CN112472095A - Instrument amplifier for bioelectric signals - Google Patents
Instrument amplifier for bioelectric signals Download PDFInfo
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- CN112472095A CN112472095A CN202011472128.XA CN202011472128A CN112472095A CN 112472095 A CN112472095 A CN 112472095A CN 202011472128 A CN202011472128 A CN 202011472128A CN 112472095 A CN112472095 A CN 112472095A
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
- A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal
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- A—HUMAN NECESSITIES
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- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
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- A61B5/7225—Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation
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- A—HUMAN NECESSITIES
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- A61B5/725—Details of waveform analysis using specific filters therefor, e.g. Kalman or adaptive filters
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
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- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/56—Modifications of input or output impedances, not otherwise provided for
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
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- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/42—Amplifiers with two or more amplifying elements having their dc paths in series with the load, the control electrode of each element being excited by at least part of the input signal, e.g. so-called totem-pole amplifiers
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Abstract
The invention discloses an instrument amplifier for bioelectricity signals, which comprises a signal input module, a signal output module and a signal output module, wherein the signal input module is used for amplifying the bioelectricity signals received by the signal input module, performing impedance matching and outputting low-impedance signals; the charge transfer module is used for carrying out low-pass high-frequency clutter removal on the amplified low-impedance signal and then carrying out waveform reduction on the amplified low-impedance signal, and outputting a low-pass frequency point signal; and the signal module is used for providing a signal source to the charge transfer module for charge transfer output. The mode that a circuit with a higher common mode ratio can be built by a common operational amplifier is realized through a charge transfer principle, so that the invention is easier to realize in practical application while reducing the number of original components, and has the advantages of reducing the volume of an application circuit, reducing the application cost and expanding the application of the single operational amplifier in the space of an instrument circuit.
Description
Technical Field
The invention relates to the technical field of biomedical electronics, in particular to an 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 three-operational-amplifier structure has higher price, and is mainly characterized in that the matching resistance of the third pole is higher in requirement and difficult to match; meanwhile, the chopping operational amplifier structure is applied to more analog switches, and has a complex circuit, is difficult to integrate and is difficult to realize in application.
Therefore, the invention 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.
Disclosure of Invention
The invention aims to provide an instrument amplifier for bioelectricity signals, which realizes a mode that a circuit with higher common mode ratio can be built by a common operational amplifier through a charge transfer principle, thereby reducing the number of original components, being easier to realize practical application, having the advantages of reducing the volume of an application circuit, reducing the application cost, expanding the space of the instrument circuit applied by a single operational amplifier and solving the problems in the prior art.
In order to achieve the purpose, the invention provides the following technical scheme: an instrument amplifier for bioelectric signals comprises a signal input module 1, wherein the signal input module 1 amplifies the bioelectric signals received by the signal input module for impedance matching and then outputs low-impedance signals;
the charge transfer module 2 is used for carrying out low-pass high-frequency clutter removal on the amplified low-impedance signal and then carrying out waveform reduction on the amplified low-impedance signal, and outputting a low-pass frequency point signal;
and the signal module 3 is used for providing a signal source to the charge transfer module 2 for charge transfer output.
As an improvement of the instrumentation amplifier for bioelectrical signals in the present invention, the signal input module 1 includes an RC filter circuit composed of a resistor R1, a capacitor C4, a resistor R8, and a capacitor C7, and an amplifier circuit composed of a first operational amplifier U2A, a second operational amplifier U2B, a resistor R4, and a resistor R6, wherein a first end of the resistor R1 and a first end of the resistor R8 are respectively connected to the bioelectrical signals, a second end of the resistor R1 is respectively connected to a first end of the capacitor C4 and a same-direction input end of the first operational amplifier U2A, a second end of the resistor R8 is respectively connected to a first end of the capacitor C7 and a same-direction input end of the second operational amplifier U2B, a second end of the capacitor C5 and a second end of the capacitor C5857323 are respectively connected to ground, an inverting input end of the first operational amplifier U2A is connected to an inverting-direction input end of the second operational amplifier U2U B, and a first end of the resistor R A is connected to an inverting-direction input end of the first operational amplifier U5, the second end of the resistor R6 is connected with the output end of the first operational amplifier U2A, the first end of the resistor R6 is connected with the inverting input end of the second operational amplifier U2B, and the second end of the resistor R6 is connected with the output end of the second operational amplifier U2B, and the resistor R is used for amplifying the bioelectrical signal, performing impedance matching and outputting a low-impedance signal.
