WO2019104827A1 - 采集电路、血氧饱和度采集芯片及装置 - Google Patents
采集电路、血氧饱和度采集芯片及装置 Download PDFInfo
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- WO2019104827A1 WO2019104827A1 PCT/CN2018/070073 CN2018070073W WO2019104827A1 WO 2019104827 A1 WO2019104827 A1 WO 2019104827A1 CN 2018070073 W CN2018070073 W CN 2018070073W WO 2019104827 A1 WO2019104827 A1 WO 2019104827A1
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- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 41
- 239000001301 oxygen Substances 0.000 title claims abstract description 41
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 39
- 239000008280 blood Substances 0.000 title claims abstract description 39
- 210000004369 blood Anatomy 0.000 title claims abstract description 39
- 239000003990 capacitor Substances 0.000 claims description 38
- 238000006243 chemical reaction Methods 0.000 claims description 14
- 238000005070 sampling Methods 0.000 claims description 5
- 230000005540 biological transmission Effects 0.000 claims description 4
- 238000005286 illumination Methods 0.000 claims description 3
- 230000003321 amplification Effects 0.000 claims description 2
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 2
- 230000000717 retained effect Effects 0.000 abstract description 2
- 238000011156 evaluation Methods 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 12
- 101100113701 Dictyostelium discoideum clkA gene Proteins 0.000 description 6
- 101100434411 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) ADH1 gene Proteins 0.000 description 6
- 101150102866 adc1 gene Proteins 0.000 description 6
- 101150042711 adc2 gene Proteins 0.000 description 6
- 230000031700 light absorption Effects 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 101100113692 Caenorhabditis elegans clk-2 gene Proteins 0.000 description 5
- 230000008859 change Effects 0.000 description 5
- 101100003180 Colletotrichum lindemuthianum ATG1 gene Proteins 0.000 description 4
- 101710096660 Probable acetoacetate decarboxylase 2 Proteins 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 2
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- 101100328957 Caenorhabditis elegans clk-1 gene Proteins 0.000 description 1
- 230000003044 adaptive effect Effects 0.000 description 1
- 210000001367 artery Anatomy 0.000 description 1
- 230000017531 blood circulation Effects 0.000 description 1
- -1 clkB Proteins 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000002496 oximetry Methods 0.000 description 1
- 230000036284 oxygen consumption Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
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- 210000002345 respiratory system Anatomy 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
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Classifications
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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
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/1455—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters
Definitions
- the present invention relates to the field of electronic circuit technologies, and in particular, to an acquisition circuit, a blood oxygen saturation acquisition chip, and a device.
- SpO2 is an important physiological parameter reflecting the health of the human body. By detecting the oxygen saturation, it can effectively determine whether the functions of the human circulatory system and the respiratory system are normal.
- Today's non-invasive detection method has long been mainstream, and light-sensing blood oxygen saturation monitoring technology is also applied. Since the pulsation of the human artery can cause a change in the blood flow rate at the test site, thereby causing a change in the amount of light absorption, the amount of light absorption of the non-blood tissue is generally considered to be constant.
- the light-sensing oximetry technique utilizes this feature to determine blood oxygen saturation by detecting changes in light absorption caused by fluctuations in blood volume and eliminating the effects of non-blood tissue.
- the converter outputs the corresponding DC and the DC of the input signal to cancel each other, which additionally increases the design complexity and power consumption of the DAC circuit, and also requires the use of a high-order analog-to-digital converter (ADC) for signal conversion, such as Using a 22-bit ADC increases chip power and area. In some other scenarios, the data processing workload of the MCU is increased, which results in high oxygen consumption and power consumption of the pulse acquisition device.
- ADC analog-to-digital converter
- an object of the embodiments of the present invention is to provide an acquisition circuit, a blood oxygen saturation acquisition chip and a device, which solve the problem that the acquisition circuit of the prior art needs to output an electrical signal with a high dynamic range, thereby increasing the power consumption of the entire device. The problem.
