CN110755067A - Front-end analog circuit and front-end analog chip for electrocardio and pulse wave combined acquisition - Google Patents
Front-end analog circuit and front-end analog chip for electrocardio and pulse wave combined acquisition Download PDFInfo
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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
- A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
- A61B5/316—Modalities, i.e. specific diagnostic methods
- A61B5/318—Heart-related electrical modalities, e.g. electrocardiography [ECG]
- A61B5/319—Circuits for simulating ECG signals
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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
- A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
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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
- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
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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
- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
- A61B5/0205—Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
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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
- A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
- A61B5/25—Bioelectric electrodes therefor
- A61B5/279—Bioelectric electrodes therefor specially adapted for particular uses
- A61B5/28—Bioelectric electrodes therefor specially adapted for particular uses for electrocardiography [ECG]
- A61B5/282—Holders for multiple electrodes
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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
- A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
- A61B5/30—Input circuits therefor
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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
- A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
- A61B5/30—Input circuits therefor
- A61B5/304—Switching circuits
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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
- 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
- A61B5/7225—Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
Abstract
The utility model belongs to the technical field of physiological signal detection, a front-end analog circuit and front-end analog chip that electrocardio, pulse wave jointly gathered are provided, amplify the processing through transconductance instrumentation amplifier circuit to the signal of detecting electrode input, will through transimpedance amplifier circuit the current signal conversion that photodiode provided is voltage signal to amplify the processing with the first detected signal that output corresponds to voltage signal, then control its inside switch switching state through change-over switch circuit, adopt same programmable gain amplifier circuit, low pass filter circuit and output buffer circuit to handle detected signal, solved current electrocardio, pulse wave signal acquisition chip exist the consumption higher, the complicated scheduling problem of structure.
Description
Technical Field
The application belongs to the technical field of physiological signal detection, and particularly relates to a front-end analog circuit and a front-end analog chip for electrocardio and pulse wave combined collection.
Background
Electrocardio (ECG), blood oxygen (SPO2) and blood pressure are all more common human physiological signals, and wearable equipment is usually adopted to acquire Electrocardio (ECG) and pulse wave (PPG) signals, so that the heart rate and the blood oxygen saturation can be calculated, and noninvasive continuous blood pressure can also be calculated. However, the conventional electrocardio and pulse wave signal acquisition chip has the problems of high power consumption, complex structure and the like, and the application range of the wearable device is greatly influenced.
Disclosure of Invention
The application aims to provide a front-end analog circuit and a front-end analog chip for electrocardio and pulse wave combined acquisition, and aims to solve the problems of high power consumption, complex structure and the like of the conventional electrocardio and pulse wave signal acquisition chip.
The embodiment of the application provides a front end analog circuit that electrocardio, pulse wave jointly gathered, is connected with a plurality of detection electrodes, photodiode and emitting diode, front end analog circuit includes:
the transconductance instrumentation amplifier circuit is connected with the multiple pairs of detection electrodes and is used for amplifying signals input by the detection electrodes;
the transimpedance amplifier circuit is connected with the photosensitive diode and is used for converting a current signal provided by the photosensitive diode into a voltage signal and amplifying the voltage signal so as to output a corresponding first detection signal;
the programmable gain amplifier circuit is used for amplifying an input signal;
the switching switch circuit is respectively connected with the transconductance instrument amplifier circuit, the transimpedance amplifier circuit and the programmable gain amplifier circuit and is used for receiving a switching switch circuit control signal and controlling the switching state of the switch in the switching switch circuit according to the switching switch circuit control signal;
the low-pass filter circuit is connected with the programmable gain amplifier circuit and is used for eliminating high-frequency noise in an output signal of the programmable gain amplifier circuit;
the output buffer circuit is connected with the low-pass filter circuit and is used for providing output driving capability for the second detection signal output by the low-pass filter circuit;
the light source driving circuit is connected with the light emitting diode and used for receiving a light source control signal and generating a light source driving signal according to the light source control signal so as to drive the light emitting diode to be lightened; and
and the clock control circuit is connected with the light source driving circuit and the change-over switch circuit and is used for receiving a clock signal and generating a change-over switch circuit control signal and a light source control signal according to the clock signal.
