TW202022398A - Detection device and detection circuit thereof - Google Patents

Abstract

The instant disclosure provides a detection device and detection circuit thereof. The detection device includes a detection circuit, a signal source and a signal analyzing unit. The detection circuit has a sensing oscillator to form a first signal with a first frequency. The signal source provides a second signal with second frequency. The detection circuit produces an output signal including its intermodulation signals based on the first signal and the second signal. The signal analyzing unit produces an enhanced sensitive detection result in accordance with the change of the frequency of the intermodulation signals.

Description

Detection device and detection circuit

The present invention relates to a detection technology, especially a detection technology using electromagnetic waves.

There are currently a variety of detection technologies using different sensing principles. For example, radar detection uses electromagnetic waves sent to the detection object, and uses the time, wavelength, and waveform of the rebound reflected wave to infer the distance, direction, and shape of the detection object. Another example is the optical detection technology that uses the change in the absorption of light by the detected object to perform detection, such as the optical change scanning method (Photoplethysmography, PPG). For another example, electrocardiogram measurement involves attaching electrode patches to the body surface to capture electrical signals from the cardiac conduction system. Some of these detection technologies are limited to contact measurement methods, and some can achieve non-contact measurement, but their cost threshold is high, or they are susceptible to external noise interference.

In view of this, an embodiment of the present invention provides a detection device and a detection circuit thereof. The detection device includes a detection circuit, a signal source, and a signal analysis unit. The detection circuit includes a resonator, an active feedback loop and an output terminal. The resonator includes a signal input terminal and a signal output terminal. The active feedback loop is coupled to the resonator to form a sensing oscillator with the resonator. The oscillation frequency of the sensing oscillator is a first frequency, and the signal input terminal receives an input signal with a second frequency. The output terminal is coupled to the signal output terminal to output an output signal. The output signal includes an intermodulation signal generated according to the first frequency and the second frequency. The signal source is coupled to the signal input terminal of the detection circuit to provide an input signal. The signal analysis unit is coupled to the output terminal of the detection circuit to generate a detection result according to the frequency change of the intermodulation signal.

Another embodiment of the present invention provides a detection device and a detection circuit thereof. The detection device includes a detection circuit, a signal source, and a signal analysis unit. The detection circuit includes a sensing oscillator, a power amplifier, a mixer, and an output terminal. The sensing oscillator oscillates to generate a first signal with a first frequency. The power amplifier is coupled to the sensing oscillator to amplify the first signal. The mixer is coupled to the power amplifier to receive the amplified first signal, and coupled to the signal source to receive the second signal having a second frequency. The mixer mixes the amplified first signal and the second signal, and outputs an output signal. The output signal includes an intermodulation signal generated according to the first frequency and the second frequency. The output terminal is coupled to the mixer to output an output signal. The signal analysis unit is coupled to the output terminal of the detection circuit to generate a detection result according to the frequency change of the intermodulation signal, and obtain an improved sensitivity detection effect through the intermodulation demodulation technology.

The detection device and its detection circuit proposed according to the embodiments of the present invention can provide highly sensitive and non-contact vibration detection.

Referring to FIG. 1, it is a schematic diagram of the structure of the detection device according to the first embodiment of the present invention. The detection device includes a signal source 100, a detection circuit 300, an output terminal 500 and a signal analysis unit 700 coupled in sequence. The detection circuit 300 includes a resonator 320 and an active feedback loop 330.

The active feedback loop 330 is coupled to the resonator 320 to form a non-linear sensing oscillator (Sensing Oscillator) 340 with the resonator 320. The sensing oscillator 340 has an oscillating frequency (hereinafter referred to as a “first frequency”), and can be coupled to an environmental electromagnetic field to form a first signal having a first frequency. The resonator 320 has a signal input terminal 321 and a signal output terminal 322. The signal input terminal 321 is coupled to the signal source 100 to receive an input signal (or “second signal”) transmitted by the signal source 100, and the second signal has a second frequency. Due to the non-linear characteristics, the first signal and the second signal are mixed in the sensing oscillator 340, and the intermodulation phenomenon caused by the non-linearity will generate an intermodulation signal in the output signal according to the first frequency and the second frequency. in. The output terminal 500 is coupled to the signal output terminal 322 to output an output signal. The signal source 100 may be a signal generator or a voltage controlled oscillator, but the embodiment of the present invention is not limited to this.

