Built-in IEPE circuit for piezoelectric shock wave pressure sensor

Abstract

The utility model provides a built-in IEPE circuit used for a piezoelectric type shock wave pressure sensor, comprising a high gain amplifier, a feedback capacitor and a constant current source, the high gain amplifier is composed of an N channel enhanced field effect transistor, a P channel enhanced field effect transistor, a resistor R1, a resistor R2, a feedback resistor R3 and a resistor R4, the two ends of the high-gain amplifier are connected with the constant current source, the positive electrode of the constant current source is an output end, and the constant current source is connected to the P-channel enhanced field effect transistor; the piezoelectric sensor sensitive element is connected with the input end and receives a charge signal generated by the piezoelectric sensor sensitive element through the input end; the feedback capacitor is installed between the input end and the output end to form negative feedback to form a charge amplifying circuit, a small number of electronic components are used for constructing a complete IEPE circuit, and the charge amplifying circuit has the advantages of being high in integration level, small in size and high in anti-interference capacity and can be integrated in a sensor to amplify charge signals.

Description

Technical Field

[0001] In the field of electronic technology, this utility model relates to a built-in IEPE circuit for a piezoelectric shock wave pressure sensor. Background Technology

[0002] IEPE type charge amplifier circuits are common charge amplifier circuits, typically built into piezoelectric sensors, powered by a constant current source, with the signal output sharing the same cable as the power supply. IEPE type charge amplifier circuits are significant for simplifying testing systems because they do not require a separate power supply cable. Furthermore, the miniaturized IEPE circuit can be sealed inside the sensor, greatly shortening the distance between the piezoelectric sensing element and the conditioning circuit, avoiding interference caused by using long cables to transmit charge signals, and improving testing accuracy. IEPE circuits are of great importance to the development and testing of shock wave pressure sensors, possessing irreplaceable advantages in shock wave pressure testing. Generally, the size of the sensor is limited, leaving little space for the IEPE circuit, placing high demands on the circuit's size. Charge amplifier circuits based on existing operational amplifier chips are insufficient to meet these requirements. Summary of the Invention

[0003] This invention provides a built-in IEPE circuit for a piezoelectric shock wave pressure sensor. This circuit uses a small number of electronic components to build a complete IEPE circuit, which has the advantages of high integration, small size and strong anti-interference ability. It can be integrated into the sensor to amplify the charge signal.

[0004] The specific technical solution is as follows:

[0005] An embedded IEPE circuit for a piezoelectric shock wave pressure sensor is characterized by comprising a high-gain amplifier, a feedback capacitor, and a constant current source. The high-gain amplifier consists of an N-channel enhancement-mode MOSFET, a P-channel enhancement-mode MOSFET, resistors R1 and R2, a feedback resistor R3, and a resistor R4. The constant current source is connected to both ends of the high-gain amplifier.

[0006] The gate of the N-channel enhancement-mode MOSFET is the input terminal of the circuit. Resistors R1 and R2 are connected in series to a constant current source to generate a bias voltage at point A. The gate of the N-channel enhancement-mode MOSFET is connected to point A through resistor R3. The static operating voltage of the circuit is V. S The relationship between resistors R1 and R2 is given by the following formula:

[0007]

[0008] Among them, V TR1 is the turn-on voltage of the N-channel enhancement-mode MOSFET, R2 is the resistance of R1, and R4 is the resistance of R2. The drain of the N-channel enhancement-mode MOSFET is connected to the positive terminal of the constant current source through resistor R4. Resistor R4 converts the current signal in the N-channel enhancement-mode MOSFET into a voltage signal, realizing the first-stage amplification of the voltage signal. The input voltage ΔV IN Voltage ΔV between the drain of the N-channel enhancement-mode MOSFET G1 The relationship can be expressed by the following formula:

[0009]

[0010] Where k1 is an arbitrary constant related to the N-channel enhancement-mode field-effect transistor.

[0011] The drain of the N-channel enhancement-mode MOSFET is connected to the gate of the P-channel enhancement-mode MOSFET. A voltage signal, amplified by one stage, is input to the gate of the P-channel enhancement-mode MOSFET, controlling the current ΔI flowing through the P-channel enhancement-mode MOSFET. D2 This achieves two-stage amplification of voltage signals, and for AC signals, the current ΔI in the P-channel enhancement-mode MOSFET... D2 Voltage ΔV between gate and source G2 The relationship can be represented as:

[0012] ΔI D2 =k2ΔV G2 (3)

[0013] Where k2 is an arbitrary constant related to the P-channel enhancement-mode field-effect transistor.

[0014] The P-channel enhancement-mode MOSFET is connected to the N-channel enhancement-mode MOSFET. For AC signals, its amplification factor K can be expressed by the following formula:

[0015]

[0016] Where V IN Input voltage, V O R4 represents the output voltage of the circuit, and R4 represents the resistance value of resistor R4.

[0017] The positive terminal of the constant current source is the output terminal, and the constant current source is connected to the P-channel enhancement-mode MOSFET.

