PPG signal acquisition and processing circuit

Abstract

The utility model discloses a PPG signal acquisition and processing circuit. The PPG signal acquisition and processing circuit comprises a signal acquisition and processing circuit. The signal acquisition circuit is responsible for acquiring human body PPG heart rate physiological signals, transmitting the signals to the processing circuit, and outputting the signals after processing. The signal acquisition circuit is composed of a sensor J1, a resistor R81, an inductor L8 and a capacitor C34. A first pin of the U1 is connected with the output end through a resistor R81, a second pin of the U1 is grounded, a third pin of the U1 is connected with one end of the C34 and one end of the L8, the other end of the C34 is grounded, and the other end of the L8 is connected with a power source. The sensor J1 can be in direct contact with a human body, original signals reflecting heart rate and other characteristics are collected according to the photoelectric sensing principle, and a foundation is laid for follow-up analysis and processing. The inductor L8 can filter and stabilize the power supply and provide stable working voltage for the U1, so that acquisition errors caused by power supply fluctuation are avoided, and the signal quality and reliability are improved. The capacitor C34 can filter high-frequency noise and interference, so that the collected PPG signals are purer, and the physiological state of the human body is reflected more truly.

Description

Technical Field

[0001] This utility model belongs to the field of signal acquisition technology, specifically a PPG signal acquisition and processing circuit. Background Technology

[0002] PPG (Photoplethysmography) is a physiological signal related to heart rate, obtained through photoplethysmography (PPG). The basic principle of PPG is based on the absorption and scattering characteristics of light by human tissues. When a beam of light shines on the skin surface, some of the light is absorbed and scattered by the skin, tissues, and blood, while the rest is reflected back. Because the blood volume in arteries changes periodically with the contraction and relaxation of the heart, the degree of light absorption and scattering also changes periodically accordingly.

[0003] In the prior art, for example, the technical solution described in patent publication number CN212465979U is a PPG-based cuff blood pressure monitoring system, which consists of a main control circuit, a power management circuit, and other circuits and modules. Specifically, the PPG signal acquisition module uses an AFE4900 ultra-low power chip to acquire PPG signals, and the pressure sensor circuit acquires cuff blood pressure data through a pressure sensor.

[0004] In existing technologies, PPG signals are easily interfered with by various factors, such as motion artifacts, changes in ambient light, and skin conditions (e.g., sweating, sebum secretion). These interferences may lead to a decrease in signal quality and affect the accuracy of heart rate measurement. Utility Model Content

[0005] The purpose of this invention is to provide a PPG signal acquisition and processing circuit to solve the problem in the prior art mentioned in the background that the acquisition of PPG signals is easily affected by various factors, which will affect the accuracy of the acquisition.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0007] A PPG signal acquisition and processing circuit includes a signal acquisition circuit and a signal processing circuit. The signal acquisition circuit is used to acquire the PPG heart rate physiological signal of the human body and transmit the acquired signal to the signal processing circuit. After the signal processing circuit processes the signal, the signal is output.

[0008] The signal acquisition circuit includes sensor J1, resistor R81, inductor L8, and capacitor C34. Pin 1 of sensor J1 is connected to one end of resistor R81, and the other end of resistor R81 is connected to the output terminal. Pin 2 of sensor J1 is grounded. Pin 3 of sensor J1 is connected to one end of capacitor C34 and one end of inductor L8. The other end of capacitor C34 is grounded, and the other end of inductor L8 is connected to the power supply.

[0009] According to the above technical solution, the signal processing circuit includes chip U3, a first processing circuit, a second processing circuit, a crystal oscillator circuit, and peripheral circuits; wherein chip U3 is connected to the first processing circuit, the second processing circuit, the crystal oscillator circuit, and the peripheral circuits respectively.

[0010] According to the above technical solution, the first processing circuit includes connector J2, and pins 1 and 2 of connector J2 are connected to pins 13 and 14 of chip U3, respectively.

[0011] According to the above technical solution, the second processing circuit includes connector J3, capacitor C40, capacitor C96, capacitor C97, and resistor R50; wherein, pin 1 of connector J3 is connected to one end of capacitor C40, and the other end of capacitor C40 is connected to pin 2 of connector J3, one end of resistor R50, and pin 9 of chip U3; the other end of resistor R50 is grounded, and pin 1 of connector J3 and resistor C40 are both connected to the power supply.

[0012] According to the above technical solution, the crystal oscillator circuit includes crystal oscillator X3, capacitor C46, ​​and capacitor C50; one end of crystal oscillator X3 is connected to pin 8 of chip U3 and one end of capacitor C50 respectively; the other end of crystal oscillator X3 is connected to pin 7 of chip U3 and one end of capacitor C46 respectively, the other end of capacitor C46 is connected to the other end of capacitor C50, and both capacitor C46 and capacitor C50 are grounded.