- an embodiment of the present invention provides an acquisition circuit for electrically connecting to a micro control unit, where the acquisition circuit includes a receiving module and a clock control module, and the receiving module includes a transimpedance amplifier electrically connected in sequence, and sampling and maintaining.
- the micro control unit being electrically coupled to the amplifier and the sample and hold circuit, the transimpedance amplifier for connecting a photodiode to induce red and infrared light to the photodiode
- the generated current signal is converted into a voltage signal
- the sample and hold unit is configured to separately collect a red light direct current signal, an infrared light direct current signal, an ambient light direct current signal, and the ambient light direct current signal from the voltage signal according to the timing control logic signal sent by the clock control module.
- red light direct current signal, the infrared light direct current signal, the ambient light direct current signal are transmitted to the micro control unit, and the first filter is used to filter to obtain the red light alternating current a signal and an infrared light alternating current signal, the amplifier being used to filter the red light exchange letter Amplifying and transmitting the infrared light signal to the micro control unit, so that the micro control unit is configured to perform the amplified red light alternating current signal and infrared light alternating current signal and the red light direct current signal, the infrared
- the optical DC signal and the ambient light DC signal are calculated to obtain pulse rate and/or blood oxygen saturation.
- the sample and hold circuit includes a first branch, a second branch, a first charging capacitor and a second charging capacitor, the first branch comprising a first switch and a second switch, the first switch setting Between the output end of the transimpedance amplifier and the first filter, one end of the second switch is connected between the first switch and the first filter, and the second switch is further One end is connected to the micro control unit, one end of the first charging capacitor is connected between the first switch and the second switch, and the other end of the first charging capacitor is used for connecting with a reference voltage power source;
- the second branch is connected in parallel with the first branch, the second branch includes a third switch and a fourth switch, the third switch and the fourth switch are connected in series, and the third switch is One end is connected between the output end of the transimpedance amplifier and the first switch, one end of the fourth switch is connected to the micro control unit, and one end of the second charging capacitor is connected to the third switch Between the fourth switch and the second charging capacitor The other end is grounded.
- the first branch further includes a first buffer register, the first buffer register is serially connected between the second switch and the micro control unit; and the second branch further includes a second buffer a register, the second buffer register being serially connected between the fourth switch and the micro control unit.
- the sample and hold circuit is configured to control the first switch, the second switch, the third switch, and the fourth switch to be in a first state or a second state according to the timing control logic signal; In the first state, the first switch and the fourth switch are closed, the second switch and the third switch are disconnected, the first charging capacitor is charged, and the second charging capacitor is discharged.
- the micro control unit Receiving, by the micro control unit, the ambient light direct current signal from the sample and hold circuit, and receiving an amplified red light alternating current signal or the infrared light alternating current signal from the amplifier; in the second state, The first switch and the fourth switch are disconnected, the second switch and the third switch are closed, the first charging capacitor is discharged, the second charging capacitor is charged, and the micro control unit is The sample and hold circuit receives the red light direct current signal or the infrared light direct current signal.
- the method further includes a second filter and a third buffer register, wherein the second filter and the third buffer register are sequentially connected between the amplifier and the micro control unit, and the second filter is The amplifier is connected, and the third buffer register is connected to the micro control unit.
- the first filter is a high pass filter
- the second filter is a low pass filter
- the amplifier is a programmable gain amplifier
- the positive input terminal of the transimpedance amplifier is used to connect a photodiode, and the negative input terminal of the transimpedance amplifier is connected to a reference voltage source.
