WO2019093685A1 - Highly sensitive flow sensor - Google Patents

Highly sensitive flow sensor Download PDF

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Publication number
WO2019093685A1
WO2019093685A1 PCT/KR2018/012524 KR2018012524W WO2019093685A1 WO 2019093685 A1 WO2019093685 A1 WO 2019093685A1 KR 2018012524 W KR2018012524 W KR 2018012524W WO 2019093685 A1 WO2019093685 A1 WO 2019093685A1
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Prior art keywords
temperature sensor
heaters
signal
control circuit
voltage signal
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PCT/KR2018/012524
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French (fr)
Korean (ko)
Inventor
채영철
장기석
이상우
유성필
안종현
이용준
Original Assignee
엘지디스플레이 주식회사
연세대학교 산학협력단
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Publication of WO2019093685A1 publication Critical patent/WO2019093685A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
    • G01F25/10—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume of flowmeters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/56—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using electric or magnetic effects
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume

Definitions

  • the present invention relates to a high-sensitivity flow rate measuring sensor.
  • Flow meters are widely used not only for environmental monitoring sensors such as airflow meters, but also for industrial equipment such as pipelines and gas pipes.
  • flow meters are also being used as biometric sensors as health-care devices are gaining attention in the market.
  • a temperature difference occurs at both ends of the object depending on the flow of the fluid.
  • a particular flow meter can calculate the flow rate by measuring the temperature difference across the object.
  • An object of the present invention is to provide a flow measurement sensor with improved flow measurement sensitivity through maximization of heat exchange rate and minimization of quantization noise.
  • An aspect of a flow rate sensor includes first and second heaters arranged to be spaced apart from each other in an active layer formed on a silicon layer to generate heat, A temperature sensor disposed between the first and second heaters for sensing a temperature difference between both ends and converting the temperature difference into a voltage signal; and a control unit, formed in the active layer, for receiving the feedback signal of the voltage signal received from the temperature sensor, And a control circuit for transmitting the voltage signal to the second heater, wherein the control circuit includes an electronic filter that receives the voltage signal from the temperature sensor and increases the degree of the output signal through filtering .
  • the control circuit may further include an ADC for converting the voltage signal received from the temperature sensor into a bit stream and a DAC for converting the bit stream into an operation signal for operating the first and second heaters .
  • the electronic filter may be arranged between the temperature sensor and the ADC, and may receive a signal having a specific gain applied to the output signal of the DAC as a feedback signal.
  • the electronic filter may include a Gm-C filter using a mutual conductance (Gm) and a capacitance (C) value.
  • the temperature sensor and the first and second heaters can constitute an ETF (Electrothermal Filter) which is adjacent to each other and operates as a first order low-pass filter (LPF).
  • ETF Electromothermal Filter
  • the electronic filter may operate as a low-pass filter (LPF) that removes high-frequency components of the received voltage signal.
  • LPF low-pass filter
  • the thickness of the silicon layer in which the control circuit is formed may be 12 micrometers or less.
  • the width of the temperature sensor may be larger than the width of the control circuit.
  • the active layer may be formed of a glass substrate or a flexible substrate.
  • the flow rate measuring sensor of the present invention can improve the flow measurement sensitivity by amplifying the magnitude of the signal and increasing the order of the ETF by minimizing the thickness of the silicon chip and expanding the contact area with the fluid.
  • the flow rate measuring sensor of the present invention includes an electronic filter of a high order (Nth order), thereby minimizing the quantization noise and improving the signal-to-noise ratio (SNR), thereby improving the flow measurement sensitivity.
  • FIG. 1 is a view of a flow measurement sensor in which the entire flow meter is made of silicon.
  • Fig. 2 shows a side view of the silicon chip included in the flow measurement sensor.
  • FIG. 3 is a block diagram illustrating a flow measurement sensor according to an embodiment of the present invention.
  • FIG. 4 is a plan view of a flow measurement sensor according to an embodiment of the present invention.
  • FIG. 5 is a cross-sectional view illustrating a flow rate measuring sensor according to an embodiment of the present invention.
  • FIG. 6 is a graph for explaining the operation of the flow rate measuring sensor according to an embodiment of the present invention.
  • FIG. 7 is a block diagram illustrating a flow measurement sensor according to another embodiment of the present invention.
  • FIG. 8 is a graph for explaining the operation of the flow measurement sensor according to another embodiment of the present invention.
  • FIG. 1 is a view of a flow measurement sensor in which the entire flow meter is made of silicon.
  • Fig. 2 shows a side view of the silicon chip included in the flow measurement sensor of Fig. 1; Fig.
  • a silicon chip used as a flow rate measuring sensor includes a temperature sensor 10 (Thermopile) and heaters 22 and 24 (Heater). At this time, the heaters 22 and 24 are disposed at both ends of the temperature sensor 10
  • the silicon chips uniformly heated by the heaters 22 and 24 have a temperature difference ⁇ T at both ends depending on the flow of the fluid.
  • the temperature sensor 10 located at the center of the silicon chip senses this temperature difference ⁇ T and converts it into a voltage signal, and the voltage signal can be replaced with information of a flow rate quantified through an ADC (Analog Digital Converter). That is, the temperature sensor 10 can measure the amount of heat that is heated by the heaters 22 and 24 due to the flow rate of the fluid, and convert the amount of heat to a voltage to indicate the speed of the fluid.
  • ADC Analog Digital Converter
  • the heaters 22 and 24 located at both ends of the temperature sensor 10 can operate periodically. Accordingly, the temperature balance at both ends of the temperature sensor 10 is adjusted from time to time, and the flow rate can be measured by causing the temperature sensor 10 to sense the temperature difference DELTA T according to the flow rate.
  • the flow rate sensor detects a signal by causing a heat loss of the chip due to the flow of the fluid on the surface of the silicon chip. That is, the flow rate measuring sensor can be manufactured by combining the temperature sensor 10 and the heaters 22 and 24 together with the driving IC, and the AFE (Analog Front End) is included so that all the sensors can be implemented as a single chip Do.
  • the AFE Analog Front End
  • the sensitivity of the sensor is somewhat limited due to the physical characteristics of the silicon integrated circuit itself, which is not suitable for measuring a liquid having a large specific heat.
  • the ETF Electromal Filter
  • LPF Low Pass Filter
  • FIG. 3 is a block diagram illustrating a flow measurement sensor according to an embodiment of the present invention.
  • 4 is a plan view of a flow measurement sensor according to an embodiment of the present invention.
  • 5 is a cross-sectional view illustrating a flow rate measuring sensor according to an embodiment of the present invention.
  • 6 is a graph for explaining the operation of the flow rate measuring sensor according to an embodiment of the present invention.
  • a flow rate sensor utilizes a characteristic of a low-pass filter (LPF) generated during a heat transfer process based on a DSM (Delta-Sigma Modulator) And an embedded structure with AFE (Analog Front-End).
  • LPF low-pass filter
  • the flow sensor has a two-chip structure that is divided into a thermal domain and an electrical domain.
  • a flow measurement sensor can be implemented as an Fully Integrated CMOS device. In this way, the chip size included in the flow measurement sensor can be reduced, and the flow measurement system can be further integrated.
  • the flow rate measuring sensor includes an ETF 100 provided on a thermal domain, an ADC 250 and an DAC 260 provided on an electrical domain, .
  • the ETF 100 includes a thermal LPF 110, a temperature sensor 120, and one or more heaters 130.
  • the thermal LPF 110 represents a transfer function generated during a heat transfer process occurring between the temperature sensor 120 and the heater 130.
  • the temperature sensor 120 measures temperatures at both ends.
  • the temperature sensor 120 measures the temperature difference at both ends, and converts the measured temperature difference into a voltage signal. That is, the temperature sensor 120 senses the temperature difference of the fluid flowing in contact with the surface, and converts it into a voltage signal.
  • This temperature sensor 120 may include a Thermopile temperature sensor that operates based on the Seeback effect. The Seeback effect is used to change the measured voltage across the conductor to a voltage.
  • the heater 130 generates heat to transfer heat generated in the adjacent fluid or object.
  • the heater 130 includes a first heater 132 disposed on one side of the temperature sensor 120 and a second heater 134 disposed on the other side of the temperature sensor 120.
  • the first heater 132 and the second heater 134 may be spaced apart from each other. At this time, the first and second heaters 133 and 134 generate the same heat to transfer heat to the adjacent fluid.
  • a diffusion resistor or a MOSFET may be used as the first and second heaters 133 and 134.
  • the ADC 250 converts the voltage signal received from the temperature sensor 120 into an electrical signal.
  • the ADC 250 converts the voltage signal received from the temperature sensor 120 into a bit stream of '1' and '0', and outputs the bit stream. That is, the ADC 250 converts an analog voltage signal into a digital signal and outputs it.
