
The utility model aims to provide a high-voltage-resistance instrument amplifier for bioelectricity signals, which achieves a very small noise level and increases common-mode voltage by adopting high-frequency chopping and increasing the using mode of an amplifier structure, realizes the elimination of output ripples of a coupling chopping amplifier, ensures that the output of the instrument amplifier is not interfered by ripple signals, obtains a larger signal swing amplitude, has the advantages of reducing the number of original components and reducing the volume of an application circuit, and solves the problems in the prior art.
In order to achieve the purpose, the utility model provides the following technical scheme: a high voltage-withstanding instrument amplifier for bioelectricity signals comprises a signal amplification module 1, wherein a weak bioelectricity signal received by the signal amplification module 1 is subjected to impedance matching after amplification, and a low-impedance signal is output;
the modulation circuit module 2 is used for processing the low-impedance signal through an anti-aliasing circuit so as to prevent the low-impedance signal from being interfered by high-frequency waves, and modulating and outputting a high-frequency chopping signal after removing high-frequency noise in the low-impedance signal through a primary low-pass filter circuit;
the isolation power supply module 3 forms a voltage-multiplying rectification circuit to supply power to the signal amplification module 1 and the modulation circuit module 2;
the signal isolation module 4 is used for reducing common-mode current in the isolation power supply module 3, and synchronously receiving and outputting the high-frequency chopping signal;
the chopping signal module 5 is used for providing a power supply signal and synchronously demodulating the high-frequency chopping signal;
a demodulation module 6, wherein the demodulation module 6 is used for carrying out secondary low-pass filtering on the high-frequency chopped wave signal output after modulation by the signal isolation module 4 to form a fluctuating direct current signal and outputting the fluctuating direct current signal,
the modulation circuit module 2 comprises a resistor R2, a resistor R8, a capacitor C11, a chip U3, a capacitor C10 and a capacitor C12, wherein a first end of the resistor R2 is connected with a first end of the capacitor C11, a second end of the capacitor C11 is connected with a first end of a resistor R8, a second end of the resistor R2 is connected with a pin 6 of the chip U3, a second end of the resistor R8 is connected with a pin 4 of the chip U3 for forming an anti-aliasing circuit, a pin 2 of the chip U3 is connected with VCC +, a pin 3 is connected with VCC-, a pin 6 of the chip U3 is connected with a first end of a capacitor C10, a pin 4 is connected with a first end of the capacitor C12, and a second end of the capacitor C10 is connected with a second end of the capacitor C12 for forming a primary low-pass filter circuit with the resistor R2, the resistor R8 and the capacitor C11;
the isolation power supply module 3 comprises a voltage doubling rectifying circuit consisting of a voltage stabilizing diode D1, a capacitor C3 and a capacitor C5, wherein the first end of the capacitor C3 is connected with the anode of the voltage stabilizing diode D1 and then is connected with VCC-, the first end of the capacitor C5 is connected with the cathode of the voltage stabilizing diode D1 and then is connected with VCC +, the second end of the capacitor C3 is connected with the second end of the capacitor C5, and the cathode of the voltage stabilizing diode D1 is connected with a pin 1 of the chip U3 to provide a power supply for the acquisition circuit.
As an improvement of the high voltage-withstanding instrumentation amplifier for bioelectrical signals in the present invention, the signal amplification module 1 includes an RC filter circuit composed of a resistor R1, a capacitor C9, a resistor R9, and a capacitor C14, and an amplification circuit composed of a first operational amplifier U2A, a second operational amplifier U2B, a resistor R4, and a resistor R7, wherein a first end of the resistor R1 and a first end of the resistor R9 are respectively connected to the bioelectrical signals, a second end of the resistor R1 is respectively connected to a first end of the capacitor C9 and a same-direction input end of the first operational amplifier U2A, a second end of the resistor R9 is respectively connected to a first end of the capacitor C14 and a same-direction input end of the second operational amplifier U2B, a second end of the capacitor C9 and a second end of the capacitor C14 are respectively grounded, an inverting input end of the first operational amplifier U2A is connected to an inverting input end of the second operational amplifier U2B after being connected to the resistor R6 in series, the first end of the resistor R4 is connected with the inverting input end of the first operational amplifier U2A, the second end is connected with the output end of the first operational amplifier U2A, the first end of the resistor R7 is connected with the inverting input end of the second operational amplifier U2B, the second end is connected with the output end of the second operational amplifier U2B, the output end of the first operational amplifier U2A is connected with the first end of the resistor R2, and the output end of the second operational amplifier U2B is connected with the first end of the resistor R8, so that the bioelectrical signal is amplified, impedance matching is carried out, and a low-impedance signal is output to the modulation circuit module 2.