- an embodiment of the present invention further provides a blood oxygen saturation acquisition chip for electrically connecting with a micro control unit
- the blood oxygen saturation acquisition chip includes an acquisition circuit and a transmission module
- the acquisition circuit and the The transmitting modules are each configured to be electrically connected to the micro control unit
- the transmitting module includes a driving circuit and a digital to analog conversion circuit electrically connected to each other, and the driving circuit and the digital to analog conversion circuit are respectively used for controlling and transmitting
- the collecting circuit comprises a receiving module and a clock control module, and the receiving module comprises a transimpedance amplifier, a sample and hold circuit, a first filter and an amplifier which are electrically connected in sequence, a micro control unit is simultaneously electrically coupled to the amplifier and the sample and hold circuit, the transimpedance amplifier for connecting a photodiode to convert a current signal generated by the photodiode sensing red light and infrared light into a voltage signal
- an embodiment of the present invention further provides a blood oxygen saturation acquisition device, including an acquisition circuit, a transmission module, and a micro control unit, where the acquisition circuit includes a receiving module and a clock control module, and the micro control unit respectively
- the transmitting module is electrically connected to the receiving module and the clock control module, the transmitting module includes a driving circuit, the driving circuit is connected with a first light source and a second light source, and the first light source emits red light, The second light source emits infrared light, and the micro control unit is configured to control, by the driving circuit, a lighting time of the first light source and the second light source according to a clock signal sent by the clock control module;
- the receiving module comprises an electrical connection sequentially a transimpedance amplifier, a sample and hold circuit, a first filter, and an amplifier, the micro control unit being electrically connected to the amplifier and the sample and hold circuit, the transimpedance amplifier for connecting a photodiode to sense the photodiode The current signal generated by the red light and the acquisition
- the transmitting module further includes a digital-to-analog conversion circuit, one end of the digital-to-analog conversion circuit is connected to the driving circuit, and the other end of the digital-to-analog conversion circuit is connected to the micro control unit, the digital-analog A conversion circuit is configured to control the luminance of the light emitted by the first light source and the second light source.
- a digital-to-analog conversion circuit one end of the digital-to-analog conversion circuit is connected to the driving circuit, and the other end of the digital-to-analog conversion circuit is connected to the micro control unit, the digital-analog A conversion circuit is configured to control the luminance of the light emitted by the first light source and the second light source.
- the sampling and holding unit can collect the red light direct current signal, the infrared light direct current signal, the ambient light direct current signal, the red light alternating current signal at intervals.
- the infrared light AC signal the first filter is used to filter the DC signal, only the red light AC signal and the infrared light AC signal are retained, and then the red light AC signal and the infrared light AC signal are amplified, so that the micro control unit calculates the pulse rate and Blood oxygen saturation.
- the invention solves the problem that the amplifier needs to have a high dynamic output caused by the DC voltage, and adopts the solution of the embodiment of the invention, does not require the micro control unit to evaluate the DC voltage in advance, and avoids using the additional DAC to output the corresponding DC amount. To offset, it also avoids the use of high-resolution ADC, saving power.
- FIG. 1 is a circuit block diagram of a blood oxygen saturation acquisition device according to an embodiment of the present invention.
- FIG. 2 is a schematic structural diagram of a circuit of an acquisition circuit according to an embodiment of the present invention.
- FIG. 3 is a waveform diagram of signals sent by a clock control module and a signal waveform received by a micro control unit according to an embodiment of the present invention.
- FIG. 4 is a schematic structural diagram of a circuit of a transmitting module according to a preferred embodiment of the present invention.
- Figure 5 is a control logic diagram of the DAC of Figure 4 in accordance with a preferred embodiment of the present invention.
- Icons 1-oxygen saturation acquisition device; 10-oxygen saturation acquisition chip; 20-micro control unit; 11-receive module; 12-clock control module; 13-transmit module; 14-power module; Resistive amplifier; 111-sample-and-hold circuit; 112-high-pass filter; 113-programmable gain amplifier; 114-low-pass filter; 131-drive circuit; 141-reference voltage supply; K1-first switch; K2-second Switch; K3-third switch; K4-fourth switch; C1-first charging capacitor; C2-second charging capacitor.
- FIG. 1 is a circuit block diagram of a blood oxygen saturation acquisition device 1 according to an embodiment of the present invention.
- the embodiment of the present invention provides an oxygen saturation acquiring device 1 which can obtain blood oxygen saturation by detecting a change in the amount of light absorption caused by fluctuations in blood volume, and can also obtain a pulse rate.
- the blood oxygen saturation acquisition device 1 includes a blood oxygen saturation acquisition chip 10 and a micro control unit 20 (MCU).