  • the output digital signal is delivered to an external digital device and can include data on the currently measured flow rate.
  • the DAC 260 converts the digital signal (i.e., the bit stream) output from the ADC 250 into an analog signal and transmits the analog signal to the heater 130.
  • the signal transmitted from the DAC 260 to the heater 130 may be used as an operation signal for operating the heater 130.
  • the DAC 260 may operate as a driver IC of the heater 130 and may apply an operation signal as a feedback signal to the heater 130.
  • the flow measurement sensor can operate as a thermal DSM circuit.
  • the flow measurement sensor includes a Close-Loop control.
  • the closed loop interface increases the linearity of the system and can relax the interface constraints.
  • the flow rate measuring sensor is configured to use the ETF 100 including the close-loop control and the two heaters 130 and the temperature sensor 120 provided in one chip, The compensation value for the thermal balancing can be determined, and the temperature difference can be measured.
  • the flow measurement sensor is composed of an active layer and a bottom silicon layer (bottom Si). At this time, the thermal domain and the electrical domain described above are formed in the active layer. That is, the flow sensor of the present invention includes a two-chip structure including a thermal domain and an electrical domain.
  • a temperature sensor 120 and first and second heaters 132 and 134 are formed on one side of the active layer and a control circuit 200 including an ADC 250 and a DAC 260 is provided on the other side of the active layer. .
  • the width L2 of the temperature sensor 120 may be larger than the width L3 of the control circuit 200.
  • the magnitude of the signal generated by the flow measuring sensor can be increased.
  • the magnitude of the signal is determined according to how much heat exchange is generated by the fluid passing through the heat generated by the heater 130. That is, how much heat is generated by the heat generated by the first heater 132 in the flow direction of the fluid, to the point where the second heater 134 is located, . Accordingly, the flow measurement sensor of the present invention becomes larger in size as the area of the region where the fluid passes through the temperature sensor 120 (i.e., the size of the temperature sensor 120 increases).
  • the flow rate measuring sensor of the present invention is formed in a size larger than that of the conventional flow rate measuring sensor, the sensing sensitivity can be improved.
  • the temperature sensor 120 and the heater 130 may be formed on a thin glass substrate or a flexible circuit.
  • Such a flow rate measuring sensor of the present invention can be used as a wearable device or a medical instrument as a blood flow measuring sensor or the like.
  • the flow measurement sensor can increase the comfort and sensitivity by making a large-area temperature sensor, a heater structure and a small CMOS integrated structure into a two-chip structure on a flexible substrate, and can be used as a wearable device .
  • the present invention is not limited thereto.
  • the thickness H1 of the lower silicon layer has about 100 ⁇ m.
  • a lower silicon layer having a thickness of about 100 ⁇ m is formed through a mechanical etching process with a thickness of about 700 ⁇ m.
  • the ETF formed in the conventional flow measurement sensor A forms a low-pass DSM of a one-order degree and has a LPF characteristic of a one-order degree. Therefore, the conventional flow measurement sensor has a somewhat high level of quantization noise, which is a great restriction to improve the sensitivity of the flow measurement sensor.
  • the flow sensor (B) of the present invention forms a thickness (H2) of the lower silicon layer of about 10 mu m through a chemical etching process.
  • the lower silicon layer may be formed to have a thickness of about 12 mu m in the case of the center portion and about 10 mu m in the edge portion.
  • the numerical values for the thicknesses of the lower silicon layer described above are merely illustrative, and the present invention is not limited thereto.
  • the thickness H2 of the lower silicon layer can be formed to be about 10 mu m through the wet etching or the dry etching in the flow sensor B of the present invention.
  • the sensor sensitivity of the flow measurement sensor B is improved as the signal to noise ratio (SNR) of the flow measurement sensor B of the present invention is improved.
  • the LPF characteristic of the loop-filter of the flow rate sensor is improved from the conventional one-order LPF to the one-order LPF.
  • the quantization noise of the flow measurement sensor is reduced, and the signal size increases as the area of the flow measurement sensor increases, so that the signal-to-noise ratio (SNR) increases and the sensing sensitivity can be maximized.
  • SNR signal-to-noise ratio
  • the flow measurement sensor according to an embodiment of the present invention has a higher sensitivity than a conventional flow measurement sensor, since the flow measurement sensor has a slope of a frequency in decibels (dB / dec).
  • the flow measurement sensor amplifies the signal magnitude and increases the order of the ETF by minimizing the thickness of the silicon chip and expanding the contact area with the fluid, thereby improving the flow measurement sensitivity .
  • FIG. 7 is a block diagram illustrating a flow measurement sensor according to another embodiment of the present invention.
  • 8 is a graph for explaining the operation of the flow measurement sensor according to another embodiment of the present invention.
  • the flow rate measuring sensor includes an ETF 100 on a thermal domain, an electrical filter (not shown) on an electrical domain, ) 210, an ADC 250 and a DAC 260 are provided.
  • the flow measurement sensor according to another embodiment of the present invention further includes an electronic filter 210 in the flow measurement sensor according to the above-described embodiment.
  • the flow rate measuring sensor includes an ETF 100 provided on a thermal domain, an electronic filter 210 provided on an electrical domain, an ADC 250, DAC < / RTI >
  • the ETF 100 includes a thermal LPF 110, a temperature sensor 120, and one or more heaters 130.
  • the thermal LPF 110 represents a transfer function generated during a heat transfer process occurring between the temperature sensor 120 and the heater 130.
  • the temperature sensor 120 measures temperatures at both ends.
  • the temperature sensor 120 measures the temperature difference at both ends, and converts the measured temperature difference into a voltage signal.
  • the heater 130 generates heat to transfer heat generated in the adjacent fluid or object.
  • the heater 130 includes a first heater 132 disposed on one side of the temperature sensor 120 and a second heater 134 disposed on the other side of the temperature sensor 120.
  • the electronic filter 210 receives the voltage signal from the temperature sensor 120, increases the degree of the signal output through the filtering, and transmits the signal to the ADC 250.
  • the electronic filter 210 can operate as an Nth order LPF. Accordingly, the flow measurement sensor according to another embodiment of the present invention can maximize the flow measurement sensitivity by implementing the DSM-based flow measurement sensor having 1 + N-order LPF characteristics.
  • the electronic filter 210 includes a Gm-C filter 214 that uses a transconductance Gm and a capacitance C value.
  • the electronic filter 210 also receives a feedback signal 216 having a gain of alpha (alpha) value from the output of the DAC 260.
  • the alpha (alpha) value corresponds to a feedback factor for matching the stability of the electronic filter 210.
  • the present invention is not limited thereto, and various types of filters may be used for the electronic filter 210.
  • the quantization noise can be minimized and the size of the signal generated by the flow measurement sensor can be increased by increasing the contact surface with the fluid as described above,
  • the signal-to-noise ratio (SNR) generated in the circuit itself can be improved.
  • the ADC 250 converts the N-order filtered signal received from the electronic filter 210 into an electrical signal.
  • the ADC 250 converts the voltage signal received from the temperature sensor 120 into a bit stream of '1' and '0' and outputs the bit stream. That is, the ADC 250 converts an analog voltage signal into a digital signal and outputs it.
  • the output digital signal is delivered to an external digital device and can include data on the currently measured flow rate.
  • the DAC 260 converts the digital signal (i.e., the bit stream) output from the ADC 250 into an analog signal and transmits the analog signal to the heater 130.
  • the signal transmitted from the DAC 260 to the heater 130 may be used as an operation signal for operating the heater 130.
  • the DAC 260 may operate as a driver IC of the heater 130 and may apply an operation signal as a feedback signal to the heater 130.
  • the flow measurement sensor can operate as a thermal DSM circuit.
  • the flow rate measuring sensor is configured to measure the thermal equilibrium state of the fluid in the thermal equilibrium state using the ETF 100 including the closed loop control and the two heaters 130 and the temperature sensor 120 provided on one chip. Balancing), and thereby the temperature difference can be measured.
  • the active layer includes a temperature sensor 120 and first and second heaters 132 and 134 and a control circuit 200 including an electronic filter 210, an ADC 250 and a DAC 260, Is formed.
  • the flow sensor including the electronic filter 210 may have a larger frequency-to-decibel gradient than the flow sensor according to the embodiment described with reference to FIG. 6 dB / dec), it has a high sensing sensitivity.
  • the flow rate sensor according to another embodiment of the present invention includes the Nth order electronic filter 210, thereby minimizing the quantization noise and improving the signal-to-noise ratio to improve the flow measurement sensitivity of the flow rate measuring sensor Can be improved.