Optionally, the clock control circuit is further configured to generate a plurality of clock timing signals according to the switch circuit control signal and the plurality of light source control signals, where the clock timing signals correspond to types of signals collected by the front-end analog circuit.
Optionally, the front-end analog circuit further includes: the right leg driving circuit is connected with the plurality of pairs of detection electrodes and is used for generating a right leg driving signal according to signals input by the plurality of detection electrodes; the right leg driving signal is fed back to the surface of the skin of the human body through the right leg electrode so as to inhibit common mode noise.
Optionally, the front-end analog circuit further includes: and the digital-to-analog conversion circuit is connected with the light source driving circuit and is used for receiving an external driving current control signal and adjusting the light source driving signal according to the driving current control signal.
Optionally, the front-end analog circuit further includes a plurality of gain control signal sources for adjusting the gain of the programmable gain amplifier circuit.
Optionally, the plurality of gain control signal sources are further configured to adjust a gain of the transimpedance amplifier circuit.
Optionally, the plurality of light emitting diodes include a red light emitting diode and an infrared light emitting diode.
Optionally, a filter capacitor is further disposed between the switch circuit and the programmable gain amplifier circuit.
Optionally, the switch circuit is an alternative switch circuit.
The embodiment of the application also provides a front-end analog chip for reconfigurable electrocardio and pulse wave combined acquisition, which comprises:
a plurality of detection electrode access ends;
a plurality of light emitting diode access ends;
a photodiode access terminal;
a first detection signal output terminal;
a second detection signal output terminal; and
the front-end analog circuit according to any one of the above claims, wherein the front-end analog circuit is connected to the plurality of detection electrode access ends, the plurality of light emitting diode access ends, the photodiode access end, the first detection signal output end and the second detection signal output end, respectively.
In the front-end analog circuit and the front-end analog chip that electrocardio, pulse wave jointly gathered that this application provided, amplify the processing through transconductance instrumentation amplifier circuit to the signal of detecting electrode input, will through transimpedance amplifier circuit the current signal that photodiode provided converts voltage signal into to amplify the processing with the first detected signal that output corresponds to voltage signal, then control its inside switch switching state through the change over switch circuit, adopt same programmable gain amplifier circuit, low pass filter circuit and output buffer circuit to handle detected signal, solved current electrocardio, the problem such as the consumption that pulse wave signal acquisition chip exists is higher, the structure is complicated.
Drawings
Fig. 1 is a schematic structural diagram of a front-end analog circuit according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of a front-end analog circuit according to another embodiment of the present application;
fig. 3 is a schematic structural diagram of a front-end analog circuit according to another embodiment of the present application;
fig. 4 is a schematic structural diagram of a front-end analog circuit according to another embodiment of the present application;
fig. 5 is a schematic structural diagram of a front-end analog circuit according to another embodiment of the present application;
FIG. 6 is a timing diagram of clock signals according to an embodiment of the present application;
FIG. 7 is a schematic diagram of an ECG signal collected by the chip according to the embodiment of the present application;
fig. 8 is a schematic diagram of a PPG ac signal and a PPG dc signal acquired by using a chip according to an embodiment of the present application;
fig. 9 is a schematic structural diagram of a switch circuit according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In the description of the present application, it is to be understood that the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.