- the blood oxygen saturation acquisition chip 10 includes an acquisition circuit, a transmission module 13 and a power supply module 14.
- the acquisition module includes a receiving module 11 and a clock control module 12, and the receiving module 11, the clock control module 12, and the transmitting module 13 are electrically connected to the micro control unit 20, respectively.
- the power module 14 can be a receiving module 11, a clock control module 12, and a transmitting module 13. Power is supplied to the micro control unit 20 or the like.
- the power module 14 includes a reference voltage source 141 for providing a reference supply voltage V ref , and the power module 14 may further include a linear regulator source and a paranoid current source.
- the transmitting module 13 needs to connect the first light source D R that emits red light and the second light source D IR that emits infrared light.
- the transmitting module 13 can emit red light and infrared light.
- the source of light Preferably, the first light source D R is an LED light emitting red light, and the second light source D IR is an LED light emitting infrared light.
- the transmitting module 13 includes a driving circuit 131.
- the driving circuit 131 is electrically connected to the first light source D R and the second light source D IR .
- the micro control unit 20 can be controlled according to a clock signal sent by the clock control module 12 , and the driving circuit 131 can control the clock according to the clock signal.
- the illuminating time of a light source D R and a second light source D IR illuminating.
- the transmitting module 13 may further include a digital-to-analog converter (DAC), and the micro control unit 20 may send a digital signal to the DAC to control the current flowing through the first light source D R and the second light source D IR .
- the size further controls the illuminance of the first light source D R and the second light source D IR to meet the usage of different users.
- the receiving module 11 includes a transimpedance amplifier 110, a sample and hold circuit 111, a first filter, and an amplifier which are electrically connected in sequence, and the micro control unit 20 is electrically connected to the amplifier and the sample and hold circuit 111 at the same time.
- the transimpedance amplifier 110 is connected with a photodiode D1, which can induce red and infrared light to generate a current signal, and the transimpedance amplifier 110 can convert the current signal into a voltage signal.
- the current generated by the photodiode D1 by the change in the amount of light absorption includes a direct current portion and an alternating current portion, and the usual direct current range is several tens of uA, and the alternating current range is from 50 nA to 100 nA.
- the dynamic DC range of the transimpedance amplifier 110 of this embodiment is 100 nA to 80 uA, and the maximum amplitude of the alternating current is about 100 nA.
- the sampling and holding unit is configured to separately collect a red light DC signal, an infrared light direct current signal, an ambient light direct current signal, a red light alternating current signal, and an infrared light exchange from the voltage signal according to the timing control logic signal sent by the clock control module 12
- the signal because the DC signal of the DC signal, the infrared light DC signal, and the ambient light DC signal are large, can be directly sent to the micro control unit 20, and the red light AC signal and the infrared light AC signal need to be further amplified.
- the first filter is configured to filter the red light alternating current signal and the infrared light alternating current signal from a red light direct current signal, an infrared light direct current signal, an ambient light direct current signal, a red light alternating current signal, and an infrared light alternating current signal to make only the red
- the optical AC signal and the infrared light AC signal are filtered by the amplifier.
- the first filter is a high pass filter 112.
- the amplifier is configured to amplify and transmit the filtered red light alternating current signal and infrared light alternating current signal to the micro control unit 20.
- the amplifier is a programmable gain amplifier 113.
- the MCU can control the adaptive adjustment of the gain of the programmable gain amplifier 113, select an appropriate dynamic range, and effectively amplify the red light AC signal and the infrared light AC signal.
- a low pass filter 114 is further disposed between the programmable gain amplifier 113 and the MCU, and the higher frequency signal can be filtered.
- the micro control unit 20 may include an analog-to-digital converter (ADC).
- ADC analog-to-digital converter
- the analog-to-digital conversion circuit includes an ADC1 and an ADC2.
- the ADC1 is directly connected to the sample-and-hold circuit 111, and the red-light DC signal is obtained from the sample-and-hold circuit 111.
- ADC2 is connected with low-pass filter 114 to obtain the red-light AC signal and the infrared light AC signal after filtering and amplification.
