Sensor circuit and electronic device

Abstract

The embodiment of the application provides a sensor circuit, which comprises a power supply circuit, a signal processing circuit and a filtering circuit. The power supply circuit is used to provide voltage to the signal processing circuit so that the signal processing circuit can normally operate. The filtering circuit is connected to the output end of the signal processing circuit and the ground end of the power supply circuit respectively, and filters noise signals from the ground end. In this way, for a high-precision requirement scene, the voltage at both ends of the signal processing circuit can be stabilized, noise can be suppressed, and finally the sensor circuit can achieve better performance and higher accuracy.

Description

Technical Field

[0001] This application relates to the field of terminal technology, and in particular to a sensor circuit and electronic device. Background Technology

[0002] With the development of technology, various sensors have been incorporated into everyday electronic devices. Different sensors can perform different functions, which can greatly enrich users' lives.

[0003] A common type of sensor uses a Wheatstone bridge, and to maintain high accuracy, the stability of the power supply to the Wheatstone bridge can be improved. One existing technical solution is to use a linear DC regulator to convert the input voltage into a stable output voltage, which serves as the positive terminal of the Wheatstone power supply.

[0004] However, the voltage of the negative terminal of the Wheatstone bridge, which is usually the ground terminal, may fluctuate, which can reduce the measurement accuracy of the Wheatstone bridge. Summary of the Invention

[0005] This application provides a sensor circuit for use in the field of terminal technology. By adding a filtering circuit between the power supply grounding terminal and the signal processing circuit, noise fluctuations from the power supply grounding terminal are reduced, thereby further enhancing the measurement accuracy and precision of the sensor circuit.

[0006] In a first aspect, embodiments of this application provide a sensor circuit, including: a power supply circuit, a signal processing circuit, and a filtering circuit;

[0007] The input terminal of the signal processing circuit is connected to the power supply terminal of the power supply circuit, and the output terminal of the signal processing circuit is connected to the ground terminal of the power supply circuit through the filtering circuit. The filtering circuit is used to filter noise signals.

[0008] The first measurement terminal of the signal processing circuit is used to provide a first voltage, the second measurement terminal of the signal processing circuit is used to measure a second voltage, and the sensor circuit is used to output a differential signal based on the first voltage and the second voltage.

[0009] In this implementation, the signal processing circuit outputs a first voltage from the first measurement terminal and a second voltage from the second strategy terminal. The sensor circuit can calculate the change in resistance in the signal processing circuit based on the changes in the first and second voltages, and thus deduce the change in the actual physical quantity to be measured. During this process, the measurement accuracy of the signal processing circuit is affected by various factors, with the stability of the power supply voltage being a crucial one. In actual circuits, besides fluctuations at the positive terminal of the power supply, fluctuations may also occur at the negative terminal, or ground, which can reduce the accuracy of the signal processing circuit to some extent. Therefore, setting a filter circuit between the power supply ground and the signal processing circuit to reduce noise fluctuations from the ground can make the differential signal output by the signal processing circuit more stable and reliable.

[0010] In one possible implementation, the signal processing circuit includes a first bridge, which includes a first branch circuit and a second branch circuit connected in parallel. The first branch circuit includes a first resistor and a second resistor connected in series, and the second branch circuit includes a third resistor and a fourth resistor connected in series. The first bridge may be the Wheatstone bridge described in the specification section.

[0011] The two intersections of the first branch circuit and the second branch circuit correspond to the input and output terminals of the first bridge, respectively. The port between the first resistor and the second resistor is the first measurement terminal, and the port between the third resistor and the fourth resistor is the second measurement terminal.

[0012] The filter circuit includes a fifth resistor.

[0013] The first resistor mentioned above can be, for example, R1 as described in the instruction manual. Similarly, the second resistor can be R2 as described in the instruction manual, the third resistor can be R3 as described in the instruction manual, the fourth resistor can be R4 as described in the instruction manual, and the fifth resistor can be, for example, R5 as described in the instruction manual.

[0014] In one possible implementation, the first voltage is the voltage division of the second resistor on the first branch circuit with respect to the first voltage difference, and the second voltage is the voltage division of the fourth resistor on the second branch circuit with respect to the first voltage difference.

[0015] The first voltage difference is the voltage difference between the power supply terminal voltage and the ground terminal voltage of the power supply circuit.

[0016] This implementation illustrates one form of signal processing and filtering circuits. First, the signal processing circuit is a Wheatstone bridge circuit with two branches, each containing two resistors. The points between the two resistors on each branch of the Wheatstone bridge are the measuring terminals, outputting a first voltage and a second voltage, respectively. By measuring the first voltage, the second voltage, and their difference, the change in resistance value within the signal processing circuit can be determined. Next, the filtering circuit can be a resistor placed between the output of the signal processing circuit and the ground terminal of the power supply. Understandably, the voltage at the ground terminal is typically 0V, and may contain some random noise fluctuations, which are relatively small. When the noise signal encounters the resistance during propagation, it is effectively reduced or eliminated. This ensures that the output of the signal processing circuit is not directly affected by noise fluctuations at the ground terminal, with the filtering circuit acting as an isolation barrier.

[0017] In one possible implementation, the resistance of the fifth resistor is less than or equal to the first threshold.

[0018] This implementation further explains the value of the fifth resistor in the filtering circuit. Understandably, on the one hand, it's desirable for the filtering circuit to reduce or eliminate random noise fluctuations from the power supply ground terminal; on the other hand, it's also desirable to minimize the significant voltage drop at the signal processing circuit's output due to the filtering circuit's presence. Therefore, the value of the fifth resistor can be set relatively small. For example, a first threshold value can be set for the fifth resistor based on the actual sensor circuit's power supply and signal processing circuit configuration. When the fifth resistor's value is less than or equal to the first threshold value, it can effectively block noise fluctuations from the power supply ground terminal while ignoring its impact on the voltage drop at the signal processing circuit's output.

[0019] In one possible implementation, the circuit further includes a voltage divider unit, one end of which is connected to the power supply terminal of the power supply circuit, and the other end of which is connected to the ground terminal of the power supply circuit through a filter circuit.

[0020] This implementation describes a sensor circuit that includes a power supply circuit, a signal processing circuit, a filtering circuit, and a voltage divider unit. The two ends of the voltage divider unit are connected to the power supply terminal of the power supply circuit and the filtering circuit, respectively. Alternatively, the voltage divider unit and the signal processing circuit can be connected in parallel, and then connected in series with the filtering circuit. In this way, the voltage divider unit can be used to adjust the voltage at the output of the signal processing circuit, ensuring a quantitative relationship between the voltage divider unit's resistance and the voltage at the positive terminal of the power supply. It can be understood that by changing the voltage at the output of the signal processing circuit through the voltage divider unit, the output voltage of the signal processing circuit is influenced and controlled by the positive voltage of the power supply, which itself has been stabilized. In other words, after adding the voltage divider unit, the voltage at the output of the signal processing circuit can also avoid being affected by noise fluctuations from the power supply ground terminal.

[0021] In one possible implementation, the voltage divider unit includes a sixth resistor, the value of which is greater than or equal to the second threshold. This fifth resistor could be, for example, R6 as described in the specification.

[0022] This implementation describes a voltage divider unit where a sixth resistor is connected in parallel with the signal processing circuit, and then in series with a fifth resistor serving as a filter circuit. The resistance value of the sixth resistor in the voltage divider unit is limited to be greater than or equal to a second threshold. This second threshold can be reasonably set according to the actual power supply circuit and signal processing circuit. Understandably, a larger resistance value for the sixth resistor allows for a larger voltage difference across its terminals, thus providing a larger voltage difference for the parallel signal processing circuit to support normal operation. Furthermore, a larger resistance value reduces the current flowing through the sixth resistor, resulting in smaller changes in the voltage difference between the input and output terminals of the parallel signal processing circuit when the resistance value changes, thus not affecting the normal operation of the signal processing circuit. In addition, a larger resistance value for the sixth resistor significantly reduces the power consumption of the power supply circuit, allowing the sensor circuit to operate stably for extended periods.

[0023] In one possible implementation, the first voltage is the voltage division of the second resistor on the first branch circuit with respect to the second voltage difference, and the second voltage is the voltage division of the fourth resistor on the second branch circuit with respect to the second voltage difference.

