KR101440494B1 - sensor for measuring vital signal and method for operating the same - Google Patents

Abstract

The present invention relates to a vital signal measuring sensor and a measuring method thereof and, more particularly, to a respiration or heartbeat signal measuring sensor and a measuring method thereof. According to an embodiment, the present invention includes a resonator which changes input impedance by corresponding to the vital signal; a phase locked loop which feeds back a loop control voltage which is a voltage in proportion to a phase difference with a preset reference frequency by receiving an oscillation frequency which is shifted by the change of the input impedance of the resonator; a voltage controlled oscillator which outputs the oscillation frequency within a preset frequency range by changing the capacitance of L-C resonance according to the loop control voltage which is fed back; and a signal processor which outputs the loop control voltage as the respiration signal and the heartbeat signal.

Description

Technical Field [0001] The present invention relates to a sensor for measuring a biological signal,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor and a method for measuring a bio-signal, and a sensor for measuring a respiration signal or a pulse signal and a method for measuring the bio-signal.

The non-contact type bio-signal measurement sensor is divided into Doppler radar-based measurement sensor using Doppler effect, electrocardiograph measurement sensor which is mainly used in medical field, and measurement sensor using input impedance change of RF resonator which is emerging recently.

The Doppler radar-based measurement sensor transmits a signal generated by the oscillator 12 to the transmission antenna 10 via the amplifier 11 as shown in FIG. The transmitted signal causes a phase shift of the transmitted signal according to the normal biological activity of the human body, that is, the movement of the body by breathing and the contraction and expansion of the heart inside the body. The signal including the shifted phase is received through the receiving antenna 20 and then down-converted by the same oscillation frequency after passing through a low noise amplifier 21 (LNA), so that the carrier signal (transmission signal) Only a heart signal can be extracted. Various studies have been carried out, such as the application of a double polarized antenna for unifying the structure.

Electrocardiogram (ECG) sensors have been mainly used in contact-type medical field. Recently, non-contact type structures have been studied to meet various needs such as respect for privacy, long-term health check, and remote examination. The representative structure uses an active electrode, and the active electrode measures a biological signal by detecting a change in capacitance value between the human body and the electrode.

The measurement sensor using the input impedance change of the RF resonator uses the input impedance of the resonator changed according to the separation distance between the human body and the RF resonator as shown in FIG. Respiration and heartbeat perform periodic motion, so the distance is constantly changing. Periodic motion changes the input impedance of the resonator, and the frequency of the oscillator changes by interlocking with the oscillator. In particular, in Korean Patent No. 10-1252740, in order to express a change in frequency as a DC voltage, a frequency shift is represented by a voltage using a SAW filter (30; Surface Acoustic Wave Filter 30) and a detector (40) A desired biological signal can be extracted by processing the signal.

However, the above-described Doppler radar-based measurement sensor, electrocardiogram measurement sensor, and RF resonator measurement sensor have the following problems.

In the case of the Doppler radar-based measurement sensor, since the biological signal is detected using the phase difference of the transmission and reception signals, there is a possibility of malfunction if interference of similar frequency components exists. Also, when the same sensors are installed in one place, the operation is restricted by mutual interference. In particular, when a plurality of subjects are present in the same space, the mapping between the measurement signals and the measured subjects increases the signal processing load considerably, which is a problem of commercialization.

In addition, the electrocardiogram sensor has the advantage of acquiring a bio-signal even when wearing clothes without touching the skin, but it is greatly influenced by the material and thickness of the clothes. The results reported so far are only measurable for thicknesses less than 2 mm. In addition, there is a problem that the capacitance value between the human body and the electrode can not be measured due to a serious change in the portion related to moisture such as sweat.