The embodiment of the present application provides a front-end analog circuit for jointly collecting electrocardiographic waves and pulse waves, fig. 1 is a schematic structural diagram of the front-end analog circuit provided in the embodiment, as shown in fig. 1, the front-end analog circuit in the embodiment is connected to a plurality of detection electrodes 11, a photodiode 21, and a light emitting diode 71, and the front-end analog circuit includes: a transconductance instrumentation amplifier circuit 10 connected to the plurality of pairs of detection electrodes 11, for amplifying signals input from the detection electrodes 11; the transimpedance amplifier circuit 20 is connected to the photodiode 21 and configured to convert a current signal provided by the photodiode 21 into a voltage signal and amplify the voltage signal to output a corresponding first detection signal; a programmable gain amplifier circuit 40 for amplifying an input signal; the switch circuit 30 is respectively connected to the transconductance instrumentation amplifier circuit 10, the transimpedance amplifier circuit 20, and the programmable gain amplifier circuit 40, and configured to receive a switch circuit control signal and control a switch switching state therein according to the switch circuit control signal; a low pass filter circuit 50 connected to the programmable gain amplifier circuit 40 for removing high frequency noise from the output signal of the programmable gain amplifier circuit 40; an output buffer circuit 60 connected to the low pass filter circuit 50 for providing an output driving capability for the second detection signal outputted from the low pass filter circuit 50; the light source driving circuit 70 is connected to the light emitting diode 71 and configured to receive a light source control signal and generate a light source driving signal according to the light source control signal to drive the light emitting diode 71 to light up; the clock control circuit 80, connected to the light source driving circuit 70 and the switch circuit 30, is configured to receive a clock signal and generate a switch circuit control signal and a light source control signal according to the clock signal.
In this embodiment, the front-end analog circuit in this embodiment mainly amplifies a signal input by the detection electrode 11 through the transconductance amplifier circuit 10, and converts a current signal provided by the photodiode 21 into a voltage signal through the transimpedance amplifier circuit 20, wherein the detection electrode 11 mainly collects a human body physiological electrical signal, such as an ECG signal, through contact with human skin, and the transimpedance amplifier circuit 20 mainly collects a human body pulse wave signal through the photodiode 21, converts the current signal provided by the photodiode 21 into a corresponding voltage signal, and then amplifies the voltage signal to output a first detection signal through the first detection signal output port. In this embodiment, the connection state between the transconductance instrumentation amplifier circuit 10 and the programmable gain amplifier circuit 40 and the connection state between the transimpedance amplifier circuit 20 and the programmable gain amplifier circuit 40 are controlled by the switch circuit 30, so that the detection signal is processed by using the same programmable gain amplifier circuit 40, the low-pass filter circuit 50 and the output buffer circuit 60, and the problems of high power consumption, complex structure and the like of the conventional electrocardio and pulse wave signal acquisition chip are solved.
In this embodiment, to monitor the pulse wave, it is necessary to acquire the blood flow signal under the skin, so that a great amount of hemodynamic information is stored in the pulse wave, the change of hemodynamic parameters is closely related to the change of waveform characteristics of the pulse wave, and the blood flow parameters can make a relatively comprehensive evaluation on the function and potential of the cardiovascular system. In this embodiment, the clock control circuit 80 generates the light source control signal to control the light source driving circuit 70 to generate the corresponding light source driving signal, so as to drive the light emitting diode 71 to light up, and the light emitting diode 71 illuminates the blood vessel of the human body, and provide different light sources for the photodiode 21 to collect the pulse wave signal of the human body, for example, the light source driving circuit 70 drives the light emitting diode 71 to light up periodically based on the light source control signal, or controls the magnitude of the driving current of the light emitting diode, so as to provide light source brightness of multiple levels, and at this time, the photodiode 21 can collect the pulse wave signals under different brightness environments in a larger collection period.
Further, the light emitting diodes 71 may also include a plurality of light emitting diodes, such as a red light diode and an infrared light diode, and at this time, the light source driving circuit 70 drives the red light diode and the infrared light diode to light respectively based on the light source control signal, for example, drives the red light diode and the infrared light diode to light alternately, or increases the light emitting brightness thereof step by step in a period during the alternate lighting.
In one embodiment, referring to fig. 2, the front-end analog circuit further includes: a right leg driving circuit 91 connected to the plurality of pairs of detection electrodes, for generating a right leg driving signal according to signals inputted from the plurality of detection electrodes; the right leg driving signal is fed back to the surface of the skin of the human body through the right leg electrode so as to inhibit common mode noise.