- the micro control unit 20 may calculate a pulse rate according to the amplified red light alternating current signal and the infrared light alternating current signal, and then calculate the red light direct current signal, the infrared light direct current signal, and the ambient light direct current signal. Get blood oxygen saturation.
- FIG. 2 is a schematic diagram of a circuit structure of an acquisition circuit according to an embodiment of the present invention.
- the current signal induced by the photodiode D1 enters the transimpedance amplifier 110 and is converted into a voltage signal.
- the transimpedance amplifier 110 the positive input terminal is connected to the photodiode D1
- the negative input terminal is connected to the reference voltage power source 141
- the reference voltage V ref is connected.
- the transimpedance amplifier 110 is a chopper differential structure, which can effectively reduce input noise. Since the negative input terminal is connected to the reference voltage V ref , the output voltage signal can be stabilized at the reference voltage, and the baseline drift is removed. .
- the sample and hold circuit 111 includes a first branch, a second branch, a first charging capacitor C1 and a second charging capacitor C2, and the first branch includes a first switch K1 and a second switch K2, the first The switch K1 is disposed between the output end of the transimpedance amplifier 110 and the first filter, and one end of the second switch K2 is connected between the first switch K1 and the first filter. The other end of the second switch K2 is connected to the micro control unit 20, and one end of the first charging capacitor C1 is connected between the first switch K1 and the second switch K2, the first charging capacitor The other end of C1 is for connection with a reference voltage source 141.
- three buffer registers are also provided, which are a first buffer register, a second buffer register, and a third buffer register, that is, buffer1, buffer2, and buffer3.
- the buffer 1 is connected in series between the second switch K2 and the ADC1.
- the second branch is connected in parallel with the first branch, the second branch includes a third switch K3 and a fourth switch K4, and the third switch K3 and the fourth switch K4 are connected in series, One end of the third switch K3 is connected between the output end of the transimpedance amplifier 110 and the first switch K1, and one end of the fourth switch K4 is connected to the micro control unit 20, the second charging capacitor One end of the C2 is connected between the third switch K3 and the fourth switch K4, the other end of the second charging capacitor C2 is grounded, and the buffer 2 is connected in series between the fourth switch K4 and the ADC2.
- the high pass filter 112 includes a capacitor C H, C H may be DC capacitor filter, only allowing a high frequency alternating current through.
- Programmable gain amplifier 113 and the positive input of the capacitor C H is connected to the negative input terminal of the access reference voltage V ref.
- the low pass filter 114 includes a resistor R L and a capacitor C L .
- the resistor R L is connected in series between the output of the programmable gain amplifier 113 and the ADC 2 .
- One end of the capacitor C L is connected between the resistor R L and the ADC 2 , and the capacitor C The other end of L is connected to the reference voltage V ref , and buffer 3 is connected between the low pass filter 114 and the ADC 2 .
- the sample and hold circuit 111 is configured to control the first switch K1, the second switch K2, the third switch K3, and the first according to a timing control logic signal sent by the clock control module 12.
- the four switch K4 is in the first state or the second state.
- the clock control module 12 controls the opening and closing times of the first light source D R and the second light source D IR by a clock signal corresponding to the timing control logic signal in time.
- the micro control unit 20 receives the ambient light DC signal from the sample and hold circuit 111, and receives the amplified red light alternating current signal or the infrared light alternating current signal from the amplifier.
- the first switch K1 and the fourth switch K4 are disconnected, the second switch K2 and the third switch K3 are closed, and the first charging capacitor C1 is discharged, The second charging capacitor C2 is charged, and the micro control unit 20 receives the red DC signal or the infrared DC signal from the sample and hold circuit 111.
- FIG. 3 is a signal waveform diagram sent by the clock control module 12 and a signal waveform diagram received by the micro control unit 20 according to an embodiment of the present invention.
- the clock control module 12 is configured to issue a timing control logic signal to control the sample and hold circuit 111 and send a clock signal to the MCU, and further control the time when the first light source D R and the second light source D IR emit red light and infrared light, and the timing control logic
- the signal corresponds to the clock signal so that the MUC separates the acquisition of red and infrared light.