As an improvement of the high voltage-withstanding instrumentation amplifier for bioelectrical signals in the present invention, the signal isolation module 4 includes a first signal isolation transformer T1 and a second signal isolation transformer T2, a pin 1 of the first signal isolation transformer T1 is grounded, a pin 3 is grounded, a pin 2 is connected to a pin 1 of the chip U3 and then connected to a negative electrode of the zener diode D1, a pin 1 of the second signal isolation transformer T2 is connected to a second end of the capacitor C10, a pin 2 is connected to a resistor R5 and then connected to a pin 5 of the chip U3, and a pin 3 of the second signal isolation transformer T2 is grounded.
As an improvement of the high voltage-withstanding instrumentation amplifier for bioelectrical signals in the present invention, the chopping signal module 5 includes a chopping signal circuit composed of a capacitor C2, a capacitor C1, a capacitor C4, a capacitor C6, and a chip U1, wherein a pin 3 of the chip U1 is connected to a first end of the capacitor C2, a pin 2 is connected to a first end of the capacitor C4, a pin 1 of the chip U1 is connected to a first end of the capacitor C6, a pin 4 is grounded, a pin 5 of the chip U1 is connected to a first end of the capacitor C4 and then connected to a pin 2 of the chip U1, a pin 6 of the chip U1 is connected to a second end of the capacitor C2 and then connected to a series capacitor C1 and then connected to a pin 4 of the first signal isolation transformer T1, and a second end of the capacitor C6 is connected to a second end of the capacitor C4 and then grounded.
As an improvement of the high withstand voltage instrumentation amplifier for bioelectric signals described in the present invention, the demodulation module 6 comprises a secondary low-pass filter circuit consisting of a resistor R3 and a capacitor C8, a chip U4, a capacitor C7 and a capacitor C13, wherein, pin 1 of the chip U4 is connected with pin 3 of the chip U1 for demodulating and outputting the high-frequency chopping signal, the pin 3 of the chip U4 is grounded, the pin 4 is grounded after being connected with the capacitor C13 in series, the pin 5 of the chip U4 is connected with the pin 4 of the second signal isolation transformer T2 in series after being connected with the resistor R3 in series, and the pin 5 of the chip U4 is grounded after being connected with the capacitor C8 in series, for forming a secondary low-pass filter circuit to filter the modulated signal outputted from the second signal isolation transformer T2, the capacitor C7 is connected in parallel with the capacitor C8, the second end of the capacitor C7 is connected with the capacitor C8 and then grounded, and the first end of the capacitor C7 is connected to the pin 6 of the chip U4 and then output.
As an improvement of the high withstand voltage instrumentation amplifier for bioelectrical signals in the present invention, the second terminal of the capacitor C10 and the second terminal of the capacitor C12 in the primary low-pass filter circuit are both low-pass frequency points, and the output voltage of the capacitance value is calculated by: UO ═ Ui/[ (2 ^ Pi ^ f ^ R ^ C) ^2+1] ^0.5, wherein: uo is the output voltage; ui is the input voltage; pi is the circumference ratio; f is the signal frequency.
As an improvement of the high voltage-withstanding instrumentation amplifier for bioelectric signals in the present invention, the amplification factors of the first operational amplifier U2A and the second operational amplifier U2B are both: GAIN ═ 1+ (R4+ R7)/R6.
