WO2018036212A1

WO2018036212A1 - Precision measurement circuit for micro signals

Info

Publication number: WO2018036212A1
Application number: PCT/CN2017/084230
Authority: WO
Inventors: 张贯京; 高伟明; 唐昭月
Original assignee: 深圳市前海安测信息技术有限公司
Priority date: 2016-08-26
Filing date: 2017-05-12
Publication date: 2018-03-01
Also published as: CN206151465U

Abstract

A precision measurement circuit (1) for micro signals, comprising a first biosensor (2), a second biosensor (3), a third biosensor (4), a fourth biosensor (5), a first differential amplifier (11), a second differential amplifier (12), a third differential amplifier (13), an ADC amplification chip (14), and a single chip microcomputer (15). The first differential amplifier (11) has a first input end connected to the first biosensor (2) and a second input end connected to the second biosensor (3). The second differential amplifier (12) has a first input end connected to the third biosensor (4) and a second input end connected to the fourth biosensor (5). An output end of the first differential amplifier (11) is connected to a first input end of the third differential amplifier (13). An output end of the second differential amplifier (12) is connected to a second input end of the third differential amplifier (13). An output end of the third differential amplifier (13) is connected to an input end of the ADC amplification chip (14). An output end of the ADC amplification chip (14) is connected to the single chip microcomputer (15). The precision measurement circuit for micro signals can accurately measure weak signals.

Description

Micro signal precision measurement circuit

[0001] The present invention relates to the technical field of signal measurement, and in particular, to a micro signal precision measurement circuit.

Background technique

[0002] The amplification of micro signals is the basis of signal measurement and measurement. For small signals within 50mV, it cannot be directly used for chips such as AD sampling. It must be amplified by the amplifier circuit in the signal measurement circuit to measure. Micro-signal measurement is often a difficult point in signal measurement, and small signals within 50mV are difficult to detect by signal measurement circuits. Generally, bioelectrical signals output by biosensors (such as blood glucose, body temperature, heart rate biosensors, etc. in vital signs monitoring biosensors) are relatively weak. Since the bioelectrical signals to be measured are weak, the bioelectricity to be measured must be measured by an amplifying circuit. The signal can only be measured after it has been amplified. In the existing signal measuring equipment, the amplifying circuit amplifies the weak signal, and the existing signal measuring circuit often generates a temperature drift phenomenon and causes strong signal interference, so that the weak bioelectric signal is submerged in the interference signal. The measurement result of the weak bioelectric signal to be measured is inaccurate, and even the weak bioelectric signal to be measured cannot be measured.

technical problem

[0003] The main object of the present invention is to provide a micro-signal precision measuring circuit, which aims to solve the problem that the existing signal measuring circuit cannot accurately measure a weak signal.

Problem solution

Technical solution

[0004] In order to achieve the above object, the present invention provides a micro signal precision measuring circuit, including a first biosensor, a second biosensor, a third biosensor, a fourth biosensor, a first differential amplifier, and a second differential. An amplifier, a third differential amplifier, an ADC amplification chip, and a single chip microcomputer, the ADC amplification chip includes an amplification circuit chip and an ADC circuit chip, wherein:

[0005] The first input end of the first differential amplifier is connected to the first biosensor, and the second input end of the first differential amplifier is connected to the second biosensor;

[0006] The first input end of the second differential amplifier is connected to the third biosensor, and the second differential amplifier The second input is coupled to the fourth biosensor;

[0007] an output of the first differential amplifier is coupled to a first input of the third differential amplifier, and an output of the second differential amplifier is coupled to a second input of the third differential amplifier;

[0008] an output end of the third differential amplifier is connected to an input end of the amplifying circuit chip, an output end of the amplifying circuit chip is connected to an input end of an ADC circuit chip, and an output end of the ADC circuit chip is connected to The single chip microcomputer.

[0009] Preferably, the first differential amplifier includes two first resistors, two second resistors, and a first transistor.

[0010] Preferably, one of the first resistors of the first differential amplifier is connected in series to the first input end of the first transistor, and the other one of the first differential amplifiers is connected in series to the first transistor. a second input end, one end of one of the second resistors of the first differential amplifier is connected to a first input end of the first transistor and the other end of the second resistor is connected to an output end of the first transistor, One of the other second resistors of the first differential amplifier is connected to the second input terminal of the first transistor and the other end of the second resistor is connected to the ground line.

