A signal acquisition and amplification circuit

Abstract

This utility model discloses a signal acquisition and amplification circuit, relating to the field of signal acquisition and transmission. The circuit includes: a Wheatstone bridge module for feeding back a fixed voltage signal and a temperature change signal to a differential amplifier module; and a differential amplifier module for varying the output voltage when there is a difference between the input fixed voltage signal and the temperature change signal. The advantages of this utility model are: by setting a differential amplifier module, the small signal obtained from the sensor is linearly amplified, which is more conducive to acquisition and identification by subsequent circuits; the circuit makes the correspondence between the output voltage signal Vout and the NTC resistor value clear and easy for subsequent circuits to acquire; the signal input impedance is high and the output impedance is low, which is beneficial for impedance matching with subsequent circuits and reduces power consumption; the differential amplifier module provides filtering for high-frequency noise; and the NTC resistor has low self-heating, ensuring the accuracy and stability of temperature acquisition.

Description

Technical Field

[0001] This utility model relates to the field of signal acquisition and transmission, specifically a signal acquisition and amplitude expansion circuit. Background Technology

[0002] Currently, with the development of smart lighting, the application of sensors in smart lamps is becoming increasingly widespread. Common sensors collect weak physical signals, convert them into electrical signals, filter and amplify them, and then send them to a control device (such as a microcontroller). The control device then uses the obtained signals to control the brightness, color temperature, and switching of the lamps.

[0003] Because smart lighting fixtures often operate in a long standby state, it's crucial to minimize the power consumption of the sensing components and processing circuitry. For example, temperature sensors typically use NTC sensors, and a typical circuit would look like this... Figure 1 As shown. An NTC (Negative Temperature Coefficient) resistor decreases with increasing temperature. The advantages of this circuit are its simple structure. However, it has several disadvantages: 1) Its signal processing capability is relatively weak, especially under low supply voltage and high noise conditions, making the output Temp_Signal signal susceptible to interference; 2) As temperature increases, the current flowing through the NTC increases, leading to higher standby power consumption; 3) The increased current flowing through the NTC causes the thermistor to dissipate power as heat, resulting in self-heating. This heat, generated within the thermistor's core, can affect measurement accuracy; 4) If the input impedance of the subsequent circuit is low, the acquired signal is easily affected by the operating state of the subsequent circuit.

[0004] In summary, existing smart lighting fixtures suffer from susceptibility to interference and high power consumption in signal acquisition, and therefore require improvement. Utility Model Content

[0005] The purpose of this invention is to provide a signal acquisition and amplitude expansion circuit to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A signal acquisition and amplitude expansion circuit, comprising:

[0008] The Wheatstone bridge module is used to feed back a fixed voltage signal and a temperature change signal to the differential amplifier module;

[0009] The differential amplifier module is used to vary the output voltage and output a processed temperature signal when there is a difference between the input fixed voltage signal and the temperature change signal.

[0010] The output of the Wheatstone bridge module is connected to the input of the differential amplifier module;

[0011] The Wheatstone bridge module includes resistors R1, R2, R3, R4, and R5. Resistor R3 is an NTC resistor. One end of resistor R1 is connected to one end of resistor R2 and voltage V_Signal. The other end of resistor R1 is connected to common point B, one end of resistor R5, and one end of resistor R3. The other end of resistor R2 is connected to the other end of resistor R5, common point A, and one end of resistor R4. The other end of resistor R3 and the other end of resistor R4 are grounded.

[0012] As a further embodiment of this utility model: the differential amplifier module includes resistors R6, R7, R8, and R9, capacitor C2, and amplifier U1. One end of resistor R6 is connected to common point A, one end of resistor R7 is connected to common point B, the other end of resistor R6 is connected to one end of resistor R9 and the non-inverting input of amplifier U1, the other end of resistor R9 is grounded, the other end of resistor R7 is connected to the inverting input of amplifier U1, one end of resistor R8 and one end of capacitor C2, and the other end of resistor R8 is connected to the other end of capacitor C2 and the output terminal of amplifier U1.

[0013] As a further solution of this utility model: When the two bridges in the Wheatstone bridge module are in a balanced state, the resistance values ​​of resistors R1, R2, R3, and R4 are equal. To determine the resistance value, Va-Vb = 0, where Va is the voltage at common point A and Vb is the voltage at common point B.

[0014] The voltage at point A is expressed as:

[0015]

[0016] The voltage at point B is expressed as:

[0017]

[0018] As a further solution of this utility model: When the two bridges in the Wheatstone bridge module are in an unbalanced state, the resistance values ​​of resistors R1, R2, and R4 are the same. In order to determine the resistance value, resistor R3 is an NTC resistor, and the resistance value changes with temperature, with a change of ΔR3.