As an improvement of the high voltage resistance instrumentation amplifier for bioelectric signals in the present invention, the effective values of the isolation voltages of the first signal isolation transformer T1 and the second signal isolation transformer T2 are each 4000 VAC.
As an improvement of the high-voltage-resistance instrumentation amplifier for bioelectrical signals, the models of the chip U1, the chip U3 and the chip U4 are all SGM 3204.
Compared with the prior art, the utility model has the following beneficial effects:
1. by adopting high-frequency chopping and increasing the use mode of the amplifier structure, the utility model achieves very small noise level and increases common-mode voltage, realizes the elimination of output ripples of the coupling chopping amplifier, ensures that the output of the instrument amplifier is not interfered by ripple signals, obtains larger signal swing amplitude, and has the advantages of reducing the number of original components and reducing the volume of an application circuit;
2. this circuit adopts the charge pump circuit that is close 1MHZ, and the collection bandwidth theoretical value is 0-100KHZ, satisfies ordinary biological electricity greatly and gathers the demand, and has reached very little noise level through adopting the high-frequency chopping, simultaneously, reduces original paper quantity, changes in the realization of actual application, reduces the application circuit volume, and the cost is lower.
Drawings
FIG. 1 is an exemplary graph of the output waveform of the raw bioelectric signal after modulation and demodulation according to one embodiment of the present invention.
FIG. 2 is a schematic diagram of the electrical circuit of an instrumentation amplifier for bioelectric signals in an embodiment of the present invention.
FIG. 3 is a schematic diagram of a process for transmitting bioelectrical signals according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating the effect of high common mode ratio of the bioelectrical signal instrumentation amplifier according to an embodiment of the present invention.
The figures are labeled as follows: the device comprises a 1-signal amplification module, a 2-modulation circuit module, a 3-isolation power supply module, a 4-signal isolation module, a 5-chopping signal module and a 6-demodulation module.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by a person of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
As an embodiment of the present invention, a high withstand voltage instrumentation amplifier for bioelectric signals, as shown in fig. 1 to 3, includes a signal amplification module 1, wherein a weak bioelectric signal received by the signal amplification module 1 is subjected to impedance matching after amplification, and outputs a low impedance signal;
the modulation circuit module 2 processes the low-impedance signal through an anti-aliasing circuit so as to prevent the low-impedance signal from being interfered by high-frequency waves, removes high-frequency noise in the low-impedance signal through a primary low-pass filter circuit and then modulates and outputs a high-frequency chopping signal;
the isolation power supply module 3, the isolation power supply module 3 forms a voltage doubling rectifying circuit for supplying power to the signal amplification module 1 and the modulation circuit module 2;
the signal isolation module 4 adopts 1MHZ oscillation frequency, so that the volume and coupling capacitance of the transformer are greatly reduced, the coupling capacitance is reduced, namely, common-mode current passing by mains supply is reduced, the interference resistance of the mains supply is improved, and a high-frequency chopping signal is synchronously received and output;
the chopping signal module 5 is used for outputting a power supply driving capability and an oscillation signal of the charge pump, providing a power supply signal and synchronously demodulating a high-frequency chopping signal;
In an embodiment of the present invention, the modulation circuit module 2 includes a resistor R2, a resistor R8, a capacitor C11, a chip U3, a capacitor C10, and a capacitor C12, a first end of the resistor R2 is connected to a first end of the capacitor C11, a second end of the capacitor C11 is connected to a first end of a resistor R8, a second end of the resistor R2 is connected to a pin 6 of the chip U3, a second end of the resistor R8 is connected to a pin 4 of the chip U3 for forming an anti-aliasing circuit, a pin 2 of the chip U3 is connected to VCC +, a pin 3 is connected to VCC-, a pin 6 of the chip U3 is connected to a first end of the capacitor C10, a pin 4 is connected to a first end of the capacitor C12, and a second end of the capacitor C10 is connected to a second end of the capacitor C12 for forming a primary low-pass filter circuit with the resistor R2, the resistor R8, and the capacitor C11;
the isolation power supply module 3 comprises a voltage doubling rectifying circuit consisting of a voltage stabilizing diode D1, a capacitor C3 and a capacitor C5, the first end of the capacitor C3 is connected with the anode of the voltage stabilizing diode D1 and then is connected with VCC-, the first end of the capacitor C5 is connected with the cathode of the voltage stabilizing diode D1 and then is connected with VCC +, the second end of the capacitor C3 is connected with the second end of the capacitor C5, and the cathode of the voltage stabilizing diode D1 is connected with a pin 1 of a chip U3 and used for providing a power supply for the acquisition circuit.