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Abstract

The present invention relates to a highly sensitive flow sensor. The flow sensor comprises: first and second heaters which are disposed in an active layer formed on a silicon layer while being spaced apart from each other, so as to generate heat; a temperature sensor which is disposed between the first and second heaters in the active layer so as to detect the difference between temperatures at both ends thereof and convert the same into a voltage signal; and a control circuit which is formed in the active layer so as to transmit, to the first and second heaters, a feedback signal of the voltage signal received from the temperature sensor, wherein the control circuit comprises an electrical filter for receiving, as an input signal, the voltage signal from the temperature sensor and increasing, through filtering, the order of a signal output therefrom.

Description

고감도 유량 측정 센서High Sensitivity Flow Sensor
본 발명은 고감도 유량 측정 센서에 관한 것이다.The present invention relates to a high-sensitivity flow rate measuring sensor.
유량계는 풍량계와 같은 환경 관측 센서뿐만 아니라 송유관, 가스관과 같은 산업 장비 등에 다양하게 사용되고 있다. 뿐만 아니라, 유량계는 최근 헬스케어 디바이스(Health-care Device)가 시장에서 주목 받음에 따라 생체 인식 센서로도 이용되고 있다. Flow meters are widely used not only for environmental monitoring sensors such as airflow meters, but also for industrial equipment such as pipelines and gas pipes. In addition, flow meters are also being used as biometric sensors as health-care devices are gaining attention in the market.
일반적으로, 모든 유체는 흐르면서 맞닿는 물체에 열 손실을 일으킨다. 열 분포의 균형이 맞추어져 있는 물체가 어떠한 유체를 만나게 되면, 물체 내부의 열 분포가 유체의 흐름에 따라 한 쪽으로 치우쳐지게 된다. 이때, 물체 내부의 열 분포의 차이는 유량의 속도에 비례하게 된다. Generally, all the fluids cause heat loss to objects that touch while flowing. When an object with a well-balanced thermal distribution meets any fluid, the heat distribution inside the object is biased toward the fluid flow. At this time, the difference in the heat distribution inside the object is proportional to the velocity of the flow rate.
이때, 유체의 흐름에 따라 물체의 양 단에는 온도 차이가 발생하게 된다. 따라서, 특정 유량계는 물체 양단의 온도 차이를 측정함으로써 유량을 산출할 수 있다. At this time, a temperature difference occurs at both ends of the object depending on the flow of the fluid. Thus, a particular flow meter can calculate the flow rate by measuring the temperature difference across the object.
본 발명은 열 교환율의 극대화와, 양자화 잡음의 최소화를 통해, 유량 측정 감도를 향상된 유량 측정 센서를 제공하는 것을 목적으로 한다.An object of the present invention is to provide a flow measurement sensor with improved flow measurement sensitivity through maximization of heat exchange rate and minimization of quantization noise.
본 발명의 목적들은 이상에서 언급한 목적으로 제한되지 않으며, 언급되지 않은 본 발명의 다른 목적 및 장점들은 하기의 설명에 의해서 이해될 수 있고, 본 발명의 실시예에 의해 보다 분명하게 이해될 것이다. 또한, 본 발명의 목적 및 장점들은 특허 청구 범위에 나타낸 수단 및 그 조합에 의해 실현될 수 있음을 쉽게 알 수 있을 것이다.The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description and more clearly understood by the embodiments of the present invention. It will also be readily apparent that the objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
본 발명의 일 실시예에 따른 유량 측정 센서에 대한 일 면(aspect)은, 실리콘층 상에 형성된 액티브층 내에 서로 이격되도록 배치되어 열을 발생시키는 제1 및 제2 히터, 상기 액티브층 내에서 상기 제1 및 제2 히터 사이에 배치되고, 양단의 온도 차이를 감지하여 전압 신호로 변환하는 온도 센서, 및 상기 액티브층 내에 형성되고, 상기 온도 센서로부터 수신한 상기 전압 신호의 피드백 신호를 상기 제1 및 제2 히터에 전달하는 제어 회로를 포함하되, 상기 제어 회로는, 상기 온도 센서로부터 상기 전압 신호를 입력받고, 필터링을 통해, 출력되는 신호의 차수를 증가시키는 전자 필터(Electrical Filter)를 포함한다.An aspect of a flow rate sensor according to an embodiment of the present invention includes first and second heaters arranged to be spaced apart from each other in an active layer formed on a silicon layer to generate heat, A temperature sensor disposed between the first and second heaters for sensing a temperature difference between both ends and converting the temperature difference into a voltage signal; and a control unit, formed in the active layer, for receiving the feedback signal of the voltage signal received from the temperature sensor, And a control circuit for transmitting the voltage signal to the second heater, wherein the control circuit includes an electronic filter that receives the voltage signal from the temperature sensor and increases the degree of the output signal through filtering .
또한, 상기 제어 회로는, 상기 온도 센서로부터 수신한 상기 전압 신호를 비트스트림으로 변환시키는 ADC와, 상기 비트스트림을 상기 제1 및 제2 히터를 동작시키기 위한 동작 신호로 변환하는 DAC를 더 포함할 수 있다.The control circuit may further include an ADC for converting the voltage signal received from the temperature sensor into a bit stream and a DAC for converting the bit stream into an operation signal for operating the first and second heaters .
또한, 상기 전자 필터는, 상기 온도 센서와 상기 ADC 사이에 배치되고, 상기 DAC의 출력 신호에 특정 게인이 인가된 신호를 피드백 신호로서 수신할 수 있다.The electronic filter may be arranged between the temperature sensor and the ADC, and may receive a signal having a specific gain applied to the output signal of the DAC as a feedback signal.
또한, 상기 전자 필터는, 상호컨덕턴스(Gm)와 커패시턴스(C)값을 이용하는 Gm-C 필터를 포함할 수 있다.In addition, the electronic filter may include a Gm-C filter using a mutual conductance (Gm) and a capacitance (C) value.
또한, 상기 온도 센서와 상기 제1 및 제2 히터는, 상호 인접하여 1차(1st order) 저역 통과 필터(LPF)로서 동작하는 ETF(Electrothermal Filter)를 구성할 수 있다.In addition, the temperature sensor and the first and second heaters can constitute an ETF (Electrothermal Filter) which is adjacent to each other and operates as a first order low-pass filter (LPF).
또한, 상기 전자 필터는, 수신된 상기 전압 신호의 고주파 성분을 제거하는 저역 통과 필터(LPF)로서 동작할 수 있다.In addition, the electronic filter may operate as a low-pass filter (LPF) that removes high-frequency components of the received voltage signal.
또한, 상기 제어 회로가 형성된 상기 실리콘층의 두께는, 12 마이크로 미터 이하로 형성될 수 있다.The thickness of the silicon layer in which the control circuit is formed may be 12 micrometers or less.
또한, 상기 온도 센서의 너비는, 상기 제어 회로의 너비보다 크게 형성될 수 있다.The width of the temperature sensor may be larger than the width of the control circuit.
또한, 상기 액티브층은, 글래스 기판 또는 유연 기판의 소재로 형성될 수 있다.The active layer may be formed of a glass substrate or a flexible substrate.
본 발명의 유량 측정 센서는, 실리콘 칩의 두께를 최소화하고, 유체와의 접촉 면적을 확장함으로써, 신호의 크기를 증폭시키고 ETF의 차수를 증가시켜 유량 측정 감도를 향상시킬 수 있다. The flow rate measuring sensor of the present invention can improve the flow measurement sensitivity by amplifying the magnitude of the signal and increasing the order of the ETF by minimizing the thickness of the silicon chip and expanding the contact area with the fluid.
또한, 본 발명의 유량 측정 센서는, 높은 차수(Nth order)의 전자 필터를 포함함으로써, 양자화 잡음의 최소화하고, 신호대 잡음비(SNR)를 개선함에 따라 유량 측정 감도를 향상시킬 수 있다. In addition, the flow rate measuring sensor of the present invention includes an electronic filter of a high order (Nth order), thereby minimizing the quantization noise and improving the signal-to-noise ratio (SNR), thereby improving the flow measurement sensitivity.
도 1은 유량계 전체가 실리콘으로 구성된 유량 측정 센서에 대한 도면이다. 1 is a view of a flow measurement sensor in which the entire flow meter is made of silicon.
도 2는 유량 측정 센서에 포함된 실리콘 칩의 측면도를 나타낸다.Fig. 2 shows a side view of the silicon chip included in the flow measurement sensor.
도 3은 본 발명의 일 실시예에 따른 유량 측정 센서를 나타내는 블록도이다.3 is a block diagram illustrating a flow measurement sensor according to an embodiment of the present invention.
도 4는 본 발명의 일 실시예에 따른 유량 측정 센서를 나타내는 평면도이다.4 is a plan view of a flow measurement sensor according to an embodiment of the present invention.