[0013] According to the above technical solution, the peripheral circuit includes resistors R63, R64, R65, R66, R85, R86, capacitors C96 and C97, transistors Q1, Q2, and Q3; one end of resistor R64 is connected to pin 22 of chip U3, and the other end of resistor R64 is connected to the base of transistor Q1; the emitter of transistor Q1 is grounded, and the collector of transistor Q1 is connected to resistor R63;

[0014] One end of resistor R66 is connected to pin 21 of chip U3, and the other end of resistor R66 is connected to the base of transistor Q2; the emitter of transistor Q2 is grounded, and the collector of transistor Q2 is connected to resistor R65; resistor R65 is also connected to resistor R63, and both resistors R65 and R63 are connected to the power supply.

[0015] One end of capacitors C96 and C97 is connected to pin 10 of chip U3, and the other end of capacitors C96 and C97 is grounded.

[0016] According to the above technical solution, both capacitors C96 and C97 are connected to the power supply.

[0017] According to the above technical solution, the emitter of transistor Q3 is grounded, the collector of transistor Q3 is connected to one end of diode D4, the other end of diode D4 is connected to one end of resistor R85, and the other end of resistor R85 is connected to the power supply.

[0018] The base of transistor Q3 is connected to one end of resistor R86, and the other end of resistor R86 is connected to pin 3 of chip U3.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] In this invention, sensor J1 can directly contact the human body and utilizes its photoelectric sensing principle to collect PPG heart rate physiological signals, ensuring that raw signals reflecting physiological characteristics such as heart rate can be obtained, providing a basis for subsequent analysis and processing.

[0021] Pin 3 of sensor J1 is connected to the power supply through inductor L8. Inductor L8 acts as a filter and stabilizer of the power supply, providing a stable operating voltage for sensor J1. This ensures that the sensor will not experience acquisition errors or instability due to power fluctuations during signal acquisition, thereby improving the quality and reliability of the acquired signal.

[0022] Pin 3 of sensor J1 is also connected to capacitor C34 to ground. Capacitor C34 can act as a filter, effectively filtering out high-frequency noise and interference signals in the signal collected by sensor J1, making the collected PPG signal purer and more realistically reflecting the physiological state of the human body. Attached Figure Description

[0023] Figure 1 This is the signal acquisition circuit of the present invention;

[0024] Figure 2 This is the signal processing circuit of the present invention. Detailed Implementation

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0026] Example 1

[0027] A PPG signal acquisition and processing circuit includes a signal acquisition circuit and a signal processing circuit. The signal acquisition circuit is used to acquire the PPG heart rate physiological signal of the human body and transmit the acquired signal to the signal processing circuit. After the signal processing circuit processes the signal, the signal is output.

[0028] like Figure 1 As shown, the signal acquisition circuit includes sensor J1, resistor R81, inductor L8, and capacitor C34. Pin 1 of sensor J1 is connected to one end of resistor R81, and the other end of resistor R81 is connected to the output terminal. Pin 2 of sensor J1 is grounded. Pin 3 of sensor J1 is connected to one end of capacitor C34 and one end of inductor L8. The other end of capacitor C34 is grounded, and the other end of inductor L8 is connected to the power supply.

[0029] In this invention, sensor J1 can directly contact the human body and utilizes its photoelectric sensing principle to collect PPG heart rate physiological signals, ensuring that raw signals reflecting physiological characteristics such as heart rate can be obtained, providing a basis for subsequent analysis and processing.

[0030] Pin 3 of sensor J1 is connected to the power supply through inductor L8. Inductor L8 acts as a filter and stabilizer of the power supply, providing a stable operating voltage for sensor J1. This ensures that the sensor will not experience acquisition errors or instability due to power fluctuations during signal acquisition, thereby improving the quality and reliability of the acquired signal.

[0031] Pin 3 of sensor J1 is also connected to capacitor C34 to ground. Capacitor C34 can act as a filter, effectively filtering out high-frequency noise and interference signals in the signal collected by sensor J1, making the collected PPG signal purer and more realistically reflecting the physiological state of the human body.

[0032] Example 2

[0033] This embodiment is a further refinement of Embodiment 1.

[0034] It includes chip U3, a first processing circuit, a second processing circuit, a crystal oscillator circuit, and peripheral circuits; wherein chip U3 is connected to the first processing circuit, the second processing circuit, the crystal oscillator circuit, and the peripheral circuits respectively.

[0035] The first processing circuit includes connector J2, and pins 1 and 2 of connector J2 are connected to pins 13 and 14 of chip U3, respectively.