As an improvement of the instrumentation amplifier for bioelectrical signals in the present invention, the charge transfer module 2 includes a first low pass filter circuit composed of a resistor R2, a capacitor C5 and a resistor R9 for removing irrelevant high frequency signals, a charge and discharge circuit composed of a resistor R3, a resistor R10, a single-pole double-throw analog switch Q1, a single-pole double-throw analog switch Q2 and a capacitor C6, and a second low pass filter circuit composed of a resistor R7 and a capacitor C8, wherein a first end of the resistor R2 and a first end of the resistor R9 are respectively connected to an output terminal of a first operational amplifier U2A and an output terminal of a second operational amplifier U2B, a second end of the resistor R2 and a second end of the resistor R9 are respectively connected to a first end and a second end of a capacitor C5, a second end of the resistor R2 is connected in series with a resistor R3 and then connected to a normally open pin 6 of a single-pole double-throw analog switch Q1, and a second end of the resistor R9 and a resistor R5928 are connected in series to a normally open pin Q9, the pin 1 of the single-pole double-throw analog switch Q1 is connected with the pin 1 of the single-pole double-throw analog switch Q2, the pin 2 of the single-pole double-throw analog switch Q1 is connected with VCC, the pin 3 of the single-pole double-throw analog switch Q1 is grounded, the normally closed pin 5 of the single-pole double-throw analog switch Q1 is connected with the first end of a capacitor C6, the second end of the capacitor C6 is connected with the normally closed pin 4 of the single-pole double-throw analog switch Q2, the pin 2 of the single-pole double-throw analog switch Q2 is connected with VCC, the pin 3 of the single-pole double-throw analog switch Q2 is grounded, the normally closed pin 4 of the single-pole double-throw analog switch Q2 is connected with the first end of a resistor R7 in series and then outputs a low-pass frequency point signal, the first end of the capacitor.
As an improvement of the instrumentation amplifier for bioelectrical signals in the present invention, the signal module 3 includes a signal source circuit composed of a chip U1, a capacitor C1, a capacitor C2 and a capacitor C3, wherein, the pin 5 of the chip U1 is connected with the pin 1 of the single-pole double-throw analog switch Q1 and is used for outputting an oscillating signal, pin 4 of the chip U1 is grounded, pin 5 and pin 3 of the chip U1 are connected to the first terminal and the second terminal of the capacitor C1 respectively, pin 1 of the chip U1 is grounded, the first end of the capacitor C2 is connected with pin 1 of the chip U1, the second end of the capacitor C2 is grounded, the first end of the capacitor C3 is connected with the pin 2 of the chip U1, the second end is grounded, the pin 2 of the chip U1 is grounded, the charge pump is used for negative power supply driving capacity and oscillation signal output of the charge pump, and realizes quick switching of normally open and normally closed of the single-pole double-throw analog switch Q1 and the single-pole double-throw analog switch Q2.
As an improvement to the instrumentation amplifier for bioelectrical signals in the present invention, the amplification factors of the first operational amplifier U2A and the second operational amplifier U2B are: GAIN ═ 1+ (R4+ R7)/R6.
As an improvement of the instrumentation amplifier for bioelectrical signals in the present invention, two ends of the capacitor C5 in the primary low-pass filter circuit are low-pass frequency points, and the output voltage of the capacitance values at the two ends is calculated as follows:
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 instrumentation amplifier for bioelectrical signals in the present invention, the chip U1 is of SGM3204 type.
As a second aspect of the invention, the instrumentation amplifier for bioelectric signals is applied in the field of biomedical electronics.