[0011] Preferably, the second differential amplifier comprises two first resistors, two second resistors, and a first transistor.

[0012] Preferably, one of the first resistors of the second differential amplifier is connected in series to the first input end of the first transistor, and the other one of the second differential amplifiers is connected in series to the first transistor. a second input end, one end of one of the second resistors of the second differential amplifier is connected to the first input end of the first transistor and the other end of the second resistor is connected to the output end of the first transistor, One of the other second resistors of the second differential amplifier is connected to the second input terminal of the first transistor and the other end of the second resistor is connected to the ground line.

[0013] Preferably, the third differential amplifier comprises two third resistors, two fourth resistors and a second transistor.

[0014] Preferably, one of the third resistors of the third differential amplifier is connected in series to the first input end of the second transistor, and the other third resistor of the third differential amplifier is connected in series to the second transistor. a second input end, one end of one of the fourth resistors of the third differential amplifier is connected to the first input end of the second transistor and the other end of the fourth resistor is connected to the output end of the second transistor One end of the other fourth resistor of the third differential amplifier is connected to the second input end of the second transistor and the other end of the fourth resistor is connected to the ground line.

[0015] Preferably, the first biosensor is configured to sense a first micro-signal generated by the first wavelength infrared light to be irradiated on the target detection object, and the second biosensor is configured to sense the second wavelength infrared light to be irradiated on the target Detecting a second micro signal generated on the object, a third biosensor for sensing a third micro signal generated by the third wavelength infrared light on the target detection object, and a fourth biosensor for sensing the fourth wavelength infrared light irradiation A fourth microsignal generated on the target detection object.

Advantageous effects of the invention

Beneficial effect

Compared with the prior art, the micro-signal precision measuring circuit of the present invention adopts the above technical solution, and achieves the following technical effects: by acquiring four weak characteristic electric signals and performing differential operation through multi-stage differential amplifiers. The high-magnification amplification is performed to obtain the measurement characteristic signal, so that the weak characteristic electrical signal can be accurately measured.

Brief description of the drawing

DRAWINGS

1 is a schematic diagram showing the circuit structure of a preferred embodiment of the micro-signal precision measuring circuit of the present invention.

[0018] The implementation, functional features, and advantages of the present invention will be further described with reference to the accompanying drawings.

BEST MODE FOR CARRYING OUT THE INVENTION

[0019] To further illustrate the technical means and functions of the present invention in order to achieve the above objects, the specific embodiments, structures, features and functions of the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in FIG. 1, FIG. 1 is a schematic diagram of a circuit structure of a preferred embodiment of the micro-signal precision measuring circuit of the present invention. In this embodiment, the micro-signal precision measuring circuit 1 includes a first biosensor 2, a second biosensor 3, a third biosensor 4, a fourth biosensor 5, a first differential amplifier 11, and a second difference. The sub-amplifier 12, the third differential amplifier 13, the ADC (digital-to-analog conversion) amplifier chip 14, and the single chip microcomputer 15. A first input of the first differential amplifier 11 is coupled to the first biosensor 2, a second input of the first differential amplifier 11 is coupled to the second biosensor 3, and a first input of the second differential amplifier 12 is coupled to the third The biosensor 4, the second input of the second differential amplifier 12 is connected to the fourth biosensor 5. The output of the first differential amplifier 11 is connected to the first input of the third differential amplifier 13, and the output of the second differential amplifier 12 is connected to the second input of the third differential amplifier 13, the output of the third differential amplifier 13. Connected to the input of the AD amplifier chip 14, the output of the ADC amplifier chip 14 is connected to the microcontroller 15.

[0021] The first biosensor 2 is for acquiring a first micro signal from a target detection object, the second biosensor 3 is for acquiring a second micro signal from a target detection object, and the third biosensor 4 is for detecting a target object from a target The third micro-signal is acquired, and the fourth biosensor 5 is configured to acquire the fourth micro-signal from the target detection object. In this embodiment, by using infrared light of four different wavelengths to respectively illuminate the target detection object, the first micro signal is that the first biosensor 2 senses that the first wavelength infrared light is generated on the target detection object. a characteristic electric signal, the second micro signal is that the second biosensor 3 senses a characteristic electric signal generated by the second wavelength infrared light on the target detection object, and the third micro signal is that the third biosensor 4 senses the third The wavelength infrared light illuminates the characteristic electrical signal generated on the target detection object, and the fourth micro signal is the fourth electrical sensor 5 senses the characteristic electric signal generated by the fourth wavelength infrared light irradiation on the target detection object. In this embodiment, four kinds of micro signals which are irradiated to the target detection object by infrared light of four different wavelengths are obtained, and the measurement characteristic signals of the target detection object are measured by performing multi-level differential operation on the four kinds of micro signals and amplifying. For example, it is necessary to measure the blood glucose concentration of the human body, and use four different wavelengths of infrared light to irradiate the blood glucose measurement site (target detection site), respectively, and then obtain four weak blood glucose concentration electrical signals through the four biosensors, and then pass The micro-signal precision measuring circuit 1 performs multi-stage differential operation and amplifies to obtain a blood glucose concentration signal of the human body, and outputs the signal to the single-chip microcomputer 5 for subsequent blood glucose concentration analysis.