[0024] The second voltage difference is the voltage difference between the power supply terminal voltage of the power supply circuit and the voltage at the first terminal of the fifth resistor, and the first terminal of the fifth resistor is the terminal connected to the sixth resistor.

[0025] This implementation illustrates how the first and second voltages at the measurement terminals of the signal processing circuit are determined due to the presence of the voltage divider unit. The second voltage difference needs to take into account both the fifth and sixth resistors; or, it can be understood that different second voltage differences can be obtained by setting different values ​​for the fifth and sixth resistors. Thus, in a practical sensor circuit, when the power supply voltage is fixed, the signal processing circuit can operate under a better voltage environment by adjusting the values ​​of the fifth and sixth resistors, based on the signal processing circuit's requirement for the second voltage difference.

[0026] In one possible implementation, a voltage stabilization unit is further included between the signal processing circuit and the filtering circuit. The first end of the voltage stabilization unit is connected to the output end of the signal processing circuit, and the second end of the voltage stabilization unit is connected to the filtering circuit.

[0027] In this implementation, the sensor circuit includes a voltage stabilization unit in addition to the power supply circuit, signal processing circuit, filtering circuit, and voltage divider unit. This voltage stabilization unit is positioned between the output of the signal processing circuit and the filtering circuit. It is understandable that changes in the resistance value of the resistor in the signal processing circuit will cause changes in the first and second voltages, and simultaneously, will also cause changes in the voltage at the output of the signal processing circuit. In other words, during the measurement process of the sensor circuit, the voltage across the signal processing circuit will also change to some extent. To stabilize the voltage difference between the input and output of the signal processing circuit at a fixed value, a voltage stabilization unit can be placed at the output of the signal processing circuit. This ensures that the voltage difference between the input and output of the signal processing circuit remains constant during measurement, making the sensor circuit's measurement faster and more accurate.

[0028] In one possible implementation, the first voltage is the voltage division of the second resistor on the first branch circuit with respect to the third voltage difference, and the second voltage is the voltage division of the fourth resistor on the second branch circuit with respect to the third voltage difference.

[0029] The third voltage difference is the voltage difference between the power supply terminal voltage of the power supply circuit and the first terminal voltage of the voltage stabilizing unit.

[0030] In one possible implementation, the voltage stabilization unit is a voltage follower.

[0031] In this implementation, the voltage difference between the input and output terminals of the signal processing circuit is defined as the third voltage difference, corresponding to the power supply voltage of the power supply circuit and the first terminal voltage of the voltage stabilization unit, respectively. The first terminal of the voltage stabilization unit refers to the terminal connected to the signal processing circuit. The voltage stabilization unit can be a voltage follower. Because voltage followers have high input impedance, low output impedance, and can maintain their output voltage equal to their input voltage, the output voltage of the signal processing circuit remains stable and does not change with variations in resistance within the signal processing circuit, thus further improving the accuracy of the sensor circuit.

[0032] Secondly, embodiments of this application provide an electronic device that includes a sensor circuit as described in the first aspect or any possible implementation thereof.

[0033] Thirdly, embodiments of this application provide a chip system that includes a sensor circuit as described in the first aspect or any possible implementation of the first aspect.

[0034] Fourthly, embodiments of this application provide a printed circuit board (PCB) that includes a sensor circuit as described in the first aspect or any possible implementation of the first aspect.

[0035] It should be understood that the second to fourth aspects of this application correspond to the technical solutions of the first aspect of this application, and the beneficial effects achieved by each aspect and the corresponding feasible implementation are similar, and will not be repeated here. Attached Figure Description

[0036] Figure 1 A schematic diagram of the structure of the Wheatstone bridge balance provided in the embodiments of this application;

[0037] Figure 2 A schematic diagram of the structure for measuring the Wheatstone bridge signal provided in an embodiment of this application;

[0038] Figure 3 This is a schematic diagram of the power supply positive voltage stabilization circuit provided in an embodiment of this application;

[0039] Figure 4 A schematic diagram of the sensor parameter interface of the terminal device provided in the embodiments of this application;

[0040] Figure 5 A schematic diagram illustrating the application of sensors in an electronic device according to an embodiment of this application;

[0041] Figure 6This is a schematic diagram of the sensor data processing flow provided in the embodiments of this application;

[0042] Figure 7 A schematic diagram of power supply voltage fluctuations provided in the embodiments of this application. Figure 1 ;

[0043] Figure 8 This is a schematic diagram of the hardware structure of the terminal device provided in the embodiments of this application;

[0044] Figure 9 A schematic diagram of the sensor circuit provided in the embodiments of this application. Figure 1 ;

[0045] Figure 10 A schematic diagram of the sensor circuit provided in the embodiments of this application. Figure 2 ;

[0046] Figure 11 A schematic diagram of power supply voltage fluctuations provided in the embodiments of this application. Figure 2 ;

[0047] Figure 12 A schematic diagram of the sensor circuit provided in the embodiments of this application. Figure 3 ;

[0048] Figure 13 A schematic diagram of the sensor circuit provided in the embodiments of this application. Figure 4 ;

[0049] Figure 14 This is a schematic diagram illustrating the voltage variation with resistance value provided in an embodiment of this application.

[0050] Figure 15 A schematic diagram of the sensor circuit provided in the embodiments of this application. Figure 5 ;

[0051] Figure 16 A schematic diagram of the sensor circuit provided in the embodiments of this application. Figure 6 ;

[0052] Figure 17 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0053] To facilitate a clear description of the technical solutions in the embodiments of this application, some terms and technologies involved in the embodiments of this application will be briefly introduced below:

[0054] 1. Sensor

[0055] A sensor is a detection device that can sense the information being measured and transform the sensed information into an electrical signal or other required form of information output according to a certain rule, so as to meet the requirements of information transmission, processing, storage, display, recording and control.

[0056] Common sensors include pressure sensors, temperature sensors, accelerometers, gyroscopes, and magnetometers. Among these, the core component of some sensors is the Wheatstone bridge. For example, in a temperature sensor, the resistance of the thermistor changes with temperature, and this can be measured using a Wheatstone bridge.

[0057] 2. Wheatstone bridge

[0058] A Wheatstone bridge is a circuit used to measure changes in resistance. It is widely used in various sensors, such as temperature sensors and pressure sensors. A Wheatstone bridge consists of two parallel circuits, each with two resistors. The change in resistance is measured by the voltage output between the resistors on both sides of the bridge.

[0059] When the bridge circuit is in equilibrium, the voltages output on both sides of the bridge are equal. However, when the resistance of one or more resistors in the bridge changes, the voltages output on both sides of the bridge will also change accordingly. There is a quantitative relationship between the change in voltage across the bridge and the resistance value. Therefore, the change in resistance can be calculated using the change in voltage across the bridge, and thus the target physical quantity, such as temperature or pressure, can be measured.

[0060] 3. Single-arm / Full-bridge

[0061] Wheatstone bridges can be further categorized into different types based on the number and resistance values ​​of the variable resistors. For example, one type is called a single-arm Wheatstone bridge, which contains only one variable resistor. Another type is called a full-bridge Wheatstone bridge, where all four resistors are variable resistors. There are also other types of Wheatstone bridges, such as those with two variable resistors on the same side or two variable resistors diagonally, which will not be elaborated upon here.

[0062] 4. LDO

[0063] A low dropout regulator (LDO), also known as a low dropout linear regulator, is a commonly used power management chip widely applied in applications requiring high precision, low noise, and fast response. The primary function of an LDO is to maintain output voltage stability, even under conditions of input voltage fluctuations or load current variations.

[0064] The working principle of an LDO can be roughly understood as follows: an error amplifier in an LDO constantly detects the voltage of the power supply. By comparing the voltage of the feedback network with the reference voltage, the conduction level of the regulating transistor is controlled, thereby ensuring that the output voltage of the LDO is always maintained at the level of the reference voltage.

[0065] 5. Impedance

[0066] Impedance is a relatively broad concept, applicable not only to direct current (DC) circuits but also to alternating current (AC) circuits. Impedance includes not only resistance but also the opposition to current flow caused by capacitance and inductance. Impedance is a complex number, usually represented by Z, and its unit is ohms (Ω). In a DC circuit or a purely resistive circuit, impedance equals resistance. However, in an AC circuit with capacitance or inductance, the magnitude of impedance changes with the frequency of the AC current.

