Signal acquisition circuit of medical electromagnetic sensor

Abstract

The invention discloses a signal acquisition circuit of a medical electromagnetic sensor, which is characterized in that the signal output end of a signal amplification module is respectively connected with each stage of signal acquisition module, so that the multi-stage signal acquisition module is used for respectively carrying out graded acquisition on magnetic sensing signals amplified by different times; magnetic sensing signals under different amplification conditions can be acquired, and sampling can be covered no matter how large the amplitude span of the magnetic sensing signals is, so that the amplification gain of the magnetic sensing signals does not need to be independently controlled, signal sampling distortion is avoided, and the magnetic sensing signals can still be effectively acquired even under the condition that the signal span is relatively large; moreover, the configured signal processing unit carries out screening processing on each stage of sampling amplification signals and outputs the screened target amplification signals, so that effective amplification screening and reliable communication output of the magnetic sensing signals are realized. And meanwhile, the power management unit for supplying power is arranged to ensure that signal sampling has good stability and continuity.

Description

Technical Field

[0001] The present invention relates to the technical field of medical applications, and in particular to a signal acquisition circuit for a medical electromagnetic sensor. Background Art

[0002] In a medical magnetic navigation system, since the magnetic field strength decays exponentially with distance, the amplitude span of the finally sampled magnetic sensing signal will be very large. For example, in some application scenarios, the induced voltages on the electromagnetic sensors at the nearest and farthest distances differ by nearly 1000 times. Such a large signal amplitude span is extremely likely to cause signal distortion, which poses a great challenge to the accuracy requirement of the ADC and the improvement of the signal-to-noise ratio. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this purpose, the present invention provides a signal acquisition circuit for a medical electromagnetic sensor, which can conveniently and effectively acquire magnetic sensing signals in the case of a large signal amplitude span.

[0004] An embodiment of the present invention provides a signal acquisition circuit for a medical electromagnetic sensor, including: A signal amplification and acquisition unit, including a signal amplification module for amplifying an input magnetic sensing signal and a signal acquisition module for extracting the amplified magnetic sensing signal. Among them, the signal acquisition module is configured in multiple stages, and the signal amplification gains set by at least two stages of the signal acquisition module are different; the signal output end of the signal amplification module is respectively connected to each stage of the signal acquisition module to hierarchically acquire the amplified magnetic sensing signal through the signal sampling ends of each stage of the signal acquisition module, and obtain multi-stage sampled and amplified signals; A signal processing unit, respectively connected to the signal sampling ends of each stage of the signal acquisition module, for screening at least one stage from all the sampled and amplified signals as a target amplified signal and digitally filtering the target amplified signal for output; A power management unit, respectively connected to the signal amplification module, the signal acquisition module and the signal processing unit, for stably supplying power to the signal amplification module, the signal acquisition module and the signal processing unit based on an input supply voltage.

[0005] Optionally, in an embodiment of the present invention, the signal amplification module includes a first signal amplification module for pre-amplifying the input magnetic sensing signal, and a second signal amplification module for further amplifying the magnetic sensing signal and filtering out the bias voltage. The second signal amplification module includes a pre-stage signal amplification module and a secondary signal amplification module. The signal output end of the first signal amplification module is connected to the signal input end of the pre-stage signal amplification module. The signal output end of the pre-stage signal amplification module is connected to the signal input end of the secondary signal amplification module. The signal output end of the secondary signal amplification module is respectively connected to each level of the signal acquisition module. Wherein, the first signal amplification module, the pre-stage signal amplification module and the secondary signal amplification module all include a first low-pass filter module for filtering high-frequency noise in the magnetic sensing signal.