- the timing control logic signal includes clkA and clkB
- the clock signal includes clk1, clk2, clk3, and clk4.
- the periods of clkA, clkB, clk1, clk2, clk3, and clk4 are the same, and T1, T2, T3, and T4 are respectively four quarter cycles of the timing control logic signal and the clock signal.
- Clk1 is used to control the first light source D R to emit red light
- clk2 is used to control the second light source D IR to emit infrared light
- clk3 and clk4 control whether the first light source D R and the second light source D IR do not emit light.
- clkB can be generated by clk1 and clk2 superposition
- clkA can be composed of clk3 and clk4.
- clkA is used to control the closing and opening of the third switch K3 and the fourth switch K4.
- the third switch K3 is closed, and the fourth switch K4 is turned off; when the level of clkA is low, the third switch K3 Disconnected, the fourth switch K4 is closed.
- clkB is used to control the closing and opening of the first switch K1 and the second switch K2.
- the level of clkB is high, the first switch K1 is closed and the second switch K2 is turned off; when the low level of clkB is, the first switch K1 Disconnected, the second switch K2 is closed.
- DC and AC are signal waveform diagrams received by the micro control unit 20 from ADC1 and ADC2, respectively.
- the DC includes a red DC signal, an infrared DC signal, and an ambient light DC signal.
- ADC1 receives an ambient light DC signal; at T2 and T4, ADC1 receives a red DC signal and an infrared DC signal.
- the AC includes a red light AC signal and an infrared light AC signal.
- ADC2 receives a red light AC signal; at T4, ADC2 receives an infrared light AC signal.
- the MCU calculates the pulse rate according to the collected red light AC signal and the infrared light AC signal, and then calculates the blood oxygen saturation by combining the red light direct current signal, the infrared light direct current signal and the ambient light direct current signal, and the blood oxygen saturation can be as follows The formula is calculated:
- AC R represents a red light AC signal
- AC IR represents an infrared light AC signal
- DC R represents a red light DC signal that removes ambient light DC signals
- DC IR represents an infrared light DC signal that removes ambient light DC signals.
- FIG. 4 is a schematic diagram of a circuit structure of a transmitting module 13 according to a preferred embodiment of the present invention.
- the transmitting module 13 includes a driving circuit 131.
- the driving circuit 131 adopts a bridge driving structure, and alternately controls the first light source D R and the second light source D IR to emit light through the switch.
- the driving circuit 131 includes a switch K5, a switch K6, a MOS transistor Q1 and a MOS transistor Q2.
- the MCU controls the closing or opening of the switch K5 and the switch K6 through the clock signals clk1, clk2, clk3 and clk4, and controls the MOS transistor Q1 and MOS.
- the voltage of the gate of the tube Q2 is such that the illumination time of the first source D R and the second source D IR is achieved.
- FIG. 5 is a control logic diagram of the DAC of FIG. 4 in accordance with a preferred embodiment of the present invention.
- the DAC can be composed of 8 subunits, and any one of the subunits includes an inverter, a switch Di, and And MOS transistors, switches Di and switches It can only be opened in an alternative way, that is, one of them closes and the other is broken.
- MCU can control switch Di and switch When Di is closed, the gate voltage of the corresponding MOS transistor in the DAC is V ref , when When closed, the gate of the corresponding MOS transistor in the DAC is grounded. Since the MCU controls the switch Di to connect the MOS transistor to the reference voltage V ref , the temperature and process error are not affected, so that the transmitting module 13 provides a stable LED driving current.
- the current through the first source D R or the second source D IR is controlled by the DAC as:
- D 0 ... D 7 is 0 or 1
- ⁇ 0 is the electron mobility
- C ox is the unit gate oxygen area
- W/L is the transistor size
- V th is the transistor threshold.
- the sampling and holding unit can collect the red light DC signal, the infrared light direct current signal, the ambient light direct current signal, the red light alternating current signal and the infrared interval.