Compared with the prior art, the invention has the following beneficial effects:
1. the mode that a circuit with a higher common mode ratio can be built by a common operational amplifier is realized through a charge transfer principle, so that the invention is easier to realize in practical application while reducing the number of original components, and has the advantages of reducing the volume of an application circuit, reducing the application cost and expanding the application of a single operational amplifier in the space of an instrument 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 charge transfer 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 input module, a 2-charge transfer module and a 3-signal 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, an instrumentation amplifier for bioelectric signals, as shown in fig. 1 to 3, includes a signal input module 1, where the signal input module 1 amplifies a bioelectric signal received by the signal input module for impedance matching, and then outputs a low impedance signal;
the charge transfer module 2 is used for carrying out low-pass high-frequency clutter removal on the amplified low-impedance signal and then carrying out waveform reduction on the amplified low-impedance signal, and outputting a low-pass frequency point signal;
the signal module 3 is used for providing a signal source to the charge transfer module 2 for charge transfer output, and a circuit with a high common mode ratio can be built by realizing a common operational amplifier according to a charge transfer principle, so that the circuit has the advantages of reducing the volume of an application circuit, reducing the application cost and expanding the application space of the single operational amplifier in an instrument circuit while reducing the number of original components and being easy to realize practical application.
IN an embodiment of the present invention, the signal input module 1 includes an RC filter circuit composed of a resistor R1, a capacitor C4, a resistor R8, and a capacitor C7, and an amplifier circuit composed of a first operational amplifier U2A, a second operational amplifier U2B, a resistor R4, and a resistor R6, wherein a first end of the resistor R1 and a first end of the resistor R8 are respectively connected to the bioelectrical signals IN 5 and IN2, a second end of the resistor R57324 is respectively connected to a first end of the capacitor C4 and a common-direction input end of the first operational amplifier U2A, a second end of the resistor R8 is respectively connected to a first end of the capacitor C7 and a common-direction input end of the second operational amplifier U2B, a second end of the capacitor C4 and a second end of the capacitor C7 are respectively connected to ground, an inverting input end of the first operational amplifier U2A is connected to an inverting input end of the second operational amplifier U2B, a first end of the resistor R4 is connected to an inverting input end of the operational amplifier U A, the second end of the resistor R6 is connected with the output end of the first operational amplifier U2A, the first end of the resistor R6 is connected with the inverting input end of the second operational amplifier U2B, the second end of the resistor R6 is connected with the output end of the second operational amplifier U2B, the IN1 and the IN2 bioelectricity signals are amplified to the first operational amplifier U2A and the second operational amplifier U2B through an RC filter circuit consisting of a resistor R1, a capacitor C4, a resistor R8 and a capacitor C7, and the amplification coefficients are as follows: GAIN is 1+ (R4+ R7)/R6, and is used to amplify a weak bioelectric signal, perform impedance matching, and output a low output impedance.
In an embodiment of the present invention, the charge transfer module 2 includes a first low pass filter circuit composed of a resistor R2, a capacitor C5 and a resistor R9 for removing uncorrelated high frequency signals, a charging and discharging circuit composed of a resistor R3, a resistor R10, a single-pole double-throw analog switch Q1, a single-pole double-throw analog switch Q2 and a capacitor C6, and a second low pass filter circuit composed of a resistor R7 and a capacitor C8, wherein a first end of the resistor R2 and a first end of the resistor R9 are respectively connected to an output terminal of the first operational amplifier U2A and an output terminal of the second operational amplifier U2B, a second end of the resistor R2 and a second end of the resistor R9 are respectively connected to a first end and a second end of the capacitor C5, a second end of the resistor R2 is connected in series with a normally open pin 6 of the single-pole double-throw analog switch Q1, a second end of the resistor R9 is connected in series with a normally open pin of the resistor R10 and then connected with a pin of the single-pole double, a pin 1 of a single-pole double-throw analog switch Q1 is connected with a pin 1 of a single-pole double-throw analog switch Q2, a pin 2 of a single-pole double-throw analog switch Q1 is connected with VCC, a pin 3 of a single-pole double-throw analog switch Q1 is grounded, a normally closed pin 5 of a single-pole double-throw analog switch Q1 is connected with a first end of a capacitor C6, a second end of the capacitor C6 is connected with a normally closed pin 4 of a single-pole double-throw analog switch Q2, a pin 2 of a single-pole double-throw analog switch Q2 is connected with VCC, a pin 3 of a single-pole double-throw analog switch Q2 is grounded, a normally closed pin 4 of the single-pole double-throw analog switch Q2 is connected with a first end of a resistor R7 in series and then outputs a low-pass frequency point signal, a first end of the capacitor C8 is connected with a second end of a resistor R7, a second end of the capacitor C8 is grounded, a signal amplified by a first operational amplifier U2 and a second operational amplifier U2B passes through a high-pass filter circuit composed of, at this time, the output voltage of the capacitance value at the two ends of the capacitor C5 is calculated as follows: 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 signal frequency, the circuit adopts a charge pump circuit close to 1MHZ, the theoretical value of the acquisition bandwidth is 0-100KHZ, the requirement of common bioelectricity acquisition is greatly met, a small noise level is achieved by adopting high-frequency chopping, the number of original parts is reduced, the practical application is easier to realize, the size of an application circuit is reduced, and the cost is lower.