[0006] Optionally, in an embodiment of the present invention, the signal acquisition module is at least configured as a first level and a second level. Among them, the signal acquisition module corresponding to the first level includes a first voltage follower, a first capacitor, a second capacitor, a third capacitor and a fourth capacitor. The first capacitor, the second capacitor, the third capacitor and the fourth capacitor are connected in parallel to form a first bypass capacitor circuit. One end of the first bypass capacitor circuit is connected to one of the signal sampling ends of the corresponding signal acquisition module and the other end is connected to the reference ground. The input end of the first voltage follower is connected to the signal output end of the secondary signal amplification module. The output end of the first voltage follower is connected to one of the signal sampling ends of the corresponding signal acquisition module; the signal acquisition module corresponding to the second level includes a second voltage follower, a second low-pass filter module, a fifth capacitor, a sixth capacitor, a seventh capacitor and an eighth capacitor. The fifth capacitor, the sixth capacitor, the seventh capacitor and the eighth capacitor are connected in parallel to form a second bypass capacitor circuit. One end of the second bypass capacitor circuit is connected to one of the signal sampling ends of the corresponding signal acquisition module and the other end is connected to the reference ground. The signal output end of the secondary signal amplification module is connected to the input end of the second voltage follower through the second low-pass filter module. The output end of the second voltage follower is connected to one of the signal sampling ends of the corresponding signal acquisition module.

[0007] Optionally, in an embodiment of the present invention, the second low-pass filter module adopts an infinite gain multiple negative feedback low-pass filter.

[0008] Optionally, in an embodiment of the present invention, the power management unit includes a preprocessing conversion module, a first power output module, and a second power output module. The input end of the preprocessing conversion module is connected to the supply voltage, and the output end is respectively connected to the input ends of the first power output module and the second power output module. The output end of the first power output module is respectively connected to the power input ends of the signal amplification module and the signal acquisition module. One output end of the second power output module is connected to the power input end of the signal processing unit. Wherein, the preprocessing conversion module is used to rectify, filter, and convert the input supply voltage to output a first voltage. The first power output module is used to convert the first voltage into a second voltage for output. The second power output module is used to convert the first voltage into a third voltage for output. The second voltage is the operating voltage of the signal amplification module and the signal acquisition module. The third voltage is the operating voltage of the signal processing unit.

[0009] Optionally, in an embodiment of the present invention, it further includes a signal control unit for communicating with the outside based on the target amplified signal. The signal input end of the signal control unit is connected to the digital signal output end of the signal processing unit. The power management unit further includes a third power output module for converting the third voltage into a fourth voltage for output. The input end of the third power output module is connected to another output end of the second power output module. The output end of the third power output module is connected to the power input end of the signal control unit to provide the fourth voltage as the operating voltage to the signal control unit.

[0010] Optionally, in an embodiment of the present invention, the signal amplification gain of the first signal amplification module is 50, the signal amplification gain of the pre-stage signal amplification module is 10, and the signal amplification gain of the secondary signal amplification module is 10.

[0011] Optionally, in an embodiment of the present invention, the first voltage is 15V, the second voltage is 12V, the third voltage is 5V, and the fourth voltage is 3.3V.

[0012] A signal acquisition circuit of a medical electromagnetic sensor proposed by the present invention, compared with the signal acquisition methods in related prior arts, by connecting the signal output terminals of the signal amplification module to each level of the signal acquisition module respectively, thus using multiple levels of signal acquisition modules to separately collect the magnetic sensing signals after being amplified by different multiples. Since the signal amplification gains set by at least two levels of signal acquisition modules are different, different amplified magnetic sensing signals can be collected through multiple levels of signal acquisition modules. That is to say, no matter how large the amplitude span of the magnetic sensing signal is, it can be covered for sampling. Therefore, there is no need to separately control the amplification gain of the magnetic sensing signal, avoiding signal sampling distortion. Even in the case of a large signal span, the magnetic sensing signal can still be conveniently and effectively collected. And, the configured signal processing unit also screens and processes the sampled and amplified signals at each level and outputs the target amplified signals after screening and processing, so as to facilitate the effective amplification and screening of the magnetic sensing signal and reliable communication output. At the same time, a power management unit is also provided to stably supply power to the signal amplification module, the signal acquisition module and the signal processing unit, to ensure good stability and continuity of signal sampling. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 FIG. 6 is a schematic structural diagram of the signal acquisition circuit of the medical electromagnetic sensor provided by an embodiment of the present invention; Figure 2 FIG. 7 is a schematic diagram of the connector for inputting the magnetic sensing signal provided by an embodiment of the present invention; Figure 3 FIG. 8 is a schematic circuit diagram of the first signal amplification module provided by an embodiment of the present invention; Figure 4 FIG. 9 is a schematic circuit diagram of the pre-stage signal amplification module provided by an embodiment of the present invention; Figure 5 FIG. 10 is a schematic circuit diagram of the secondary signal amplification module provided by an embodiment of the present invention; Figure 6 FIG. 11 is a schematic circuit diagram of the signal acquisition module corresponding to the first level provided by an embodiment of the present invention; Figure 7 FIG. 12 is a schematic circuit diagram of the signal acquisition module corresponding to the second level provided by an embodiment of the present invention; Figure 8 FIG. 13 is a schematic circuit diagram of the preprocessing conversion module provided by an embodiment of the present invention; FIG. 9(a) is a schematic circuit diagram of the first power output module provided by an embodiment of the present invention; FIG. 9(b) is a schematic circuit diagram of the second power output module provided by an embodiment of the present invention; FIG. 9(c) is a schematic circuit diagram of the third power output module provided by an embodiment of the present invention; Figure 10 It is the circuit schematic diagram of the signal processing unit provided by an embodiment of the present invention; Figure 11 It is the circuit schematic diagram of the signal control unit provided by an embodiment of the present invention. Detailed implementation manners