- the optical AC signal uses a high-pass filter to filter the DC signal, and only retains the red AC signal and the infrared light AC signal, and then amplifies the red AC signal and the infrared light AC signal, so that the micro control unit calculates the pulse rate and blood oxygen saturation. degree.
- the invention solves the problem that the amplifier needs to have a high dynamic output caused by the DC voltage, and adopts the solution of the embodiment of the invention, does not require the micro control unit to evaluate the DC voltage in advance, and avoids using the additional DAC to output the corresponding DC amount. To offset, it also avoids the use of high-resolution ADC, saving power.
- the transimpedance amplifier's negative feedback single-ended input can stabilize the signal from the reference voltage, remove the baseline drift, and use chopping technology for the transimpedance amplifier to effectively reject the input noise. Using the reference voltage as the supply voltage of the DAC, the DAC will not be affected by temperature and process error to provide a stable power supply drive current.
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Abstract
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- 一种采集电路,配置成与微控制单元电连接,其特征在于,所述采集电路包括接收模块和时钟控制模块,所述接收模块包括依次电连接的跨阻放大器、采样保持电路、第一滤波器以及放大器,所述微控制单元同时和所述放大器和所述采样保持电路电连接,所述跨阻放大器配置成连接光敏二极管,以将光敏二极管感应红光和红外光而生成的电流信号转换为电压信号,所述采样保持单元配置成依据所述时钟控制模块发出的时序控制逻辑信号从所述电压信号分别采集红光直流信号、红外光直流信号、环境光直流信号、红光交流信号和红外光交流信号,其中所述红光直流信号、红外光直流信号和环境光直流信号被传送至所述微控制单元,所述第一滤波器配置成过滤得到所述红光交流信号和红外光交流信号,所述放大器配置成将过滤后的所述红光交流信号和红外光交流信号进行放大并传送至所述微控制单元,以便所述微控制单元依据所述放大后的所述红光交流信号和红外光交流信号以及所述红光直流信号、所述红外光直流信号和所述环境光直流信号计算得到脉率和/或血氧饱和度。
- 根据权利要求1所述的采集电路,其特征在于,所述采样保持电路包括第一支路、第二支路、第一充电电容及第二充电电容,所述第一支路包括第一开关和第二开关,所述第一开关设置于所述跨阻放大器的输出端与所述第一滤波器之间,所述第二开关的一端连接与所述第一开关与所述第一滤波器之间,所述第二开关的另一端与所述微控制单元连接,所述第一充电电容的一端连接于所述第一开关与所述第二开关之间,所述第一充电电容的另一端配置成与基准电压电源连接;所述第二支路与所述第一支路并联,所述第二支路包括第三开关和第四开关,所述第三开关和所述第四开关串连,所述第三开关的一端连接于 所述跨阻放大器的输出端与所述第一开关之间,所述第四开关的一端与所述微控制单元连接,所述第二充电电容的一端连接于所述第三开关与所述第四开关之间,所述第二充电电容的另一端接地。