IN an embodiment of the present invention, the signal amplification module 1 includes an RC filter circuit composed of a resistor R1, a capacitor C9, a resistor R9, and a capacitor C14, and an amplification circuit composed of a first operational amplifier U2A, a second operational amplifier U2B, a resistor R4, and a resistor R7, wherein a first end of the resistor R1 and a first end of the resistor R9 are respectively connected to the bioelectrical signals IN1 and IN2, a second end of the resistor R1 is respectively connected to a first end of the capacitor C9 and a same-direction input end of the first operational amplifier U2A, a second end of the resistor R9 is respectively connected to a first end of the capacitor C14 and a same-direction input end of the second operational amplifier U2B, and amplification coefficients of the first operational amplifier U2A and the second operational amplifier U2B are both: GAIN is 1+ (R4+ R7)/R6, the second terminal of the capacitor C9 and the second terminal of the capacitor C14 are grounded, the inverting input terminal of the first operational amplifier U2A is connected in series with the resistor R6 and then connected to the inverting input terminal of the second operational amplifier U2B, the first terminal of the resistor R4 is connected to the inverting input terminal of the first operational amplifier U2A, the second terminal of the resistor R7 is connected to the output terminal of the first operational amplifier U2A, the first terminal of the resistor R7 is connected to the inverting input terminal of the second operational amplifier U2B, the second terminal of the resistor R2B, the output terminal of the first operational amplifier U2A is connected to the first terminal of the resistor R2, and the output terminal of the second operational amplifier U2B is connected to the first terminal of the resistor R8, so as to amplify, match impedance and output a low-impedance signal to the modulation circuit module 2.
In an embodiment of the present invention, the signal isolation module 4 includes a first signal isolation transformer T1 and a second signal isolation transformer T2, the pin 1 of the first signal isolation transformer T1 is grounded, the pin 3 is grounded, the pin 2 is connected to the pin 1 of the chip U3 and then connected to the negative electrode of the zener diode D1, the pin 1 of the second signal isolation transformer T2 is connected to the second end of the capacitor C10, the pin 2 is connected in series with the resistor R5 and then connected to the pin 5 of the chip U3, and the pin 3 of the second signal isolation transformer T2 is grounded.
In an embodiment of the present invention, the chopping signal module 5 includes a chopping signal circuit including a capacitor C2, a capacitor C1, a capacitor C4, a capacitor C6, and a chip U1, wherein a pin 3 of the chip U1 is connected to a first end of the capacitor C2, a pin 2 is connected to a first end of the capacitor C4, a pin 1 of the chip U1 is connected to a first end of the capacitor C6, a pin 4 is grounded, a pin 5 of the chip U1 is connected to a first end of the capacitor C4 and then connected to a pin 2 of the chip U1, a pin 6 of the chip U1 is connected to a second end of the capacitor C2 and then connected to a pin 4 of the first signal isolation transformer T1, and a second end of the capacitor C6 is connected to a second end of the capacitor C4 and then connected to ground.