[0067] 6. Voltage Follower

[0068] A voltage follower is a common type of operational amplifier whose primary function is to transmit the input voltage to the output without attenuation. A voltage follower has a very high input impedance and draws almost no current from the signal source. This means that the voltage of the input signal source will not change significantly when connected to a voltage follower. Simultaneously, a voltage follower has a very low output impedance, allowing it to drive multiple loads without significantly affecting the output voltage. Voltage followers are very useful in signal buffering and impedance matching.

[0069] 7. Other terms

[0070] In the embodiments of this application, terms such as "first" and "second" are used to distinguish identical or similar items with substantially the same function and purpose. For example, "first chip" and "second chip" are used only to distinguish different chips and do not limit their order of execution. Those skilled in the art will understand that terms such as "first" and "second" do not limit the quantity or execution order, and that "first" and "second" do not necessarily imply that they are different.

[0071] It should be noted that, in the embodiments of this application, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design scheme described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0072] In this application embodiment, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, a--c, bc, or abc, where a, b, and c can be single or multiple.

[0073] 8. Electronic equipment

[0074] The electronic devices in this application embodiment may include handheld devices with camera functions, vehicle-mounted devices, etc. For example, some electronic devices are: mobile phones, tablet computers, PDAs, laptops, mobile internet devices (MIDs), wearable devices, virtual reality (VR) devices, augmented reality (AR) devices, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical surgery, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, personal digital assistants (PDAs), handheld devices with camera functions, computing devices, terminal devices in 5G networks, or terminal devices in future evolved public land mobile networks (PLMNs), etc., and this application embodiment is not limited to these.

[0075] Furthermore, in this embodiment of the application, the electronic device can also be a terminal device in the Internet of Things (IoT) system. IoT is an important part of the future development of information technology. Its main technical feature is to connect objects to the network through communication technology, thereby realizing an intelligent network of human-machine interconnection and object-to-object interconnection.

[0076] The electronic devices in the embodiments of this application may also be referred to as: terminal equipment, user equipment (UE), mobile station (MS), mobile terminal (MT), access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication equipment, user agent, or user device, etc.

[0077] In this embodiment, the electronic device or various network devices include a hardware layer, an operating system layer running on top of the hardware layer, and an application layer running on top of the operating system layer. The hardware layer includes hardware such as a central processing unit (CPU), a memory management unit (MMU), and memory (also called main memory). The operating system can be any one or more computer operating systems that implement business processing through processes, such as Linux, Unix, Android, iOS, or Windows. The application layer includes applications such as browsers, address books, word processing software, and instant messaging software.

[0078] Based on the above introduction, the relevant technologies involved in this application will be further described in detail below.

[0079] In today's digital age, sensor technology has become an indispensable part of our daily lives and work. From home automation systems to smartphones, from smart wearable devices to industrial production processes, the application of sensors is almost ubiquitous. They serve human society in different forms, greatly improving our quality of life and work efficiency.

[0080] In the field of smart homes, sensors play a particularly prominent role. For example, temperature and humidity sensors can monitor changes in the indoor environment in real time and automatically adjust the working status of air conditioners or humidifiers to ensure the comfort of the living space; smoke sensors can issue timely alarms in the early stages of a fire to protect the lives of family members; and door and window sensors can effectively improve the level of home security, immediately notifying users to take appropriate measures once abnormal opening is detected.

[0081] As one of the most commonly used electronic devices in modern life, mobile phones integrate a variety of sensors. Accelerometers and gyroscopes enable mobile phones to sense their own motion, providing users with a smoother gaming experience and accurate map navigation services; proximity sensors can turn off the screen when the user is answering a call to avoid accidental touches; light sensors adjust the screen brightness according to the ambient light intensity, protecting both the eyes and saving power; and fingerprint and facial recognition sensors provide mobile phones with efficient and convenient security verification methods.

[0082] Sensors also play a crucial role in industrial production. Various sensors installed on machines enable precise monitoring of parameters such as temperature, pressure, and flow rate on the production line, helping engineers to promptly identify and resolve potential problems, ensuring the stability of the production process and the quality of the products. Furthermore, wireless sensor network technology can be used to build remote monitoring systems, enabling unified management of geographically dispersed factories and reducing operating costs.

[0083] In conclusion, with technological advancements and social development, the application scope of sensors is becoming increasingly broad, and their importance is becoming ever more prominent. In the future, with the further development of IoT technology, more types of sensors will be invented and applied to more fields, bringing more convenience and surprises to people's lives.

[0084] Among numerous sensors, those based on the Wheatstone Bridge principle are widely used measurement tools, primarily used for accurately measuring changes in resistance, which are then converted into sensing changes in physical quantities such as displacement, pressure, and temperature. A Wheatstone Bridge consists of four resistors forming a closed loop. Two diagonals are connected to a power source, and a voltmeter or galvanometer is connected between the other two diagonals. When the four resistance values ​​are exactly equal, the bridge is in equilibrium, and the voltmeter displays zero voltage difference. If one or more resistors change, the bridge becomes unbalanced, producing a measurable voltage difference, which is proportional to the change in resistance. The resistors in a Wheatstone Bridge can be divided into two categories: standard resistors, which have a known and fixed resistance; and variable resistors, whose resistance changes with external conditions.

[0085] The following is combined with Figure 1 This section will provide a detailed explanation of the circuit structure of the Wheatstone bridge. For example... Figure 1As shown, terminals A and C of the Wheatstone bridge circuit correspond to the current input and output terminals, respectively. Terminal A is connected to the positive terminal of the power supply, and terminal C is connected to the negative terminal. The Wheatstone bridge circuit has two branches: one on the left (A→D→C) and the other on the right (A→B→C). The A→D→C branch contains two resistors, R1 and R2, while the A→B→C branch also contains two resistors, R3 and R4. x An ammeter or galvanometer can be connected between terminals B and D of the circuit to detect the current between them.

[0086] Initially, the Wheatstone bridge could be used to measure the resistance value. According to Ohm's law:

[0087] R = U / I (Formula 1)

[0088] Where U represents the voltage across the resistor being measured, I represents the current flowing through the resistor, and R represents the resistance value of the resistor. However, directly measuring the current flowing through a resistor may have relatively large errors in some cases. Therefore, other methods can be designed to measure the resistance value. The Wheatstone bridge can be used to measure the resistance value. Under certain conditions, the Wheatstone bridge can achieve a balanced state. Bridge balance specifically means that the resistance values ​​in the bridge satisfy a certain relationship, still based on... Figure 1 For example:

[0089] R1 / R2=R3 / R X Formula 2

[0090] When the resistance in the Wheatstone bridge satisfies Formula 2 above, the bridge can be said to be in a balanced state. In a balanced state, the current displayed on the ammeter between terminals B and D is 0.

[0091] Taking advantage of this characteristic, let's assume that... Figure 1 In the Wheatstone bridge, R1 and R3 are fixed resistors, R2 is a variable resistor, and R... x Let R be the resistor to be measured. x When the resistance of the resistor to be measured is unknown and the bridge balance is broken, the current in the ammeter between terminals B and D is not zero. At this point, by adjusting the variable resistor R2, the ammeter reading becomes zero, indicating that the bridge balance has been restored. Since the resistances of R1, R3, and R2 are known, the resistance of the resistor to be measured, R, can be determined using Formula 2, which applies when the bridge is balanced. x Solve the problem.

[0092] Besides measuring resistance through the bridge's balanced state, the Wheatstone bridge offers broader and more efficient functionality. When the voltage applied across the Wheatstone bridge remains constant, if the variable resistor changes its resistance due to external factors, the bridge's output voltage will also change accordingly. This change can be measured using a voltmeter connected between the two diagonal points. By calculating the relationship between the voltage change and the resistance change, the physical quantity causing the resistance change can be indirectly measured.

[0093] refer to Figure 2 The two Wheatstone bridges shown are used for sensor measurements. Figure 2 In (a), the current input terminal of the Wheatstone bridge is connected to the positive terminal of the power supply, and the current output terminal is connected to the ground or GND. The left branch includes two resistors, R1 and R2, which output a voltage signal V1. The right branch also includes two resistors, R3 and R4, which output a voltage signal V2. In the bridge, R1, R3, and R4 are fixed resistors, and R2 is a variable resistor. Because only one resistor in this type of Wheatstone bridge is variable, changing with the measured physical quantity, this type of Wheatstone bridge is also called a single-arm Wheatstone bridge or a quarter-bridge.