Furthermore, the resonator 320 in this embodiment is a split ring resonator (SRR). Here, the split resonant ring is a single ring structure, but the embodiment of the present invention is not limited to this. In some embodiments, the split resonator ring may also be a complementary split ring resonator (CSRR) with a multi-ring structure.

As shown in FIG. 1, the split resonant ring includes a split ring 323, a signal input strip line 324, a signal output strip line 325, and two signal coupling strip lines 326 and 327. The split ring 323 includes a first section 3231, a second section 3232, and a third section 3233 coupled in sequence. The first section 3231 is on the left, the second section 3232 is below, and the third section 3233 is on the right. The second section 3232 is opposite to the opening 3234 of the split ring 323, and the first section 3231 is opposite to the third section 3233. Here, although the shape of the split ring 323 is a rectangle as an example, the embodiment of the present invention is not limited to this. In some embodiments, the split ring 323 may also have other geometric shapes.

The signal coupling strip lines 326 and 327 are respectively coupled to the two ends of the active feedback loop 330, the free end of the signal coupling strip line 326 is adjacent to the first section 3231, and the free end of the signal coupling strip line 327 is adjacent to the third section 3233 . In this way, the passive resonant cavity structure of the split resonant ring is combined with the active feedback loop 330 to form a sensing oscillator 340 whose oscillation frequency is the first frequency. The active feedback loop 330 can amplify the first signal. Here, the active feedback loop 330 includes an amplifier 331, which can be realized by a transistor. The transistor may be a Bipolar Junction Transistor (BJT) or a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). Here, BJT is taken as an example. The base of the transistor is coupled to the signal coupling strip line 326, the collector of the transistor is coupled to the signal coupling strip line 327, and the emitter of the transistor is grounded.

The signal input strip line 324 and the signal output strip line 325 are located on the same straight line, extend in the same direction, and are separated by a gap. The signal input strip line 324 is adjacent to the connection between the first section 3231 and the second section 3232. The signal input strip line 324 couples the received second signal to the sensing oscillator 340. Since the sensing oscillator 340 has a non-linear characteristic, an intermodulation phenomenon will occur between the first signal and the second signal, and the intermodulation signal will be generated according to the first frequency and the second frequency. The signal output strip line 325 is adjacent to the connection between the second segment 3232 and the third segment 3233, and can output output signals including intermodulation signals.

展開後組成，其表示為式4。例如第三階諧振頻率為2f _w1 -f _w2 ，第五階諧振頻率為3f _w1 -2f _w2 ，第七階諧振頻率為4f _w1 -3f _w2 ，第九階諧振頻率為5f _w1 -4f _w2 。若將第一信號與第二信號的頻率差值定義為∆ f=f _w2 -f _w1 ，則奇數階諧振頻率可視為f _w1 -n∆ f。例如，三階諧振頻率的頻率變化為2∆f，五階諧振頻率的頻率變化為3∆f。因此，愈高階可獲得更高的放大倍率。Here, the intermodulation phenomenon is explained. As shown in FIG. 1, the input of the amplifier 331 is the base emitter voltage Vbe, and the output is the collector current Ic. The input of the amplifier 331 is composed of the first signal and the second signal, which can be expressed as Equation 1, f _w1 is the frequency of the first signal (first frequency), f _w2 is the frequency of the second signal (second frequency), A, B is a constant and t is time. According to the current equation of the transistor, the output of the amplifier 331 can be expressed as Equation 2. Expansion of the exponential term through Taylor series can be expressed as Equation 3. This nonlinear phenomenon can be obtained by the expansion of natural exponents to obtain high-order resonance frequencies, which can be obtained by

The composition after expansion is expressed as Equation 4. For example, the third-order resonance frequency is 2 f _w1 - f _w2 , the fifth-order resonance frequency is 3 f _w1 -2 f _w2 , the seventh-order resonance frequency is 4 f _w1 -3 f _w2 , and the ninth-order resonance frequency is 5 f _w1 -4 f _w2 . If the frequency difference between the first signal and the second signal is defined as ∆ f = f _w2 - f _w1 , then the odd-order resonance frequency can be regarded as f _w1- n∆ f. For example, the frequency change of the third-order resonant frequency is 2∆f, and the frequency change of the fifth-order resonant frequency is 3∆f. Therefore, the higher the order, the higher the magnification can be obtained.