[0014] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0015] It should be noted that although functional module division is performed in the device schematic diagram, in some cases, it can be divided differently from the modules in the device.

[0016] Figure 1 It is the structural schematic diagram of the signal acquisition circuit of the medical electromagnetic sensor provided by an embodiment of the present invention.

[0017] As Figure 1 shown, the signal acquisition circuit of the medical electromagnetic sensor may include but is not limited to: The signal amplification and acquisition unit 100 includes a signal amplification module 110 for amplifying the input magnetic sensing signal and a signal acquisition module 120 for extracting the amplified magnetic sensing signal. Among them, the signal acquisition module 120 is configured in multiple stages, and the signal amplification gains set by at least two stages of the signal acquisition module 120 are different; the signal output end of the signal amplification module 110 is respectively connected to each stage of the signal acquisition module 120, so as to perform hierarchical acquisition of the amplified magnetic sensing signal through the signal sampling ends of each stage of the signal acquisition module 120, and obtain multi-stage sampled and amplified signals; It should be noted that as Figure 2 shown, the magnetic sensing signal can be input through a 10-pin connector, and it can be connected to the input of two or even more magnetic sensing signals at the same time. The magnetic sensing signal is input in a differential form, and double series switching diodes D8 and D9 are added at the same time for ESD protection, voltage clamping and signal integrity maintenance; the signal amplification gains set by different stages of the signal acquisition module 120 may be the same, but for all stages of the signal acquisition module 120, at least two stages of the signal acquisition module 120 have different signal amplification gains set; after each stage of the signal acquisition module 120 acquires the corresponding sampled and amplified signal, each stage of the signal acquisition module 120 may convert the acquired sampled and amplified signal into the corresponding digital signal and then send it to the signal processing unit 200; The signal processing unit 200 is respectively connected to the signal sampling ends of each stage of the signal acquisition module 120, and is used to screen at least one stage from all the sampled and amplified signals as the target amplified signal, and perform digital filtering on the target amplified signal and output it. Among them, the number of specifically screened target amplified signals needs to be determined according to the actual scenario, and there is no limitation here; The power management unit 300 is respectively connected to the signal amplification module 110, the signal acquisition module 120 and the signal processing unit 200, and is used to stably supply power to the signal amplification module 110, the signal acquisition module 120 and the signal processing unit 200 based on the input power supply voltage.

[0018] It can be seen that, compared with the signal acquisition method in the related prior art, by respectively connecting the signal output end of the signal amplification module 110 to each stage of the signal acquisition module 120, the multi-stage signal acquisition module 120 is used to respectively perform hierarchical acquisition on the magnetosensing signals amplified by different multiples. Since the signal amplification gains set by at least two stages of the signal acquisition module 120 are different, the magnetosensing signals in different amplification situations can be acquired through the multi-stage signal acquisition module 120. That is to say, no matter how large the amplitude span of the magnetosensing signal is, it can be covered for sampling. Therefore, there is no need to separately control the amplification gain of the magnetosensing signal, avoiding signal sampling distortion. Even in the case of a large signal span, the magnetosensing signal can still be conveniently and effectively acquired; moreover, the configured signal processing unit 200 screens and processes the sampled and amplified signals at each stage and outputs the screened target amplified signal, so as to facilitate the effective amplification screening and reliable communication output of the magnetosensing signal. At the same time, a power management unit 300 is also provided to stably supply power to the signal amplification module 110, the signal acquisition module 120 and the signal processing unit 200 to ensure good stability and continuity of signal sampling.