In the case of the RF resonator measurement sensor, in particular, in Korean Patent No. 10-1252740, a free running oscillator, a SAW filter, and an RF detector are used. The free oscillator not only moves according to the distance from the human body but also oscillates according to the external environment such as temperature. In addition, the signal detection capability has a problem in that the detection capability of the biological signal is different depending on the attenuation characteristics of the SAW filter and the resolution of the RF detector. Therefore, when the SAW filter having excellent attenuation characteristics is used, the detection ability of the living body signal is excellent, but the abnormal operation is performed due to the frequency shift of the free oscillator according to the environmental change such as temperature. That is, the attenuation range has a range of about 15 MHz in the 2.4 GHz ISM band. The narrow frequency operating range can cause abnormal operation if the long-term frequency stability of the oscillator (temperature characteristics of the component, ambient temperature change, etc.) is taken into consideration. On the other hand, when a filter having a flat attenuation characteristic is applied, the ability to detect a biological signal remarkably deteriorates. The deterioration of the characteristics of the devices applied at the time of long-term use causes a change in the free oscillation frequency, thereby lowering the reliability of the sensor. Also, in terms of miniaturization, the use of a filter has a problem in that it can not be designed in the form of a single monolithic microwave integrated circuit (MMIC).

Particularly, the bio-signal measurement sensors such as the Doppler radar-based measurement sensor, the electrocardiogram measurement sensor, and the RF resonator measurement sensor using the SWA filter described above have a common problem with low measurement reliability in various use environments. For example, the environment within a medical facility maintains a stable room temperature condition, while the environment for fire fighting activities, emergency medical services for 119 firefighters, and the battlefield environment where soldiers are dispatched varies from time to time according to local and situational requirements. Currently used measurement sensors have different measurement values depending on the change of measurement environment. Therefore, there is a need for a bio-signal measurement sensor that operates without affecting the measurement reliability despite the change of the measurement environment.

Korean Patent No. 10-1252740

The technical problem of the present invention is to operate without affecting the measurement reliability of the bio-signal measurement sensor despite the change of the measurement environment such as temperature. In addition, the technical problem of the present invention is to acquire bio-signals without regard to the position of the attachment (the front or back of the chest, etc.).

The present invention relates to a resonance circuit which includes a resonator in which an input impedance is changed in accordance with a living body signal and a resonance circuit which receives an oscillation frequency which is frequency-shifted by a change in the input impedance of the resonator and which is a voltage value proportional to a phase difference A voltage controlled oscillator for outputting an oscillation frequency within a preset frequency range by varying the capacitance value of the LC resonance according to the feedback loop control voltage; And a signal processor for outputting a signal and a pulse signal.

The voltage-controlled oscillator further includes: an LC resonance unit whose LC resonance is controlled by the loop control voltage; a control terminal receiving an oscillation control signal according to a change in input impedance of the resonance; an input connected to the LC resonance unit; And a switching element including an output terminal for outputting an oscillation frequency by the LC resonance.

The switching element is an NPN transistor including an NPN transistor including an emitter as an input terminal, a base as a control terminal and a collector as an output terminal, or an emitter as a base and a control terminal as an input terminal.

Also, the L-C resonance unit varies a capacitance value used for the L-C resonance by using a collector diode whose capacitance value changes according to a voltage applied to the device.

Further, the loop control voltage is applied to the collector diode, and the capacitance value used for the L-C resonance varies depending on the loop control voltage.

The LC resonance unit includes an inductor connected between the output terminal and the ground, a fixed capacitor having a fixed capacitance whose one end is connected to the node of the output terminal and the inductor, and a fixed capacitor connected between the other terminal of the fixed capacitor and the ground, A collector diode, and a feedback signal line connected to a node between the fixed capacitor and the collector diode to apply the loop control voltage.

According to another aspect of the present invention, there is provided a method for controlling a living organism, comprising the steps of: receiving an oscillation frequency that is frequency-shifted by a change in input impedance corresponding to a living body signal and feeding back a loop control voltage that is a voltage value proportional to a preset reference frequency; Outputting an oscillation frequency within a predetermined frequency range by varying a capacitance value of the LC resonance according to a feedback loop control voltage; outputting a respiration signal and a pulse signal using the loop control voltage; And displaying a respiration signal and a pulse signal.