In an embodiment of the present invention, the demodulation module 6 includes a secondary low-pass filter circuit composed of a resistor R3 and a capacitor C8, a chip U4, a capacitor C7, and a capacitor C13, where a pin 1 of the chip U4 is connected to a pin 3 of a chip U1 for demodulating and outputting a high-frequency chopping signal, a pin 3 of the chip U4 is grounded, a pin 4 is connected in series with the capacitor C13 and then grounded, a pin 5 of the chip U4 is connected in series with the resistor R3 and then connected to a pin 4 of a second signal isolation transformer T2, a pin 5 of the chip U4 is connected in series with the capacitor C8 and then grounded, so as to form a secondary low-pass filter circuit for filtering a modulated signal output by the second signal isolation transformer T2, the capacitor C7 is connected in parallel with the capacitor C8, a second end of the capacitor C7 is connected to the capacitor C8 and then grounded, and a first end of the capacitor C7 is connected to a pin 6 of the chip U4 and then output.
In an embodiment of the present invention, the second terminal of the capacitor C10 and the second terminal of the capacitor C12 in the first low-pass filter circuit are low-pass frequency points, and the output voltage of the capacitance value is calculated by: UO ═ Ui/[ (2 ^ Pi ^ f ^ R ^ C) ^2+1] ^0.5, wherein: uo is the output voltage; ui is the input voltage; pi is the circumference ratio; f is the signal frequency.
In an embodiment of the present invention, the effective isolation voltage values of the first signal isolation transformer T1 and the second signal isolation transformer T2 are 4000 VAC.
In an embodiment of the utility model, the models of the chip U1, the chip U3 and the chip U4 are SGM 3204.
As an embodiment of the present invention, as shown in fig. 4, the main factors affecting the common triple operational amplifier are:
in the formula, CMR is common mode rejection of the instrument amplifier, and the error of the resistor R1 and the resistor R2 seriously affects the common mode rejection ratio as can be seen from the formula, for example, if the ratio of the resistor R1 to the resistor R2 to the resistor R3 and the resistor R4 take the same value, if the ratio of the resistor R1 to the resistor R2 has 0.1% error, the ideal level is reduced to 66dB level from the last great reduction of the instrument amplifier CMR, but the circuit adopts a design similar to a three-operational amplifier structure, a chopper circuit is used for replacing a three-operational amplifier rear-stage operational amplifier circuit, the defect of low common mode ratio caused by rear-stage resistor matching is overcome, and a novel instrument amplification structure is provided.
In one embodiment of the utility model, when the utility model works, the bioelectric signal is amplified by the amplifying circuit of the signal amplifying module 1, the amplified signal is changed into a modulated signal by the modulating circuit module 2, the modulated signal is isolated by the signal isolating module 4 and output to the chopping signal module 5 for demodulation and output, the isolating power supply module 3 supplies power to the signal amplifying module 1 and the modulating circuit module 2, one path of the signal isolating module 4 is output to the isolating power supply module 3, the other path of the signal isolating module is output to the chip U3 for providing a synchronous modulated signal, the chopping signal module 5 provides a power supply signal and a demodulation synchronous signal, the utility model achieves a very small noise level and increases a common mode voltage by adopting high-frequency chopping and increasing the use mode of an amplifier structure, the elimination of output ripples of a coupling chopping amplifier is realized, and the output of an instrumentation amplifier is not interfered by ripple signals, obtain bigger signal swing amplitude to possess and reduce original paper quantity, reduce the advantage of using circuit volume.