[0019] The voltage at point B is expressed as:

[0020]

[0021] The voltage at point A is expressed as:

[0022]

[0023] The voltage change between points A and B is:

[0024]

[0025] As a further improvement of this utility model: in the Wheatstone bridge module, the circuit is designed so that ΔR3≤R3, simplifying formula (5) to:

[0026]

[0027] That is, the magnitude of voltage ΔUa-b is related to the power supply voltage V_Signal and the change in resistance R3 ΔR3. When designing the circuit, a fixed voltage V_Signal is used to power the circuit, then voltage ΔUa-b is only related to the corresponding change in resistance ΔR3 due to temperature change.

[0028] As a further improvement of this utility model: In the differential amplifier module, resistors R6 = R7, resistors R8 = R9, the voltage change between points A and B is Ua-b, and the output voltage Vout is:

[0029]

[0030] Compared with the prior art, the beneficial effects of this utility model are as follows: This utility model linearly expands the small signal obtained by the sensor by setting a differential amplification module, which is more conducive to the acquisition and recognition of subsequent circuits; the circuit makes the correspondence between the output voltage signal Vout and the resistance value of the NTC resistor clear and easy for subsequent circuits (such as microcontrollers) to acquire and use; the signal input impedance (Wheatstone bridge module) is large and the output impedance (differential amplification module) is low, which is conducive to impedance matching with subsequent circuits and reduces power consumption; the differential operational amplifier of the differential amplification module has a filtering effect on high-frequency noise; the NTC resistor has low self-heating, ensuring the accuracy and stability of temperature acquisition. Attached Figure Description

[0031] Figure 1 This is a circuit diagram of an existing NTC temperature sensor.

[0032] Figure 2 This is a circuit diagram of a signal acquisition and amplitude expansion circuit.

[0033] Figure 3 This is a circuit diagram showing the temperature variation of a Wheatstone bridge module.

[0034] Figure 4 This is a numerical simulation circuit diagram of a signal acquisition and amplitude expansion circuit.

[0035] Figure 5 This is a numerical simulation waveform diagram of a signal acquisition amplitude expansion circuit. Detailed Implementation

[0036] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model.

[0037] Please see Figure 1 A signal acquisition and amplitude expansion circuit, comprising:

[0038] The Wheatstone bridge module is used to feed back a fixed voltage signal and a temperature change signal to the differential amplifier module;

[0039] The differential amplifier module is used to vary the output voltage and output a processed temperature signal when there is a difference between the input fixed voltage signal and the temperature change signal.

[0040] The output of the Wheatstone bridge module is connected to the input of the differential amplifier module;

[0041] The Wheatstone bridge module includes resistors R1, R2, R3, R4, and R5. Resistor R3 is an NTC resistor. One end of resistor R1 is connected to one end of resistor R2 and voltage V_Signal. The other end of resistor R1 is connected to common point B, one end of resistor R5, and one end of resistor R3. The other end of resistor R2 is connected to the other end of resistor R5, common point A, and one end of resistor R4. The other end of resistor R3 and the other end of resistor R4 are grounded.

[0042] In this embodiment: Please refer to Figure 2 The differential amplifier module includes resistors R6, R7, R8, and R9, capacitor C2, and amplifier U1. One end of resistor R6 is connected to common point A, one end of resistor R7 is connected to common point B, the other end of resistor R6 is connected to one end of resistor R9 and the non-inverting input of amplifier U1, the other end of resistor R9 is grounded, the other end of resistor R7 is connected to the inverting input of amplifier U1, one end of resistor R8 and one end of capacitor C2, and the other end of resistor R8 is connected to the other end of capacitor C2 and the output terminal of amplifier U1.

[0043] In this embodiment: Please refer to Figure 2 In the Wheatstone bridge module, when the two bridges are in a balanced state, the resistance values ​​of resistors R1, R2, R3, and R4 are equal. To determine the resistance value, Va - Vb = 0, where Va is the voltage at common point A and Vb is the voltage at common point B.

[0044] The voltage at point A is expressed as:

[0045]

[0046] The voltage at point B is expressed as:

[0047]

[0048] Resistors R1, R2, R3, and R4 have equal resistance values. Resistor R3 is an NTC resistor, and its resistance will change with environmental conditions. The goal is to design a circuit so that the resistance values ​​of resistors R1, R2, R3, and R4 are equal at 25°C. This example uses 25°C; in practice, the exact temperature at which the resistance values ​​of resistors R1, R2, R3, and R4 are equal is not a limitation.

[0049] In this embodiment: Please refer to Figure 2 and Figure 3 In the Wheatstone bridge module, when the two bridges are in an unbalanced state, the resistance values ​​of resistors R1, R2, and R4 are the same. To determine the resistance value, resistor R3 is an NTC resistor whose resistance value changes with temperature by ΔR3.

[0050] The voltage at point B is expressed as:

[0051]

[0052] The voltage at point A is expressed as:

[0053]

[0054] The resistance values ​​of resistors R1, R2, and R4 are the same, and the actual formula (4) is the same as formula (1);

[0055] The voltage change between points A and B is:

[0056]

[0057] In this embodiment: Please refer to Figure 2 and Figure 3 In the Wheatstone bridge module, the circuit is designed so that ΔR3≤R3, simplifying formula (5) to:

[0058]

[0059] That is, the magnitude of voltage ΔUa-b is related to the power supply voltage V_Signal and the change in resistance R3 ΔR3. When designing the circuit, a fixed voltage V_Signal is used to power the circuit, then voltage ΔUa-b is only related to the corresponding change in resistance ΔR3 due to temperature change.