[0022] In the embodiment, the first differential amplifier 11 and the second differential amplifier 12 each include two first resistors R1, two second resistors R2, and a first transistor Q1. One of the first resistors R1 of the first differential amplifier 11 is connected in series to the first input terminal of the first transistor Q1, and the other one of the first resistors R1 of the first differential amplifier 11 is connected in series to the second input terminal of the first transistor Q1. One end of one of the second resistors R2 of the first differential amplifier 11 is connected to the first input terminal of the first transistor Q1 and the second The other end of the resistor R2 is connected to the output end of the first transistor Q1, and one end of the other second resistor R2 of the first differential amplifier 11 is connected to the second input end of the first transistor Q1 and the second resistor R2 Connect the other end to the ground wire. One of the first resistors R1 of the second differential amplifier 12 is connected in series to the first input terminal of the first transistor Q1, and the other one of the first resistors R1 of the second differential amplifier 12 is connected in series to the second input terminal of the first transistor Q1. One end of one of the second resistors R 2 of the second differential amplifier 12 is connected to the first input end of the first transistor Q1 and the other end of the second resistor R2 is connected to the output end of the first transistor Q1, the second One end of the other second resistor R2 of the differential amplifier 12 is connected to the second input terminal of the first transistor Q1 and the other end of the second resistor R2 is connected to the ground line.

[0023] The first differential op amp 11 is configured to acquire a first micro signal from the first biosensor 2 and acquire a second micro signal from the second biosensor 3, and pass the first micro signal and the second micro signal through the first The amplification of a differential op amp 11 is differentially operated and amplified to obtain a first differential signal. The second differential amplifier 12 is configured to acquire a third micro signal from the third biosensor 4 and acquire a fourth micro signal from the fourth biosensor 5, and pass the third differential signal and the fourth micro signal through the second differential amplifier The amplification of 12 is differentially operated and amplified to obtain a second differential signal. The amplification factor of the first differential amplifier 11 is equal to the ratio of the resistance of the second resistor R2 in the first differential amplifier 11 and the first resistor R1, and the amplification factor of the second differential amplifier 12 is equal to the amplification factor of the first differential amplifier 11.

In the present embodiment, the temperature coefficient K1 of the first differential amplifier 11 is determined by the temperature coefficient of the second resistor R2 and the first resistor R1 in the first differential amplifier 11. It can be understood that the temperature coefficient of the one resistor refers to the relative change value of the resistance value of the resistor when the temperature changes by 1 ° C, and the unit is ppm : . For example, the temperature coefficient of the first resistor R1 is expressed as QCR1=?R1

/R1??T, the temperature coefficient of the second resistor R2 is expressed as QCR2=?R2/R2??T, where QCR1 is the temperature coefficient of the first resistor R1, and QCR2 is the temperature coefficient of the second resistor R2, ? T is the temperature change value, ? R1 is the change in resistance of the first resistor R1 under temperature change, ? R2 is the resistance change value of the second resistor R2 under temperature change, / represents the division operation, ? Represents multiplication. In practical applications, the temperature coefficient usually uses the average temperature coefficient, and has a negative temperature coefficient, a positive temperature coefficient, and a critical temperature coefficient at which the resistance will only abrupt at a certain temperature. The temperature coefficient K1 of the first differential amplifier 11 is equal to the ratio of the temperature coefficient QCR2 of the second resistor R 2 to the temperature coefficient QCR1 of the first resistor R1, that is, Kl=QCR2/ QCR1. The temperature coefficient of the second differential amplifier 12 is equal to the temperature coefficient of the first differential amplifier 11

In the present embodiment, the third differential amplifier 13 includes two third resistors R3, two fourth resistors R4, and a second transistor Q2. One of the third resistors R3 of the third differential amplifier 13 is connected in series to the first input terminal of the second transistor Q2, wherein the other third resistor R3 is connected in series to the second input terminal of the second transistor Q2; the third differential amplifier 13 One end of the fourth resistor R4 is connected to the first input end of the second transistor Q2 and the other end is connected to the output end of the second transistor Q2, wherein one end of the other fourth resistor R4 is connected to the second transistor The second input of Q2 and the other end are connected to the ground line.