While there have been shown and described the fundamental principles and essential features of the utility model and advantages thereof, it will be apparent to those skilled in the art that the utility model is not limited to the details of the foregoing exemplary embodiments, but is capable of other specific forms without departing from the spirit or essential characteristics thereof; the present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the utility model being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein, and any reference signs in the claims are not intended to be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (10)
1. A high withstand voltage instrumentation amplifier for bioelectric signals, comprising:
the signal amplification module (1) is used for carrying out amplified impedance matching on the weak bioelectric signals received by the signal amplification module (1) and outputting low-impedance signals;
the modulation circuit module (2) is used for processing the low-impedance signal through an anti-aliasing circuit so as to prevent the low-impedance signal from being interfered by high-frequency waves, and modulating and outputting a high-frequency chopping signal after removing high-frequency noise in the low-impedance signal through a primary low-pass filter circuit;
the isolation power supply module (3) forms a voltage-multiplying rectification circuit to supply power to the signal amplification module (1) and the modulation circuit module (2);
the signal isolation module (4) is used for reducing common-mode current in the isolation power supply module (3), and synchronously receiving and outputting the high-frequency chopping signal;
the chopping signal module (5) is used for providing a power supply signal and synchronously demodulating the high-frequency chopping signal;
the demodulation module (6), the demodulation module (6) is used for carrying out secondary low-pass filtering on the high-frequency chopped wave signal output after the modulation of the signal isolation module (4) to form a fluctuating direct current signal and outputting the fluctuating direct current signal,
the modulation circuit module (2) comprises a resistor R2, a resistor R8, a capacitor C11, a chip U3, a capacitor C10 and a capacitor C12, wherein a first end of the resistor R2 is connected with a first end of the capacitor C11, a second end of the capacitor C11 is connected with a first end of a resistor R8, a second end of the resistor R2 is connected with a pin 6 of the chip U3, a second end of the resistor R8 is connected with a pin 4 of the chip U3 for forming an anti-aliasing circuit, a pin 2 of the chip U3 is connected with VCC +, a pin 3 is connected with VCC-, a pin 6 of the chip U3 is connected with a first end of a capacitor C10, a pin 4 is connected with a first end of the capacitor C12, and a second end of the capacitor C10 is connected with a second end of the capacitor C12 for forming a primary low-pass filter circuit with the resistor R2, the resistor R8 and the capacitor C11;
the isolation power supply module (3) comprises a voltage-doubling rectifying circuit consisting of a voltage-stabilizing diode D1, a capacitor C3 and a capacitor C5, wherein the first end of the capacitor C3 is connected with the anode of the voltage-stabilizing diode D1 and then is connected with VCC-, the first end of the capacitor C5 is connected with the cathode of the voltage-stabilizing diode D1 and then is connected with VCC +, the second end of the capacitor C3 is connected with the second end of the capacitor C5, and the cathode of the voltage-stabilizing diode D1 is connected with a pin 1 of the chip U3 and used for providing a power supply for the acquisition circuit;
the signal isolation module (4) comprises a first signal isolation transformer T1 and a second signal isolation transformer T2, wherein a pin 1 of the first signal isolation transformer T1 is grounded, a pin 3 is grounded, a pin 2 is connected with a pin 1 of the chip U3 and then connected with a cathode of the voltage stabilizing diode D1, a pin 1 of the second signal isolation transformer T2 is connected with a second end of the capacitor C10, a pin 2 of the pin 2 is connected with a series resistor R5 and then connected with a pin 5 of the chip U3, and a pin 3 of the second signal isolation transformer T2 is grounded.
2. A high withstand voltage instrumentation amplifier for bioelectric signals according to claim 1, characterized in that: the signal amplification module (1) comprises an RC filter circuit consisting of a resistor R1, a capacitor C9, a resistor R9 and a capacitor C14, and an amplification circuit consisting of a first operational amplifier U2A, a second operational amplifier U2B, a resistor R4 and a resistor R7, wherein a first end of a resistor R1 and a first end of a resistor R9 are respectively connected with the bioelectricity signal, a second end of a resistor R1 is respectively connected with a first end of a capacitor C9 and a same-direction input end of a first operational amplifier U2A, a second end of a resistor R9 is respectively connected with a first end of a capacitor C14 and a same-direction input end of a second operational amplifier U2B, a second end of the capacitor C9 and a second end of a capacitor C14 are respectively grounded, an inverting input end of the first operational amplifier U2A is connected with a resistor R6 in series and then connected with an inverting-direction input end of the second operational amplifier U2B, a first end of the resistor R4 is connected with a second end of a first operational amplifier U2A and a second end of the inverting-direction input end of the operational amplifier U2A, the first end of the resistor R7 is connected with the inverting input end of the second operational amplifier U2B, the second end is connected with the output end of the second operational amplifier U2B, the output end of the first operational amplifier U2A is connected with the first end of the resistor R2, the output end of the second operational amplifier U2B is connected with the first end of the resistor R8, the first end of the resistor R8 is used for amplifying the bioelectrical signal, performing impedance matching, and outputting a low-impedance signal to the modulation circuit module (2).