[0094] To facilitate understanding of the subsequent scheme, a brief explanation of the voltage differential signals output by the Wheatstone bridge is provided here. Ideally, voltage signals V1 and V2 can be expressed as follows:

[0095] U1=V×R2 / (R1+R2) Formula 3

[0096] U2=V×R4 / (R3+R4) Formula 4

[0097] Where U1 represents the voltage at terminal V1, U2 represents the voltage at terminal V2, and V represents the magnitude of the power supply voltage. Therefore, the differential voltage between terminals V1 and V2 can be calculated:

[0098]

[0099] For a single-arm Wheatstone bridge, the resistance values ​​are typically limited to facilitate practical measurements. Here, we assume that the resistance of R2 changes due to a change in the measured physical quantity, and that this change is ΔR. Then, Formula 5 becomes:

[0100]

[0101] Assume that the four resistors of the original single-arm Wheatstone bridge satisfy the following relationship:

[0102] Formula 7: R1 = R2 and R3 = R4

[0103] Formula 6 can then be simplified to the following form:

[0104]

[0105] At the same time, if the following conditions can be met:

[0106] R2 >> ΔR (Formula Nine)

[0107] Formula 8 can then be further simplified to:

[0108]

[0109] In this way, the differential voltage ΔU between V1 and V2 becomes linearly related to the magnitude of the variable resistor R2. The resistance value of the variable resistor can be easily calculated from the magnitude of the differential voltage, and thus the magnitude of the physical quantity to be measured can be obtained.

[0110] In practical applications, besides single-arm Wheatstone bridges, full-bridge Wheatstone bridges are also frequently used in sensor measurements. For example... Figure 2 As shown in (b), for a full-bridge Wheatstone bridge, all four resistors are variable resistors, and their values ​​change with the physical quantity being measured. Similarly, for a full-bridge Wheatstone bridge, its specific working principle is briefly explained here. The differential voltage signal output from its V1 and V2 terminals can be expressed as:

[0111]

[0112] Where ΔR1 represents the change in resistance R1, ΔR2 represents the change in resistance R2, ΔR3 represents the change in resistance R3, and ΔR4 represents the change in resistance R4. Similarly, if the resistance values ​​satisfy the following relationship:

[0113] Formula Twelve: R1 = R2 = R3 = R4 R1>>ΔR1, R2>>ΔR2, R3>>ΔR3, R4>>ΔR4 Formula Thirteen

[0114] Therefore, Formula 11 can be simplified to:

[0115]

[0116] In some scenarios, the changes in the four resistors of a full-bridge Wheatstone bridge can also satisfy the following relationship:

[0117] ΔR1=-ΔR2 ΔR3=-ΔR4 Formula Fifteen

[0118] The final formula can then be obtained as follows:

[0119]

[0120] Compared to a single-arm Wheatstone bridge, a full-bridge Wheatstone bridge has higher requirements for resistance changes. Comparing Equations 16 and 10, we can see that the differential voltages differ by a factor of 4. In other words, a full-bridge Wheatstone bridge has higher sensitivity than a single-arm Wheatstone bridge.

[0121] The Wheatstone bridge has various applications in sensors, including as a strain gauge. It's a very common sensor based on the Wheatstone bridge principle, used to measure the deformation or stress of an object. The strain gauge is attached to the object being measured; when the object deforms, the resistance of the strain gauge changes, causing a change in the bridge's output voltage. This method is commonly used in bridge and building structural health monitoring, as well as fatigue testing of mechanical components.

[0122] Some types of pressure sensors also utilize the Wheatstone bridge principle. These sensors contain one or more resistive elements whose resistance changes with pressure. When external pressure is applied to the sensor, the resistance of these elements changes, causing an imbalance in the bridge, thus allowing the pressure to be measured.

[0123] Some temperature sensors, such as thermistors, can also be configured to operate in the form of a Wheatstone bridge. The resistance of a thermistor changes significantly with temperature, so the temperature change can be determined by measuring the output voltage of the bridge.

[0124] Sensors based on the Wheatstone bridge are widely used in scientific research, engineering, and daily life due to their high precision and stability. Through ingenious design and precise calibration, these sensors can provide accurate and reliable measurement results, making them an indispensable component of modern measurement technology.

[0125] Understandably, many factors can negatively impact sensor measurement accuracy during actual measurements. One crucial factor is the stability of the power supply voltage. For instance, the load on a power supply is not fixed; as connected devices increase or decrease, or as the operating state of the devices changes, the load current fluctuates. If the power supply cannot adapt to these changes promptly, it can lead to unstable output voltage. Furthermore, ambient temperature conditions can affect the normal operation of internal electronic components in the power supply, thus impacting its stability.

[0126] If the power supply voltage is unstable, then even for the same change in the measured physical quantity, the differential voltage output of the Wheatstone bridge will change, which will significantly reduce the measurement accuracy of the sensor. To improve the stability of the power supply voltage, one approach is to use a linear regulator (LDO). The following section will discuss this further. Figure 3 Let me give a brief explanation of LDO.

[0127] like Figure 3 As shown, the basic structure of an LDO includes a regulating transistor, an error amplifier, a reference voltage source, and a feedback network. The regulating transistor is connected to the input voltage and the output voltage, respectively. Its control terminal is connected to the output of the error amplifier. The reference voltage source is connected to the non-inverting input of the error amplifier. The feedback network is connected to the output voltage and the inverting input of the error amplifier, respectively.

[0128] When an LDO is operating, the error amplifier compares the reference voltage with the feedback voltage sampled from the output and adjusts the conduction level of the regulating transistor based on this difference, thereby controlling the output voltage to remain constant. Since the regulating transistor typically operates in the linear region, an LDO is a type of linear regulator.

[0129] However, the aforementioned sensor circuit implementation methods have some shortcomings or problems. To better illustrate this issue, we will first explain it in the context of some practical scenarios.

[0130] Sensors are now used in all aspects of life and work. Some sensors can be used independently, while others operate as part of terminal devices. For example... Figure 4 As shown, the smartphone 401 allows users to view various relevant physical parameters of their current environment in the environmental parameters interface. These parameters include the current location as District B, City A, temperature of 23°C, humidity of 56%, air pressure of 1022 hPa, and a 10% probability of rainfall. Parameters such as temperature, humidity, and air pressure can be measured by sensors based on a Wheatstone bridge. Accurate measurement parameters help users understand their current environmental conditions and make appropriate decisions. For example, if the ambient temperature is low, appropriate measures to keep warm should be taken.

[0131] In addition, you can refer to Figure 5 The content shown is in Figure 5In (a), a fitness tracker is shown, which can also be manufactured based on a Wheatstone bridge. The tracker displays the wearer's current heart rate, such as 85 beats per minute. Users can adjust the intensity of their exercise based on the heart rate displayed on the tracker. For example, users with weak cardiopulmonary function who cannot tolerate high-intensity exercise can reduce the intensity when their heart rate exceeds a certain threshold to avoid accidents. Figure 5 In (b), there is a weighing scale, which can still be manufactured based on the Wheatstone bridge. Users can stand on the scale to check their weight, or place items on it to see their weight. For some users who are concerned about their weight, such as those who want to lose weight or maintain a certain weight level, it is important for them to know their current weight accurately.

[0132] The data measured by sensors is generally not the final data displayed to the user, but rather requires a series of processing steps. For example... Figure 6 As shown, the process of sensor data from measurement to final display involves several key processing steps, each with its specific function and role. Here is a brief description of these steps: 1. Sensor measurement, for example, outputting differential voltage signals through the two measuring terminals of a Wheatstone bridge; 2. Signal conditioning: The raw signal output by the sensor is often weak, so signal conditioning is needed to enhance signal quality, including signal amplification and filtering; 3. Analog-to-digital conversion (ADC): The conditioned analog signal needs to be converted into a digital signal for subsequent digital processing. The ADC converts continuously changing analog signals into discrete digital values; 4. Digital processing: The converted digital signal can be further processed by a microprocessor or application-specific integrated circuit (ASIC), including data filtering, correction, and calculation; 5. Display or transmission: The processed data can be presented to the user in various ways, such as directly displaying values ​​on an LED screen or providing a more intuitive data display through a graphical interface. Furthermore, the data can also be transmitted to remote locations via wired or wireless communication technologies for monitoring, recording, or further analysis.