[0018] It also includes a piezoelectric sensor sensing element, which is connected to the input terminal and receives the charge signal it generates through the input terminal;

[0019] The feedback capacitor is installed between the input and output terminals to form negative feedback, constituting a charge amplification circuit. The relationship between the output charge Q of the piezoelectric sensor's sensitive element and the output voltage can be expressed by the following formula:

[0020]

[0021] Where Q is the charge input to the circuit, C F This is the resistance value of the feedback capacitor.

[0022] Furthermore, the resistors R1, R2, R3, N-channel enhancement-mode MOSFET, and P-channel enhancement-mode MOSFET are packaged on a single wafer to form a single chip.

[0023] Furthermore, the high-gain amplifier has an amplification factor greater than 80dB.

[0024] Furthermore: the feedback capacitor is C1, and the feedback capacitor is 100pF.

[0025] Furthermore: the sensitive element of the piezoelectric sensor includes a capacitor C2 and a voltage regulator V1, wherein the capacitor C2 is 100pF.

[0026] In the above structure: the built-in IEPE circuit for a piezoelectric shock wave pressure sensor proposed in this utility model includes a high-gain amplifier, a feedback capacitor, and a constant current source. The high-gain amplifier consists of an N-channel enhancement-mode MOSFET, a P-channel enhancement-mode MOSFET, resistors R1 and R2, a feedback resistor R3, and a resistor R4. The high-gain amplifier is used to convert the current signal and amplify the converted voltage signal multiple times. In use, its input terminal is connected to the sensitive element of the piezoelectric sensor to receive the charge signal generated by it, as detailed below:

[0027] Resistors R1 and R2 are connected in series to the constant current source, thus generating a bias voltage at point A. The gate of the N-channel enhancement-mode MOSFET is connected to point A through resistor R3. The bias voltage is applied to the gate of the N-channel enhancement-mode MOSFET through the high-value resistor R3, thus providing it with a bias voltage. Therefore, by changing the ratio of resistors R1 to R2, the static operating voltage can be controlled, that is, the voltage across the constant current source can be controlled when there is no signal input.

[0028] The static operating voltage V of the circuit S The relationship between resistors R1 and R2 is given by the following formula:

[0029]

[0030] Among them, V T R1 is the turn-on voltage of the N-channel enhancement-mode MOSFET, and R2 is the resistance value of resistor R1.

[0031] The drain of the N-channel enhancement-mode MOSFET is connected to the positive terminal of the constant current source through resistor R4. Resistor R4 converts the current signal in the N-channel enhancement-mode MOSFET into a voltage signal, achieving a first-stage amplification of the voltage signal. For the AC signal input voltage ΔV... IN Voltage ΔV between the drain of N-channel enhancement-mode MOSFET 7 and the drain G1 The relationship can be expressed by the following formula.

[0032]

[0033] Where k1 is a constant related to the N-channel enhancement-mode field-effect transistor.

[0034] The drain of the N-channel enhancement-mode MOSFET is connected to the gate of the P-channel enhancement-mode MOSFET. A voltage signal, amplified by one stage, is input to the gate of the P-channel MOSFET, controlling the current ΔI flowing through it. D2 This achieves two-stage amplification of voltage signals, and for AC signals, the current ΔI in the P-channel enhancement-mode MOSFET... D2 Voltage ΔV between gate and source G2 The relationship can be represented as:

[0035] ΔI D2 =k2ΔV G2 (3)

[0036] Where k2 is an arbitrary constant related to the P-channel enhancement-mode field-effect transistor.

[0037] This invention connects an N-channel enhancement-mode MOSFET and a P-channel enhancement-mode MOSFET together to form a two-stage amplification, thereby achieving high-gain amplification. For AC signals, the amplification factor K can be expressed by the following formula:

[0038]

[0039] Where V IN Input voltage, V O R is the output voltage of the circuit, and R4 is the resistance value of resistor R4.

[0040] By adding a feedback capacitor between the input and output terminals to form negative feedback, a charge amplifier circuit can be constructed. The amplification capability of the charge amplifier circuit is determined by the capacitance value of the feedback capacitor. The relationship between the output charge Q of the piezoelectric sensor's sensitive element and the output voltage can be expressed by the following formula.

[0041]

[0042] Where Q is the charge input to the circuit, C F The resistance value of feedback capacitor 5

[0043] To further reduce the size of the circuit, this invention packages resistors R1, R2, feedback resistor R3, N-channel enhancement-mode MOSFETs, and P-channel enhancement-mode MOSFETs onto a single wafer to form an independent chip. An external feedback resistor R3 and a feedback capacitor are added to form a charge amplification circuit.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] This invention constructs a complete IEPE circuit using a small number of electronic components, which has the advantages of high integration, small size and strong anti-interference ability. It can be integrated into the sensor to amplify the charge signal.

[0046] This invention generates a bias voltage by connecting resistors R1 and R2 in series with a constant current source. This bias voltage is then applied to the gate of an N-channel enhancement-mode MOSFET through a high-resistance resistor. The static operating point (the voltage across the constant current source when there is no signal input) can be controlled by changing the ratio of the two voltage divider resistors.