The third differential amplifier 13 is configured to perform differential operation on the first differential signal and the second differential signal by the amplification factor of the third differential amplifier 13 and amplify the measured characteristic signal. In the present embodiment, the amplification factor of the third differential amplifier 13 is equal to the ratio of the resistance values of the fourth resistor R4 and the third resistor R3 in the third differential amplifier 13. The temperature coefficient K2 of the third differential amplifier 13 is determined by the temperature coefficients of the fourth resistor R4 and the third resistor R3 in the third differential amplifier 13. For example, the temperature coefficient of the third resistor R3 is expressed as QCR3=?R3/R3??T, and the temperature coefficient of the fourth resistor R4 is expressed as QCR4=?R4/R4??T, where QCR3 is the temperature of the third resistor R3. The coefficient, QCR4 is the temperature coefficient of the fourth resistor R4, ? T is the temperature change value, ? R3 is the resistance change value of the third resistor R3 under temperature change, ? R4 is the resistance change value of the fourth resistor R4 under temperature change, / represents the division operation, ? Represents multiplication. The temperature coefficient K2 of the third differential amplifier 13 is equal to the ratio of the temperature coefficient QCR4 of the fourth resistor R4 to the temperature coefficient QCR3 of the third resistor R3, that is, K2 = QCR4 / QCR3.

In the present embodiment, the ADC amplification chip 14 includes, but is not limited to, an amplification circuit chip 141 and an ADC circuit chip 142. The input end of the amplifying circuit chip 141 is connected to the output end of the third differential amplifier 13. The output end of the amplifying circuit chip 141 is connected to the input end of the ADC circuit chip 142, and the output end of the ADC circuit chip 142 is connected to The single chip microcomputer 15. The amplifying circuit chip 141 is configured to amplify the measured characteristic signal by the amplification factor of the amplifying circuit chip 141 and output the signal to the ADC circuit chip 142. The ADC circuit chip 142 is configured to count the amplified measured characteristic signals. The mode is converted and output to the microcontroller 15 for subsequent signal measurement analysis.

[0028] In the embodiment, the amplifying circuit chip 141 is composed of an amplifying circuit in the prior art, and the AD The C circuit chip 142 is composed of a digital to analog conversion circuit in the prior art. It can be understood by those skilled in the art that the amplification factor of the amplifying circuit chip 141 is an inherent specific value of the amplifying circuit chip 141, that is, an intrinsic amplification property of the amplifying circuit chip 141, but is subjected to the amplifying circuit chip during operation. The temperature coefficient K3 of 141 produces the effect of temperature drift. The temperature coefficient K3 of the amplifying circuit chip 141 is a temperature characteristic inherent to the amplifying circuit chip 141, which reflects the severity of temperature drift of the amplifying circuit chip 141 when the amplifying circuit chip 141 changes in operating temperature. The amplifying circuit chip 141 generates a temperature drift phenomenon as a function of the operating temperature, causing a signal interference with the measurement characteristic signal, thereby causing the measurement characteristic signal to be submerged in the interference signal, and thus the measurement characteristic signal cannot be accurately measured. In the present embodiment, by determining the temperature coefficients of the first resistor R1 and the second resistor R2 in the first differential amplifier 11 and the second differential amplifier 12, and by determining the third resistor R3 and the third in the third differential amplifier 13 The temperature coefficient of the fourth resistor R4 is such that the product of the temperature coefficient K1 of the first differential amplifier 11 and the temperature coefficient K2 of the third differential amplifier 13 is equal in magnitude and opposite in sign to the temperature coefficient K3 of the amplifying circuit chip 141, thus making the first The influence of the temperature drift generated by the differential amplifier 11 and the third differential amplifier 13 on the signal interference and the influence of the temperature drift generated by the amplifying circuit chip 141 on the signal interference cancel each other, thereby eliminating the signal amplification of the weak signal in the high-magnification amplifier circuit. Signal interference caused by temperature drift encountered, improving the accuracy of measuring weak signals.

