Pressure sensor circuit

Abstract

The embodiment of the utility model discloses a pressure sensor circuit. The pressure sensor circuit comprises a first voltage end, a second voltage end, a grounding voltage end, a power supply voltage end and a substrate voltage end, the first resistor is coupled between a first voltage end and a power supply voltage end; the second resistor is coupled between the second voltage end and the power supply voltage end; the third resistor is coupled between the second voltage end and the grounding voltage end; the fourth resistor is coupled between the first voltage end and the grounding voltage end; the first filter circuit forms a noise filter path between the first voltage end and the substrate voltage end; the second filter circuit forms a noise filtering path between the power supply voltage end and the substrate voltage end; the third filter circuit forms a noise filtering path between the second voltage end and the substrate voltage end; and the fourth filter circuit forms a noise filtering path between the grounding voltage end and the substrate voltage end. By arranging the filter circuit, the noise coupled to the output voltage by the external environment is filtered, and the electromagnetic interference is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of pressure sensors, and in particular to a pressure sensor circuit. Background Art

[0002] Pressure sensors are widely used in automotive, consumer, and industrial electronics. MEMS pressure sensors utilize four pressure-sensing piezoresistors placed parallel to each other at the center of a strain gauge membrane, forming a Wheatstone bridge circuit. When pressure acts on the strain gauge membrane, it deforms and generates stress. The stress change is greatest at the center of the membrane edge. The four piezoresistors placed there sense the stress change, causing their resistance to increase or decrease, leading to bridge imbalance. The output voltage at the resistor connection point is proportional to the applied pressure: Vout = V2 - V1.

[0003] However, when this MEMS pressure sensor is used in harsh environments such as automobiles and industry, high-frequency noise and electromagnetic interference in the environment are coupled to the output end of the piezoresistor, which will cause the MEMS pressure sensor's anti-interference ability to deteriorate, the output signal to be unstable, and the voltage to fluctuate greatly, which will lead to problems such as poor signal-to-noise ratio and reduced accuracy. Utility Model Content

[0004] The present application provides a pressure sensor circuit, which aims to effectively solve the problems of poor anti-interference ability and low signal-to-noise ratio of MEMS pressure sensor circuits in the prior art.

[0005] According to a first aspect of the present application, the present application provides a pressure sensor circuit, comprising: a first voltage terminal outputting a first voltage, a second voltage terminal outputting a second voltage, a ground voltage terminal receiving a reference ground voltage, a power supply voltage terminal receiving a power supply voltage, and a substrate voltage terminal receiving a substrate voltage; the pressure sensor circuit further comprises: a first resistor coupled between the first voltage terminal and the power supply voltage terminal; a second resistor coupled between the second voltage terminal and the power supply voltage terminal; a third resistor coupled between the second voltage terminal and the ground voltage terminal; a fourth resistor coupled between the first voltage terminal and the ground voltage terminal; a first filter circuit coupled between the first voltage terminal and the substrate voltage terminal, for forming a noise filter path between the first voltage terminal and the substrate voltage terminal; a second filter circuit coupled between the power supply voltage terminal and the substrate voltage terminal, for forming a noise filter path between the power supply voltage terminal and the substrate voltage terminal; a third filter circuit coupled between the second voltage terminal and the substrate voltage terminal, for forming a noise filter path between the second voltage terminal and the substrate voltage terminal; and a fourth filter circuit coupled between the ground voltage terminal and the substrate voltage terminal, for forming a noise filter path between the ground voltage terminal and the substrate voltage terminal.

[0006] Through one or more of the above embodiments in this application, at least the following technical effects can be achieved:

[0007] By adding filter capacitors and resistors to the pressure sensor circuit that uses a resistor bridge for pressure detection, high-frequency noise and electromagnetic interference from the external environment are filtered out, blocking their coupling to the output end, suppressing common-mode noise, improving the signal-to-noise ratio and anti-interference ability of the pressure sensor circuit, and making the pressure sensor circuit more stable and the output accuracy higher.

[0008] At the same time, since the filter circuit is already included in the pressure sensor circuit, after the circuit is integrated into a chip, there is no need to add filter resistors and capacitors in the back-end processing circuit or the pressure sensor conditioning chip, which reduces the use of large-area capacitors in components or integrated circuits and reduces system costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and other beneficial effects of the present application apparent.

