CN111685761A - Time domain biological impedance detection circuit based on comparator - Google Patents
Time domain biological impedance detection circuit based on comparator Download PDFInfo
- Publication number
- CN111685761A CN111685761A CN202010457278.7A CN202010457278A CN111685761A CN 111685761 A CN111685761 A CN 111685761A CN 202010457278 A CN202010457278 A CN 202010457278A CN 111685761 A CN111685761 A CN 111685761A
- Authority
- CN
- China
- Prior art keywords
- impedance
- circuit
- time domain
- voltage
- comparator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
- A61B5/053—Measuring electrical impedance or conductance of a portion of the body
Landscapes
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biomedical Technology (AREA)
- Heart & Thoracic Surgery (AREA)
- Radiology & Medical Imaging (AREA)
- Biophysics (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Physics & Mathematics (AREA)
- Medical Informatics (AREA)
- Molecular Biology (AREA)
- Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
Abstract
The invention belongs to the technical field of integrated circuits, and particularly relates to a time domain biological impedance detection circuit based on a comparator. The invention comprises the following steps: the device comprises a pseudo-sine current excitation generating circuit, an analog front end amplifying circuit, a PWM wave generating circuit and an impedance reconstruction circuit. The biological impedance to be measured is converted into a voltage signal through pseudo-sinusoidal current excitation, after the voltage signal is amplified by the analog front-end amplifying circuit, the impedance information is converted into a time domain from a voltage domain by the PWM wave generating circuit, and finally the impedance signal is reconstructed by an impedance reconstruction algorithm. The invention avoids the requirement for high-performance analog filter and high-precision analog-to-digital converter; the conversion and processing of signals after information is converted into a time domain are realized by a digital circuit, the advantages of the most advanced integrated circuit process can be fully utilized, a high-performance signal processing circuit is realized under a lower power supply voltage, and the power consumption of a system is further reduced. The invention has the characteristics of strong anti-interference capability, low power consumption and simple reconstruction algorithm.
Description
Technical Field
The invention belongs to the technical field of integrated circuits, and particularly relates to a time domain biological impedance detection circuit based on a comparator.
Background
With the cooperation of the integrated circuit industry and medical and life science disciplines going deep, the multifunctional biological detection circuit is expected to appear in the daily life of people in the future, changes the current medical care form, realizes the biological activation and autonomy of medical treatment, and particularly, the development of an implanted miniature biological signal detection system makes the real-time monitoring and treatment of the focus possible. And the bio-impedance detection circuit is an indispensable part thereof. At present, a plurality of researches show that the bioimpedance detection plays a crucial role in the aspects of new drug research and development, cell structure research, postoperative monitoring in the operation and the like. The basic principle of bioimpedance measurement is to apply an excitation current to the tissue to be measured and to detect a voltage signal generated in response thereto. The traditional biological impedance detection circuit adopts a two-way quadrature demodulation principle to carry out detection, and has the advantages that the calculation of a detection result is independent of the frequency of an excitation signal, and the harmonic generated by demodulation has higher performance requirements on an analog filter and an analog-to-digital converter. In addition, the requirement of the voltage domain signal for a high-performance analog circuit makes it difficult for the whole system to utilize the advantages brought by the advanced integrated circuit process, and limits the reduction of power consumption.
In order to overcome the defects, the invention provides a time domain biological impedance detection circuit based on a comparator, information is converted from a voltage domain to a time domain by using the comparator, the conversion and the processing of signals are realized by a digital circuit, the requirements on a high-performance analog filter and a high-precision analog-to-digital converter are avoided, the advantages of the most advanced integrated circuit process can be fully utilized, and a high-performance signal processing circuit is realized under a lower power supply voltage, so that the power consumption of a system is further reduced. Compared with the traditional phase-locking method, the impedance reconstruction algorithm consumes less hardware resources, thereby being beneficial to the whole-chip integration of the analog front end and the digital processing. However, the reconstruction algorithm requires that the frequency of the known excitation signal is relatively accurate, so the detection circuit has a certain limitation on the generation mode of the excitation current.
Disclosure of Invention
The invention aims to provide a biological impedance detection circuit with low power consumption and high integration level.