[0133] Throughout the process, ensuring data accuracy and reliability is crucial, while also considering system efficiency and cost-effectiveness. With technological advancements, sensor technology and data processing methods are constantly evolving, providing more precise and efficient solutions for various application scenarios. In this series of processing steps, the accuracy of the data obtained from sensor measurements is paramount, as subsequent processing steps may introduce further errors. If the sensor data itself contains significant errors, these errors may be amplified after further processing, ultimately leading to data distortion.

[0134] The scenarios described above demonstrate the widespread application of Wheatstone bridge-based sensors in our lives and work, with some applications requiring high sensor accuracy. However, when considering the impact of power supply voltage stability on the measurement accuracy of the Wheatstone bridge, only the positive voltage of the power supply (i.e., the stability of the power supply terminal) is typically taken into account, while the negative voltage, or the stability of the grounding terminal, is not considered.

[0135] For the power supply grounding terminal, several factors can cause noise fluctuations. Here are some common causes: 1. Electromagnetic interference: External electromagnetic fields can induce noise on the ground wire, generating unnecessary current, which manifests as noise in the circuit. 2. Internal interference from electronic equipment: High-frequency noise generated by internal components can be conducted to the ground wire if there is no proper filtering. 3. Improper grounding system design: An unreasonable grounding design, such as using different grounding reference points or failing to establish effective equipotential bonding, can increase noise on the ground wire. 4. Wireless communication modules: The noise from Wi-Fi, Bluetooth, and GPRS modules in mobile phones can cause noise fluctuations. 5. NFC and cellular network communication modules transmit and receive radio frequency signals during operation. If these high-frequency signals are not properly shielded and filtered, they may couple to the ground wire, creating noise. 6. Display screen and touch screen: The liquid crystal display (LCD) or organic light-emitting diode (OLED) screen and its driving circuit used in modern smartphones also generate electromagnetic interference during operation, especially when the screen refresh rate is high. 7. Software operation: Running complex applications or background processes and frequently switching CPU states may cause a surge in transient current. This current change can also cause noise on the ground wire. 8. Physical damage: If the phone is dropped or impacted, it may cause internal connections to become loose, including poor ground wire contact, thus generating noise.

[0136] like Figure 7As shown, the horizontal axis of the coordinate system represents time, and the vertical axis represents voltage. In a sensor circuit, assuming that an existing linear regulator is used to regulate the voltage at the power supply terminal, the voltage curve 701 at the power supply terminal will appear stable over time, tending to be a horizontal straight line. However, for the voltage curve 702 at the power supply ground terminal, noise fluctuations may still exist, with random and brief positive or negative voltages appearing near 0V.

[0137] If we take into account the noise fluctuations at the power supply ground terminal, and then look at the differential voltage signal output by the Wheatstone bridge, it can be represented as follows:

[0138] U1=(V+V′)×R2 / (R1+R2) Formula Seventeen

[0139] U2=(V+V′)×R4 / (R3+R4) Formula 18

[0140]

[0141] Where V′ represents the noise fluctuation voltage at the ground terminal. The noise fluctuation at the power supply's ground terminal is generally small, but if left unattended, in some cases, such as Equation 19, it can directly affect the differential voltage output by the Wheatstone bridge.

[0142] Based on this, the embodiments of this application propose the following technical concept: In the original sensor circuit, which includes the power supply circuit and the Wheatstone bridge circuit, a filter circuit is added specifically to filter noise fluctuations from the power supply's ground terminal. Unlike the voltage stabilization method of the power supply's output terminal, the default voltage of the power supply's ground terminal is 0V, and the noise fluctuations are generally small. When designing the filter circuit, it is desirable to reduce or block noise without affecting the normal operation of the original circuit. Therefore, a small resistor can be used as the filter circuit, placed between the output terminal of the Wheatstone bridge circuit and the ground terminal of the power supply circuit. In this way, the noise fluctuation signal from the power supply circuit's ground terminal attenuates after being impeded by the small resistor, and is therefore not transmitted to the Wheatstone bridge circuit. This prevents it from affecting the differential signal output by the Wheatstone bridge circuit, allowing the sensor circuit to be more accurate and meeting scenarios requiring higher measurement accuracy.

[0143] The technical solution provided in this application can be applied to terminal devices. The terminal devices will be briefly introduced below.

[0144] For example, Figure 8 A schematic diagram of the hardware structure of a terminal device provided in an embodiment of this application is shown.

[0145] Figure 8This is a schematic diagram of the terminal device provided in an embodiment of this application. The terminal device may include a processor 110, an external memory interface 120, an internal memory 121, a universal serial bus (USB) interface 130, a charging management module 140, a power management module 141, a battery 142, antenna 1, antenna 2, a mobile communication module 150, a wireless communication module 160, an audio module 170, a speaker 170A, a receiver 170B, a microphone 170C, a headphone jack 170D, a sensor module 180, buttons 190, a motor 191, an indicator 192, a camera 193, a display screen 194, and a subscriber identification module (SIM) card interface 195, etc. The sensor module 180 may include pressure sensors, gyroscope sensors, barometric pressure sensors, magnetic sensors, accelerometers, distance sensors, proximity sensors, fingerprint sensors, temperature sensors, touch sensors, ambient light sensors, bone conduction sensors, etc.

[0146] It is understood that the structures illustrated in the embodiments of this application do not constitute a specific limitation on the terminal device. In other embodiments of this application, the terminal device may include more or fewer components than illustrated, or combine some components, or split some components, or have different component arrangements. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0147] Processor 110 may include one or more processing units, such as application processors (APs), modem processors, graphics processing units (GPUs), image signal processors (ISPs), controllers, video codecs, digital signal processors (DSPs), baseband processors, and / or neural network processing units (NPUs). These different processing units may be independent devices or integrated into one or more processors.

[0148] The processor 110 can control the various sensors in the sensor module 180 to perform related functions, including measurement, conversion, and calculation.

[0149] The power management module 141 connects the battery 142, the charging management module 140, and the processor 110. The power management module 141 receives input from the battery 142 and / or the charging management module 140, providing power to the processor 110, internal memory 121, display screen 194, camera 193, and wireless communication module 160, etc. The power management module 141 can also monitor parameters such as battery capacity, battery cycle count, and battery health status (leakage current, impedance). In some other embodiments, the power management module 141 may also be located within the processor 110. In other embodiments, the power management module 141 and the charging management module 140 may be located in the same device.

[0150] It is understood that the interface connection relationships between the modules illustrated in the embodiments of this application are illustrative and do not constitute a structural limitation on the terminal device. In other embodiments of this application, the terminal device may also adopt different interface connection methods or a combination of multiple interface connection methods as described in the above embodiments.

[0151] The battery 142 includes a power supply terminal and a ground terminal. Instability in the voltage of the battery 142 itself may lead to instability in the voltage of the power supply terminal. The power management module 141 may include a voltage regulator to regulate the voltage of the power supply terminal of the battery 142, so that it outputs a stable voltage for use by other power-consuming modules.

[0152] Display screen 194 is used to display images, videos, etc. Display screen 194 includes a display panel. The display panel may be a liquid crystal display (LCD), an organic light-emitting diode (OLED), an active-matrix organic light-emitting diode (AMOLED), a flexible light-emitting diode (FLED), a miniature LED, a microLED, a quantum dot light-emitting diode (QLED), etc. In some embodiments, the terminal device may include one or N displays 194, where N is a positive integer greater than 1.

[0153] Data measured by sensors and processed by the processor, such as temperature and pressure, can be displayed to the user on the screen 194.

[0154] The sensor module 180 of the terminal device may include a variety of sensors, some of which can be implemented based on the Wheatstone bridge. Examples are given below.

[0155] For example, a pressure sensor is used to sense pressure signals and can convert the pressure signals into electrical signals. In some embodiments, the pressure sensor may be disposed on the display screen 194. When a touch operation is applied to the display screen 194, the terminal device detects the intensity of the touch operation based on the pressure sensor.

[0156] For example, a barometric pressure sensor is used to measure air pressure. In some embodiments, the terminal device calculates altitude using the air pressure value measured by the barometric pressure sensor to assist in positioning and navigation.