[0010] Figure 1 This is a physical principle diagram of a pressure sensor;

[0011] Figure 2 1. A schematic diagram of a circuit structure of a pressure sensor circuit;

[0012] Figure 3 Schematic diagram of the circuit structure of a pressure sensor circuit provided according to an embodiment of the present application;

[0013] Figure 4 Schematic diagram of the circuit structure of a pressure sensor circuit provided according to another embodiment of the present application;

[0014] Figure 5 Schematic diagram of the circuit structure of a pressure sensor circuit provided according to another embodiment of the present application;

[0015] Figure 6 Schematic diagram of the circuit structure of a pressure sensor circuit provided according to another embodiment of the present application;

[0016] Figure 7 Schematic diagram of the circuit structure of a pressure sensor circuit provided according to another embodiment of the present application; DETAILED DESCRIPTION

[0017] Throughout the description of this application, it should be noted that "coupled" as used throughout the specification and claims is defined as a connection, either directly or indirectly, electrically or non-electrically. When an element is described as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or one or more intervening elements may be present. In contrast, when an element is described as being "directly connected" or "directly coupled" to another element, no intervening elements are present. Throughout this specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of this application. Therefore, the phrases "in one embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout this specification do not necessarily refer to the same embodiment or example. Furthermore, particular features, structures, or characteristics may be combined in any suitable combination and / or subcombination in one or more embodiments or examples. Furthermore, those skilled in the art will appreciate that the figures provided herein are for illustrative purposes only and are not necessarily drawn to scale. Identical reference numerals indicate identical components. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0018] MEMS pressure sensors are widely used in automotive electronics, consumer electronics, industrial electronics and other fields. Figure 1 This is a schematic diagram of a pressure sensor. The four piezoresistors that sense pressure changes are placed parallel to each other at the center of the edge of the strain film. Figure 2 Schematic diagram of a circuit structure of a pressure sensor circuit. Figure 2 The resistors in the circuit are connected to form a bridge circuit. When pressure acts on the strain film, it deforms and generates stress. The stress change is greatest at the center of the strain film edge. The four piezoresistors placed there sense the stress change, causing their resistance values ​​to increase or decrease, causing the bridge to become unbalanced. The voltage difference Vout = V2 - V1, proportional to the applied pressure, is output from nodes V1 and V2.

[0019] In response to the above technical problems, the embodiment of the present application provides a pressure sensor circuit. Figure 3 A schematic diagram of the circuit structure of a pressure sensor circuit 300 according to an embodiment of the present application is provided. The circuit includes a first voltage terminal V1, a second voltage terminal V2, a ground voltage terminal GND, a supply voltage terminal VDD, and a substrate voltage terminal Vsub. The circuit also includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first filter circuit, a second filter circuit, a third filter circuit, and a fourth filter circuit.

[0020] The first voltage terminal V1 outputs a first voltage Vin1, the second voltage terminal V2 outputs a second voltage Vin2, the ground voltage terminal GND receives a reference ground voltage, the power supply voltage terminal VDD receives a power supply voltage, and the substrate voltage terminal Vsub receives a substrate voltage. A first resistor R1 is coupled between the first voltage terminal V1 and the power supply voltage terminal VDD, a second resistor R2 is coupled between the second voltage terminal V2 and the power supply voltage terminal VDD, a third resistor R3 is coupled between the second voltage terminal V2 and the ground voltage terminal GND, and a fourth resistor R4 is coupled between the first voltage terminal V1 and the ground voltage terminal GND. The first filter circuit is coupled between the first voltage terminal and the substrate voltage terminal, and is used to form a noise filter path between the first voltage terminal and the substrate voltage terminal. The second filter circuit is coupled between the power supply voltage terminal and the substrate voltage terminal, and is used to form a noise filter path between the power supply voltage terminal and the substrate voltage terminal. The third filter circuit is coupled between the second voltage terminal and the substrate voltage terminal, and is used to form a noise filter path between the second voltage terminal and the substrate voltage terminal. The fourth filter circuit is coupled between the ground voltage terminal and the substrate voltage terminal, and is used to form a noise filter path between the ground voltage terminal and the substrate voltage terminal.

[0021] In practical applications, the first resistor R1 and the third resistor R3 are symmetrically arranged on the strain gauge membrane of the pressure sensor, and the second resistor R2 and the fourth resistor R4 are symmetrically arranged on the strain gauge membrane of the pressure sensor. The first and third resistors share the same center of symmetry, and the second and fourth resistors share the same center of symmetry. When the strain gauge membrane deforms due to pressure, the voltage at the first voltage terminal V1 and the second voltage terminal V2 of the bridge formed by the first resistor R1 to the fourth resistor R4 changes. By detecting the voltage difference Vout = Vin2 - Vin1 between the first voltage Vin1 and the second voltage Vin2, the strain gauge membrane pressure proportional to the voltage difference Vout can be calculated. In some embodiments, the resistance of the first resistor R1 ranges from 1 kΩ to 10 kΩ, and for example, a typical value of 5 kΩ is used.