도 5는 본 발명의 일 실시예에 따른 유량 측정 센서를 나타내는 단면도이다.5 is a cross-sectional view illustrating a flow rate measuring sensor according to an embodiment of the present invention.
도 6은 본 발명의 일 실시예에 따른 유량 측정 센서의 동작을 설명하기 위한 그래프이다.6 is a graph for explaining the operation of the flow rate measuring sensor according to an embodiment of the present invention.
도 7은 본 발명의 다른 실시예에 따른 유량 측정 센서를 나타내는 블록도이다.7 is a block diagram illustrating a flow measurement sensor according to another embodiment of the present invention.
도 8은 본 발명의 다른 실시예에 따른 유량 측정 센서의 동작을 설명하기 위한 그래프이다.8 is a graph for explaining the operation of the flow measurement sensor according to another embodiment of the present invention.
전술한 목적, 특징 및 장점은 첨부된 도면을 참조하여 상세하게 후술되며, 이에 따라 본 발명이 속하는 기술분야에서 통상의 지식을 가진 자가 본 발명의 기술적 사상을 용이하게 실시할 수 있을 것이다. 본 발명을 설명함에 있어서 본 발명과 관련된 공지 기술에 대한 구체적인 설명이 본 발명의 요지를 불필요하게 흐릴 수 있다고 판단되는 경우에는 상세한 설명을 생략한다. 이하, 첨부된 도면을 참조하여 본 발명에 따른 바람직한 실시예를 상세히 설명하기로 한다. 도면에서 동일한 참조부호는 동일 또는 유사한 구성요소를 가리키는 것으로 사용된다.The above and other objects, features, and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, which are not intended to limit the scope of the present invention. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to denote the same or similar elements.
이하에서는, 본 발명의 몇몇 실시예에 따른 유량 측정 센서에 대해 살펴보도록 한다.Hereinafter, a flow measurement sensor according to some embodiments of the present invention will be described.
도 1은 유량계 전체가 실리콘으로 구성된 유량 측정 센서에 대한 도면이다. 도 2는 도 1의 유량 측정 센서에 포함된 실리콘 칩의 측면도를 나타낸다.1 is a view of a flow measurement sensor in which the entire flow meter is made of silicon. Fig. 2 shows a side view of the silicon chip included in the flow measurement sensor of Fig. 1; Fig.
도 1 및 도 2를 참조하면, 유량 측정 센서로 이용되는 실리콘 칩은 온도 센서(10)(Thermopile)와 히터(22, 24)(Heater)를 포함한다. 이때, 온도 센서(10)의 양단에는 각각의 히터(22, 24)가 배치된다1 and 2, a silicon chip used as a flow rate measuring sensor includes a temperature sensor 10 (Thermopile) and heaters 22 and 24 (Heater). At this time, the heaters 22 and 24 are disposed at both ends of the temperature sensor 10
실리콘 칩 상에서 유체의 흐름이 발생하게 되면, 히터(22, 24)에 의해 균일하게 데워진 실리콘 칩은 유체의 흐름에 따라 양 단에 온도 차이(δT)가 발생하게 된다. 실리콘 칩의 중앙에 위치한 온도 센서(10)는 이러한 온도 차이(δT)를 감지하여 전압 신호로 변환시키며, 전압 신호는 ADC(Analog Digital Converter)를 통해 정량화된 유량의 정보로 치환될 수 있다. 즉, 온도 센서(10)는 히터(22, 24)에서 가열된 열이 유체의 유속에 의해 뺏기는 양을 측정하고, 이를 전압으로 변환하여 유체의 속도를 나타낼 수 있다.When the flow of the fluid occurs on the silicon chip, the silicon chips uniformly heated by the heaters 22 and 24 have a temperature difference δT at both ends depending on the flow of the fluid. The temperature sensor 10 located at the center of the silicon chip senses this temperature difference ΔT and converts it into a voltage signal, and the voltage signal can be replaced with information of a flow rate quantified through an ADC (Analog Digital Converter). That is, the temperature sensor 10 can measure the amount of heat that is heated by the heaters 22 and 24 due to the flow rate of the fluid, and convert the amount of heat to a voltage to indicate the speed of the fluid.
이때, 온도 센서(10)의 양단에 위치한 히터(22, 24)는 주기적으로 동작할 수 있다. 이를 통해, 온도 센서(10) 양단의 온도 균형은 수시로 맞추게 되며, 유량에 따른 온도 차이(δT)를 온도 센서(10)가 감지하도록 하여 유량을 측정할 수 있다. At this time, the heaters 22 and 24 located at both ends of the temperature sensor 10 can operate periodically. Accordingly, the temperature balance at both ends of the temperature sensor 10 is adjusted from time to time, and the flow rate can be measured by causing the temperature sensor 10 to sense the temperature difference DELTA T according to the flow rate.
유량 측정 센서는 도 2에서 나타난 바와 같이 실리콘 칩(Chip)의 표면에서 유체의 흐름으로 인해 칩의 열 손실을 유발하여 신호를 검출하게 된다. 즉, 유량 측정 센서는 온도 센서(10)와 히터(22, 24)가 구동 IC와 함께 결합된 형태로 제작이 가능하며, AFE(Analog Front End)가 포함되어 모든 센서가 단일 칩으로 구현이 가능하다.As shown in FIG. 2, the flow rate sensor detects a signal by causing a heat loss of the chip due to the flow of the fluid on the surface of the silicon chip. That is, the flow rate measuring sensor can be manufactured by combining the temperature sensor 10 and the heaters 22 and 24 together with the driving IC, and the AFE (Analog Front End) is included so that all the sensors can be implemented as a single chip Do.
다만, 전술한 유량 측정 센서의 경우, 실리콘 집적 회로 자체의 물질적인 특성에 의해 센서의 감도(sensitivity)가 다소 제한되므로 비열이 큰 액체를 측정하는데 적합하지 않다는 문제점이 있었다.However, in the case of the above-mentioned flow rate measuring sensor, the sensitivity of the sensor is somewhat limited due to the physical characteristics of the silicon integrated circuit itself, which is not suitable for measuring a liquid having a large specific heat.
또한, 전술한 유량 측정 센서의 경우, 실리콘 칩의 ETF(Electrothermal Filter; 이하 ETF)는 1/2차(1/2 order) LPF(Low Pass Filter) 특성을 가지므로, 유량 측정 센서에서 발생되는 양자화 잡음(Quantization Noise)도 1/2차 형태로 감소하였다. 즉, 종래의 유량 측정 센서는 이러한 ETF의 차수(order)가 제한되어 있어, 유량 측정 센서의 감도를 향상시키는 데 제약이 있었다.Also, in the above-described flow rate sensor, the ETF (Electrothermal Filter) of the silicon chip has a 1/2 order LPF (Low Pass Filter) characteristic. Therefore, quantization Quantization noise is also reduced to a half-order. That is, since the order of the ETF is limited in the conventional flow measurement sensor, there is a restriction in improving the sensitivity of the flow measurement sensor.
도 3은 본 발명의 일 실시예에 따른 유량 측정 센서를 나타내는 블록도이다. 도 4는 본 발명의 일 실시예에 따른 유량 측정 센서를 나타내는 평면도이다. 도 5는 본 발명의 일 실시예에 따른 유량 측정 센서를 나타내는 단면도이다. 도 6은 본 발명의 일 실시예에 따른 유량 측정 센서의 동작을 설명하기 위한 그래프이다.3 is a block diagram illustrating a flow measurement sensor according to an embodiment of the present invention. 4 is a plan view of a flow measurement sensor according to an embodiment of the present invention. 5 is a cross-sectional view illustrating a flow rate measuring sensor according to an embodiment of the present invention. 6 is a graph for explaining the operation of the flow rate measuring sensor according to an embodiment of the present invention.
우선, 도 3을 참조하면, 본 발명의 일 실시예에 따른 유량 측정 센서는 DSM(Delta-Sigma Modulator; 이하 DSM)를 기반으로 열 전달 과정에서 생기는 로우 패스 필터(LPF)의 특성을 활용하며, AFE(Analog Front-End)가 내장된(Embedded) 구조를 포함한다. 3, a flow rate sensor according to an exemplary embodiment of the present invention utilizes a characteristic of a low-pass filter (LPF) generated during a heat transfer process based on a DSM (Delta-Sigma Modulator) And an embedded structure with AFE (Analog Front-End).