In one embodiment, the right leg driving circuit can also generate a lead shielding line driving signal, so that the leakage current between the lead wire and the shielding line can be reduced, the safety of a patient is guaranteed, and the input impedance of the circuit is improved. Because distributed capacitance exists between the lead wire and the shielding wire, capacitance reactance presented to 50Hz signals is several megaohms, if the shielding wire is directly grounded, the capacitance reactance and the input impedance of the input circuit are in a parallel state, the input impedance of the whole machine is greatly reduced, leakage current from a human body to the ground is increased, and the safety factor is reduced. The lead shielding line is used for driving a signal to provide higher input impedance, so that the equipotential between the shielding line and a signal ground is ensured, and the shielding ground is skillfully isolated from the signal ground, thereby keeping the advantage that an input circuit has high input impedance.
In one embodiment, the right leg driving circuit 91 may be composed of a buffer and an inverting amplifier circuit, wherein the buffer generates a lead shielding line driving signal according to a common mode signal provided by a plurality of signal detection channels, and the inverting amplifier circuit performs an inverting amplification filtering process on the lead shielding line driving signal to generate a right leg driving signal.
In one embodiment, referring to fig. 3, the front-end analog circuit further includes: the digital-to-analog conversion circuit 92 connected to the light source driving circuit 70 is configured to receive an external driving current control signal and adjust the light source driving signal according to the driving current control signal.
In this embodiment, the digital-to-analog conversion circuit 92 adjusts the light source driving signal according to the driving current control signal, so as to control the magnitude of the driving current of the light emitting diode 71, and provide a plurality of levels of light source brightness for the signal collected by the photodiode 21, at this time, the photodiode 21 can collect pulse wave signals under different brightness environments in a larger collection period.
In one embodiment, the clock control circuit 80 is further configured to generate a plurality of clock timing signals according to the switch circuit control signal and the plurality of light source control signals, wherein the clock timing signals correspond to the signal types collected by the front-end analog circuit.
In the present embodiment, referring to fig. 4, the clock control circuit 80 is connected to the main control circuit 93, the switch circuit control signal is used for controlling the connection state of the switch circuit 30, the light source control signal is used for controlling the light emitting state of the light emitting diode 71, the clock control circuit 80 provides a plurality of clock timing signals to the main control circuit 93, thereby feeding back to the main control circuit 93 the type of the signal provided at this time at the first detection signal output terminal and the second detection signal output terminal, for example, if the switch circuit 30 controls the transconductance instrumentation amplifier circuit 10 and the programmable gain amplifier circuit 40 to be connected, at this time, the signal type output by the first detection signal output terminal VOUT is an ECG signal, if the light source control signal drives the red light emitting diode to light up at this time, the signal type output by the second detection signal output terminal VO _ LED is a red PPG alternating signal.
Further, in this embodiment, the main control circuit 93 is configured to acquire the blood oxygen saturation formula of the human body based on the ECG signal output by the first detection signal output terminal and the PPG signal output by the second detection signal output terminal under different illumination environments, that is, by acquiring the PPG signals of different lights, the blood oxygen saturation formula is acquired.
Fig. 5 is a schematic structural diagram of integrating a front-end analog circuit into an acquisition chip according to an embodiment of the present disclosure, and referring to fig. 5, the front-end analog circuit in this embodiment not only integrates an ECG and a PPG signal acquisition circuit of two wavelengths of light into one chip, but also implements sharing of two channel signals by using the structure, which greatly simplifies a circuit structure, reduces a chip area, and reduces overall power consumption of the chip.
Further, the front-end analog circuit provided in the embodiment of the present application further includes a plurality of gain control signal sources, which are used to adjust the gain of the programmable gain amplifier circuit 40. Referring to fig. 5, the signal output from the switching circuit 30 is further amplified by a gain control signal source EN1 and a gain control signal source EN2, for example, the gain of the programmable gain amplifier circuit 40 is controlled by two signals, EN1 and EN2, where EN1 is 1, EN2 is 0, the gain is 100 times, EN1 is 0, and EN2 is 1, the gain is 215 times.