The invention provides a biological impedance detection circuit, which is a time domain biological impedance detection circuit based on a comparator. The circuit comprises a pseudo-sinusoidal current excitation generating circuit and a voltage signal receiving circuit; wherein:
the pseudo-sinusoidal current excitation generating circuit is used for generating sinusoidal current signals with known frequency and good linearity and is respectively applied to the biological impedance to be detected and the reference resistor. The resistance value of the reference resistor is known and is selected according to the range of the biological impedance to be detected;
the voltage signal receiving circuit comprises an analog front end amplifying circuit, a PWM wave generating circuit and an impedance reconstruction circuit; the PWM wave generating circuit comprises a comparator and a logic gate circuit; the impedance reconstruction circuit comprises a time-to-digital conversion module, a (Cordic) sine function, a multiplication function and a division function module.
In the present invention, the pseudo-sinusoidal current excitation generating circuit may be implemented in various ways, typically, for example, a circuit composed of a read only memory, a sigma-delta modulator, and a current-mode digital-to-analog converter.
In the invention, the analog front end amplification path has two identical paths, wherein one path is used for detecting the voltage at two ends of the impedance to be detected, and the other path is used for detecting the voltage at two ends of the reference resistor; each analog front-end amplification path comprises a programmable voltage amplifier and a filter, and the gain is adjustable through the programmable voltage amplifier, so that a wider impedance measurement range is realized.
In the invention, the output of the two analog amplification paths enters a PWM wave generating circuit, and the information of a voltage domain is converted into a time domain through a comparator and a plurality of logic gate circuits, and is expressed by the width of a pulse.
In the invention, the impedance reconstruction circuit firstly converts the pulse width into digital information through the time-to-digital conversion module, and then reconstructs the amplitude and phase information of the impedance to be measured through the multiplication function, the division function and the sine operation function module. The multiplication, division and sine operation can be realized by software, or can be realized by an Application Specific Integrated Circuit (ASIC) or a programmable gate array (FPGA).
Compared with the traditional impedance detection method of phase-locked amplification, the invention avoids the requirements on a high-performance analog filter and a high-precision analog-to-digital converter, simultaneously, the conversion and the processing of the signals after the information is converted into the time domain are realized by a digital circuit, the advantages of the most advanced integrated circuit process can be fully utilized, a high-performance signal processing circuit is realized under the lower power supply voltage, and the power consumption of the system is further reduced. Compared with the traditional phase-locking method, the impedance reconstruction algorithm consumes less hardware resources, thereby being beneficial to the whole-chip integration of the analog front end and the digital processing. The invention has the characteristics of strong anti-interference capability, low power consumption and simple reconstruction algorithm.
Drawings
FIG. 1 is a block diagram showing the structure of a bio-impedance detection circuit according to the present invention.
Fig. 2 is a schematic diagram of an analog front end amplification path structure according to the present invention.
Fig. 3 is a schematic diagram of a PWM wave generating circuit according to the present invention.
Fig. 4 is a schematic diagram of the impedance reconstruction circuit of the present invention.
Reference numbers in the figures: the device comprises a pseudo-sinusoidal current excitation generating circuit 1, an analog front end amplifying circuit 2, a PWM wave generating circuit 3, an impedance reconstruction circuit 4, a to-be-detected bio-impedance 5, a reference resistor 6, a current analog-to-digital converter 7, a Sigma-delta modulator 8, a read-only memory 9, a programmable voltage amplifier 10, a low-pass filter 11, a comparator 12, an exclusive-or gate circuit 13, a time-to-digital converter 14, a multiplier module 15, a sinusoidal function calculating module 16 and a divider module 17.
Detailed Description
The invention is further illustrated with reference to the following figures and examples.
In fig. 1, a pseudo-sinusoidal current excitation generating circuit 1 is used to generate a sinusoidal current signal with a known frequency and good linearity. The generation of the pseudo-sinusoidal current excitation can be achieved in a number of ways, one specific embodiment being illustrated in fig. 1: the read-only memory 9 stores pre-generated sine signals, the data are modulated by the sigma-delta modulator 8 after being read out, and then the data are converted into current excitation signals by the low-precision current digital-to-analog converter 7 to be applied to the biological impedance 5 to be detected and the reference resistor 6 respectively. The two analog front end amplification paths 2 respectively detect voltage signals generated on the biological impedance 5 to be detected and the reference resistor 6, and perform amplification and filtering processing. The two analog amplification paths 2 input the processed voltage signals into the PWM wave generating circuit 3, the PWM wave generating circuit 3 converts the information of the voltage domain into the time domain, outputs pulse signals, and expresses the amplitude and phase information of the impedance to be measured by the width of the output pulses. The pulse signal is finally input into an impedance reconstruction circuit 4, converted into a digital domain and further calculated, so that the reconstruction of the amplitude and phase information of the bio-impedance 5 to be measured is realized.