In an embodiment of the invention, a low-pass bioelectricity signal is conducted by a resistor R3 and a resistor R10 through a single-pole double-throw analog switch Q1 and a single-pole double-throw analog switch Q2 normally open pin to charge and discharge a capacitor C6, a capacitor C6 after charge is charged and discharged is conducted through a single-pole double-throw analog switch Q1 and a single-pole double-throw analog switch Q2 normally closed pin to charge and discharge the resistor R7 and the capacitor C8, a secondary low-pass filter circuit consisting of the resistor R7 and the capacitor C8 filters out unnecessary high-frequency noise and restores the waveform of the original bioelectricity signal, in an embodiment of the invention, an oscillation signal is selected to be 10 times of a signal acquisition frequency, the circuit adopts a charge pump circuit close to 1MHZ, and the theoretical value of acquisition bandwidth is 0HZ-100K to greatly meet the requirement of ordinary bioelectricity.
In an embodiment of the present invention, the signal module 3 includes a signal source circuit composed of a chip U1, a capacitor C1, a capacitor C2, and a capacitor C3, and the chip U1 is of an SGM3204 type, wherein a pin 5 of the chip U1 is connected to a pin 1 of a single-pole double-throw analog switch Q1 for outputting an oscillation signal, a pin 4 of the chip U1 is grounded, the pin 5 and the pin 3 of the chip U1 are respectively connected to a first end and a second end of a capacitor C1, a pin 1 of the chip U1 is grounded, a first end of the capacitor C2 is connected to a pin 1 of the chip U1, a second end of the capacitor C2 is grounded, a first end of the capacitor C3 is connected to a pin 2 of the chip U1, a second end of the capacitor C1 is grounded, and is used for outputting a negative power source and an oscillation signal of the charge pump, so as to realize a normally-closed fast switching of the driving capability of the single-pole double-throw analog switch Q.
As an embodiment of the present invention, as shown in fig. 4, the main factors affecting the common triple operational amplifier are:
While there have been shown and described the fundamental principles and essential features of the invention and advantages thereof, it will be apparent to those skilled in the art that the invention 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 invention 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 (7)
1. An instrumentation amplifier for bioelectric signals, comprising:
the signal input module 1 amplifies the received bioelectricity signal for impedance matching, and then outputs a low-impedance signal;
the charge transfer module 2 is used for carrying out low-pass high-frequency clutter removal on the amplified low-impedance signal and then carrying out waveform reduction on the amplified low-impedance signal, and outputting a low-pass frequency point signal;
the signal module 3 is used for providing a signal source to the charge transfer module 2 for charge transfer output;
wherein, the signal input module 1 comprises an RC filter circuit composed of a resistor R1, a capacitor C4, a resistor R8 and a capacitor C7, and an amplifier circuit composed of a first operational amplifier U2A, a second operational amplifier U2B, a resistor R4 and a resistor R6, wherein a first end of the resistor R1 and a first end of the resistor R8 are respectively connected to the bioelectricity signal, a second end of the resistor R1 is respectively connected to a first end of the capacitor C4 and a same-direction input end of the first operational amplifier U2A, a second end of the resistor R8 is respectively connected to a first end of the capacitor C7 and a same-direction input end of the second operational amplifier U2B, a second end of the capacitor C4 and a second end of the capacitor C7 are respectively connected to ground, 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 a resistor R5, a first end of the resistor R4 is connected to a second end of the first operational amplifier U2A, and a second end of the inverting input end of the operational amplifier U2A is connected, the first end of the resistor R6 is connected with the inverting input end of the second operational amplifier U2B, and the second end is connected with the output end of the second operational amplifier U2B, and the resistor R6 is used for amplifying the bioelectrical signal, performing impedance matching and outputting a low-impedance signal.