[0019] In one embodiment, the signal amplification module 110 may, but is not limited to, include a first signal amplification module for pre-amplifying the input magnetic sensing signal, and a second signal amplification module for further amplifying the magnetic sensing signal and filtering out the bias voltage. The second signal amplification module includes a pre-stage signal amplification module and a secondary signal amplification module. The signal output end of the first signal amplification module is connected to the signal input end of the pre-stage signal amplification module. The signal output end of the pre-stage signal amplification module is connected to the signal input end of the secondary signal amplification module. The signal output end of the secondary signal amplification module is respectively connected to each signal acquisition module 120. Among them, the first signal amplification module, the pre-stage signal amplification module, and the secondary signal amplification module all include a first low-pass filtering module for filtering out high-frequency noise in the magnetic sensing signal. By setting the first low-pass filtering module, it is ensured that the output signals of each amplification module have good output performance, so as to improve the accuracy of the next-stage sampling process and reduce the possibility of distortion. It can be understood that in different amplification modules, the specific form of the first low-pass filtering module can be different, that is, it is configured accordingly according to the actual application scenario, and there is no limitation here.

[0020] It should be noted that the signal amplification gains of the first signal amplification module, the pre-stage signal amplification module, and the secondary signal amplification module can be set accordingly according to the specific scenario, and there is no limitation here. For example, the signal amplification gain of the first signal amplification module may, but is not limited to, be 50, the signal amplification gain of the pre-stage signal amplification module may, but is not limited to, be 10, and the signal amplification gain of the secondary signal amplification module may, but is not limited to, be 10. Then the final gain of the signal amplification and acquisition unit 100 in this scenario is 5000.

[0021] Specifically, as Figure 3 shown, the first signal amplification module is connected to the magnetic sensor to the acquisition board through twisted pairs. By connecting the common-mode inductor L8, paralleling capacitors C109, C116, C111, C117 to the ground, and connecting resistors R53, R54 and inductors L9, L10 in series to introduce them to the instrumentation amplifier U15, the effect of amplifying 50 times is achieved. It can be seen that the first low-pass filtering module in the front stage adopts Figure 3The low-pass filter shown, but this is not the only limitation. Those skilled in the art can make corresponding settings according to the scenario requirements, and it can filter out high-frequency noise; on one side of the instrumentation amplifier U15, there are multiple capacitors connected in series to reduce the oscillation of the instrumentation amplifier U15. The actual traces of the multiple capacitors connected in series should be as close as possible to reduce the differential-mode signal; preferably, the instrumentation amplifier U15 uses a low-noise model, so as to effectively filter out the common-mode signal and retain the differential-mode signal, and reduce the introduced thermal noise. L28 and L27 are filter inductors, and their function is to filter out high-frequency noise. Pins 8 and 9 of the instrumentation amplifier U15 are connected to the output after amplification of the first signal amplification module, that is, connected to the signal output terminal OUT1 of the first signal amplification module; among them, the amplification factor of the instrumentation amplifier U15 can be adjusted by adjusting the resistor R49, and the adjustment relationship is: .

[0022] Specifically, as Figure 4 shown, the pre-stage signal amplification module uses a second-order active low-pass filter as the first low-pass filtering module, and its gain is 10 times. The operational amplifier U24B uses a low-noise precision operational amplifier, such as MAX44246, etc., to reduce the introduced thermal noise. Its pin 7 is connected to the signal output terminal OUT2 of the pre-stage signal amplification module; a capacitor C236 is connected in series in front of the filter to filter the bias voltage. The adjustment relationship of the signal gain is: , and at the same time, the cut-off frequency of the set second-order active low-pass filter is: .

[0023] Specifically, as Figure 5 shown, the secondary signal amplification module uses a multiple-feedback filter as the first low-pass filtering module, and its signal gain is 10 times. The adjustment relationship of the signal gain is: , and the cut-off frequency is: , about 10.5KHz. The pin 4 of the operational amplifier U24A is connected to the -12V power supply through the decoupling capacitors C229 and C233 connected in parallel. The pin 8 is connected to the +12V power supply through the decoupling capacitors C241 and C244 connected in parallel. The pin 1 is connected to the signal output terminal OUT3 of the secondary signal amplification module, and the pin 2 is connected to the signal output terminal OUT2 of the pre-stage signal amplification module through the resistors R121 and R122 connected in series.