[0157] For example, a temperature sensor is used to detect temperature. In some embodiments, the terminal device uses the temperature detected by the temperature sensor to execute a temperature processing strategy. For instance, when the temperature reported by the temperature sensor exceeds a threshold, the terminal device reduces the performance of a processor located near the temperature sensor to reduce power consumption and implement thermal protection.

[0158] The software system of a terminal device can adopt a layered architecture, event-driven architecture, microkernel architecture, microservice architecture, or cloud architecture, etc. This application uses the layered architecture Android system as an example to illustrate the software structure of the terminal device.

[0159] First, combine Figures 9 to 11 A sensor circuit provided in an embodiment of this application will be described. Wherein, Figure 9 A schematic diagram of the sensor circuit provided in the embodiments of this application. Figure 1 , Figure 10 A schematic diagram of the sensor circuit provided in the embodiments of this application. Figure 2 , Figure 11 A schematic diagram of power supply voltage fluctuations provided in the embodiments of this application. Figure 2 .

[0160] refer to Figure 9 The sensor circuit structure shown includes three parts: a power supply circuit, a signal processing circuit, and a filtering circuit. The power supply terminal of the power supply circuit is connected to the input terminal of the signal processing circuit, and the filtering circuit is connected to both the output terminal of the signal processing circuit and the ground terminal of the power supply circuit. The function of each part of the sensor circuit will be explained below:

[0161] 1. Power supply circuit

[0162] This includes the power supply terminal and the ground terminal, which also correspond to the positive and negative terminals of the power supply. The power supply terminal can be understood as having undergone voltage regulation to continuously provide a stable voltage to the signal processing circuit, enabling the signal processing circuit to operate stably for a long period of time.

[0163] 2. Signal processing circuit

[0164] The signal processing circuit is a crucial part of the sensor circuit. It receives electrical energy from the power supply circuit and outputs a voltage differential signal to the outside world through its first and second measuring terminals. Other external electronic devices can then use the voltage differential signal from the signal processing circuit to process and calculate the measured physical parameters.

[0165] 3. Filtering circuit

[0166] The filtering circuit is connected between the ground terminal of the power supply circuit and the output terminal of the signal processing circuit, respectively, to block and isolate noise fluctuation signals from the ground terminal of the power supply circuit, and reduce or eliminate the influence of noise fluctuation signals from the ground terminal of the power supply circuit on the signal processing circuit.

[0167] The three parts described above together constitute the sensor circuit of this application embodiment. The power supply circuit continuously provides voltage to the input terminal of the signal processing circuit to ensure its normal operation. The filter circuit is connected to the output terminal of the signal processing circuit and blocks noise fluctuations from its other end, the ground terminal, from being transmitted to the signal processing circuit. In this way, the voltages at both the input and output terminals of the signal processing circuit can remain stable and noise-free, resulting in a more ideal voltage difference. Based on this voltage difference, the differential signal output can be more accurate.

[0168] Corresponding to Figure 9 The sensor circuit structure in the text is described below in conjunction with... Figure 10 This section introduces a specific sensor circuit structure. For example... Figure 10 As shown, the positive terminal or power supply terminal of the power supply circuit corresponds to the voltage Vdd above the circuit, and the negative terminal or ground terminal of the power supply circuit corresponds to GND below the circuit.

[0169] Directly connected to the power supply is a Wheatstone bridge circuit, corresponding to the signal processing circuit described above. It includes two branch circuits, each containing two resistors, for a total of four resistors: R1, R2, R3, and R4. Here, it is assumed that all four resistors in the Wheatstone circuit are variable resistors; that is, this Wheatstone bridge circuit is a full-bridge Wheatstone bridge circuit. There are two measurement terminals on each side of the Wheatstone bridge circuit. The first measurement terminal V1 is located between R1 and R2 on the left side, and the first measurement terminal V2 is located between R3 and R4 on the right side.

[0170] There is a resistor R5 between the full-bridge Wheatstone bridge and the ground terminal GND of the power supply circuit, which corresponds to the filtering circuit. Due to the presence of resistor R5, noise fluctuations from the ground terminal GND are not directly transmitted to the Wheatstone bridge, but are eliminated or significantly reduced by the resistance of resistor R5.

[0171] Considering that noise fluctuations from the power supply circuit's ground terminal GND are generally small, the resistance value of resistor R5 can be set as small as possible. A threshold value can be preset for resistor R5 by combining this with the resistance values ​​in the Wheatstone bridge circuit, allowing the selectable range of resistor R5's value to be less than or equal to this threshold.

[0172] For example, assuming the resistance in the Wheatstone bridge circuit is around several hundred ohms, then resistor R5 can be set to a value one order of magnitude smaller than the resistance in the Wheatstone bridge circuit, such as around tens of ohms. In this way, resistor R5 can filter noise fluctuations at the power supply ground terminal GND without affecting the voltage difference between the input and output terminals of the Wheatstone bridge. That is, in this case, the voltage difference between the input and output terminals of the Wheatstone bridge can still be considered equal to the voltage difference Vdd between the power supply terminal and the ground terminal; this voltage difference can also be called the first voltage difference.

[0173] Adding a filter circuit to the sensor circuit prevents noise fluctuations at the ground terminal of the power supply circuit from directly affecting the signal processing circuit. For example... Figure 11 As shown, the horizontal axis of the coordinate system represents time, and the vertical axis represents voltage magnitude. The curves on the coordinate system represent the magnitude of voltage change over time. Curve 1101 at the top represents the voltage at the power supply terminal of the power circuit, which is assumed to have been regulated and is relatively stable. Curve 1102 at the bottom, coinciding with the horizontal axis, represents the voltage magnitude at the output terminal of the signal processing circuit. With the filtering circuit in place, it can be seen that compared to without the filtering circuit... Figure 7 , Figure 11 The voltage curve in the middle tends to be a smooth horizontal straight line, without obvious noise fluctuation signals.

[0174] After adding the filtering circuit, the differential voltage signal output by the entire sensor circuit can be expressed as:

[0175]

[0176] Since the filtering circuit blocks noise from the ground terminal of the power supply circuit on the one hand, and does not affect the voltage at the output terminal of the signal processing circuit on the other hand, the formula for the output differential voltage signal at this time is consistent with the ideal formula five mentioned above.

[0177] Based on the above description, the sensor circuit will be further summarized below. The sensor circuit proposed in this embodiment adds an additional filtering circuit to the traditional sensor circuit structure. This filtering circuit is positioned between the output terminal of the signal processing circuit and the ground terminal of the power supply circuit to isolate noise fluctuations from the ground terminal of the power supply circuit, ensuring that noise fluctuations at the ground terminal do not directly affect the signal processing circuit. Furthermore, the resistance value in the filtering circuit is set to be relatively small, so that in the sensor circuit, the voltage difference between the input and output terminals of the signal processing circuit can still be considered as the voltage difference between the power supply terminal and the ground terminal of the power supply circuit. This embodiment achieves further improvement in the measurement accuracy of the signal processing circuit through a relatively simple filtering circuit, enabling such a sensor to operate normally in environments with significant noise interference and meeting the requirements for higher measurement accuracy.

[0178] Based on the above embodiments, the following will combine... Figure 12 and Figure 14 Another sensor circuit provided in the embodiments of this application will be described in detail. Among them, Figure 12 A schematic diagram of the sensor circuit provided in the embodiments of this application. Figure 3 , Figure 13 A schematic diagram of the sensor circuit provided in the embodiments of this application. Figure 4 , Figure 14 This is a schematic diagram illustrating the voltage variation with resistance value provided in an embodiment of this application.

[0179] refer to Figure 12 The sensor circuit structure shown includes four parts: a power supply circuit, a signal processing circuit, a filtering circuit, and a voltage divider unit. The power supply terminal of the power supply circuit is connected to the input terminal of the signal processing circuit. The filtering circuit is connected to both the output terminal of the signal processing circuit and the ground terminal of the power supply circuit. The voltage divider unit can be considered as being connected in parallel with the signal processing circuit. Its two ends are connected to the power supply terminal of the power supply circuit and the first terminal of the filtering circuit, which is also the terminal connected to the output terminal of the signal processing circuit.