According to the embodiment of the present invention, normal operation can be performed irrespective of external environmental conditions, and measurement reliability can be improved. The measuring distance can also be easily extended for a variety of mounting locations. In addition, it is easy to apply existing infrastructure or new networking for acquired signal transmission, and it can be manufactured in the form of monolithic microwave integrated circuit (MMIC) in mass production.

1 is a view showing a conventional Doppler radar-based measurement sensor.
2 is a view illustrating a measurement sensor using a change in input impedance of a conventional RF resonator.
3 is a block diagram of a bio-signal measurement sensor according to an embodiment of the present invention.
4 is a view showing an example of the structure of a resonator of a bio-signal measurement sensor according to an embodiment of the present invention.
5 is a cross-sectional view of a resonator and an active circuit layer according to an embodiment of the present invention.
6 is a graph illustrating a deviation of an oscillation frequency of a voltage-controlled oscillator according to an embodiment of the present invention.
7 is a circuit diagram of a voltage-controlled oscillator that receives an input impedance of a resonator according to an embodiment of the present invention and performs oscillation.
8 is a graph showing an output of an oscillation frequency in a state in which a loop control voltage is not applied by a phase locked loop according to an embodiment of the present invention.
FIG. 9 is a diagram illustrating a voltage proportional to a voltage applied to a collector diode and an oscillation frequency according to an exemplary embodiment of the present invention. Referring to FIG.
10 is a graph illustrating a frequency deviation according to an oscillation frequency and a separation distance according to an embodiment of the present invention.
11 is a block diagram of a phase locked loop according to an embodiment of the present invention.
12 is a table summarizing the parameter values of FIG. 11 according to the embodiment of the present invention.
13 is a graph showing time-base signals including breathing and pulse according to an embodiment of the present invention.
FIG. 14 is a graph showing respiration and pulse signals measured according to a separation distance according to an embodiment of the present invention. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know. Wherein like reference numerals refer to like elements throughout.

Hereinafter, the term "living body signal" means a concept including the "breathing signal" and the pulse signal due to the heartbeat, and also includes all other biological signals detectable from living organisms. The heart that repeats the expansion becomes beating with a certain pattern, and by measuring a certain pattern of this heart beat, it becomes possible to grasp the health state of life.

FIG. 3 is a block diagram of a bio-signal measurement sensor according to an embodiment of the present invention, FIG. 4 is a view illustrating an example of a structure of a resonator of a bio-signal measurement sensor according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a resonator and an active circuit layer according to an embodiment of the present invention. FIG.

The biological signal measurement sensor includes a resonator 100, a voltage controlled oscillator (VCO) 200, a phase locked loop (PLL) 300, and a digital signal processor (DSP) . And a voltage amplifier 400 (OP-Amp) may be included in the front end of the signal processor 500.

The resonator 100 is a resonance plate whose input impedance changes in accordance with a living body signal. Any type of resonator that can be used as a radiator can be applied to the resonator 100, and a planar resonator is preferably applicable. The resonator 100 can be measured at a distance of less than 50 mm from the subject of the biological signal measurement. The resonator 100 is used as a near-field radiator or as a series re-circulating element of an oscillator. The frequency change of the voltage controlled oscillator 200 corresponding to the input impedance change of the resonator 100 is changed to the voltage signal by the phase locked loop 300 (PLL). The resonator 100 is preferably a resonator having a low quality factor, but a low quality factor can lead to a large frequency deviation. Therefore, the bio-signal measurement sensor of the present invention has advantages of PLL (Phase Locked Loop), narrow gain of voltage-controlled oscillation, and wide variable range. Therefore, the conventional bio-signal measurement sensor including the SAW filter, RF detector and free oscillator The detection distance and the long-time frequency stability characteristics can be improved.

On the other hand, the resonator 100 is connected to the base (B) portion of the transistor which is the switching element of the voltage controlled oscillator 200. Adjusting the impedance input to the base (B) of the transistor can satisfy the oscillation condition of the voltage controlled oscillator.