In fig. 2, two analog front-end amplification paths 2 respectively detect voltage signals generated on a bio-impedance 5 to be detected and a reference resistor 6. The analog front-end amplification path 2 is composed of a programmable voltage amplifier 10 and a low-pass filter 11. The programmable voltage amplifier 10 is used for amplifying a voltage signal on the impedance 5 to be measured or the reference resistor 6, and the gain can be configured by a digital signal to realize a plurality of adjustable gains. The low-pass filter 11 is used for filtering high-frequency noise and harmonic waves and improving the linearity of the voltage signal. The output signal of the analog front end amplification path 2 for detecting the biological impedance 5 to be detected is Vin, and the output signal of the analog front end amplification path 2 for detecting the reference resistor 6 is Vref.
In fig. 3, the signals Vin and Vref are input to the PWM wave generating circuit 3, and converted by the comparator 12 into square wave signals Comp1, Comp2, and Comp3 having a duty ratio of 50% but different phases. Subsequently, the signals Comp1, Comp2 and Comp3 are converted into pulse signals O _ phi, O _ t2 and O _ t1 of different widths through the logic operation of the xor gate 13.
In fig. 4, the aforementioned pulse signals O _ phi, O _ T2, and O _ T1 are input to the impedance reconstruction circuit 4, and a time-to-digital converter (TDC) converts the pulse widths of the signals O _ phi, O _ T2, and O _ T1 into digital signals T3, T2, and T1, respectively. And then, the multiplier module, the sine function module and the divider module calculate the amplitude and the phase of the impedance to be measured according to the following formulas, so that the reconstruction of the impedance to be measured is realized:
where ω represents the angular frequency of the excitation current signal,R ref representing the resistance of the reference resistor.
The multiplier module, sine function module and divider module may be implemented by software, or may be implemented by an Application Specific Integrated Circuit (ASIC) or a programmable gate array (FPGA). Wherein, the sine function module can be realized by a Cordic algorithm.
The above is only one embodiment of the present invention for convenience of illustration, and the present disclosure is not limited by the embodiment, and any alternative design falling within the scope of the present invention is included in the scope of the present invention.
Claims (5)
1. A time domain biological impedance detection circuit based on a comparator is characterized by comprising a pseudo-sinusoidal current excitation generation circuit and a voltage signal receiving circuit; wherein:
the pseudo-sinusoidal current excitation generating circuit is used for generating sinusoidal current signals with known frequency and good linearity and applying the sinusoidal current signals to the biological impedance to be detected and the reference resistor respectively; the resistance value of the reference resistor is known and is selected according to the range of the biological impedance to be detected;
the voltage signal receiving circuit comprises an analog front end amplifying circuit, a PWM wave generating circuit and an impedance reconstruction circuit; the PWM wave generating circuit comprises a comparator and a logic gate circuit; the impedance reconstruction circuit comprises a time-to-digital conversion module, a Cordic sine function, a multiplication function and a division function module.
2. The comparator-based time domain bioimpedance detection circuit according to claim 1, wherein said analog front end amplification path comprises two identical paths, one for detecting the voltage across the impedance to be measured and the other for detecting the voltage across the reference resistor; the analog front-end amplification path comprises a programmable voltage amplifier and a filter, and the gain is adjustable through the programmable voltage amplifier, so that a wider impedance measurement range is realized;
the output of the two analog amplification paths enters a PWM wave generating circuit, and the information of a voltage domain is converted into a time domain through a comparator and a plurality of logic gate circuits and is expressed by the width of a pulse;
in the impedance reconstruction circuit, a time-to-digital conversion module converts pulse width into digital information, and amplitude and phase information of impedance to be measured is reconstructed through a multiplication function, a division function and a sine operation function module.
3. The comparator-based time domain bioimpedance detection circuit according to claim 2, wherein the multiplication function, division function and sine function operations are implemented in software, or in an application specific integrated circuit or a programmable logic gate array.