유량 측정 센서는 열적 도메인(Thermal Domain)과 전기적 도메인(electrical Domain)으로 분할되는 2-칩 구조(two chip)를 갖는다. 이러한 유량 측정 센서는 CMOS 소자로만 구성된 집적 회로(Fully CMOS integrated)로써 구현될 수 있다. 이를 통해, 유량 측정 센서가 포함된 칩 사이즈는 감소될 수 있으며, 유량 측정 시스템은 더욱 집적화(integrated)될 수 있다.The flow sensor has a two-chip structure that is divided into a thermal domain and an electrical domain. Such a flow measurement sensor can be implemented as an Fully Integrated CMOS device. In this way, the chip size included in the flow measurement sensor can be reduced, and the flow measurement system can be further integrated.
구체적으로, 본 발명의 일 실시예에 따른 유량 측정 센서는 열적 도메인(Thermal Domain) 상에 구비된 ETF(100)와, 전기적 도메인(electrical Domain) 상에 구비된 ADC(250)와 DAC(260)를 포함한다.In detail, the flow rate measuring sensor according to an embodiment of the present invention includes an ETF 100 provided on a thermal domain, an ADC 250 and an DAC 260 provided on an electrical domain, .
ETF(100)는 열적 LPF(Thermal Low Pass Filter)(110)와, 온도 센서(Temperature Sensor)(120), 하나 이상의 히터(Heater)(130)를 포함한다. The ETF 100 includes a thermal LPF 110, a temperature sensor 120, and one or more heaters 130.
열적 LPF(110)는 온도 센서(120)와 히터(130) 사이에 발생하는 열전달 과정에서 생기는 전달 함수(Transfer Function)을 나타낸다.The thermal LPF 110 represents a transfer function generated during a heat transfer process occurring between the temperature sensor 120 and the heater 130.
온도 센서(120)는 양단의 온도를 측정한다. 온도 센서(120)는 양단의 온도 차이를 측정하고, 측정된 온도 차이를 전압 신호로 변환한다. 즉, 온도 센서(120)는 표면에 접하여 흐르는 유체의 온도 차이를 감지하여, 이를 전압 신호로 변환시킨다. 이러한 온도 센서(120)는 씨백 효과(Seeback effect)를 기초로 동작하는 써모파일(Thermopile) 온도 센서를 포함할 수 있다. 씨백 효과(Seeback effect)는 도전체 양단의 측정치를 전압으로 변경시키는데 이용된다.The temperature sensor 120 measures temperatures at both ends. The temperature sensor 120 measures the temperature difference at both ends, and converts the measured temperature difference into a voltage signal. That is, the temperature sensor 120 senses the temperature difference of the fluid flowing in contact with the surface, and converts it into a voltage signal. This temperature sensor 120 may include a Thermopile temperature sensor that operates based on the Seeback effect. The Seeback effect is used to change the measured voltage across the conductor to a voltage.
히터(130)는 열을 발생시켜 인접한 유체 또는 물체에 발생된 열을 전달한다. 히터(130)는 온도 센서(120)의 일측에 배치되는 제1 히터(132)와, 온도 센서(120)의 타측에 배치되는 제2 히터(134)를 포함한다. 제1 히터(132)와 제2 히터(134)는 서로 이격되어 배치될 수 있다. 이때, 제1 및 제2 히터(133, 134)는 동일한 열을 발생시켜 인접한 유체에 열을 전달한다. 이러한 제1 및 제2 히터(133, 134)로는 확산 저항(diffusion resistor) 또는 MOSFET이 이용될 수 있다.The heater 130 generates heat to transfer heat generated in the adjacent fluid or object. The heater 130 includes a first heater 132 disposed on one side of the temperature sensor 120 and a second heater 134 disposed on the other side of the temperature sensor 120. The first heater 132 and the second heater 134 may be spaced apart from each other. At this time, the first and second heaters 133 and 134 generate the same heat to transfer heat to the adjacent fluid. As the first and second heaters 133 and 134, a diffusion resistor or a MOSFET may be used.
ADC(250)는 온도 센서(120)로부터 수신한 전압 신호를 전기적 신호로 변환한다. ADC(250)는 온도 센서(120)로부터 수신한 전압 신호를 '1'과 '0'으로 이루어진 비트 스트림(bit stream)으로 변환하여 출력한다. 즉, ADC(250)는 아날로그의 전압 신호를 디지털 신호로 변환하여 출력한다. 출력된 디지털 신호는 외부 디지털 장치에 전달되며, 현재 측정된 유량에 대한 데이터를 포함할 수 있다.The ADC 250 converts the voltage signal received from the temperature sensor 120 into an electrical signal. The ADC 250 converts the voltage signal received from the temperature sensor 120 into a bit stream of '1' and '0', and outputs the bit stream. That is, the ADC 250 converts an analog voltage signal into a digital signal and outputs it. The output digital signal is delivered to an external digital device and can include data on the currently measured flow rate.
DAC(260)는 ADC(250)에서 출력된 디지털 신호(즉, 비트 스트림)를 아날로그 신호로 변환하여 히터(130)에 전달한다. DAC(260)에서 히터(130)에 전달한 신호는 히터(130)를 동작시키기 위한 동작 신호로 이용될 수 있다. 이때, DAC(260)는 히터(130)의 구동 IC(Driver IC)로써 동작할 수 있으며, 히터(130)에 피드백 신호로써 동작 신호를 인가할 수 있다. 이러한 피드백 신호를 통해, 유량 측정 센서는 열적 DSM 회로로써 동작할 수 있다. The DAC 260 converts the digital signal (i.e., the bit stream) output from the ADC 250 into an analog signal and transmits the analog signal to the heater 130. The signal transmitted from the DAC 260 to the heater 130 may be used as an operation signal for operating the heater 130. At this time, the DAC 260 may operate as a driver IC of the heater 130 and may apply an operation signal as a feedback signal to the heater 130. [ With this feedback signal, the flow measurement sensor can operate as a thermal DSM circuit.
더 구체적으로, 유량 측정 센서는 폐쇄형 루프 제어(Close-Loop control)를 포함한다. 폐쇄형 루프 인터페이스는 시스템의 선형성을 증가시키며, 인터페이스의 제한 조건을 완화할 수 있다. 또한, 유량 측정 센서는 폐쇄형 루프 제어(Close-Loop control)와, 하나의 칩에 구비된 2개의 히터(130) 및 온도 센서(120)를 포함하는 ETF(100)를 이용하여, 열적 평형 상태(Thermal Balancing)를 위한 보상 값을 결정하고, 이를 통해 온도 차이를 측정할 수 있다. More specifically, the flow measurement sensor includes a Close-Loop control. The closed loop interface increases the linearity of the system and can relax the interface constraints. Further, the flow rate measuring sensor is configured to use the ETF 100 including the close-loop control and the two heaters 130 and the temperature sensor 120 provided in one chip, The compensation value for the thermal balancing can be determined, and the temperature difference can be measured.
도 4 를 참조하면, 유량 측정 센서는 액티브층(Active layer)과, 하부 실리콘층(Bottom Si)으로 구성된다. 이때, 앞에서 설명한 열적 도메인(Thermal Domain)과 전기적 도메인(electrical Domain)은 액티브층 내에 형성된다. 즉, 본 발명의 유량 측정 센서는 열적 도메인과 전기적 도메인을 포함하는 투-칩 구조(Two-Chip Structure)를 포함한다.Referring to FIG. 4, the flow measurement sensor is composed of an active layer and a bottom silicon layer (bottom Si). At this time, the thermal domain and the electrical domain described above are formed in the active layer. That is, the flow sensor of the present invention includes a two-chip structure including a thermal domain and an electrical domain.
이때, 액티브층의 일측에는 온도 센서(120)와 제1 및 제2 히터(132, 134)가 형성되고, 액티브층의 타측에는 ADC(250)와 DAC(260)를 포함하는 제어 회로(200)가 형성된다. A temperature sensor 120 and first and second heaters 132 and 134 are formed on one side of the active layer and a control circuit 200 including an ADC 250 and a DAC 260 is provided on the other side of the active layer. .
이때, 온도 센서(120)의 너비(L2)는 제어 회로(200)의 너비(L3)보다 크게 형성될 수 있다. 유체와 접하는 유량 측정 센서의 단면적 증가를 통해, 유량 측정 센서에서 발생되는 신호의 크기는 증가될 수 있다. 유량 측정 센서는 히터(130)에서 생성되는 열이 지나가는 유체에 의해 얼마나 많은 열 교환을 발생시키냐에 따라서 신호의 크기가 결정된다. 즉, 유체가 흘러오는 방향에서의 제1 히터(132)가 발생시키는 열이 제2 히터(134)가 위치해 있는 지점까지 얼마나 많은 열을 손실하여 온도 차이를 발생시키냐가 발생되는 신호의 크기를 결정하게 된다. 따라서, 본 발명의 유량 측정 센서는 유체가 온도 센서(120)를 지나는 영역의 면적이 증가함에 따라(즉, 온도 센서(120)의 크기가 증가함에 따라) 신호의 크기가 커지게 된다.At this time, the width L2 of the temperature sensor 120 may be larger than the width L3 of the control circuit 200. By increasing the cross-sectional area of the flow measuring sensor in contact with the fluid, the magnitude of the signal generated by the flow measuring sensor can be increased. The magnitude of the signal is determined according to how much heat exchange is generated by the fluid passing through the heat generated by the heater 130. That is, how much heat is generated by the heat generated by the first heater 132 in the flow direction of the fluid, to the point where the second heater 134 is located, . Accordingly, the flow measurement sensor of the present invention becomes larger in size as the area of the region where the fluid passes through the temperature sensor 120 (i.e., the size of the temperature sensor 120 increases).