4 shows an example of the structure of a resonator of a bio-signal measurement sensor according to an embodiment of the present invention. Referring to FIG. 4, the resonator 100 has a width of 22.5 mm and a thickness of 0.787 mm, a relative permittivity of 2.2, and a loss tangent coefficient of 0.0009. The overall size is 55mm * 55mm and has vertical vias connected to the voltage-controlled oscillator, which is the active circuit, at a distance of 12.5mm from the center to achieve the desired quality factor. The range of the near field estimated from the size of the resonator is within 103 mm. Is a value determined by the 2.4 GHz wavelength of the Industrial Scientific Medical (ISM) band used in the embodiment of the present invention. The ISM band is a frequency band that is available in industrial, scientific, and medical devices and includes the 2.4 GHz to 2.48 GHz band. These ISM bands can be used free of charge from the government without separate frequency licenses. When a human body exists in a proximity distance, a resonator having characteristics of an antenna changes the input impedance of the planar resonator due to a change in the separation distance due to human respiration or pulse. For example, when the resonator is located near (within 50 mm) from the object to be detected (human body), the periodic movement of the human body due to respiratory activity generates an additional capacitor component between the resonator and the detection object. This additional capacitor component leads to a change in the input impedance of the resonator, and this change in input impedance causes a frequency transition (deviation) of the oscillation frequency of the voltage controlled oscillator.

5 is a cross-sectional view of an oscillation module A including a resonator and an active circuit layer. In the lower portion of the resonator, an active circuit layer 200 'designed as an active circuit portion of a voltage-controlled oscillator is stacked. An input impedance is provided to the voltage controlled oscillator 200 formed in the active circuit layer 200 'through the via 110 of the resonator. At this time, the transmission line of the input impedance of the resonator may be implemented as a microstrip line or the like.

A PLL (Phase Locked Loop) 300 receives an oscillation frequency that is frequency-shifted by a change in input impedance of a resonator, and feeds back a loop control voltage that is a voltage value proportional to a phase difference with a predetermined reference frequency. That is, the oscillation frequency oscillated by the voltage-controlled oscillator 200 is fed back and compared with a preset phase difference to output a loop control voltage proportional thereto. The PLL 300 includes a frequency divider 310, a phase-frequency detector 320, and a loop filter 330. The phase-locked loop 300 includes a frequency divider 310, a phase-frequency detector 320, and a loop filter 330. The frequency divider 310 converts the oscillation frequency input from the voltage controlled oscillator 200 to a frequency equal to the reference frequency, and the PFD 320 compares the frequency-divided oscillation frequency with a reference frequency The loop filter 330 (LP) removes noise from the component output from the phase frequency detector 320 (PFD) 320 and outputs only the DC component as the loop control voltage.

The voltage-controlled oscillator 200 outputs the oscillation frequency in accordance with the input impedance of the resonator 100. 6 showing the shift of the oscillation frequency of the voltage-controlled oscillator 200,? ₀ represents the oscillation frequency, and? ₁ and? ₂ represent the shifted oscillation frequency. For example, when the human body breathed in the process of breathing, the oscillation frequency shift occurs in the direction of? _1, and when the breath is extinguished, the oscillation frequency shift occurs in the? ₂ direction. On the other hand, when outputting the oscillation frequency, the voltage controlled oscillator outputs a frequency proportional to the loop control voltage fed back from the phase locked loop (PLL) as the oscillation frequency. The oscillation frequency within a preset frequency range can be outputted by changing the capacitance value of the LC resonance according to the loop control voltage. Therefore, the frequency-shifted output frequency can be always corrected to the desired frequency output with respect to the input impedance change of the resonator. The voltage-controlled oscillator will be described in detail with reference to Fig.

7 is a circuit diagram of a voltage-controlled oscillator that receives an input impedance of a resonator according to an embodiment of the present invention and performs oscillation.

The voltage controlled oscillator 200 includes a switching device 210 for outputting a change in input impedance of the resonator and an oscillation frequency by the LC resonance and an LC resonance unit 220 for adjusting LC resonance by a loop control voltage . In addition, the first capacitor C1 located between the control terminal of the switching element 210 and the resonator 100 is used not only for DC blocking but also for adjusting the frequency across the zero degree of phase. The second inductor L2 located in the feedback signal line from the phase locked loop 300 (PLL) transfers the loop control voltage from the loop filter 330 of the phase locked loop to the collector diode Cv.