3. A high withstand voltage instrumentation amplifier for bioelectric signals according to claim 1, characterized in that: the chopping signal module (5) comprises a chopping signal circuit composed of a capacitor C2, a capacitor C1, a capacitor C4, a capacitor C6 and a chip U1, wherein a pin 3 of the chip U1 is connected with a first end of a capacitor C2, a pin 2 is connected with a first end of a capacitor C4, a pin 1 of the chip U1 is connected with a first end of a capacitor C6, a pin 4 is grounded, a pin 5 of the chip U1 is connected with a first end of a capacitor C4 and then connected to a pin 2 of the chip U1, a pin 6 of the chip U1 is connected with a second end of the capacitor C2 and then connected to a series capacitor C1 and then connected to a pin 4 of the first signal isolation transformer T1, and a second end of the capacitor C6 is connected with a second end of the capacitor C4 and then connected to ground.
4. A high withstand voltage instrumentation amplifier for bioelectric signals according to claim 1, characterized in that: the demodulation module (6) comprises a secondary low-pass filter circuit consisting of a resistor R3 and a capacitor C8, a chip U4, a capacitor C7 and a capacitor C13, wherein a pin 1 of the chip U4 is connected with a pin 3 of a chip U1 and used for demodulating and outputting the high-frequency chopping signal, the pin 3 of the chip U4 is grounded, a pin 4 is connected with the capacitor C13 in series and then grounded, a pin 5 of the chip U4 is connected with a resistor R3 in series and then connected with a pin 4 of the second signal isolation transformer T2, the pin 5 of the chip U4 is connected with a capacitor C8 in series and then grounded and used for forming a secondary low-pass filter circuit to filter the modulation signal output by the second signal isolation transformer T2, the capacitor C7 is connected with the capacitor C8 in parallel, a second end of the capacitor C7 is connected with the capacitor C8 and then grounded, and a first end of the capacitor C7 is connected with a pin 6 of the chip U4 and then output.
5. A high withstand voltage instrumentation amplifier for bioelectric signals according to claim 1, characterized in that: the second end of the capacitor C10 and the second end of the capacitor C12 in the primary low-pass filter circuit are low-pass frequency points, and the output voltage of the capacitance value is calculated in the following manner: UO ═ Ui/[ (2 ^ Pi ^ f ^ R ^ C) ^2+1] ^0.5, wherein: uo is the output voltage; ui is the input voltage; pi is the circumference ratio; f is the signal frequency.
6. A high withstand voltage instrumentation amplifier for bioelectric signals according to claim 2, characterized in that: the amplification factors of the first operational amplifier U2A and the second operational amplifier U2B are both: GAIN ═ 1+ (R4+ R7)/R6.
7. A high withstand voltage instrumentation amplifier for bioelectric signals according to claim 1, characterized in that: the effective value of the isolation voltage of the first signal isolation transformer T1 and the effective value of the isolation voltage of the second signal isolation transformer T2 are both 4000 VAC.
8. A high withstand voltage instrumentation amplifier for bioelectric signals according to claim 3, characterized in that: the chip U1 is of SGM3204 type.
9. The high withstand voltage instrumentation amplifier for bioelectric signals according to claim 4, wherein: the model of the chip U4 is SGM 3204.
10. A high withstand voltage instrumentation amplifier for bioelectric signals according to claim 1, characterized in that: the model of the chip U3 is SGM 3204.
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| CN202023009577.9U CN216090508U (en) | 2020-12-14 | 2020-12-14 | High-voltage-resistance instrument amplifier for bioelectricity signals |
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| CN202023009577.9U CN216090508U (en) | 2020-12-14 | 2020-12-14 | High-voltage-resistance instrument amplifier for bioelectricity signals |
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