즉, 본 발명의 유량 측정 센서는 종래의 유량 측정 센서보다 큰 사이즈로 형성됨으로써, 센싱 감도가 향상될 수 있다. That is, since the flow rate measuring sensor of the present invention is formed in a size larger than that of the conventional flow rate measuring sensor, the sensing sensitivity can be improved.
본 발명의 유량 측정 센서에서, 온도 센서(120) 및 히터(130)는 얇은 유리 기판(thin glass) 또는 유연 기판(flexible circuit) 상에 형성될 수 있다. In the flow measurement sensor of the present invention, the temperature sensor 120 and the heater 130 may be formed on a thin glass substrate or a flexible circuit.
이러한 본 발명의 유량 측정 센서는 웨어러블 디바이스(Wearable device) 또는 의료용 기기로써 혈류 측정용 센서 등에 이용될 수 있다. 즉, 유량 측정 센서는 유연기판에 대면적의 온도 센서 및 히터 구조와 소형 CMOS 집적 구조를 투-칩 구조(Two-Chip Structure)로 이원화함으로써, 착용감 및 감도를 높일 수 있으며, 웨어러블 디바이스로 활용 가능할 수 있다. 다만, 본 발명이 이에 한정되는 것은 아니다. Such a flow rate measuring sensor of the present invention can be used as a wearable device or a medical instrument as a blood flow measuring sensor or the like. In other words, the flow measurement sensor can increase the comfort and sensitivity by making a large-area temperature sensor, a heater structure and a small CMOS integrated structure into a two-chip structure on a flexible substrate, and can be used as a wearable device . However, the present invention is not limited thereto.
도 5 및 도 6을 참조하면, 종래의 유량 측정 센서(A)의 경우, 하부 실리콘층의 두께(H1)는 약 100 μm를 가졌다. 일반적인 가공 전 기판의 경우, 약 700μm의 두께를 가지고, 기계적 식각 공정을 통해 약 100 μm 두께의 하부 실리콘층이 형성된다. 다만, 이 경우, 종래의 유량 측정 센서(A)에 형성된 ETF는, 1/2 차수의 로우 패스 DSM을 형성하며, 1/2 차수의 LPF 특성을 가지게 된다. 따라서, 종래의 유량 측정 센서는 다소 높은 수준의 양자화 잡음(Quantization Noise)을 발생시켜, 유량 측정 센서의 감도를 향상시키는데 큰 제약사항이 되었다.Referring to FIGS. 5 and 6, in the case of the conventional flow measurement sensor A, the thickness H1 of the lower silicon layer has about 100 μm. In the case of a general pre-processed substrate, a lower silicon layer having a thickness of about 100 μm is formed through a mechanical etching process with a thickness of about 700 μm. However, in this case, the ETF formed in the conventional flow measurement sensor A forms a low-pass DSM of a one-order degree and has a LPF characteristic of a one-order degree. Therefore, the conventional flow measurement sensor has a somewhat high level of quantization noise, which is a great restriction to improve the sensitivity of the flow measurement sensor.
반면, 본 발명의 유량 측정 센서(B)는 화학적 식각 공정(etching)을 통해, 하부 실리콘층의 두께(H2)를 약 10μm로 형성한다. 이 경우, 하부 실리콘층은 중앙 부분의 경우, 약 10μm 가장자리 부분의 경우 약 12μm의 두께로 형성될 수 있다. 다만, 앞에서 설명한 하부 실리콘층의 두께에 대한 수치는 하나의 예시에 불과하며, 본 발명이 이에 한정되는 것은 아니다.On the other hand, the flow sensor (B) of the present invention forms a thickness (H2) of the lower silicon layer of about 10 mu m through a chemical etching process. In this case, the lower silicon layer may be formed to have a thickness of about 12 mu m in the case of the center portion and about 10 mu m in the edge portion. However, the numerical values for the thicknesses of the lower silicon layer described above are merely illustrative, and the present invention is not limited thereto.
본 발명의 유량 측정 센서(B)는 습식 식각 공정(wet etching) 또는 건식 식각 공정(dry etching)을 통해, 하부 실리콘층의 두께(H2)를 약 10μm로 형성할 수 있다. 이를 통해, 본 발명의 본 발명의 유량 측정 센서(B)의 신호 대 잡음비(Signal　to　Noise　Ratio; 이하 SNR)가 개선됨에 따라, 유량 측정 센서(B)의 센싱 감도가 향상된다. 또한, 유량 측정 센서의 두께를 얇게 함에 따라, 유량 측정 센서의 루프 필터(loop-filter)에 의한 LPF 특성은 종래의 1/2 차수 LPF에서 1차수 LPF로 개선된다. The thickness H2 of the lower silicon layer can be formed to be about 10 mu m through the wet etching or the dry etching in the flow sensor B of the present invention. As a result, the sensor sensitivity of the flow measurement sensor B is improved as the signal to noise ratio (SNR) of the flow measurement sensor B of the present invention is improved. Also, as the thickness of the flow measurement sensor is reduced, the LPF characteristic of the loop-filter of the flow rate sensor is improved from the conventional one-order LPF to the one-order LPF.
이를 통해, 유량 측정 센서의 양자화 잡음이 감소되고, 유량 측정 센서의 면적이 증가함에 따라 신호의 크기가 증가하여, 신호 대 잡음비(SNR)가 증가되고, 센싱 감도가 극대화될 수 있다. As a result, the quantization noise of the flow measurement sensor is reduced, and the signal size increases as the area of the flow measurement sensor increases, so that the signal-to-noise ratio (SNR) increases and the sensing sensitivity can be maximized.
도 6을 참조하면, 본 발명의 일 실시예에 따른 유량 측정 센서는 종래의 유량 측정 센서보다 큰 주파수 대 데시벨(dB/dec)의 기울기를 가짐에 따라, 높은 센싱 감도를 갖는 것을 알 수 있다.Referring to FIG. 6, the flow measurement sensor according to an embodiment of the present invention has a higher sensitivity than a conventional flow measurement sensor, since the flow measurement sensor has a slope of a frequency in decibels (dB / dec).
즉, 본 발명의 일 실시예에 따른 유량 측정 센서는, 실리콘 칩의 두께를 최소화하고, 유체와의 접촉 면적을 확장함으로써, 신호의 크기를 증폭시키고 ETF의 차수를 증가시켜 유량 측정 감도를 향상시킬 수 있다. That is, the flow measurement sensor according to an embodiment of the present invention amplifies the signal magnitude and increases the order of the ETF by minimizing the thickness of the silicon chip and expanding the contact area with the fluid, thereby improving the flow measurement sensitivity .
도 7은 본 발명의 다른 실시예에 따른 유량 측정 센서를 나타내는 블록도이다. 도 8은 본 발명의 다른 실시예에 따른 유량 측정 센서의 동작을 설명하기 위한 그래프이다. 이하에서는 앞에서 설명한 실시예와 차이점을 위주로 설명하도록 한다.7 is a block diagram illustrating a flow measurement sensor according to another embodiment of the present invention. 8 is a graph for explaining the operation of the flow measurement sensor according to another embodiment of the present invention. Hereinafter, differences from the above-described embodiments will be mainly described.
도 7 및 도 8을 참조하면, 본 발명의 다른 실시예에 따른 유량 측정 센서는 열적 도메인(Thermal Domain) 상에 ETF(100)가 구비되고, 전기적 도메인(electrical Domain) 상에 전자 필터(Electrical Filter)(210)와, ADC(250)와 DAC(260)가 구비된다. 본 발명의 다른 실시예에 따른 유량 측정 센서는 앞에서 설명한 일 실시예에 따른 유량 측정 센서에 전자 필터(210)를 더 포함한다.7 and 8, the flow rate measuring sensor according to another embodiment of the present invention includes an ETF 100 on a thermal domain, an electrical filter (not shown) on an electrical domain, ) 210, an ADC 250 and a DAC 260 are provided. The flow measurement sensor according to another embodiment of the present invention further includes an electronic filter 210 in the flow measurement sensor according to the above-described embodiment.