In one embodiment, referring to fig. 5, an ECG signal transconductance instrumentation amplifier (INA) differentially amplifies signals collected at signal ends VP and VN of two detection electrodes 11 (i.e. ECG electrodes) and converts the signals into single-ended output, with a gain of 5 times. Meanwhile, the common-mode signal extracted from the input end is reversely amplified through the right leg driving circuit 91, fed back to the right leg electrode and transmitted to the human body through the right leg electrode, so that the common-mode signal is restrained.
In one embodiment, a plurality of gain control signal sources are also used to adjust the gain of the transimpedance amplifier circuit 20. The transimpedance amplifier circuit 20 converts the current signal of the photodiode 21 into a voltage signal, the amplification factor of which is determined by the resistance of the transimpedance, and in this embodiment, the resistance of the transimpedance can be controlled by two signals provided by the gain control signal source ENA and the gain control signal source ENB. For example, when ENA is 1 and ENB is 0, the transimpedance value is 100k Ω; when ENA is equal to 0 and ENB is equal to 1, the transimpedance value is 200k omega; when ENA is equal to 1 and ENB is equal to 1, the transimpedance value is 66.7k Ω.
In one embodiment, the ECG signal transconductance instrumentation amplifier (INA) and the optical-to-electrical signal transimpedance amplifier (TIA) are controlled by an alternative switch (MUX) with the Programmable Gain Amplifier (PGA). When an ECG signal needs to be collected, the Programmable Gain Amplifier (PGA) is connected with an ECG signal transconductance instrumentation amplifier (INA); when PPG signals need to be acquired, a Programmable Gain Amplifier (PGA) is connected with a photoelectric signal trans-impedance amplifier (TIA).
In one embodiment, a Low Pass Filter (LPF) is used to filter out high frequency noise, with a bandwidth of 150Hz, and provides a high input impedance for the output of the second detection signal by means of an output Buffer (BUF) connected after the low pass filter.
In one embodiment, referring to FIG. 5, the plurality of LEDs 71 includes a red LED and an infrared LED.
In the present embodiment, the light source driving circuit 70 (i.e., LED driving) is mainly used to drive the infrared light emitting diode LED _ IR and the red light emitting diode LED _ R. The driving current of the led 71 can be controlled by the analog output of the digital-to-analog conversion module (DAC) in the digital-to-analog conversion circuit 92. in one embodiment, the driving current is adjusted by 4 levels according to the signals received by the control signal terminals D0 and D1, for example, D0 controls the lower four bits of the DAC input, and D1 controls the upper four bits of the DAC input. Further, under the control of the main control circuit 93, the values of D0 and D1 may be: 00,01,10,11, thereby achieving four-level regulation of the light emitting diodes 71.
In one embodiment, the clock control circuit 80 sends a light source control signal to the light source driving circuit 70 according to an externally input clock signal CLK (100Hz) to realize the alternate lighting of the external infrared light emitting diode LED _ IR and the red light emitting diode LED _ R. Meanwhile, the clock control circuit 80 also controls the time sequence of an alternative switch (MUX), so as to realize the acquisition of different detection signals. In addition, the clock control circuit 80 may also output four different timing clocks to the master circuit 93: CLK1, CLK2, CLK3 and CLK4, by which the master control circuit 93 may achieve separate acquisition of the ECG signal, red PPG signal, infrared PPG signal, red DC signal, infrared DC signal and ambient light signal.