[0180] The function of each part in the sensor circuit will be explained below:

[0181] 1. Power supply circuit

[0182] Please refer to the previous text. Figure 9 The relevant descriptions of the power supply circuit are not repeated here.

[0183] 2. Signal processing circuit

[0184] In this embodiment, the input terminal of the signal processing circuit is still connected to the power supply terminal of the power supply circuit, and the output terminal is connected to both the first terminal of the filtering circuit and one terminal of the voltage divider unit. In other words, the signal processing circuit and the voltage divider unit are connected in parallel, and the voltage at the output terminal of the signal processing circuit will be affected by the voltage divider unit.

[0185] For further explanation, please refer to the previous text. Figure 9 The relevant content of the signal processing circuit in the document will not be elaborated here.

[0186] 3. Filtering circuit

[0187] Please refer to the previous text. Figure 9 The relevant explanations of the filtering circuit are not repeated here.

[0188] 4. Voltage divider unit

[0189] In this embodiment, one end of the voltage divider unit is connected to the power supply terminal of the power supply circuit, and the other end is connected to the first terminal of the filter circuit, forming a parallel connection with the signal processing circuit. Through the voltage divider unit, the voltage at the output terminal of the signal processing circuit can be controlled and adjusted to synchronize with the voltage at the power supply terminal of the power supply circuit. That is, a portion of the voltage signal from the power supply terminal can be transmitted to the output terminal of the signal processing circuit using the voltage divider unit. Since the voltage at the power supply terminal is stable, the voltage at the output terminal of the signal processing circuit is also stable. Alternatively, assuming that the voltage at the power supply terminal may still fluctuate, after transmission through the voltage divider unit, the voltage fluctuation at the output terminal of the signal processing circuit can be consistent with the fluctuation at the power supply terminal. Thus, the voltage difference between the input and output terminals of the signal processing circuit remains constant, which is beneficial for improving the measurement accuracy of the sensor circuit.

[0190] The above four parts together constitute the sensor circuit of this application embodiment. The power supply circuit continuously provides voltage to the input terminal of the signal processing circuit for its normal operation. The filter circuit is connected to the output terminal of the signal processing circuit and blocks noise fluctuations from its other end, the ground terminal, from being transmitted to the signal processing circuit. It is also connected to the voltage divider unit. By connecting the voltage divider unit in parallel with the signal processing circuit and then in series with the filter circuit, the voltage at the output terminal of the signal processing circuit can be controlled, synchronizing the voltage at the output terminal with the voltage at the power supply terminal of the power supply circuit, thereby further reducing the impact of noise fluctuations from the ground terminal. Based on the functions of the other parts, the voltage at the output terminal of the signal processing circuit can be controlled and regulated, and noise fluctuations are avoided. The differential signal output can accurately reflect the change in resistance value, resulting in better measurement accuracy.

[0191] Corresponding to Figure 12The sensor circuit structure in the text is described below in conjunction with... Figure 13 This section introduces a specific sensor circuit structure. (In the preceding text...) Figure 10 Based on the sensor circuit shown, Figure 13 In the corresponding sensor circuit, a resistor R6 is connected between the power supply terminal Vdd and the resistor R5, which serves as the filter circuit. Resistor R6 is connected in parallel with a Wheatstone bridge, and then in series with resistor R5. The voltage difference between the input and output terminals of the Wheatstone bridge is the difference between the power supply terminal voltage Vdd and the voltage at the connection point of resistors R5 and R6; this can also be called the second voltage difference. The Wheatstone bridge corresponds to a specific form of the aforementioned signal processing circuit, and resistor R6 corresponds to a specific form of the aforementioned voltage divider unit.

[0192] To further illustrate the function of the pressure divider unit in controlling the pressure difference, the following explanation is based on the formula:

[0193]

[0194]

[0195] Where R0 represents the overall equivalent resistance of the Wheatstone bridge, and R7 represents the equivalent resistance of the Wheatstone bridge connected in parallel with resistor R6, which serves as a voltage divider unit. This indicates the voltage at the output of the Wheatstone bridge. The voltage ΔU represents the input voltage of the Wheatstone bridge. 电桥 This represents the voltage difference between the input and output terminals of the Wheatstone bridge. As can be seen from Equation 22, assuming other resistor values ​​are fixed, the output voltage of the Wheatstone bridge can be adjusted by changing the resistor R6, which serves as the voltage divider unit.

[0196] like Figure 14 As shown, the horizontal axis of the coordinate system represents the resistance value, and the vertical axis represents the voltage value. The curve in the graph corresponds to Formula 23 above. The value on the horizontal axis corresponds to R6 in Formula 23, and the value on the vertical axis corresponds to ΔU in Formula 23. 电桥 As can be seen, the voltage difference between the input and output terminals of the Wheatstone bridge is proportional to the resistance R6.

[0197] Furthermore, it's understandable that the resistance value of R6 should be as large as possible. A second threshold value can be preset based on the actual sensor circuit, and the resistance value of R6 can be set to be greater than or equal to this second threshold value. For example, assuming the resistance value of R5 is in the range of a few ohms or tens of ohms, and the equivalent resistance of the Wheatstone bridge is in the range of hundreds of ohms, then the resistance of R6, which serves as a voltage divider unit, can be set to several thousand ohms or higher. This allows the Wheatstone bridge to have a larger second voltage difference and also reduces the current passing through resistor R6, ensuring that the voltage difference change caused by the internal resistance change of the Wheatstone bridge connected in parallel is very small during measurement, and will not affect the normal operation of the Wheatstone bridge. In addition, a larger resistance R6 can also reduce power consumption and enhance battery life.

[0198] In summary, the sensor circuit proposed in this application includes an additional voltage divider unit. This voltage divider unit is connected in parallel with the signal processing circuit and then in series with the filtering circuit. The voltage divider unit correlates the voltage at the output of the signal processing circuit with the voltage at the power supply terminal, thereby stabilizing the output voltage of the signal processing circuit. Furthermore, the voltage divider unit can control the output voltage of the signal processing circuit to adjust the magnitude of the second voltage difference. The resistor used to construct the voltage divider unit can be set relatively large, ensuring a sufficiently large voltage difference between the input and output terminals of the signal processing circuit while reducing power consumption, thus enabling the sensor circuit to operate stably for extended periods.

[0199] Based on the above embodiments, the following will further combine... Figure 15 and Figure 16 Another sensor circuit provided in the embodiments of this application will be described in detail. Among them, Figure 15 A schematic diagram of the sensor circuit provided in the embodiments of this application. Figure 5 , Figure 16 A schematic diagram of the sensor circuit provided in the embodiments of this application. Figure 6 .

[0200] refer to Figure 15 The sensor circuit structure shown includes five parts: a power supply circuit, a signal processing circuit, a filtering circuit, a voltage divider unit, and a voltage stabilization unit. The power supply terminal of the power supply circuit is connected to the input terminal of the signal processing circuit. The filtering circuit is connected to the second terminal of the voltage stabilization unit and the ground terminal of the power supply circuit. The voltage divider unit can be considered as being connected in parallel with the signal processing circuit, with its two ends connected to the power supply terminal of the power supply circuit and the first terminal of the filtering circuit, respectively. The first terminal of the voltage stabilization unit is connected to the output terminal of the signal processing circuit, and the second terminal of the voltage stabilization unit is connected to both the voltage divider unit and the first terminal of the filtering circuit.

[0201] The function of each part in the sensor circuit will be explained below:

[0202] 1. Power supply circuit

[0203] Please refer to the previous text. Figure 9 The relevant descriptions of the power supply circuit are not repeated here.

[0204] 2. Signal processing circuit

[0205] In this embodiment, the input terminal of the signal processing circuit is still connected to the power supply terminal of the power supply circuit, and the output terminal is connected to the first terminal of the voltage stabilization unit.

[0206] For further explanation, please refer to the previous text. Figure 9 The relevant content of the signal processing circuit in the document will not be elaborated here.

[0207] 3. Filtering circuit

[0208] Please refer to the previous text. Figure 9 The relevant explanations of the filtering circuit are not repeated here.

[0209] 4. Voltage divider unit

[0210] Please refer to the previous text. Figure 12 The relevant descriptions of the voltage divider unit are not repeated here.