[0022] The first voltage terminal V1, the second voltage terminal V2, the ground voltage terminal GND, and the supply voltage terminal VDD are all voltage terminals of the pressure sensor circuit. High-frequency noise and electromagnetic interference in the environment are easily coupled to these voltage terminals. By adding a filter circuit between the output terminal and the substrate voltage terminal Vsub, the coupling process of environmental influences is blocked, common-mode noise is suppressed, and the signal-to-noise ratio and anti-interference capability of the pressure sensor circuit are improved. This improves the stability of the pressure sensor circuit and enhances the output accuracy.

[0023] Figure 4 A circuit structure diagram of a pressure sensor circuit 400 according to another embodiment of the present application is given. Figure 4In the illustrated embodiment, the first filter circuit 10 includes a first capacitor, a first terminal of the first capacitor being coupled to the first voltage terminal V1, and a second terminal of the first capacitor being coupled to the substrate voltage terminal Vsub. The second filter circuit 20 includes a second capacitor, a first terminal of the second capacitor being coupled to the supply voltage terminal VDD, and a second terminal of the second capacitor being coupled to the substrate voltage terminal Vsub. The third filter circuit 30 includes a third capacitor, a first terminal of the third capacitor being coupled to the second voltage terminal V2, and a second terminal of the third capacitor being coupled to the substrate voltage terminal Vsub. The fourth filter circuit 40 includes a fourth capacitor, a first terminal of the fourth capacitor being coupled to the ground voltage terminal GND, and a second terminal of the fourth capacitor being coupled to the substrate voltage terminal Vsub.

[0024] The impedance of a capacitor to an AC signal is inversely proportional to its capacitance and the signal frequency; that is, the higher the frequency, the lower the impedance. When noise appears at the output terminal of the pressure sensor circuit, it is introduced into the substrate via a low-impedance capacitor, thereby filtering and reducing noise at the output terminal. In some embodiments, the capacitance of the first, second, third, or fourth capacitors ranges from 1nF to 100uf.

[0025] Figure 5 A circuit structure diagram of a pressure sensor circuit 500 according to another embodiment of the present application is given. Figure 5 In the illustrated embodiment, the first filter circuit 10 further includes a first filter resistor R5, a first end of which is coupled to the first voltage terminal V1, and a second end of which is coupled to the first end of the first capacitor. The third filter circuit 30 further includes a second filter resistor R6, a first end of which is coupled to the second voltage terminal V2, and a second end of which is coupled to the first end of the third capacitor.

[0026] Figure 6 A circuit structure diagram of a pressure sensor circuit 600 according to another embodiment of the present application is given. Figure 6 In the embodiment shown, the connection point between the first resistor R1 and the second resistor R2 is a first connection point, the connection point between the second resistor R2 and the third resistor R3 is a second connection point, the connection point between the third resistor R3 and the fourth resistor R4 is a third connection point, and the connection point between the fourth resistor R4 and the first resistor R1 is a fourth connection point.

[0027] The first filter circuit 10 further includes a first filter resistor R5, a first end of which is coupled to the fourth connection point, and a second end of which is coupled to the first end of the first capacitor. The third filter circuit 30 further includes a second filter resistor R6, a first end of which is coupled to the second connection point, and a second end of which is coupled to the first end of the third capacitor.

[0028] In some embodiments, the resistance range of the first filter resistor or the second filter resistor is 1Ω to 1kΩ.

[0029] Figure 7 A circuit structure diagram of a pressure sensor circuit 700 according to another embodiment of the present application is given. Figure 7 In the illustrated embodiment, the first filter circuit 10 includes a first diode, the anode terminal of the first diode being coupled to the first voltage terminal V1 and the cathode terminal of the first diode being coupled to the substrate voltage terminal Vsub. The second filter circuit 20 includes a second diode, the anode terminal of the second diode being coupled to the supply voltage terminal VDD and the cathode terminal of the second diode being coupled to the substrate voltage terminal Vsub. The third filter circuit 30 includes a third diode, the anode terminal of the third diode being coupled to the second voltage terminal V2 and the cathode terminal of the third diode being coupled to the substrate voltage terminal Vsub. The fourth filter circuit 40 includes a fourth diode, the anode terminal of the fourth diode being coupled to the ground voltage terminal GND and the cathode terminal of the fourth diode being coupled to the substrate voltage terminal Vsub.

[0030] In some embodiments, the junction capacitance of the first diode, the second diode, the third diode, or the fourth diode has a capacitance ranging from 1 nf to 100 uf.

[0031] Although the present application has been described with reference to several exemplary embodiments, it should be understood that the terms used are illustrative and exemplary rather than restrictive. Since the present application can be embodied in various forms without departing from the spirit or essence of the invention, it should be understood that the above-described embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all changes and modifications that fall within the scope of the claims or their equivalents are intended to be covered by the appended claims.