4. The comparator-based time domain bioimpedance detection circuit of claim 3, wherein said pseudo-sinusoidal current excitation generation circuit comprises a read only memory, a sigma-delta modulator, and a current mode digital to analog converter.
5. The time domain bioimpedance detection circuit based on a comparator according to claim 4, wherein a pre-generated sine signal is stored in a read-only memory (9), data is modulated by a sigma-delta modulator 8 after being read out, and then is converted into a current excitation signal by a current digital-to-analog converter (7) and is applied to the bioimpedance (5) to be detected and the reference resistor (6) respectively; the two analog front-end amplification paths (2) respectively detect voltage signals generated on the biological impedance (5) to be detected and the reference resistor (6), and perform amplification and filtering processing; the channel analog amplification path (2) inputs the processed voltage signal into the PWM wave generation circuit (3), the PWM wave generation circuit (3) converts the information of the voltage domain into the time domain, outputs a pulse signal, and expresses the amplitude and phase information of the impedance to be measured by the width of the output pulse; the pulse signal is finally input into an impedance reconstruction circuit (4), converted into a digital domain and further calculated, so that the reconstruction of the amplitude and phase information of the biological impedance (5) to be detected is realized;
the analog front-end amplification path (2) consists of a programmable voltage amplifier (10) and a low-pass filter (11); the programmable voltage amplifier (10) is used for amplifying a voltage signal on the impedance (5) to be measured or the reference resistor (6), and the gain is configured by a digital signal to realize adjustable gains of a plurality of gears; the low-pass filter (11) is used for filtering high-frequency noise and harmonic waves and improving the linearity of a voltage signal; the output signal of the analog front-end amplification path (2) for detecting the biological impedance (5) to be detected is Vin, and the output signal of the analog front-end amplification path (2) for detecting the reference resistor (6) is Vref;
the signals Vin and Vref are input into a PWM wave generating circuit (3) and are converted into square wave signals Comp1, Comp2 and Comp3 with duty ratio of 50% but different phases by a comparator (12); the signals Comp1, Comp2 and Comp3 are converted into pulse signals O _ phi, O _ t2 and O _ t1 with different widths through the logical operation of an exclusive-OR gate (13);
the pulse signals O _ phi, O _ T2 and O _ T1 are input into an impedance reconstruction circuit (4, a time-to-digital converter converts the pulse widths of the signals O _ phi, O _ T2 and O _ T1 into digital signals T3, T2 and T1 respectively, and then a multiplier module, a sine function module and a divider module calculate the amplitude and the phase of the impedance to be measured according to the following formula, so that the reconstruction of the impedance to be measured is realized:
where ω represents the angular frequency of the excitation current signal,R ref representing the resistance of the reference resistor.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN202010457278.7A CN111685761B (en) | 2020-05-26 | 2020-05-26 | Time domain biological impedance detection circuit based on comparator |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN202010457278.7A CN111685761B (en) | 2020-05-26 | 2020-05-26 | Time domain biological impedance detection circuit based on comparator |
Publications (2)
Publication Number | Publication Date |
---|---|
CN111685761A true CN111685761A (en) | 2020-09-22 |
CN111685761B CN111685761B (en) | 2022-10-11 |
Family
ID=72478300
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CN202010457278.7A Active CN111685761B (en) | 2020-05-26 | 2020-05-26 | Time domain biological impedance detection circuit based on comparator |
Country Status (1)
Country | Link |
---|---|
CN (1) | CN111685761B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN114668379A (en) * | 2022-03-16 | 2022-06-28 | 四川大学华西第二医院 | Method for deleting and selecting data of bioimpedance technology |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050031139A1 (en) * | 2003-08-07 | 2005-02-10 | Tymphany Corporation | Position detection of an actuator using impedance |
CN1736018A (en) * | 2002-11-14 | 2006-02-15 | 菲尔风暴有限公司 | Power converter circuitry and method |