（式1）

(Formula 1)

（式2）

(Equation 2)

（式3）

(Equation 3)

（式4）

(Equation 4)

In the first embodiment of the present invention, the resonator 320 and the active feedback loop 330 are disposed on the first surface of a substrate (such as a laminate). That is, on the first surface of the substrate, there are split ring 323, signal input strip line 324, signal output strip line 325, signal coupling strip lines 326, 327, and amplifier 331. A grounding surface is provided on the second surface of the substrate opposite to the first surface. Here, the split ring 323, the signal input strip line 324, the signal output strip line 325, the signal coupling strip lines 326, 327, and the ground plane are made of metal.

The free end of the signal coupling strip line 326 adjacent to the first segment 3231 serves as a detection area A. Taking measuring fingertips as an example, the finger can be placed on the detection area A. The surface of the resonator 320 has an insulating layer (not shown in the figure) to prevent the finger from directly touching the metal. Fig. 2 is a schematic diagram of a measurement signal according to the first embodiment of the present invention. For comparison, the solid line is the measurement result when the finger is placed on the detection area A, and the dashed line is the measurement result when the finger is not placed on the detection area A. It can be seen that when the finger is placed in the detection area A, the frequency shift is caused by the blood flow change of the fingertip capillaries, and such subtle changes can be detected by the detection device of the first embodiment of the present invention.

A schematic view of a second variation frequency f _w2 (broken line) and ninth order resonance frequency (solid line) of the first embodiment with reference to FIG. 3, the present invention is based on the timing. It can be seen that capturing high-order resonance frequencies can obtain a good amplified signal, which is conducive to detection. Therefore, the signal analysis unit 700 coupled to the output terminal 500 can generate a detection result according to the frequency change of the intermodulation signal. For example, the heart rate, heart rate variability (HRV), etc. can be obtained based on changes in odd-order resonance frequencies. Here, although the odd-order resonant frequency is used for analysis, the embodiment of the present invention is not limited to this. In some implementations, even-order resonant frequencies can also be used for analysis.

Referring to FIG. 4, it is a schematic diagram of the structure of the detection device according to the second embodiment of the present invention. The detection device includes a detection circuit 200, a signal source 400, and a signal analysis unit 600. The detection circuit 200 is coupled between the signal source 400 and the signal analysis unit 600. The detection circuit 200 includes a sensing oscillator 240, a power amplifier 250, a mixer 260, a differentiator 270, and an output terminal 280, which are sequentially coupled.

Referring to FIG. 5, it is a schematic diagram of the structure of the sensing oscillator 240 according to the second embodiment of the present invention. The sensing oscillator 240 includes a resonator 220 and an active feedback loop 230 coupled to each other. The resonator 220 includes a split ring 223, a signal output strip line 225, and signal coupling strip lines 226, 227. The split ring 223 includes a first section 2231, a second section 2232, a third section 2233, a first section 2231 and a third section 2233 There is an opening 2234 between. The active feedback loop 230 has an amplifier 231. The structure of the sensing oscillator 240 is roughly the same as that of the sensing oscillator 340 of the first embodiment. The difference is that the resonator 220 of this embodiment does not have a signal input strip line. Please refer to the description of the first embodiment for the rest of the above components. I will not repeat them here. In other words, the sensor oscillator 240 of this embodiment does not receive signal feed, but directly induces environmental electromagnetic waves to generate an oscillating signal (hereinafter referred to as “first signal”), and its oscillating frequency is the first frequency.