Claims

1. A pressure sensor circuit, characterized in that: include: The first voltage terminal outputs a first voltage, the second voltage terminal outputs a second voltage, the ground voltage terminal receives a reference ground voltage, the power supply voltage terminal receives a power supply voltage, and the substrate voltage terminal receives a substrate voltage; The pressure sensor circuit further includes: a first resistor, coupled between the first voltage terminal and the supply voltage terminal; a second resistor, coupled between the second voltage terminal and the supply voltage terminal; a third resistor, coupled between the second voltage terminal and the ground voltage terminal; a fourth resistor, coupled between the first voltage terminal and the ground voltage terminal; A first filter circuit is coupled between the first voltage terminal and the substrate voltage terminal, and is used to form a noise filter path between the first voltage terminal and the substrate voltage terminal; a second filtering circuit coupled between the power supply voltage terminal and the substrate voltage terminal, for forming a noise filtering path between the power supply voltage terminal and the substrate voltage terminal; a third filtering circuit coupled between the second voltage terminal and the substrate voltage terminal, for forming a noise filtering path between the second voltage terminal and the substrate voltage terminal; and The fourth filter circuit is coupled between the ground voltage terminal and the substrate voltage terminal, and is used to form a noise filter path between the ground voltage terminal and the substrate voltage terminal.

2. The pressure sensor circuit according to claim 1, wherein: The first filtering circuit includes a first capacitor, a first terminal of the first capacitor is coupled to the first voltage terminal, and a second terminal of the first capacitor is coupled to the substrate voltage terminal; The second filtering circuit includes a second capacitor, a first end of the second capacitor is coupled to the supply voltage end, and a second end of the second capacitor is coupled to the substrate voltage end; The third filtering circuit includes a third capacitor, a first terminal of the third capacitor is coupled to the second voltage terminal, and a second terminal of the third capacitor is coupled to the substrate voltage terminal; The fourth filtering circuit includes a fourth capacitor, a first terminal of the fourth capacitor is coupled to the ground voltage terminal, and a second terminal of the fourth capacitor is coupled to the substrate voltage terminal.

3. The pressure sensor circuit according to claim 2, wherein: The capacitance range of the first capacitor, the second capacitor, the third capacitor or the fourth capacitor is 1nf to 100uf.

4. The pressure sensor circuit according to claim 2, wherein: The first filtering circuit further includes a first filtering resistor, wherein a first end of the first filtering resistor is coupled to the first voltage end, and a second end of the first filtering resistor is coupled to the first end of the first capacitor; The third filtering circuit further includes a second filtering resistor, a first end of the second filtering resistor is coupled to the second voltage end, and a second end of the second filtering resistor is coupled to the first end of the third capacitor.

5. The pressure sensor circuit according to claim 2, wherein: The connection point between the first resistor and the second resistor is a first connection point, the connection point between the second resistor and the third resistor is a second connection point, the connection point between the third resistor and the fourth resistor is a third connection point, and the connection point between the fourth resistor and the first resistor is a fourth connection point; The first filtering circuit further includes a first filtering resistor, wherein a first end of the first filtering resistor is coupled to the fourth connection point, and a second end of the first filtering resistor is coupled to the first end of the first capacitor; The third filtering circuit further includes a second filtering resistor, a first end of the second filtering resistor is coupled to the second connection point, and a second end of the second filtering resistor is coupled to the first end of the third capacitor.

6. The pressure sensor circuit according to claim 4 or 5, characterized in that: The resistance range of the first filter resistor or the second filter resistor is 1Ω to 1kΩ.

7. The pressure sensor circuit according to claim 1, wherein: The first filtering circuit includes a first diode, wherein the positive terminal of the first diode is coupled to the first voltage terminal, and the negative terminal of the first diode is coupled to the substrate voltage terminal; The second filtering circuit includes a second diode, wherein the positive terminal of the second diode is coupled to the power supply voltage terminal, and the negative terminal of the second diode is coupled to the substrate voltage terminal; The third filtering circuit includes a third diode, wherein the positive terminal of the third diode is coupled to the second voltage terminal, and the negative terminal of the third diode is coupled to the substrate voltage terminal; The fourth filtering circuit includes a fourth diode, an anode terminal of the fourth diode is coupled to the ground voltage terminal, and a cathode terminal of the fourth diode is coupled to the substrate voltage terminal.

8. The pressure sensor circuit according to claim 7, wherein: The capacitance value of the junction capacitance of the first diode, the second diode, the third diode or the fourth diode ranges from 1 nf to 100 uf.

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