CN1875883A (en) * | 2006-06-08 | 2006-12-13 | 天津大学 | Mixing bio-impedance measurement method based on Fourier conversion |
CN104406633A (en) * | 2014-11-26 | 2015-03-11 | 深圳麦开网络技术有限公司 | Physique and environment monitor and activating method thereof |
US20170071552A1 (en) * | 2015-09-14 | 2017-03-16 | Stichting Imec Nederland | Bio-Impedance Spectroscopy System and Method for Bio-Impedance Measurement |
CN109363674A (en) * | 2018-08-22 | 2019-02-22 | 西安电子科技大学 | A kind of bio-impedance testing system |
CN110045591A (en) * | 2017-12-11 | 2019-07-23 | 硅谷实验室公司 | Use the time-to-digit converter with circulation delay |
-
2020
- 2020-05-26 CN CN202010457278.7A patent/CN111685761B/en active Active
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN1736018A (en) * | 2002-11-14 | 2006-02-15 | 菲尔风暴有限公司 | Power converter circuitry and method |
US20050031139A1 (en) * | 2003-08-07 | 2005-02-10 | Tymphany Corporation | Position detection of an actuator using impedance |
CN1875883A (en) * | 2006-06-08 | 2006-12-13 | 天津大学 | Mixing bio-impedance measurement method based on Fourier conversion |
CN104406633A (en) * | 2014-11-26 | 2015-03-11 | 深圳麦开网络技术有限公司 | Physique and environment monitor and activating method thereof |
US20170071552A1 (en) * | 2015-09-14 | 2017-03-16 | Stichting Imec Nederland | Bio-Impedance Spectroscopy System and Method for Bio-Impedance Measurement |
CN110045591A (en) * | 2017-12-11 | 2019-07-23 | 硅谷实验室公司 | Use the time-to-digit converter with circulation delay |
CN109363674A (en) * | 2018-08-22 | 2019-02-22 | 西安电子科技大学 | A kind of bio-impedance testing system |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN114668379A (en) * | 2022-03-16 | 2022-06-28 | 四川大学华西第二医院 | Method for deleting and selecting data of bioimpedance technology |
Also Published As
Publication number | Publication date |
---|---|
CN111685761B (en) | 2022-10-11 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CN102661754B (en) | Digital converter for rotary transformer | |
CN107561367B (en) | Wide-spectrum impedance measurement method based on compressed sensing theory | |
US10120005B2 (en) | Synchronous detection circuit and method for determining a bio-impedance of a biological tissue | |
Hong et al. | A 0.052 mm 2,< 0.4% THD, sinusoidal current generator for bio-impedance measurement using a recursive digital oscillator and current-domain FIR filter | |
US20090295460A1 (en) | Electronic device and method for evaluating a variable capacitance | |
CN107184211A (en) | A kind of multifrequency electrical impedance imaging device based on FPGA | |
CN103957007A (en) | Random waveform weak signal detection method and system under low signal to noise ratio | |
CN111685761B (en) | Time domain biological impedance detection circuit based on comparator | |
CN101060311A (en) | A digital phase-lock amplifier | |
RU104402U1 (en) | FUNCTIONAL GENERATOR | |
US10101371B2 (en) | Synchronous detection circuit and method for extracting magnitude and phase from a waveform | |
Regnacq et al. | A Goertzel filter-based system for fast simultaneous multi-frequency EIS | |
US6879274B2 (en) | Signal-conditioning and analog-to-digital conversion circuit architecture | |
CN106546794A (en) | A kind of Wheatstone bridge measuring circuit for raising predetermined level triangle wave excitation | |
Banerjee et al. | A novel FPGA-based LVDT signal conditioner | |
Lee et al. | 30-fps SNR equalized electrical impedance tomography IC with fast-settle filter and adaptive current control for lung monitoring | |
CN116192150A (en) | Chopper modulation method for low-frequency metering and chopper Sigma-Delta modulator | |
CN103856170A (en) | Power-stage power supply noise error elimination method of H-bridge type digital D type power amplifier | |
KR102021947B1 (en) | Sinusoidal current generator | |
CN210839531U (en) | Circuit system for improving resolution of weak signal to be measured | |
CN105193395A (en) | Wrist strap type pulse wave detection system based on bioelectric impedance and detection method thereof | |
CN113100739A (en) | Portable multi-frequency electrical impedance imaging front-end data acquisition and processing method | |
CN1595804A (en) | Novel lock phase detection circuit | |
RU2424534C1 (en) | Digital modulation metre | |
CN107612553B (en) | Signal index regeneration nuclear sparse sampling method with random pulse positions |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PB01 | Publication | ||
PB01 | Publication | ||
SE01 | Entry into force of request for substantive examination | ||
SE01 | Entry into force of request for substantive examination | ||
GR01 | Patent grant | ||
GR01 | Patent grant |