As shown in FIG. 4, in this embodiment, in order to improve the effect of non-linearity, the sensing oscillator 240 is coupled to the power amplifier 250 to amplify the first signal. The mixer 260 is coupled behind the power amplifier 250 and coupled to the signal source 400. The signal source 400 is used to provide a second signal with a second frequency. The mixer 260 mixes the amplified first signal and the second signal, and outputs an output signal. The intermodulation phenomenon caused by nonlinearity will generate intermodulation signals in the output signal according to the first frequency and the second frequency. Under the action of intermodulation, the even-order resonance frequency can be expressed as n( f _w2 - f _w1 ), that is, n∆f. As shown in FIG. 6, it is a schematic diagram of the measurement result of the output signal of the mixer 260 according to the second embodiment of the present invention. It can be seen that the mixer 260 of this embodiment is used as a downconverter, so that although the input first signal and second signal are high frequency signals ( f _w2 , f _w2 ), signals suitable for low frequencies can be used The analysis unit 600 analyzes the even-order resonance frequency of the low frequency, which can reduce the cost.

The differentiator 270 is coupled after the mixer 260 to amplify the high frequency components in the output signal. The differentiator 270 is coupled to the output terminal 280 to output the amplified output signal to the signal analysis unit 600 at the output terminal 280. As shown in FIG. 7, it is a schematic diagram of the output signal measurement result of the differentiator 270 according to the second embodiment of the present invention. It can be seen that after passing through the differentiator 270, the even-order resonance frequency is amplified. Therefore, the signal analysis unit 600 can generate a detection result according to the frequency change of the intermodulation signal. In this embodiment, the intermodulation effect is generated through the mixer 260, and the frequency offset (even-order resonant frequency n∆f) can be obtained by the multiple amplification, and then the intensity of the high-order resonant frequency is amplified again through the differentiator 270, so Can effectively improve the sensitivity of detection.

In some embodiments, the detection circuit 200 may not have the differentiator 270 so that the mixer 260 is directly coupled to the output terminal 280.

In the second embodiment, although the even-order resonant frequency is used for analysis, the embodiment of the present invention is not limited to this. In some implementations, odd-order resonant frequencies may also be used for analysis.

As shown in FIG. 8, it is a schematic diagram of another architecture of the detection device according to the first embodiment of the present invention. The difference from FIG. 1 is that, in some embodiments, the detection device may further include a differentiator 900, which is coupled between the signal output terminal 322 and the output terminal 500, so that the output terminal 500 outputs the high-frequency amplification process The signal is output to the signal analysis unit 700.

In some embodiments, the signal analysis units 700 and 600 may be, for example, a vector network analyzer (VNA), a spectrum analyzer (spectrum analyzer), or other detection circuits, such as envelope detectors. circuit).

In summary, the detection device and detection circuit proposed according to the embodiments of the present invention can provide highly sensitive and non-contact vibration detection. Although the above description is based on measuring physiological parameters as an example, the embodiments of the present invention are not limited to this application, and can also be applied to various fields, such as bridge vibration detection, machine vibration detection, etc.

100: Signal source 300: Detection circuit 320: Resonator 321: Signal input end 322: Signal output end 323: Split ring 324: Signal input belt line 325: Signal output belt line 326, 327: Signal coupling belt line 3231: No. Section 3232:Second Section 3233: Third Section 3234: Opening 330: Active Feedback Loop 331: Amplifier 340: Sensing Oscillator 500: Output 700: Signal Analysis Unit 900: Differentiator 200: Detection Circuit 220: Resonator 222: signal output terminal 223: split ring 225: signal output belt line 226, 227: signal coupling belt line 2231: first section 2232: second section 2233: third section 2234: opening 230: active feedback loop 231 : Amplifier 240: sensing oscillator 250: power amplifier 260: mixer 270: differentiator 280: output 400: signal source 600: signal analysis unit A: detection area f _w1 : first frequency f _w2 : second Frequency n∆f: even-order resonance frequency

[Figure 1] is a schematic diagram of the architecture of the detection device according to the first embodiment of the present invention. [Figure 2] is a schematic diagram of the measurement signal of the first embodiment of the present invention. [Fig. 3] is a schematic diagram of the time sequence of the second signal and the ninth-order resonant frequency of the first embodiment of the present invention. [Figure 4] is a schematic diagram of the architecture of the detection device according to the second embodiment of the present invention. [Figure 5] is a schematic diagram of the structure of the sensing oscillator according to the second embodiment of the present invention. [Figure 6] is a schematic diagram of the measurement result of the mixer output signal of the second embodiment of the present invention. [Fig. 7] is a schematic diagram of the measurement result of the output signal of the differentiator according to the second embodiment of the present invention. [Figure 8] is another schematic diagram of the architecture of the detection device according to the first embodiment of the present invention.