The switching element 210 includes a control end receiving an oscillation control signal according to a change in input impedance of the resonator 100, an input connected to the LC resonance portion, a change in input impedance of the resonator, and an oscillation frequency due to LC resonance Output terminal. For example, as shown in FIG. 7, when the switching element is implemented as an NPN transistor, the control terminal receiving the oscillation control signal according to the change of the input impedance of the resonator is called a base An input terminal connected to the LC resonance unit 220 is an emitter E and an output terminal for outputting a change in input impedance of the resonator 100 and an oscillation frequency due to LC resonance is connected to the collector C, . In addition, a PNP transistor can be realized in which the collector is the input terminal, the base is the control terminal, and the emitter is the output terminal.

The LC resonance unit 220 adjusts the LC resonance by the loop control voltage from the phase locked loop. The LC resonance unit 220 uses the collector diode Cv whose capacitance value changes according to the voltage applied to the device, Thereby varying the capacitance value. Accordingly, the loop control voltage is applied to the collector diode Cv so that the value of the capacitance used for the L-C resonance varies depending on the magnitude of the loop control voltage applied.

The LC resonance unit 220 includes a first inductor L1 connected between the output terminal E of the switching element and the ground and one end connected to the node of the output terminal E of the switching element and the first inductor L1 A collector diode Cv having a variable capacitance connected between the other end of the fixed capacitor C2 and the ground and a fixed capacitor C2 and a collector diode Cv having a fixed capacitance, And a feedback signal line connected to the node between the node and the node to apply the loop control voltage. The total capacitance consisting of the fixed capacitance of the fixed capacitor C2 and the variable capacitance Cv by the collector diode is used as the capacitance at the LC resonance and the inductance of the first inductor L1 is used as the inductance at the LC resonance An oscillation frequency having a resonance frequency corresponding to the resonance frequency can be generated.

8, the oscillation frequency of 2.4 GHz is output when the loop control voltage is not applied by the PLL 300. However, the oscillation frequency of the PLL varies depending on the voltage applied to the collector diode 9, and the frequency variable displacement is 80 MHz. Referring to FIG. 9, it can be seen that the voltage applied to the collector diode (hereinafter referred to as collector control voltage, varactor control voltage) and the oscillation frequency are proportional to each other. For example, when the varactor control voltage is increased, the capacitance due to the collector diode is reduced, and thus the L-C resonance value becomes smaller and the oscillation frequency becomes larger. On the contrary, when the collector control voltage becomes smaller, the capacitance due to the collector diode becomes larger, and accordingly, the L-C resonance value becomes larger, and the oscillation frequency becomes smaller. Therefore, if the phase difference between the oscillation frequency and the reference frequency signal is large and the loop control voltage becomes large, the voltage controlled oscillator that receives the feedback control signal can increase the oscillation frequency and reduce the phase difference.

On the other hand, the signal processor 500 receives the loop control voltage and outputs it as a respiration signal and a pulse signal. That is, the loop control voltage is subjected to discrete Fourier transform into the frequency domain and output as a breath signal and a pulse signal. Since the loop control voltage appears in the form of a DC signal according to time, the difference value between the reference frequency and the oscillation frequency is subjected to discrete Fourier transform and converted into a frequency form and output. For reference, a discrete fourier transform can be used to obtain spectral samples on a frequency from signal samples in time.

Conventionally, in the case of a measurement sensor using a SAW filter and a power detector (Korean Patent No. 10-1252740), the oscillation frequency of the oscillator is directly subjected to signal processing and then output as a living body signal. Therefore, conventionally, after the power magnitude detected at the oscillation frequency is Fourier-transformed by frequency, a signal having a peak value at 0.45 Hz is separated, a signal having a peak value at 1.1 Hz is separated, And then output to the time domain by inverse Fourier transform. Therefore, in the case of a conventional sensor using a SAW filter and a power detector, a Fourier transform unit, a filter unit, and an inverse Fourier transform unit are required.