[0024] In one embodiment, the signal acquisition module 120 is configured with at least a first level and a second level. Among them, the signal acquisition module 120 corresponding to the first level includes a first voltage follower, a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor. The first capacitor, the second capacitor, the third capacitor, and the fourth capacitor are connected in parallel to form a first bypass capacitor circuit. One end of the first bypass capacitor circuit is connected to one of the signal sampling terminals of the corresponding signal acquisition module 120, and the other end is connected to the reference ground. The input terminal of the first voltage follower is connected to the signal output terminal of the secondary signal amplification module, and the output terminal of the first voltage follower is connected to one of the signal sampling terminals of the corresponding signal acquisition module 120. The signal acquisition module 120 corresponding to the second level includes a second voltage follower, a second low-pass filtering module, a fifth capacitor, a sixth capacitor, a seventh capacitor, and an eighth capacitor. The fifth capacitor, the sixth capacitor, the seventh capacitor, and the eighth capacitor are connected in parallel to form a second bypass capacitor circuit. One end of the second bypass capacitor circuit is connected to one of the signal sampling terminals of the corresponding signal acquisition module 120, and the other end is connected to the reference ground. The signal output terminal of the secondary signal amplification module is connected to the input terminal of the second voltage follower through the second low-pass filtering module, and the output terminal of the second voltage follower is connected to one of the signal sampling terminals of the corresponding signal acquisition module 120.

[0025] It should be noted that the structures of the first voltage follower and the second voltage follower can be set to be the same, and both play the roles of reducing current consumption and reducing output impedance. The second low-pass filtering module can, but is not limited to, adopt an infinite gain multiple feedback low-pass filter.

[0026] Specifically, as Figure 6 shown, the signal acquisition module 120 corresponding to the first level is based on a pre-configured operational amplifier to form a first voltage follower. The gain of the first voltage follower is 1, and it has a certain high-frequency noise filtering ability. After the output of the operational amplifier, bypass capacitors C52, C53, C54, and C55 are connected in parallel to form a first bypass capacitor circuit, and then signal acquisition is performed through one of the signal sampling terminals ADC1 of the signal acquisition module 120, so as to obtain the signal amplified at the first level. Among them, the first bypass capacitor circuit plays the role of filtering and noise reduction output.

[0027] Specifically, as Figure 7As shown, based on the signal acquisition module 120 corresponding to the first level, the signal acquisition module 120 corresponding to the second level further introduces an infinite-gain multiple negative feedback low-pass filter at the signal output terminal OUT3 of the secondary signal amplification module. The gain of the second voltage follower is 10. In cooperation with the second voltage follower, one signal sampling terminal ADC2 of the signal acquisition module 120 will not be interfered by the original circuit during acquisition, so as to obtain a stable and reliable second-level amplified signal. Among them, the second bypass capacitor circuit plays a role in filtering and noise reduction output. Similarly, based on the signal acquisition module 120 corresponding to the second level, an infinite-gain multiple negative feedback low-pass filter can be introduced again through the signal output terminal OUT3 of the secondary signal amplification module, so as to perform acquisition through one signal sampling terminal ADC3 of the signal acquisition module 120 corresponding to the third level to obtain a third-level amplified signal. That is to say, if more levels of amplification are needed in the future, similar additions can be made according to the design of the above embodiments, which is not limited here. For example, the first-level amplified signal is 50 times, the second-level amplified signal is 10 times, and the third-level amplified signal is 5 times. Then when all signal acquisition modules 120 simultaneously acquire the above three amplified signals, amplified signals of 50 times, 500 times, and 2500 times will be acquired simultaneously. Similarly, for four-level amplification, the amplification factors are 50 times, 10 times, 10 times, and 10 times according to the levels. But at this time, all signal acquisition modules 120 only acquire the signals of the second, third, and fourth levels. Then the amplified signals of 500 times, 5000 times, and 50000 times will be acquired at this time.