In one embodiment, the second detection signal output port VOUT may be an output port for an ac signal and an ECG signal of the PPG signal, and the first detection signal output port VO _ LED is an output port for a dc voltage and an ambient light signal of the PPG signal. Specifically, in an application of the front-end analog chip, the clock control circuit 80 generates the clock signal CLK1, the clock signal CLK2, the clock signal CLK3 and the clock signal CLK4 according to an externally input clock signal CLK, wherein timing charts of the clock signals CLK, CLK1, CLK2, CLK3, CLK4 and the light source control signal are shown in fig. 6, in this embodiment, by controlling timings of the light source control signal and the alternative switch (MUX), different signals are collected, for example, the infrared light emitting diode LED _ IR and the red light emitting diode LED _ R are not turned on, when the ECG signal transconductance instrumentation amplifier (INA) is connected to the Programmable Gain Amplifier (PGA), the clock signals CLK1 and CLK2 are at high levels, at this time, a signal output by the first detection signal output port VO _ LED is an ambient light signal, a signal output by the second detection signal output port VOUT is an ECG signal, a schematic diagram of the ECG signal output from the second detection signal output port VOUT is shown in fig. 7; when a red light emitting diode (LED _ R) is lightened, an infrared light emitting diode (LED _ IR) is not lightened, and a photoelectric signal trans-impedance amplifier (TIA) is connected with a Programmable Gain Amplifier (PGA), a clock signal CLK3 is at a high level, at the moment, a signal output by a first detection signal output port VO _ LED is a direct current voltage signal of a red light PPG signal, and a signal output by a second detection signal output port VOUT is an alternating current signal of the red light PPG signal; red light emitting diode LED _ R is not lit, infrared light emitting diode LED _ IR is lit, when a photoelectric signal transimpedance amplifier (TIA) is connected to a Programmable Gain Amplifier (PGA), a clock signal CLK4 is at a high level, at this time, a signal output from a first detection signal output port VO _ LED is a direct current voltage signal of an infrared PPG signal, and a signal output from a second detection signal output port VOUT is an alternating current signal of an infrared PPG signal, where a schematic diagram of the PPG alternating current signal and the PPG direct current signal is shown in fig. 8.
In one embodiment, the sampling frequency of the ECG signal is 100Hz, the sampling frequency of the PPG dc voltage and ac signal is 50Hz, and the sampling frequency of the ambient light is 100 Hz.
In one embodiment, referring to fig. 5, a filter capacitor C0 is further disposed between the switch circuit 30 and the programmable gain amplifier circuit 40. In the present embodiment, the filter capacitor C0 is used to filter low-frequency noise in the signal output from the switch circuit 30.
In one embodiment, the switch circuit 30 is an alternative switch circuit, and its output terminal is connected to the output terminal of the transconductance instrumentation amplifier or to the output terminal of the transimpedance amplifier by timing control according to a timing signal.
In another embodiment, the switch circuit 30 is a sample-and-hold circuit, and a schematic circuit diagram thereof is shown in fig. 9. In this embodiment, the ECG signal transconductance instrumentation amplifier (INA) is connected to the Programmable Gain Amplifier (PGA) through the switch K11, the resistor R1, and the switch K12 in this order, and the photoelectric signal transimpedance amplifier (TIA) is connected to the Programmable Gain Amplifier (PGA) through the switch K21, the resistor R2, and the switch K22 in this order. In this embodiment, when the switches K11 and K22 are turned off and K12 and K21 are turned on, the ECG signal is stored in the capacitor C1, and the Programmable Gain Amplifier (PGA) amplifies the PPG signal value stored in the capacitor C2 at the previous timing; when switches K11 and K22 are open and K12 and K21 are closed, the PPG signal will be stored in capacitor C2, while a Programmable Gain Amplifier (PGA) amplifies the ECG signal value stored in capacitor C1 for the previous timing.
In one embodiment, the output buffer circuit 60 is formed by a buffer BUF for providing an output driving capability for the amplified and filtered signal to be output off-chip.
In this embodiment, the power management module 20 is configured to provide different power signals for the circuit modules in the chip, so that the front-end analog circuit can operate under a stable voltage and current even under the condition of battery power supply.
In the front-end analog circuit and the front-end analog chip that electrocardio, pulse wave jointly gathered that this application provided, amplify the processing through transconductance instrumentation amplifier circuit to the signal of detecting electrode input, will through transimpedance amplifier circuit the current signal that photodiode provided converts voltage signal into to amplify the processing with the first detected signal that output corresponds to voltage signal, then control its inside switch switching state through the change over switch circuit, adopt same programmable gain amplifier circuit, low pass filter circuit and output buffer circuit to handle detected signal, solved current electrocardio, the problem such as the consumption that pulse wave signal acquisition chip exists is higher, the structure is complicated.