On the other hand, the signal processor 500 according to the embodiment of the present invention outputs only the Fourier transform using a DC control loop control voltage which is a difference value between the oscillation frequency and the reference frequency, not the oscillation frequency. Since the loop control voltage, which is a difference value, is directly targeted, it is possible to distinguish the respiration signal and the pulse signal without separate separation filtering.

For reference, when there is no creature in front of the resonator, there is no change in the input impedance of the resonator, so that the transition of the oscillation frequency does not occur, and the loop control voltage is always constant. However, if a person such as a human being is located in front of the resonator, the input impedance of the resonator continuously changes due to heartbeat caused by the heart of the living body or chest tremor caused by breathing. The value of the loop control voltage, which is obtained by comparing the value of the oscillation frequency due to the change of the input impedance with the reference frequency, is changed and the signal is processed.

Hereinafter, experimental results according to an embodiment of the present invention will be described.

The frequency shift of the VCO is mainly determined by the resonator coupled with the characteristics of the human body (permittivity and conductivity). This is a function of the distance between the resonator and the human body. In order to precisely model the change of the input impedance of the human body related resonator, the resonator is placed in front of the human body model of the three dimensional structure. The human body model is composed of cloth (clothes), skin, fat, and muscular parts. The input impedance of the resonator is expressed as the complex component of the resonance and non-resonance part. The real and imaginary parts of the input impedance are varied as a function of the separation distance. Before quantifying the characteristics of a voltage controlled oscillator (VCO) that is affected by the separation from the human body, the following conditions must be met that can initiate oscillation.

R is _R + R _IN < 0,

X _R - X _In = 0

The input impedance Z _IN = R _IN + jX _IN , which is the impedance when viewed as the base terminal of the transistor of the switching element, is Z _R = R _R + jX _R.

FIG. 10 shows the frequency deviation according to the oscillation frequency and the separation distance. The frequency deviation is at least 0.07 MHz / mm up to 1.8 MHz / mm. Considering an average gain of 8.8 MHz / V for a voltage controlled oscillator (VCO), the frequency deviation will appear as a voltage of 6.8 mV / mm to 205 mV / mm. Therefore, it has no problem to measure up to 50 mm from the human body.

7 and FIG. 11 are connected. When the experiment is performed using the parameters according to the table of FIG. 12, the PLL maintains a steady state when there is no human on the sensor surface, and the output frequency of the voltage- The reference frequency is 2.4 GHz, which is 32 times the frequency of 75 MHz, and the loop control voltage outputs a voltage around 4.5 V. On the other hand, as a normal respirator approaches the resonator, the output frequency of the voltage-controlled oscillator moves up and down several hundreds of kHz depending on the contrast breath / pulse in the absence of a person, do. This outputs the voltage of the loop filter at a high / low voltage according to the chest motion, and always keeps the output of the voltage controlled oscillator at 2.4 GHz.

On the other hand, Fig. 13 (a) is a time-base signal including respiration and pulse. Respiration and pulse signals can be extracted from raw data. The pulse signal in the data is obtained after band-pass filtering as shown in FIG. 13 (c), and it is found that the pulse signal satisfies the reference signal of FIG. 13 (d).

14 is a graph showing normalized respiration and pulse signals measured according to the separation distance. 14 (a) shows a pulse signal directly measured by a finger sensor, and FIGS. 14 (b) to 14 (f) show specific respiration signals and pulse signals through a measurement sensor according to an embodiment of the present invention . FIG. 14 (b) is a signal graph measured at a distance of 10 mm from the front of the human body, FIG. 14 (c) is a signal graph measured at a distance of 20 mm from the front of the human body, FIG. 14 (e) is a signal graph measured at a distance of 30 mm from the rear of the human body, and FIG. 14 (f) is a graph showing a distance of 50 mm from the back of the human body It is a signal graph.