[0028] It should be noted that the parameters and types of components such as resistors and capacitors mentioned above are only for reference. The operational amplifier in the above embodiments uses a dual-channel operational amplifier, which can be replaced with a single-channel or multi-channel operational amplifier according to the actual situation in actual use, and the functions achieved are the same, which will not be elaborated here; at the same time, the signal amplification described in the above embodiments supports multi-channel synchronous input. For example, two sensor inputs. At this time, one more copy of the above relevant circuit units or modules can be set in the circuit design to achieve synchronous amplification of multi-channel signals.

[0029] It can be seen that based on the multi-level sampling method in the above embodiments, the sampling accuracy can be significantly improved, and the noise interference can be reduced. In particular, the sampling results can adapt to a wider signal range and dynamic characteristics, improving the versatility and flexibility of signal sampling.

[0030] In one embodiment, the power management unit 300 includes a preprocessing conversion module, a first power output module, and a second power output module. The input end of the preprocessing conversion module is connected to the supply voltage, and the output end is respectively connected to the input ends of the first power output module and the second power output module. The output end of the first power output module is respectively connected to the power input ends of the signal amplification module 110 and the signal acquisition module 120. One output end of the second power output module is connected to the power input end of the signal processing unit 200. Among them, the preprocessing conversion module is used to rectify, filter, and convert the input supply voltage to output a first voltage. The first power output module is used to convert the first voltage into a second voltage for output. The second power output module is used to convert the first voltage into a third voltage for output. The second voltage is the operating voltage of the signal amplification module 110 and the signal acquisition module 120, and the third voltage is the operating voltage of the signal processing unit 200.

[0031] In one embodiment, the signal acquisition circuit further includes a signal control unit for communicating with the outside based on the target amplified signal. The signal input end of the signal control unit is connected to the digital signal output end of the signal processing unit 200. The power management unit 300 further includes a third power output module for converting the third voltage into a fourth voltage for output. The input end of the third power output module is connected to the other output end of the second power output module, and the output end of the third power output module is connected to the power input end of the signal control unit to provide the fourth voltage as the operating voltage to the signal control unit.

[0032] Specifically, as Figure 8As shown, regarding the preprocessing conversion module, first, the 24V power supply is input to the preprocessing conversion module. After the common-mode filter L2 and decoupling capacitors C32, C31, C35, C36, and C34 filter out the power supply noise, it is input to the DCDC power module U8. The DCDC power module U8 is an isolated DC-DC converter, whose function is to ensure electrical isolation between modules. Finally, the DCDC power module U8 outputs 15V and -15V respectively. After rectification and filtering through capacitors C21, C22, C37, C38, C42, C43, C46, C47 and inductors L3, L4, the P15+ and P15- power supplies are obtained. At the same time, decoupling capacitors C33, C39, C40, C41, C44, and C45 are added to P15+ and P15-. As shown in Figure 9(a), after the P15+ power supply is connected in parallel with the decoupling capacitors C23 and C24, it is input to the conversion chip U7. The conversion chip U7 outputs a +12V voltage. The conversion chip U7 is connected in parallel with the decoupling capacitors C25 and C26 and is connected in series with the filter inductor L1 to obtain the 12V voltage of P12+ to increase the power supply stability and suppress noise. Similarly, after passing through the conversion chip, P15- obtains the -12V voltage of P12-. Similarly, referring to Figure 9(b), after passing through the conversion chip U10, P15+ obtains the +5V voltage. Referring to Figure 9(c), after passing through the conversion chip U11, +5V obtains the +3.3V voltage, which will not be elaborated here. That is to say, in a preferred case, the first voltage is 15V, the second voltage is 12V, the third voltage is 5V, and the fourth voltage is 3.3V.