2. An instrumentation amplifier for bioelectric signals according to claim 1, wherein: the charge transfer module 2 comprises a first low-pass filter circuit consisting of a resistor R2, a capacitor C5 and a resistor R9 and used for removing irrelevant high-frequency signals, a charging and discharging circuit consisting of a resistor R3, a resistor R10, a single-pole double-throw analog switch Q1, a single-pole double-throw analog switch Q2 and a capacitor C6, and a second low-pass filter circuit consisting of a resistor R7 and a capacitor C8, wherein a first end of the resistor R2 and a first end of the resistor R9 are respectively connected with an output end of a first operational amplifier U2A and an output end of a second operational amplifier U2B, a second end of the resistor R2 and a second end of the resistor R9 are respectively connected with a first end and a second end of a capacitor C5, a second end of the resistor R2 is connected in series with a resistor R3 and then connected with a normally open pin 6 of the single-pole double-throw analog switch Q1, a second end of the resistor R9 is connected in series with a normally open resistor R10 and then connected with a pin 6, the pin 1 of the single-pole double-throw analog switch Q1 is connected with the pin 1 of the single-pole double-throw analog switch Q2, the pin 2 of the single-pole double-throw analog switch Q1 is connected with VCC, the pin 3 of the single-pole double-throw analog switch Q1 is grounded, the normally closed pin 5 of the single-pole double-throw analog switch Q1 is connected with the first end of a capacitor C6, the second end of the capacitor C6 is connected with the normally closed pin 4 of the single-pole double-throw analog switch Q2, the pin 2 of the single-pole double-throw analog switch Q2 is connected with VCC, the pin 3 of the single-pole double-throw analog switch Q2 is grounded, the normally closed pin 4 of the single-pole double-throw analog switch Q2 is connected with the first end of a resistor R7 in series and then outputs a low-pass frequency point signal, the first end of the capacitor.
3. An instrumentation amplifier for bioelectric signals according to claim 1, wherein: the signal module 3 includes a signal source circuit composed of a chip U1, a capacitor C1, a capacitor C2 and a capacitor C3, wherein a pin 5 of the chip U1 is connected with a pin 1 of a single-pole double-throw analog switch Q1 and used for outputting an oscillation signal, a pin 4 of the chip U1 is grounded, the pin 5 and the pin 3 of the chip U1 are respectively connected with a first end and a second end of the capacitor C1, the pin 1 of the chip U1 is grounded, the first end of the capacitor C2 is connected with the pin 1 of the chip U1 and the second end of the capacitor C2 are grounded, the first end of the capacitor C3 is connected with a pin 2 of the chip U1 and the second end of the chip U1 is grounded, the negative power source driving capability and the oscillation signal output of the charge pump are used for realizing the normally-on and normally-off of the single-pole double-throw analog switch Q1 and the single-pole double-throw analog switch Q2.
4. An instrumentation amplifier for bioelectric signals according to claim 1, wherein: the amplification factors of the first operational amplifier U2A and the second operational amplifier U2B are both: GAIN ═ 1+ (R4+ R7)/R6.
5. An instrumentation amplifier for bioelectric signals according to claim 2, wherein: two ends of a capacitor C5 in the primary low-pass filter circuit are low-pass frequency points, and the output voltage of the capacitance values at the two ends is calculated as follows:
Uo＝Ui/[(2*Pi*f*R*C)^2+1]^0.5，
in the formula: uo is the output voltage; ui is the input voltage; pi is the circumference ratio; f is the signal frequency.
6. An instrumentation amplifier for bioelectric signals according to claim 3, wherein: the chip U1 is of SGM3204 type.
7. Use of an instrumentation amplifier for bioelectric signals according to any of the claims 1 to 6 in the field of biomedical electronics.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011472128.XA CN112472095A (en) | 2020-12-14 | 2020-12-14 | Instrument amplifier for bioelectric signals |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011472128.XA CN112472095A (en) | 2020-12-14 | 2020-12-14 | Instrument amplifier for bioelectric signals |
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