- 根据权利要求2所述的采集电路,其特征在于,所述第一支路还包括第一缓冲寄存器,所述第一缓冲寄存器串接于所述第二开关与所述微控制单元之间;所述第二支路还包括第二缓冲寄存器,所述第二缓冲寄存器串接于所述第四开关与所述微控制单元之间。
- 根据权利要求2或3所述的采集电路,其特征在于,所述采样保持电路配置成依据所述时序控制逻辑信号控制所述第一开关、所述第二开关、所述第三开关和所述第四开关处于第一状态或第二状态;在所述第一状态下,所述第一开关和所述第四开关闭合,所述第二开关和所述第三开关断开,所述第一充电电容充电,所述第二充电电容放电,所述微控制单元从所述采样保持电路接收所述环境光直流信号,以及从所述放大器接收放大后的红光交流信号或所述红外光交流信号;在所述第二状态下,所述第一开关和所述第四开关断开,所述第二开关和所述第三开关闭合,所述第一充电电容放电,所述第二充电电容充电,所述微控制单元从所述采样保持电路接收所述红光直流信号或所述红外光直流信号。
- 根据权利要求1或3所述的采集电路,其特征在于,还包括第二滤波器和第三缓冲寄存器,所述第二滤波器和所述第三缓冲寄存器依次连接于所述放大器和所述微控制单元之间,所述第二滤波器与所述放大器连接,所述第三缓冲寄存器与所述微控制单元连接。
- 根据权利要求5所述的采集电路,其特征在于,所述第一滤波器 为高通滤波器,所述第二滤波器为低通滤波器,所述放大器为可编程增益放大器。
- 根据权利要求1所述的采集电路,其特征在于,所述跨阻放大器的正输入端配置成连接光敏二极管,所述跨阻放大器的负输入端与基准电压电源连接。
- 一种血氧饱和度采集芯片,配置成与微控制单元电连接,其特征在于,所述血氧饱和度采集芯片包括采集电路和发射模块,所述采集电路和所述发射模块均配置成与所述微控制单元电连接,所述发射模块包括相互电连接的驱动电路和数模转换电路,所述驱动电路和所述数模转换电路配置成分别控制与所述发射模块连接的发光源的发光时间与发光亮度;所述采集电路包括接收模块和时钟控制模块,所述接收模块包括依次电连接的跨阻放大器、采样保持电路、第一滤波器以及放大器,所述微控制单元同时和所述放大器和所述采样保持电路电连接,所述跨阻放大器配置成连接光敏二极管,以将光敏二极管感应红光和红外光而生成的电流信号转换为电压信号,所述采样保持单元配置成依据所述时钟控制模块发出的时序控制逻辑信号从所述电压信号分别采集红光直流信号、红外光直流信号、环境光直流信号、红光交流信号和红外光交流信号,其中所述红光直流信号、红外光直流信号和环境光直流信号被传送至所述微控制单元,所述第一滤波器配置成过滤得到所述红光交流信号和红外光交流信号,所述放大器配置成将过滤后的所述红光交流信号和红外光交流信号进行放大并传送至所述微控制单元,以便所述微控制单元依据所述放大后的所述红光交流信号和红外光交流信号以及所述红光直流信号、所述红外光直流信号和所述环境光直流信号计算得到脉率和/或血氧饱和度。
- 一种血氧饱和度采集装置,其特征在于,包括采集电路、发射模块以及微控制单元,所述采集电路包括接收模块和时钟控制模块,所述微 控制单元分别与所述发射模块和所述接收模块以及所述时钟控制模块电连接,所述发射模块包括驱动电路,所述驱动电路连接有第一光源和第二光源,所述第一光源发出红光,所述第二光源发出红外光,所述微控制单元配置成依据时钟控制模块发出的时钟信号通过所述驱动电路控制第一光源和所述第二光源的发光时间;所述接收模块包括依次电连接的跨阻放大器、采样保持电路、第一滤波器以及放大器,所述微控制单元同时和所述放大器和所述采样保持电路电连接,所述跨阻放大器配置成连接光敏二极管,以将光敏二极管感应红光和红外光而生成的电流信号转换为电压信号,所述采样保持单元配置成依据所述时钟控制模块发出的时序控制逻辑信号从所述电压信号分别采集红光直流信号、红外光直流信号、环境光直流信号、红光交流信号和红外光交流信号,其中所述红光直流信号、红外光直流信号和环境光直流信号被传送至所述微控制单元,所述第一滤波器配置成过滤得到所述红光交流信号和红外光交流信号,所述放大器配置成将过滤后的所述红光交流信号和红外光交流信号进行放大并传送至所述微控制单元,以便所述微控制单元依据所述放大后的所述红光交流信号和红外光交流信号以及所述红光直流信号、所述红外光直流信号和所述环境光直流信号计算得到脉率和/或血氧饱和度。
- 根据权利要求9所述的血氧饱和度采集装置,其特征在于,所述发射模块还包括数模转换电路,所述数模转换电路的一端与所述驱动电路连接,所述数模转换电路的另一端与所述微控制单元连接,所述数模转换电路配置成控制所述第一光源和所述第二光源的发光亮度。
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