[0033] In one embodiment, as Figure 10As shown, the signal processing unit 200 uses an ADC chip U12. Specifically, the 3.3V output of the third power output module passes through a bead FB9 to obtain VDD33_7606 of 3.3V. After VDD33_7606 is connected in parallel with decoupling capacitors C68 and C69 to ground, it is used to provide a chip select voltage for the ADC chip U12. Further, VDD33_7606 passes through a bead FB8 to obtain VDD33_RIVE. After VDD33_RIVE is connected in parallel with decoupling capacitors C66 and C67 to ground, it is used to match the communication logic level of the 3.3V ADC chip U12. The 5V power supply output of the second power output module passes through a filter inductor L6 and a parallel decoupling capacitor C70 to ground to obtain AVCC_7606, which is used to supply power to the ADC chip U12. Among them, pin 1 of the ADC chip U12 is connected to the power supply, pin 2 is grounded, pins 3, 4, and 5 are connected to the signal control unit to configure the oversampling rate and output data rate of the ADC chip U12. Pin 6 is grounded through a resistor R19. Pins 7 and 8 are connected to VDD33_7606. Pins 9, 10, 11, 12, 13, 14 are connected to the signal control unit for the control of the ADC chip U12. Pins 16, 17, 18, 19, 20, 21, 22, 24, 25, 27, 28, 29, 30, 31, 32, and 33 are connected to the signal control unit for data width matching to achieve the transmission of 16-bit data at a time. Pin 23 is connected to VDD33_RIVE to match the communication logic level with the signal control unit. Pin 26 is grounded. Pin 34 is connected to VDD33_7606 through a resistor R20. Pin 36 is connected to ground through a capacitor C86. Pins 37 and 38 are connected to AVCC_7606. Pin 39 is connected to ground through a capacitor C85. The remaining pins 40 to 48 are configured in the conventional manner in the art and will not be elaborated here. Pins 49, 51, 53, 55, 57, 59, 61, and 63 are signal acquisition ports, that is, ADC1, ADC2, ADC3... shown in the foregoing embodiments, and are used to simultaneously acquire signals with different magnification factors.

[0034] Specifically, as Figure 11As shown, the signal control unit may, but is not limited to, use the single-chip microcomputer chip U13A. Pins 46 and 49 of the single-chip microcomputer chip U13A are used for program burning. Pins 8, 9, 10, 11, 24, 25, 37, 38, 39, 40, 51, 52, 53, 2, 3, and 4 are used to connect to the ADC chip U12 to transmit data; pins 15, 16, and 20 are used to transmit and receive information. Pins 42 and 43 are connected to an external communication module through resistors R33 and R36 for communication and data transmission. The resistors R32 and R35 pull up pins 42 and 43 of the single-chip microcomputer chip U13A through the series-connected resistors R32 and R35. Pins 26, 27, and 55 are connected to the ADC chip U12 through resistors R23, R25, and R28 to control its sampling channel number and sampling rate. Pins 57, 59, 61, 62, and 29 are connected to the ADC chip U12 through resistors R29, R30, R31, R34, and R37 to control data transmission, sampling time, etc. of the ADC chip U12. Pins 5 and 6 are connected to pins 1 and 3 of the crystal oscillator Y1 through the parallel-connected capacitors C98 and C99. Pin 60 is connected to ground through resistor R39. Pin 7 is connected to 3.3V power supply through resistor R40 and to ground through capacitor C102 respectively. Pins 31 and 47 are connected to ground through capacitors C101 and C100 respectively.

[0035] It should be noted that the signal acquisition circuit and application scenario of the medical electromagnetic sensor described in the embodiments of the present invention are for more clearly explaining the technical solutions of the embodiments of the present invention, and do not constitute a limitation to the technical solutions provided by the embodiments of the present invention. Those skilled in the art can know that with the evolution of the signal acquisition circuit of the medical electromagnetic sensor and the emergence of new application scenarios, the technical solutions provided by the embodiments of the present invention are equally applicable to similar technical problems.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A signal acquisition circuit for a medical electromagnetic sensor, characterized in that: include: A signal amplification and acquisition unit, comprising a signal amplification module for amplifying an input magnetic sensor signal and a signal acquisition module for extracting the amplified magnetic sensor signal, wherein the signal acquisition module is configured as multiple stages, and the signal amplification gains set for at least two stages of the signal acquisition modules are different; the signal output end of the signal amplification module is respectively connected to the signal acquisition modules at each stage, so as to perform hierarchical acquisition on the amplified magnetic sensor signal through the signal sampling ends of the signal acquisition modules at each stage, and obtain a multi-stage sampling amplified signal; A signal processing unit, connected to the signal sampling ends of the signal acquisition modules at each level, for selecting at least one level from all the sampled amplified signals as a target amplified signal, and performing digital filtering on the target amplified signal for output; A power management unit is respectively connected to the signal amplification module, the signal acquisition module and the signal processing unit, and is used to provide stable power supply to the signal amplification module, the signal acquisition module and the signal processing unit based on an input power supply voltage.