The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (10)
1. The utility model provides a front end analog circuit that electrocardio, pulse wave jointly gathered, with a plurality of detection electrodes, photosensitive diode and emitting diode connection, its characterized in that, front end analog circuit includes:
the transconductance instrumentation amplifier circuit is connected with the multiple pairs of detection electrodes and is used for amplifying signals input by the detection electrodes;
the transimpedance amplifier circuit is connected with the photosensitive diode and is used for converting a current signal provided by the photosensitive diode into a voltage signal and amplifying the voltage signal so as to output a corresponding first detection signal;
the programmable gain amplifier circuit is used for amplifying an input signal;
the switching switch circuit is respectively connected with the transconductance instrument amplifier circuit, the transimpedance amplifier circuit and the programmable gain amplifier circuit and is used for receiving a switching switch circuit control signal and controlling the switching state of the switch in the switching switch circuit according to the switching switch circuit control signal;
the low-pass filter circuit is connected with the programmable gain amplifier circuit and is used for eliminating high-frequency noise in an output signal of the programmable gain amplifier circuit;
the output buffer circuit is connected with the low-pass filter circuit and is used for providing output driving capability for the second detection signal output by the low-pass filter circuit;
the light source driving circuit is connected with the light emitting diode and used for receiving a light source control signal and generating a light source driving signal according to the light source control signal so as to drive the light emitting diode to be lightened; and
and the clock control circuit is connected with the light source driving circuit and the change-over switch circuit and is used for receiving a clock signal and generating a change-over switch circuit control signal and a light source control signal according to the clock signal.
2. The front-end analog circuit of claim 1, wherein the front-end analog circuit further comprises: the right leg driving circuit is connected with the plurality of pairs of detection electrodes and is used for generating a right leg driving signal according to signals input by the plurality of detection electrodes; the right leg driving signal is fed back to the surface of the skin of the human body through the right leg electrode so as to inhibit common mode noise.
3. The front-end analog circuit of claim 1, wherein the front-end analog circuit further comprises: and the digital-to-analog conversion circuit is connected with the light source driving circuit and is used for receiving an external driving current control signal and adjusting the light source driving signal according to the driving current control signal.
4. The front-end analog circuit of claim 1, wherein the clock control circuit is further configured to generate a plurality of clock timing signals according to the switcher circuit control signal and a plurality of light source control signals, wherein the clock timing signals correspond to a type of signal collected by the front-end analog circuit.
5. The front-end analog circuit of claim 1, wherein the front-end analog circuit further comprises a plurality of gain control signal sources for adjusting the gain of the programmable gain amplifier circuit.
6. The front-end analog circuit of claim 5, wherein a plurality of gain control signal sources are further used to adjust the gain of the transimpedance amplifier circuit.
7. The front-end analog circuit of claim 1, wherein the plurality of light emitting diodes comprises a red light emitting diode and an infrared light emitting diode.
8. The front-end analog circuit of claim 2, wherein a filter capacitor is further disposed between the switch circuit and the programmable gain amplifier circuit.
9. The front-end analog circuit of claim 1, wherein the switch circuit is an alternative switch circuit.
10. A front-end analog chip for reconstructing electrocardio and pulse wave joint acquisition is characterized by comprising:
a plurality of detection electrode access ends;
a plurality of light emitting diode access ends;
a photodiode access terminal;
a first detection signal output terminal;
a second detection signal output terminal; and
the front-end analog circuit of any of claims 1 to 9, connected to a plurality of detection electrode inputs, a plurality of light emitting diode inputs, a photodiode input, a first detection signal output, and a second detection signal output, respectively.
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| CN201911055290.9A CN110755067A (en) | 2019-10-31 | 2019-10-31 | Front-end analog circuit and front-end analog chip for electrocardio and pulse wave combined acquisition |
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