본 발명의 다른 실시예에 따른 유량 측정 센서는 열적 도메인(Thermal Domain) 상에 구비된 ETF(100)와, 전기적 도메인(electrical Domain) 상에 구비된 전자 필터(210), ADC(250), 및 DAC(260)를 포함한다.The flow rate measuring sensor according to another embodiment of the present invention includes an ETF 100 provided on a thermal domain, an electronic filter 210 provided on an electrical domain, an ADC 250, DAC < / RTI >
ETF(100)는 열적 LPF(110)와, 온도 센서(120), 하나 이상의 히터(130)를 포함한다. The ETF 100 includes a thermal LPF 110, a temperature sensor 120, and one or more heaters 130.
열적 LPF(110)는 온도 센서(120)와 히터(130) 사이에 발생하는 열전달 과정에서 생기는 전달 함수(Transfer Function)을 나타낸다.The thermal LPF 110 represents a transfer function generated during a heat transfer process occurring between the temperature sensor 120 and the heater 130.
온도 센서(120)는 양단의 온도를 측정한다. 온도 센서(120)는 양단의 온도 차이를 측정하고, 측정된 온도 차이를 전압 신호로 변환한다.The temperature sensor 120 measures temperatures at both ends. The temperature sensor 120 measures the temperature difference at both ends, and converts the measured temperature difference into a voltage signal.
히터(130)는 열을 발생시켜 인접한 유체 또는 물체에 발생된 열을 전달한다. 히터(130)는 온도 센서(120)의 일측에 배치되는 제1 히터(132)와, 온도 센서(120)의 타측에 배치되는 제2 히터(134)를 포함한다.The heater 130 generates heat to transfer heat generated in the adjacent fluid or object. The heater 130 includes a first heater 132 disposed on one side of the temperature sensor 120 and a second heater 134 disposed on the other side of the temperature sensor 120.
전자 필터(210)는 온도 센서(120)로부터 전압 신호를 입력받고, 필터링을 통해 출력되는 신호의 차수를 증가시켜 ADC(250)에 전달한다. 전자 필터(210)는 N차수(Nth order)의 LPF로써 동작할 수 있다. 이를 통해 본 발명의 다른 실시예에 따른 유량 측정 센서는 DSM 기반의 1+N 차수 LPF 특성을 갖는 유량 측정 센서를 구현함으로써, 유량 측정 감도를 극대화시킬 수 있다. The electronic filter 210 receives the voltage signal from the temperature sensor 120, increases the degree of the signal output through the filtering, and transmits the signal to the ADC 250. The electronic filter 210 can operate as an Nth order LPF. Accordingly, the flow measurement sensor according to another embodiment of the present invention can maximize the flow measurement sensitivity by implementing the DSM-based flow measurement sensor having 1 + N-order LPF characteristics.
구체적으로, 전자 필터(210)는 상호컨덕턴스(Gm)와 커패시턴스(C)값을 이용하는 Gm-C 필터(214)를 포함한다. 또한, 전자 필터(210)는 DAC(260)의 출력으로부터 알파(α) 값의 게인을 갖는 피드백 신호(216)를 수신한다. 여기에서, 알파(α) 값은 전자 필터(210)의 스태빌리티(stability)를 맞춰주기 위한 피드백 펙터(feedback factor)에 해당한다. 다만, 본 발명이 이에 한정되는 것은 아니며, 전자 필터(210)는 다양한 종류의 필터가 이용될 수 있다.Specifically, the electronic filter 210 includes a Gm-C filter 214 that uses a transconductance Gm and a capacitance C value. The electronic filter 210 also receives a feedback signal 216 having a gain of alpha (alpha) value from the output of the DAC 260. Here, the alpha (alpha) value corresponds to a feedback factor for matching the stability of the electronic filter 210. However, the present invention is not limited thereto, and various types of filters may be used for the electronic filter 210.
유량 측정 센서에 N차의 전자 필터(210)를 추가하는 경우, 양자화 잡음을 최소화시킬 수 있으며, 앞에서 설명한 것과 같이 유체와의 접촉면을 증가시킴으로써, 유량 측정 센서에서 발생되는 신호의 크기를 증가시키고, 회로 자체에서 발생하는 신호대 잡음비(SNR)를 향상시킬 수 있다. When the N-order electronic filter 210 is added to the flow measurement sensor, the quantization noise can be minimized and the size of the signal generated by the flow measurement sensor can be increased by increasing the contact surface with the fluid as described above, The signal-to-noise ratio (SNR) generated in the circuit itself can be improved.
ADC(250)는 전자 필터(210)로부터 수신된 N차수로 필터링된 전압 신호를 전기적 신호로 변환한다. ADC(250)는 온도 센서(120)로부터 수신한 전압 신호를 '1'과 '0'으로 이루어진 비트 스트림으로 변환하여 출력한다. 즉, ADC(250)는 아날로그의 전압 신호를 디지털 신호로 변환하여 출력한다. 출력된 디지털 신호는 외부 디지털 장치에 전달되며, 현재 측정된 유량에 대한 데이터를 포함할 수 있다.The ADC 250 converts the N-order filtered signal received from the electronic filter 210 into an electrical signal. The ADC 250 converts the voltage signal received from the temperature sensor 120 into a bit stream of '1' and '0' and outputs the bit stream. That is, the ADC 250 converts an analog voltage signal into a digital signal and outputs it. The output digital signal is delivered to an external digital device and can include data on the currently measured flow rate.
DAC(260)는 ADC(250)에서 출력된 디지털 신호(즉, 비트 스트림)를 아날로그 신호로 변환하여 히터(130)에 전달한다. DAC(260)에서 히터(130)에 전달한 신호는 히터(130)를 동작시키기 위한 동작 신호로 이용될 수 있다. 이때, DAC(260)는 히터(130)의 구동 IC(Driver IC)로써 동작할 수 있으며, 히터(130)에 피드백 신호로써 동작 신호를 인가할 수 있다. 이러한 피드백 신호를 통해, 유량 측정 센서는 열적 DSM 회로로써 동작할 수 있다.The DAC 260 converts the digital signal (i.e., the bit stream) output from the ADC 250 into an analog signal and transmits the analog signal to the heater 130. The signal transmitted from the DAC 260 to the heater 130 may be used as an operation signal for operating the heater 130. At this time, the DAC 260 may operate as a driver IC of the heater 130 and may apply an operation signal as a feedback signal to the heater 130. [ With this feedback signal, the flow measurement sensor can operate as a thermal DSM circuit.
유량 측정 센서는 폐쇄형 루프 제어(Close-Loop control)와, 하나의 칩에 구비된 2개의 히터(130) 및 온도 센서(120)를 포함하는 ETF(100)를 이용하여, 열적 평형 상태(Thermal Balancing)를 위한 보상 값을 결정하고, 이를 통해 온도 차이를 측정할 수 있다.The flow rate measuring sensor is configured to measure the thermal equilibrium state of the fluid in the thermal equilibrium state using the ETF 100 including the closed loop control and the two heaters 130 and the temperature sensor 120 provided on one chip. Balancing), and thereby the temperature difference can be measured.
액티브층에는 온도 센서(120)와 제1 및 제2 히터(132, 134)가 형성되고, 하부 실리콘층에는 전자 필터(210), ADC(250) 및 DAC(260)를 포함하는 제어 회로(200)가 형성된다. The active layer includes a temperature sensor 120 and first and second heaters 132 and 134 and a control circuit 200 including an electronic filter 210, an ADC 250 and a DAC 260, Is formed.
도 8을 참조하면, 본 발명의 다른 실시예에 따른 전자 필터(210)를 포함하는 유량 측정 센서는, 앞에서 도 6을 참조하여 설명한 일 실시예에 따른 유량 측정 센서보다 큰 주파수 대 데시벨의 기울기(dB/dec)를 가짐에 따라, 높은 센싱 감도를 갖는 것을 알 수 있다.Referring to FIG. 8, the flow sensor including the electronic filter 210 according to another embodiment of the present invention may have a larger frequency-to-decibel gradient than the flow sensor according to the embodiment described with reference to FIG. 6 dB / dec), it has a high sensing sensitivity.
즉, 본 발명의 다른 실시예에 따른 유량 측정 센서는, 높은 차수(Nth order)의 전자 필터(210)를 포함함으로써, 양자화 잡음의 최소화하고, 신호대 잡음비를 개선시켜 유량 측정 센서의 유량 측정 감도를 향상시킬 수 있다.That is, the flow rate sensor according to another embodiment of the present invention includes the Nth order electronic filter 210, thereby minimizing the quantization noise and improving the signal-to-noise ratio to improve the flow measurement sensitivity of the flow rate measuring sensor Can be improved.