2. The signal acquisition circuit of the medical electromagnetic sensor according to claim 1, characterized in that: The signal amplification module includes a first signal amplification module for pre-amplifying the input magnetic sensor signal, and a second signal amplification module for further amplifying the magnetic sensor signal and filtering the bias voltage. The second signal amplification module includes a front-stage signal amplification module and a secondary signal amplification module. The signal output end of the first signal amplification module is connected to the signal input end of the front-stage signal amplification module, and the signal output end of the front-stage signal amplification module is connected to the signal input end of the secondary signal amplification module. The signal output end of the secondary signal amplification module is respectively connected to the signal acquisition modules at each level, wherein the first signal amplification module, the front-stage signal amplification module and the secondary signal amplification module all include a first low-pass filtering module for filtering high-frequency noise in the magnetic sensor signal.

3. The signal acquisition circuit of the medical electromagnetic sensor according to claim 2, characterized in that: The signal acquisition module is configured as at least one level and two levels, wherein the signal acquisition module corresponding to the first level includes a first voltage follower, a first capacitor, a second capacitor, a third capacitor and a fourth capacitor, the first capacitor, the second capacitor, the third capacitor and the fourth capacitor are connected in parallel to form a first bypass capacitor loop, one end of the first bypass capacitor loop is connected to one of the signal sampling ends of the corresponding signal acquisition module and the other end is connected to the reference ground, the input end of the first voltage follower is connected to the signal output end of the secondary signal amplification module, and the output end of the first voltage follower is connected to one of the signal sampling ends of the corresponding signal acquisition module The corresponding secondary signal acquisition module includes a second voltage follower, a second low-pass filter module, a fifth capacitor, a sixth capacitor, a seventh capacitor and an eighth capacitor. The fifth capacitor, the sixth capacitor, the seventh capacitor and the eighth capacitor are connected in parallel to form a second bypass capacitor loop. One end of the second bypass capacitor loop is connected to one of the signal sampling terminals of the corresponding signal acquisition module and the other end is connected to the reference ground. The signal output end of the secondary signal amplification module is connected to the input end of the second voltage follower through the second low-pass filter module, and the output end of the second voltage follower is connected to one of the signal sampling terminals of the corresponding signal acquisition module.

4. The signal acquisition circuit of the medical electromagnetic sensor according to claim 3, characterized in that: The second low-pass filter module adopts an infinite gain multi-channel negative feedback low-pass filter.

5. The signal acquisition circuit of the medical electromagnetic sensor according to claim 1, characterized in that: The power management unit includes a preprocessing conversion module, a first power output module and a second power output module, wherein the input end of the preprocessing conversion module is connected to the power supply voltage and the output end is respectively connected to the input end of the first power output module and the input end of the second power output module, the output end of the first power output module is respectively connected to the power input end of the signal amplification module and the power input end of the signal acquisition module, and one output end of the second power output module is connected to the power input end of the signal processing unit, wherein the preprocessing conversion module is used to rectify and filter the input power supply voltage and convert and output a first voltage, the first power output module is used to convert the first voltage into a second voltage output, and the second power output module is used to convert the first voltage into a third voltage output, the second voltage is the working voltage of the signal amplification module and the signal acquisition module, and the third voltage is the working voltage of the signal processing unit.

6. The signal acquisition circuit of the medical electromagnetic sensor according to claim 5, characterized in that: It also includes a signal control unit for communicating with the outside based on the target amplified signal, and the signal input end of the signal control unit is connected to the digital signal output end of the signal processing unit; the power management unit also includes a third power output module for converting the third voltage into a fourth voltage output, the input end of the third power output module is connected to another output end of the second power output module, and the output end of the third power output module is connected to the power input end of the signal control unit to provide the fourth voltage as a working voltage to the signal control unit.

7. The signal acquisition circuit of the medical electromagnetic sensor according to any one of claims 2 to 4, characterized in that: The signal amplification gain of the first signal amplification module is 50, the signal amplification gain of the pre-stage signal amplification module is 10, and the signal amplification gain of the secondary signal amplification module is 10.

8. The signal acquisition circuit of the medical electromagnetic sensor according to claim 6, characterized in that: The first voltage is 15V, the second voltage is 12V, the third voltage is 5V, and the fourth voltage is 3.3V.

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