[0036] The second processing circuit includes connector J3, capacitor C40, capacitor C96, capacitor C97, and resistor R50. Pin 1 of connector J3 is connected to one end of capacitor C40, and the other end of capacitor C40 is connected to pin 2 of connector J3, one end of resistor R50, and pin 9 of chip U3. The other end of resistor R50 is grounded, and pin 1 of connector J3 and resistor C40 are both connected to the power supply.

[0037] The crystal oscillator circuit includes crystal oscillator X3, capacitor C46, ​​and capacitor C50. One end of crystal oscillator X3 is connected to pin 8 of chip U3 and one end of capacitor C50. The other end of crystal oscillator X3 is connected to pin 7 of chip U3 and one end of capacitor C46. The other end of capacitor C46 is connected to the other end of capacitor C50. Both capacitor C46 and capacitor C50 are grounded.

[0038] The peripheral circuit includes resistors R63, R64, R65, R66, R85, R86, capacitors C96 and C97, transistors Q1, Q2, and Q3. One end of resistor R64 is connected to pin 22 of chip U3, and the other end of resistor R64 is connected to the base of transistor Q1. The emitter of transistor Q1 is grounded, and the collector of transistor Q1 is connected to resistor R63.

[0039] One end of resistor R66 is connected to pin 21 of chip U3, and the other end of resistor R66 is connected to the base of transistor Q2; the emitter of transistor Q2 is grounded, and the collector of transistor Q2 is connected to resistor R65; resistor R65 is also connected to resistor R63, and both resistors R65 and R63 are connected to the power supply.

[0040] One end of capacitors C96 and C97 is connected to pin 10 of chip U3, and the other end of capacitors C96 and C97 is grounded.

[0041] Both capacitors C96 and C97 are connected to the power supply.

[0042] The emitter of transistor Q3 is grounded, the collector of transistor Q3 is connected to one end of diode D4, the other end of diode D4 is connected to one end of resistor R85, and the other end of resistor R85 is connected to the power supply.

[0043] The base of transistor Q3 is connected to one end of resistor R86, and the other end of resistor R86 is connected to pin 3 of chip U3.

[0044] The working principle of this invention is as follows: Sensor J1 is used to collect the PPG heart rate physiological signal of the human body. Its pin 1 is connected to the output terminal through resistor R81 to output the collected signal. Pin 2 is grounded to provide a reference potential for the circuit. The capacitor C34 and inductor L8 connected to pin 3 form a filter circuit. Capacitor C34 is used to filter out high-frequency noise, while inductor L8 helps to stabilize the power input and prevent power fluctuations from interfering with the collected signal, enabling sensor J1 to more accurately collect a pure PPG signal.

[0045] Pins 1 and 2 of connector J2 are connected to pins 13 and 14 of chip U3, respectively, to transmit the acquired PPG signal to chip U3 for specific processing, such as preliminary amplification, shaping, or analog-to-digital conversion of the signal (which can be adjusted according to the actual situation).

[0046] Pin 1 of connector J3 is connected to pin 9 of chip U3 via capacitor C40. Capacitor C40 is also connected to pin 2 of connector J3 and resistor R50, which is grounded. Power is supplied to pin 9 of chip U3 through pin 1 of connector J3 and capacitor C40. Capacitor C40 acts as a filter and stabilizer, while resistor R50 limits current to prevent damage to pin 9 of chip U3 due to excessive current, ensuring that chip U3 processes signals under appropriate operating conditions.

[0047] Crystal oscillator X3, along with capacitors C46 and C50, forms a crystal oscillator circuit to provide a clock signal for chip U3. The two ends of crystal oscillator X3 are connected to pins 7 and 8 of chip U3, respectively. Capacitors C46 and C50 are grounded. Their function is to stabilize the oscillation frequency of the crystal oscillator, enabling chip U3 to operate according to a precise clock cycle, ensuring the accuracy and stability of signal processing, and providing synchronization signals for various logic operations and data processing within chip U3.

[0048] Resistor R64, transistor Q1, and resistor R63 form a control circuit. Pin 22 of chip U3 controls the base of transistor Q1 through resistor R64, thereby controlling the conduction and cutoff of transistor Q1 and controlling related circuits, such as controlling the signal amplification factor or selecting different signal processing paths. Similarly, the circuit composed of resistor R66, transistor Q2, and resistor R65 is controlled by pin 21 of chip U3 and plays a similar control role. Capacitors C96 and C97 are connected to pin 10 of chip U3. On the one hand, they serve a filtering function, filtering out high-frequency noise in the power supply and providing a stable power supply for chip U3; on the other hand, they may participate in some power management or signal processing functions within chip U3. The circuit consisting of transistor Q3, diode D4, and resistors R85 and R86 controls the base of transistor Q3 via resistor R86 from pin 3 of chip U3, thus controlling the conduction and cutoff of transistor Q3. Diode D4 protects the circuit by preventing reverse current flow, and resistor R85 limits the current. This circuit may be used to implement some special functions, such as indicating the operating status of the circuit or controlling the switching of external devices.