전술한 본 발명은, 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 자에게 있어 본 발명의 기술적 사상을 벗어나지 않는 범위 내에서 여러 가지 치환, 변형 및 변경이 가능하므로 전술한 실시예 및 첨부된 도면에 의해 한정되는 것이 아니다.While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, But the present invention is not limited thereto.

Claims (18)

  1. 실리콘층 상에 형성된 액티브층 내에 서로 이격되도록 배치되어 열을 발생시키는 제1 및 제2 히터;First and second heaters arranged to be spaced apart from each other in the active layer formed on the silicon layer to generate heat;
    상기 액티브층 내에서 상기 제1 및 제2 히터 사이에 배치되고, 양단의 온도 차이를 감지하여 전압 신호로 변환하는 온도 센서; 및A temperature sensor disposed between the first and second heaters in the active layer for detecting a temperature difference between both ends and converting the temperature difference into a voltage signal; And
    상기 액티브층 내에 형성되고, 상기 온도 센서로부터 수신한 상기 전압 신호의 피드백 신호를 상기 제1 및 제2 히터에 전달하는 제어 회로를 포함하되,And a control circuit formed in the active layer and transmitting a feedback signal of the voltage signal received from the temperature sensor to the first and second heaters,
    상기 제어 회로는, 상기 온도 센서로부터 상기 전압 신호를 입력받고, 필터링을 통해, 출력되는 신호의 차수를 증가시키는 전자 필터(Electrical Filter)를 포함하는 유량 측정 센서.Wherein the control circuit includes an electronic filter that receives the voltage signal from the temperature sensor and increases the degree of the output signal through filtering.
  2. 제1 항에 있어서,The method according to claim 1,
    상기 제어 회로는,The control circuit comprising:
    상기 온도 센서로부터 수신한 상기 전압 신호를 비트스트림으로 변환시키는 ADC와,An ADC for converting the voltage signal received from the temperature sensor into a bit stream,
    상기 비트스트림을 상기 제1 및 제2 히터를 동작시키기 위한 동작 신호로 변환하는 DAC를 더 포함하는 유량 측정 센서.And a DAC for converting the bit stream into an operation signal for operating the first and second heaters.
  3. 제2 항에 있어서,3. The method of claim 2,
    상기 전자 필터는, The electronic filter includes:
    상기 온도 센서와 상기 ADC 사이에 배치되고, A temperature sensor disposed between the temperature sensor and the ADC,
    상기 DAC의 출력 신호에 특정 게인이 인가된 신호를 피드백 신호로서 수신하는 유량 측정 센서.And a signal having a specific gain applied to the output signal of the DAC is received as a feedback signal.
  4. 제1 항에 있어서,The method according to claim 1,
    상기 전자 필터는, 상호컨덕턴스(Gm)와 커패시턴스(C)값을 이용하는 Gm-C 필터를 포함하는 유량 측정 센서.Wherein the electronic filter includes a Gm-C filter using a mutual conductance (Gm) and a capacitance (C) value.
  5. 제4 항에 있어서,5. The method of claim 4,
    상기 온도 센서와 상기 제1 및 제2 히터는, 상호 인접하여 1차(1st order) 저역 통과 필터(LPF)로서 동작하는 ETF(Electrothermal Filter)를 구성하는 유량 측정 센서.Wherein the temperature sensor and the first and second heaters constitute an ETF (Electrothermal Filter) operating as a first order low-pass filter (LPF) adjacent to each other.
  6. 제1 항에 있어서,The method according to claim 1,
    상기 전자 필터는, 수신된 상기 전압 신호의 고주파 성분을 제거하는 저역 통과 필터(LPF)로서 동작하는 유량 측정 센서.Wherein the electronic filter operates as a low pass filter (LPF) that removes high frequency components of the received voltage signal.
  7. 제1 항에 있어서,The method according to claim 1,
    상기 제어 회로가 형성된 상기 실리콘층의 두께는, 12 마이크로 미터 이하로 형성되는 유량 측정 센서.Wherein the thickness of the silicon layer formed with the control circuit is less than 12 micrometers.
  8. 제1 항에 있어서,The method according to claim 1,
    상기 온도 센서의 너비는, 상기 제어 회로의 너비보다 크게 형성되는 유량 측정 센서.Wherein the width of the temperature sensor is larger than the width of the control circuit.
  9. 제8 항에 있어서,9. The method of claim 8,
    상기 액티브층은, 글래스 기판 또는 유연 기판의 소재로 형성되는 유량 측정 센서.Wherein the active layer is formed of a material of a glass substrate or a flexible substrate.
  10. 액티브층 내에 서로 이격되도록 배치되어 열을 발생시키는 제1 및 제2 히터;First and second heaters arranged to be spaced apart from each other in the active layer to generate heat;
    상기 액티브층 내에서 상기 제1 및 제2 히터 사이에 배치되고, 양단의 온도 차이를 감지하여 전압 신호로 변환하는 온도 센서; 및A temperature sensor disposed between the first and second heaters in the active layer for detecting a temperature difference between both ends and converting the temperature difference into a voltage signal; And
    상기 액티브층의 일면에 접하는 실리콘층 내에 형성되고, 상기 온도 센서로부터 수신한 상기 전압 신호의 피드백 신호를 상기 제1 및 제2 히터에 전달하는 제어 회로를 포함하되,And a control circuit formed in a silicon layer in contact with one surface of the active layer and transmitting a feedback signal of the voltage signal received from the temperature sensor to the first and second heaters,
    상기 온도 센서와 상기 제1 및 제2 히터는, 상호 인접하여 1차(1st order) 저역 통과 필터(LPF)로서 동작하는 ETF(Electrothermal Filter)를 구성하는 액체 유량 센서.Wherein the temperature sensor and the first and second heaters constitute an ETF (Electrothermal Filter) operating as a first order low-pass filter (LPF) adjacent to each other.
  11. 제10 항에 있어서,11. The method of claim 10,
    상기 제어 회로는,The control circuit comprising:
    상기 온도 센서로부터 수신한 상기 전압 신호를 비트스트림으로 변환시키는 ADC와,An ADC for converting the voltage signal received from the temperature sensor into a bit stream,
    상기 비트스트림을 상기 제1 및 제2 히터를 동작시키기 위한 동작 신호로 변환하는 DAC를 포함하는 액체 유량 센서.And a DAC for converting the bit stream into an operation signal for operating the first and second heaters.
  12. 제11 항에 있어서,12. The method of claim 11,
    상기 제어 회로는 상기 온도 센서로부터 상기 전압 신호를 입력받고, 필터링을 통해, 출력되는 신호의 차수를 증가시키는 전자 필터(Electrical Filter)를 더 포함하는 유량 측정 센서.Wherein the control circuit further includes an electronic filter that receives the voltage signal from the temperature sensor and increases the degree of the output signal through filtering.
  13. 제12 항에 있어서,13. The method of claim 12,
    상기 전자 필터는, The electronic filter includes:
    상기 온도 센서와 상기 ADC 사이에 배치되고, A temperature sensor disposed between the temperature sensor and the ADC,
    상기 DAC의 출력 신호에 특정 게인이 인가된 신호를 피드백 신호로서 수신하는 유량 측정 센서.And a signal having a specific gain applied to the output signal of the DAC is received as a feedback signal.
  14. 제12 항에 있어서,13. The method of claim 12,
    상기 전자 필터는, 상호컨덕턴스(Gm)와 커패시턴스(C)값을 이용하는 Gm-C 필터를 포함하는 유량 측정 센서.Wherein the electronic filter includes a Gm-C filter using a mutual conductance (Gm) and a capacitance (C) value.
  15. 제12 항에 있어서,13. The method of claim 12,
    상기 전자 필터는, 수신된 상기 전압 신호의 고주파 성분을 제거하는 저역 통과 필터(LPF)로서 동작하는 유량 측정 센서.Wherein the electronic filter operates as a low pass filter (LPF) that removes high frequency components of the received voltage signal.
  16. 제10 항에 있어서,11. The method of claim 10,
    상기 제어 회로가 형성된 상기 실리콘층의 두께는, 12 마이크로 미터 이하로 형성되는 유량 측정 센서.Wherein the thickness of the silicon layer formed with the control circuit is less than 12 micrometers.
  17. 제10 항에 있어서,11. The method of claim 10,
    상기 온도 센서의 너비는, 상기 제어 회로의 너비보다 크게 형성되는 유량 측정 센서.Wherein the width of the temperature sensor is larger than the width of the control circuit.
  18. 제10 항에 있어서,11. The method of claim 10,
    상기 액티브층은, 글래스 기판 또는 유연 기판의 소재로 형성되는 유량 측정 센서.Wherein the active layer is formed of a material of a glass substrate or a flexible substrate.
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