100: signal source

300: Detection circuit

320: Resonator

321: signal input

322: signal output

323: Split ring

324: signal input with wire

325: signal output with wire

326, 327: signal coupling strip line

3231: first paragraph

3232: second paragraph

3233: third paragraph

3234: opening

330: Active feedback loop

331: Amplifier

340: Sensing Oscillator

500: output

700: signal analysis unit

A: Detection area

Claims (17)

A detection circuit includes: a resonator including a signal input terminal and a signal output terminal; an active feedback loop coupled to the resonator to form a sensing oscillator with the resonator, the sensing oscillation The oscillating frequency of the device is a first frequency, the signal input terminal receives an input signal with a second frequency, and the signal output terminal outputs an output signal. The output signal includes a signal generated according to the first frequency and the second frequency. An intermodulation signal; and an output terminal, coupled to the signal output terminal to output the output signal. The detection circuit according to claim 1, wherein the resonator is a split resonant ring. The detection circuit according to claim 2, wherein the split resonant ring has a single-ring structure and includes: a split ring including a first segment, a second segment, and a third segment coupled in sequence, the The second section is opposite to an opening of the split ring, and the first section is opposite to the third section; a signal input belt line adjacent to the connection between the first section and the second section; a signal output belt Line adjacent to the connection between the second section and the third section; and two signal coupling strip lines respectively coupled to the two ends of the active feedback loop, wherein a free end of each signal coupling strip line is respectively It is adjacent to the first section and the third section. The detection circuit according to claim 3, wherein the free end of the signal coupling strip line adjacent to the first section is a detection area. The detection circuit according to claim 1, wherein the active feedback loop includes an amplifier. The detection circuit according to claim 1 further includes a differentiator coupled between the signal output terminal and the output terminal to amplify the high frequency component of the output signal. A detection device, comprising: the detection circuit according to any one of claims 1 to 6; a signal source coupled to the signal input end of the detection circuit to provide the input signal; and a signal analysis The unit is coupled to the output terminal of the detection circuit to generate a detection result according to the frequency change of the intermodulation signal. The detection device according to claim 7, wherein the signal analysis unit analyzes the odd-order resonance frequency of the intermodulation signal to output the detection result. A detection circuit, comprising: a sensing oscillator, oscillating to generate a first signal of a first frequency; a power amplifier coupled to the sensing oscillator to amplify the first signal; a mixer, coupled Connect the power amplifier and receive a second signal with a second frequency to mix the amplified first signal and the second signal, and output an output signal, the output signal including the first frequency and the An intermodulation signal generated at the second frequency; and an output terminal, coupled to the mixer to output the output signal. The detection circuit according to claim 9, further comprising a differentiator, coupled between the mixer and the output terminal, to amplify the high frequency component of the output signal. The detection circuit according to claim 9, wherein the sensing oscillator includes a coupler and an active feedback loop coupled to each other. The detection circuit according to claim 11, wherein the coupler is a split resonant ring. The detection circuit according to claim 12, wherein the split resonant ring has a single-ring structure and includes: a split ring including a first segment, a second segment, and a third segment coupled in sequence, the The second section is opposite to an opening of the split ring, and the first section is opposite to the third section; a signal output strip line is adjacent to the second section; and two signal coupling strip lines are respectively coupled to the active loop Two ends of the transmission loop, wherein a free end of each signal coupling strip line is respectively adjacent to the first section and the third section. The detection circuit according to claim 13, wherein the free end of the signal coupling strip line adjacent to the first segment is a detection area. The detection circuit according to claim 11, wherein the active feedback loop includes an amplifier. A detection device, comprising: the detection circuit according to any one of claims 9 to 15; a signal source coupled to the mixer of the detection circuit to provide the second signal; and a signal The analysis unit is coupled to the output terminal of the detection circuit to generate a detection result according to the frequency change of the intermodulation signal. The detection device according to claim 16, wherein the signal analysis unit analyzes the even-order resonance frequency of the intermodulation signal to output the detection result.

Images