[0049] In summary, the entire circuit acquires PPG heart rate physiological signals through the signal acquisition circuit, and then performs amplification, filtering, shaping, analog-to-digital conversion, and other processing on the signals through various parts of the signal processing circuit. Under the clock signal provided by the crystal oscillator circuit, the chip U3 coordinates the work of each part and finally outputs the processed signal. At the same time, the peripheral circuit realizes the control and auxiliary functions of the entire circuit to ensure that the circuit works stably and accurately.

[0050] Furthermore, all electronic components used in this invention are existing technologies; for example, sensor J1 uses a MAX30102 sensor.

[0051] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0052] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A PPG signal acquisition and processing circuit, characterized in that: It includes a signal acquisition circuit and a signal processing circuit. The signal acquisition circuit is used to acquire the PPG heart rate physiological signal of the human body and transmit the acquired signal to the signal processing circuit. After the signal processing circuit processes the signal, the signal is output. The signal acquisition circuit includes sensor J1, resistor R81, inductor L8, and capacitor C34. Pin 1 of sensor J1 is connected to one end of resistor R81, and the other end of resistor R81 is connected to the output terminal. Pin 2 of sensor J1 is grounded. Pin 3 of sensor J1 is connected to one end of capacitor C34 and one end of inductor L8. The other end of capacitor C34 is grounded, and the other end of inductor L8 is connected to the power supply.

2. The PPG signal acquisition and processing circuit according to claim 1, characterized in that: The signal processing circuit includes chip U3, a first processing circuit, a second processing circuit, a crystal oscillator circuit, and peripheral circuits; wherein chip U3 is connected to the first processing circuit, the second processing circuit, the crystal oscillator circuit, and the peripheral circuits respectively.

3. The PPG signal acquisition and processing circuit according to claim 2, characterized in that: The first processing circuit includes connector J2, and pins 1 and 2 of connector J2 are connected to pins 13 and 14 of chip U3, respectively.

4. The PPG signal acquisition and processing circuit according to claim 3, characterized in that: The second processing circuit includes connector J3, capacitor C40, capacitor C96, capacitor C97, and resistor R50. Pin 1 of connector J3 is connected to one end of capacitor C40, and the other end of capacitor C40 is connected to pin 2 of connector J3, one end of resistor R50, and pin 9 of chip U3. The other end of resistor R50 is grounded, and pin 1 of connector J3 and resistor C40 are both connected to the power supply.

5. The PPG signal acquisition and processing circuit according to claim 4, characterized in that: The crystal oscillator circuit includes crystal oscillator X3, capacitor C46, ​​and capacitor C50. One end of crystal oscillator X3 is connected to pin 8 of chip U3 and one end of capacitor C50. The other end of crystal oscillator X3 is connected to pin 7 of chip U3 and one end of capacitor C46. The other end of capacitor C46 is connected to the other end of capacitor C50. Both capacitor C46 and capacitor C50 are grounded.

6. The PPG signal acquisition and processing circuit according to claim 5, characterized in that: The peripheral circuit includes resistors R63, R64, R65, R66, R85, R86, capacitors C96 and C97, transistors Q1, Q2, and Q3. One end of resistor R64 is connected to pin 22 of chip U3, and the other end of resistor R64 is connected to the base of transistor Q1. The emitter of transistor Q1 is grounded, and the collector of transistor Q1 is connected to resistor R63. One end of resistor R66 is connected to pin 21 of chip U3, and the other end of resistor R66 is connected to the base of transistor Q2; the emitter of transistor Q2 is grounded, and the collector of transistor Q2 is connected to resistor R65; resistor R65 is also connected to resistor R63, and both resistors R65 and R63 are connected to the power supply. One end of capacitors C96 and C97 is connected to pin 10 of chip U3, and the other end of capacitors C96 and C97 is grounded.

7. The PPG signal acquisition and processing circuit according to claim 6, characterized in that: Both capacitors C96 and C97 are connected to the power supply.

8. The PPG signal acquisition and processing circuit according to claim 7, characterized in that: The emitter of transistor Q3 is grounded, the collector of transistor Q3 is connected to one end of diode D4, the other end of diode D4 is connected to one end of resistor R85, and the other end of resistor R85 is connected to the power supply. The base of transistor Q3 is connected to one end of resistor R86, and the other end of resistor R86 is connected to pin 3 of chip U3.

Images