[0060] In this embodiment: Please refer to Figure 2 and Figure 3In the differential amplifier module, resistors R6 = R7 and R8 = R9, and the output voltage Vout is:

[0061]

[0062] When designing the circuit, a fixed voltage V_Signal is used to power the circuit. The voltage △Ua-b is only related to the corresponding resistance change △R3 due to the temperature change. Since the resistance values ​​of resistors R8 and R7 are fixed, the output voltage Vout is only related to the corresponding resistance change △R3 due to the temperature change, effectively feeding back temperature change information.

[0063] For simulation experiments, please refer to [link / reference]. Figure 4 The specific values ​​for each component are as follows: Figure 4 As shown, the waveform is as follows Figure 5 As shown, the curves of the output voltage Vout, the voltage change ΔUa-b between points A and B, and the current flowing through resistor R5 are close with temperature, ensuring stability.

[0064] This invention linearly expands the small signal obtained by the sensor by setting a differential amplification module, which is more conducive to the acquisition and recognition of subsequent circuits. This circuit makes the correspondence between the output voltage signal Vout and the resistance value of the NTC resistor clear and easy for subsequent circuits (such as microcontrollers) to acquire and use. The signal input impedance (Wheatstone bridge module) is large and the output impedance (differential amplification module) is low, which is beneficial for impedance matching with subsequent circuits and reduces power consumption. The differential operational amplifier of the differential amplification module has a filtering effect on high-frequency noise. The NTC resistor has low self-heating, ensuring the accuracy and stability of temperature acquisition.

[0065] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects.

[0066] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A signal acquisition and amplitude expansion circuit, characterized in that, The signal acquisition and amplitude expansion circuit includes: The Wheatstone bridge module is used to feed back a fixed voltage signal and a temperature change signal to the differential amplifier module; The differential amplifier module is used to vary the output voltage and output a processed temperature signal when there is a difference between the input fixed voltage signal and the temperature change signal. The output of the Wheatstone bridge module is connected to the input of the differential amplifier module; The Wheatstone bridge module includes resistors R1, R2, R3, R4, and R5. Resistor R3 is an NTC resistor. One end of resistor R1 is connected to one end of resistor R2 and voltage V_Signal. The other end of resistor R1 is connected to common point B, one end of resistor R5, and one end of resistor R3. The other end of resistor R2 is connected to the other end of resistor R5, common point A, and one end of resistor R4. The other end of resistor R3 and the other end of resistor R4 are grounded.

2. The signal acquisition and amplification circuit of claim 1, wherein, The differential amplifier module includes resistors R6, R7, R8, and R9, capacitor C2, and amplifier U1. One end of resistor R6 is connected to common point A, one end of resistor R7 is connected to common point B, the other end of resistor R6 is connected to one end of resistor R9 and the non-inverting input of amplifier U1, the other end of resistor R9 is grounded, the other end of resistor R7 is connected to the inverting input of amplifier U1, one end of resistor R8 and one end of capacitor C2, and the other end of resistor R8 is connected to the other end of capacitor C2 and the output terminal of amplifier U1.

3. The signal acquisition and amplification circuit of claim 1, wherein, In the Wheatstone bridge module, when the two bridges are in a balanced state, the resistance values ​​of resistors R1, R2, R3, and R4 are equal. To determine the resistance value, Va - Vb = 0, where Va is the voltage at common point A and Vb is the voltage at common point B. The voltage at point A is expressed as: The voltage at point B is expressed as:

4. The signal acquisition and amplification circuit of claim 1, wherein, In the Wheatstone bridge module, when the two bridges are in an unbalanced state, the resistance values ​​of resistors R1, R2, and R4 are the same. To determine the resistance value, resistor R3 is an NTC resistor whose resistance value changes with temperature by ΔR3. The voltage at point B is expressed as: The voltage at point A is expressed as: The voltage change between points A and B is:

5. The signal acquisition and amplification circuit of claim 4, wherein, In the Wheatstone bridge module, the circuit is designed so that ΔR3≤R3, simplifying formula (5) to: That is, the magnitude of voltage ΔUa-b is related to the power supply voltage V_Signal and the change in resistance R3 ΔR3. When designing the circuit, a fixed voltage V_Signal is used to power the circuit, then voltage ΔUa-b is only related to the corresponding change in resistance ΔR3 due to temperature change.

6. The signal acquisition and amplitude expansion circuit according to any one of claims 2, 4, and 5, characterized in that, In the differential amplifier module, resistors R6 = R7 and R8 = R9. The voltage change between points A and B is Ua - b. Therefore, the output voltage Vout is:

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