14, the pulse signal measured from the finger sensor was 61.8 beats / min, and it was confirmed that all the data measured from the measurement sensor of the present invention (front, back, up to 50 mm) . In the frontal measurement, the size of the respiration was twice as large as the pulse, whereas in the rear measurement it was almost the same. The size of the respiratory signal from the front decreases with distance from 266 mV to 98 mV. At this time, the multiplication components of the respiration signal may overlap the pulse signal frequency region, and in such a case, a high-level signal processing method or measurement concept must be introduced to separate them. In the present invention, the measurement results can be cleanly processed without overlapping. On the other hand, the size of the pulse is larger than the respiration in the backside measurement. This leads to the frontal side of the respiratory movement, while the heartbeat expands / shrinks to the entire area. From the above results, it can be seen that the non-contact bio-signal based on PLL exhibits superior performance to other sensors.

Although the present invention has been described with reference to the accompanying drawings and the preferred embodiments described above, the present invention is not limited thereto but is limited by the following claims. Accordingly, those skilled in the art will appreciate that various modifications and changes may be made thereto without departing from the spirit of the following claims.

100: resonator 200: voltage-controlled oscillator
210: switching element 220: LC resonance part
300: phase locked loop 310: frequency divider
320: phase frequency detector 330: loop filter
400: amplifier 500: signal processor

Claims (9)

A resonator in which an input impedance is changed corresponding to a biological signal;
A phase locked loop that receives an oscillation frequency that is frequency-shifted by a change in input impedance of the resonator and feeds back a loop control voltage that is a voltage value proportional to a phase difference with a preset reference frequency;
A voltage controlled oscillator for varying a capacitance value of the LC resonance according to the feedback loop control voltage and outputting an oscillation frequency within a preset frequency range;
A signal processor for outputting a respiration signal and a pulse signal using the loop control voltage;
And a sensor for measuring a biological signal.
The voltage controlled oscillator according to claim 1,
An LC resonance part whose LC resonance is controlled by the loop control voltage;
A control terminal receiving an oscillation control signal according to a change in input impedance of the resonator, an input connected to the LC resonance unit, and an output terminal outputting a change in input impedance of the resonance and an oscillation frequency due to the LC resonance A switching element;
And a sensor for measuring a biological signal.
The semiconductor memory device according to claim 2,
Wherein the NPN transistor is an NPN transistor including an emitter, an input terminal, a base, and an output collector, or an NPN transistor including an emitter as a base and an output terminal as a collector and an input terminal.
The LC resonator according to claim 2,
And a capacitance value used for the LC resonance is varied by using a collector diode whose capacitance value is changed according to a voltage applied to the device.
5. The bio-signal measurement sensor according to claim 4, wherein the loop control voltage is applied to the collector diode, and the capacitance value used for the LC resonance is varied according to the loop control voltage.
The LC resonator according to claim 2,
An inductor connected between the output terminal and ground;
A fixed capacitor having a fixed capacitance whose one end is connected to the node of the output terminal and the inductor;
A collector diode connected between the other end of the fixed capacitor and the ground and having a variable capacitance;
A feedback signal line connected to a node between the fixed capacitor and the collector diode to apply the loop control voltage;
And a sensor for measuring a biological signal.
The signal processing apparatus according to claim 6,
Wherein the loop control voltage is subjected to discrete Fourier transform into a frequency domain and output as a respiration signal and a pulse signal.
Feeding back a loop control voltage, which is a voltage value proportional to a phase difference with a predetermined reference frequency, from an oscillation frequency that is frequency-shifted by a change in input impedance corresponding to a biological signal;
Outputting an oscillation frequency within a preset frequency range by varying the capacitance value of the LC resonance according to the feedback loop control voltage;
Outputting a respiration signal and a pulse signal using the loop control voltage;
Displaying the output of the respiration signal and pulse signal;
Wherein the bio-signal measurement method comprises the steps of:
9. The method of claim 8, further comprising: varying a capacitance value of the LC resonance by using a collector diode whose capacitance value changes according to an applied voltage, adjusting a value of an oscillation frequency, and applying the loop control voltage to a collector diode The oscillation frequency value is decreased when the loop control voltage is increased and the oscillation frequency value is increased when the loop control voltage is decreased.

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