The above is only a preferred embodiment of the present invention, and thus does not limit the scope of the patent of the present invention, and the equivalent structure or equivalent function transformation made by the specification and the drawings of the present invention, or directly or indirectly In other related technical fields, the same is included in the scope of patent protection of the present invention.

Industrial applicability

Compared with the prior art, the micro-signal precision measuring circuit of the present invention adopts the above technical solution, and achieves the following technical effects: by acquiring four weak characteristic electric signals and performing differential operations through multi-stage differential amplifiers. The high-magnification amplification is performed to obtain the measurement characteristic signal, so that the weak characteristic electrical signal can be accurately measured.

Claims

Claim

[Claim 1] A micro-signal precision measuring circuit, comprising: a first biosensor, a second biosensor, a third biosensor, a fourth biosensor, a first differential amplifier, and a first a second differential amplifier, a third differential amplifier, an ADC amplification chip, and a single chip microcomputer, wherein the ADC amplification chip includes an amplification circuit chip and an ADC circuit chip, wherein: the first input end of the first differential amplifier is connected to the first biosensor, a second input of a differential amplifier is coupled to the second biosensor; a first input of the second differential amplifier is coupled to the third biosensor, and a second input of the second differential amplifier is coupled to the fourth biosensor; An output of the first differential amplifier is coupled to a first input of the third differential amplifier, and an output of the second differential amplifier is coupled to a second input of the third differential amplifier; an output of the third differential amplifier is coupled to An input end of the amplifying circuit chip, the amplifying circuit core An output terminal connected to the input of the ADC circuit chip, the output of the ADC circuit chip connected to the microcontroller.

[Claim 2] The fine signal precision measuring circuit according to claim 1, wherein the first differential amplifier comprises two first resistors, two second resistors, and a first transistor.

[Claim 3] The micro-signal precision measuring circuit according to claim 2, wherein one of the first resistors of the first differential amplifier is connected in series to the first input end of the first transistor, the first One of the first resistors of the differential amplifier is connected in series to the second input of the first transistor, one end of one of the second resistors of the first differential amplifier is connected to the first input of the first transistor and the second The other end of the resistor is connected to the output end of the first transistor, one end of the other second resistor of the first differential amplifier is connected to the second input end of the first transistor and the other end of the second resistor is connected to Ground wire.

[Claim 4] The fine signal precision measuring circuit according to claim 1, wherein the second differential amplifier comprises two first resistors, two second resistors, and a first transistor.

[Claim 5] The fine signal precision measuring circuit according to claim 4, wherein one of the first resistors of the second differential amplifier is connected in series to the first input end of the first transistor, One of the other first resistors of the second differential amplifier is connected in series to the second input terminal of the first transistor, and one end of one of the second resistors of the second differential amplifier is connected to the first input terminal of the first transistor And the other end of the second resistor is connected to the output end of the first transistor, and one end of the other second resistor of the second differential amplifier is connected to the second input end of the first transistor and the second resistor Connect the other end to the ground wire.

[Claim 6] The fine signal precision measuring circuit according to claim 1, wherein the third differential amplifier comprises two third resistors, two fourth resistors, and a second transistor.

[Claim 7] The fine signal precision measuring circuit according to claim 6, wherein one of the third resistors of the third differential amplifier is connected in series to the first input end of the second transistor, the third The other third resistor of the differential amplifier is connected in series to the second input terminal of the second transistor, one end of one of the fourth resistors of the third differential amplifier is connected to the first input end of the second transistor and the fourth The other end of the resistor is connected to the output end of the second transistor, and one end of the other fourth resistor of the third differential amplifier is connected to the second input end of the second transistor and the other end of the fourth resistor is connected to Ground wire.

The micro-signal precision measuring circuit according to any one of claims 1 to 7, wherein the first biosensor is configured to sense a first-wavelength infrared light irradiation generated on a target detection object. a first micro-signal, the second bio-sensor is configured to sense a second micro-signal generated by the second-wavelength infrared light to be irradiated on the target detection object, and the third bio-sensor is configured to sense the third-wavelength infrared light to be irradiated on the target detection object The generated third micro-signal, the fourth biosensor is configured to sense the fourth micro-signal generated by the fourth-wavelength infrared light to be irradiated on the target detection object.