[0211] 5. Voltage stabilization unit

[0212] In this embodiment, the voltage stabilization unit is connected in series with the signal processing circuit. The first terminal of the voltage stabilization unit can also be understood as its output terminal, and its function is to maintain the voltage at its first terminal at a fixed value. In the sensor circuit, when the resistance value of the signal processing circuit changes during the measurement process, the presence of the voltage stabilization unit ensures that the voltage at the output terminal of the signal processing circuit remains constant, thus keeping the voltage difference between the input and output terminals of the signal processing circuit constant. Therefore, when calculating and processing the voltage difference signal obtained from the first and second measurement terminals of the signal processing circuit, the deviation caused by the voltage difference change during the measurement process can be disregarded, further improving the accuracy of the sensor circuit.

[0213] The above five parts together constitute the sensor circuit of this application embodiment. The power supply circuit continuously provides voltage to the input of the signal processing circuit. The output of the voltage stabilization unit is connected to the output of the signal processing circuit, ensuring that the voltage at the output of the signal processing circuit is stabilized at the voltage at the input of the voltage stabilization unit. The signal processing circuit is connected in series with a voltage follower, then in parallel with a voltage divider unit, and finally in series with a filtering circuit. Thus, the voltage at the input of the voltage stabilization unit is the voltage between the voltage divider unit and the filtering circuit. Because the voltage stabilization unit can stabilize the voltage at the output of the signal processing unit at a fixed value, the voltage difference between the input and output of the signal processing unit remains constant. Therefore, the differential signal output by the signal processing unit can directly represent the change in resistance value in the signal processing circuit, which can further improve the accuracy of the sensor circuit and simplify the subsequent data processing flow.

[0214] Corresponding to Figure 15 The sensor circuit structure in the text is described below in conjunction with... Figure 16 This section introduces a specific sensor circuit structure. (In the preceding text...) Figure 13 Based on the sensor circuit shown, Figure 16 In the corresponding sensor circuit, a voltage follower is also installed directly between the output terminal of the Wheatstone bridge and resistors R5 and R6. The Wheatstone bridge corresponds to the signal processing circuit mentioned above, resistor R5 corresponds to the filtering circuit, resistor R6 corresponds to the voltage divider unit, and the voltage follower serves as the voltage stabilization unit in the sensor circuit. The output terminal of the voltage follower is connected to the output terminal of the Wheatstone bridge. Simultaneously, the voltage follower collects the voltage signal from the output terminal of the Wheatstone bridge and connects it to its own inverting input terminal. The non-inverting input terminal of the voltage follower is connected between resistors R5 and R6. At this point, the voltage difference between the input and output terminals of the signal processing circuit corresponds to the difference between the voltage at the power supply terminal and the voltage at the output terminal of the voltage follower, which can also be referred to as the third voltage difference.

[0215] Understandably, a voltage follower, as an operational amplifier (Op-Amp), inherently possesses high input impedance and low output impedance. The high input impedance characteristic means that the voltage follower draws very little current from the signal source, ensuring that the signal source is not significantly affected by its connection. In other words, the voltage supplied by the signal source appears almost entirely at the input of the operational amplifier, which is crucial for maintaining signal integrity. Here, the signal source can be understood as the voltage signal between resistors R5 and R6. Simultaneously, the low output impedance means that it can efficiently deliver voltage to the load without causing a voltage drop. Even with load changes, the device can maintain a relatively stable output voltage; here, the load can be understood as a Wheatstone bridge.

[0216] To summarize the above explanation: In this embodiment, a voltage stabilization unit is incorporated, which stabilizes the third voltage difference. This avoids changes in the voltage difference across the Wheatstone bridge caused by variations in the resistance during actual measurement, allowing the bridge to maintain a stable voltage difference. The resulting voltage differential signal, based on this stable voltage difference, more accurately and directly represents the change in the measured physical quantity. This is beneficial for reducing measurement errors and optimizing the measurement data processing flow.

[0217] It should be noted that the module names involved in the embodiments of this application can all be defined as other names, as long as they can achieve the function of each module, and no specific restrictions are placed on the module names.

[0218] The sensor circuit of the embodiments of this application has been described above. The following describes an apparatus including the above-described sensor circuit. Those skilled in the art will understand that circuits and apparatuses can be combined and referenced together, and related apparatuses can control the above-described circuits or process the data information output by the above-described circuits.

[0219] In one implementation, this application provides an electronic device. Figure 17 This is a schematic diagram of the hardware structure of an electronic device.

[0220] like Figure 17 As shown, the electronic device 170 includes: a processor 1701 and a memory 1702; the memory 1702 stores computer execution instructions; the processor 1701 executes the computer execution instructions stored in the memory 1702, causing the electronic device 170 to control the aforementioned circuit.

[0221] When the memory 1702 is set up independently, the electronic device also includes a bus 1703 for connecting the memory 1702 and the processor 1701.

[0222] This application provides a chip. The chip includes a processor, which is used to call a computer program in memory to execute the technical solutions in the above embodiments. Its implementation principle and technical effects are similar to those in the related embodiments described above, and will not be repeated here.

[0223] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made on the basis of the technical solution of the present invention should be included within the scope of protection of the present invention.

Claims

1. A sensor circuit, characterized in that, include: Power supply circuit, signal processing circuit, and filtering circuit; The input terminal of the signal processing circuit is connected to the power supply terminal of the power supply circuit, and the output terminal of the signal processing circuit is connected to the ground terminal of the power supply circuit through the filtering circuit. The filtering circuit is used to filter noise signals. The first measuring terminal of the signal processing circuit is used to provide a first voltage, the second measuring terminal of the signal processing circuit is used to measure a second voltage, and the sensor circuit is used to output a differential signal based on the first voltage and the second voltage.

2. The circuit according to claim 1, characterized in that, The signal processing circuit includes a first bridge circuit, which includes a first branch circuit and a second branch circuit connected in parallel. The first branch circuit includes a first resistor and a second resistor connected in series, and the second branch circuit includes a third resistor and a fourth resistor connected in series. The two intersection points of the first branch circuit and the second branch circuit correspond to the input terminal and the output terminal of the first bridge, respectively. The port between the first resistor and the second resistor is the first measurement terminal, and the port between the third resistor and the fourth resistor is the second measurement terminal. The filtering circuit includes a fifth resistor.

3. The circuit according to claim 1 or 2, characterized in that, The first voltage is the voltage division of the second resistor on the first branch circuit with respect to the first voltage difference, and the second voltage is the voltage division of the fourth resistor on the second branch circuit with respect to the first voltage difference; Wherein, the first voltage difference is the voltage difference between the power supply terminal voltage and the ground terminal voltage of the power supply circuit.

4. The circuit according to claim 3, characterized in that, The resistance value of the fifth resistor is less than or equal to the first threshold.

5. The circuit according to claim 2, characterized in that, The circuit also includes a voltage divider unit, one end of which is connected to the power supply terminal of the power supply circuit, and the other end of which is connected to the ground terminal of the power supply circuit through the filter circuit.

6. The circuit according to claim 5, characterized in that, The voltage divider unit includes a sixth resistor, the resistance of which is greater than or equal to a second threshold.

7. The circuit according to claim 5 or 6, characterized in that, The first voltage is the voltage division of the second resistor on the first branch circuit with respect to the second voltage difference, and the second voltage is the voltage division of the fourth resistor on the second branch circuit with respect to the second voltage difference; Wherein, the second voltage difference is the voltage difference between the power supply terminal voltage of the power supply circuit and the voltage at the first terminal of the fifth resistor, and the first terminal of the fifth resistor is the terminal connected to the sixth resistor.

8. The circuit according to any one of claims 5-7, characterized in that, The signal processing circuit and the filtering circuit are further connected by a voltage stabilization unit. The first end of the voltage stabilization unit is connected to the output end of the signal processing circuit, and the second end of the voltage stabilization unit is connected to the filtering circuit.

9. The circuit according to claim 8, characterized in that, The first voltage is the voltage division of the second resistor on the first branch circuit with respect to the third voltage difference, and the second voltage is the voltage division of the fourth resistor on the second branch circuit with respect to the third voltage difference; The third voltage difference is the voltage difference between the power supply terminal voltage of the power supply circuit and the first terminal voltage of the voltage stabilizing unit.

10. The circuit according to claim 8 or 9, characterized in that, The voltage stabilization unit is a voltage follower.

11. An electronic device, characterized in that, The electronic device includes the sensor circuitry as described in any one of claims 1-10.

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