[0047] This invention uses resistor R4 to convert current signals into voltage signals and achieves a first-stage amplification. Then, by connecting the drain of the N-channel enhancement-mode field-effect transistor (EMT) to the gate of the P-channel EMT, the first-stage amplified voltage signal generated in the previous stage is converted into a current signal in the P-channel EMT, thus achieving a second-stage amplification of the signal.

[0048] This invention constructs a charge amplifier circuit by adding a feedback capacitor between the input terminal (gate of the N-channel enhancement-mode MOSFET) and the output terminal (positive terminal of the constant current source) to form negative feedback. The charge amplification factor can be adjusted by regulating the size of the feedback capacitor. Attached Figure Description

[0049] Figure 1 Schematic diagram of the built-in IEPE circuit of a piezoelectric shock wave pressure sensor;

[0050] Figure 2 Schematic diagram of IEPE circuit based on IEPE packaged chip.

[0051] List of reference numerals in the attached diagram:

[0052] 1. High-gain amplifier; 2. Feedback resistor R3; 3. Resistor R2; 4. Piezoelectric sensor sensing element; 5. Feedback capacitor; 6. Resistor R1; 7. N-channel enhancement-mode MOSFET; 8. Resistor R4; 9. P-channel enhancement-mode MOSFET; 10. Constant current source; 11. Chip. Detailed Implementation

[0053] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0054] like Figure 1-2 As shown, this utility model proposes a built-in IEPE circuit for a piezoelectric shock wave pressure sensor, including a high-gain amplifier 1, a feedback capacitor 5, and a constant current source 10. The high-gain amplifier 1 is composed of an N-channel enhancement-mode field-effect transistor 7, a P-channel enhancement-mode field-effect transistor 9, resistors R16 and R23, a feedback resistor R32, and a resistor R48. The two ends of the high-gain amplifier 1 are connected to the constant current source 10.

[0055] The gate of the N-channel enhancement-mode MOSFET 7 is the input terminal of the circuit. Resistors R16 and R23 are connected in series to the constant current source 10 to generate a bias voltage at point A. The gate of the N-channel enhancement-mode MOSFET 7 is connected to point A through resistor R32. The relationship between the circuit's static operating voltage VS and resistors R16 and R23 is given by the following formula:

[0056]

[0057] Among them, V T R1 is the threshold voltage of the N-channel enhancement-mode MOSFET, R2 is the resistance of resistor R16, and R2 is the resistance of resistor R23.

[0058] The drain of the N-channel enhancement-mode MOSFET 7 is connected to the positive terminal of the constant current source 10 via resistor R48. Resistor R48 converts the current signal in the N-channel enhancement-mode MOSFET 7 into a voltage signal, achieving a first-stage amplification of the voltage signal. The input voltage ΔV IN Voltage ΔV between the drain of N-channel enhancement-mode MOSFET 7 and the drain G1 The relationship can be expressed by the following formula:

[0059]

[0060] Where k1 is an arbitrary constant related to the N-channel enhancement-mode MOSFET 7.

[0061] The drain of the N-channel enhancement-mode field-effect transistor 7 is connected to the gate of the P-channel enhancement-mode field-effect transistor 9. A voltage signal, amplified by one stage, is input to the gate of the P-channel enhancement-mode field-effect transistor 9, controlling the current ΔI flowing through the P-channel enhancement-mode field-effect transistor 9. D2 This achieves two-stage amplification of the voltage signal, and for the AC signal, the current ΔI in the P-channel enhancement-mode MOSFET 9... D2 Voltage ΔV between gate and source G2 The relationship can be represented as:

[0062]

[0063] Where k2 is an arbitrary constant related to the P-channel enhancement-mode MOSFET 9.

[0064] The P-channel enhancement-mode MOSFET 9 is connected to the N-channel enhancement-mode MOSFET 7. For AC signals, its amplification factor K can be expressed by the following formula:

[0065]

[0066] Where V IN Input voltage, V O R4 represents the output voltage of the circuit, and R4 represents the resistance value of resistor R48.

[0067] The positive terminal of the constant current source 10 is the output terminal, and the constant current source 10 is connected to the P-channel enhancement-mode field-effect transistor 9.

[0068] It also includes a piezoelectric sensor sensing element 4, which is connected to the input terminal and receives the charge signal generated by it through the input terminal;

[0069] The feedback capacitor 5 is installed between the input and output terminals to form negative feedback, constituting a charge amplification circuit. The relationship between the output charge Q of the piezoelectric sensor sensitive element 4 and the output voltage can be expressed by the following formula:

[0070]

[0071] Where Q is the charge input to the circuit, C F This is the resistance value of feedback capacitor 5.

[0072] The resistors R16, R23, R32, N-channel enhancement-mode MOSFET 7, and P-channel enhancement-mode MOSFET 9 are packaged on a single wafer to form a single chip 11. The high-gain amplifier 1 has a gain greater than 80dB.

[0073] The feedback capacitor 5 is C1, and the feedback capacitor 5 has a capacitance of 100pF. The piezoelectric sensor sensing element 4 includes a capacitor C2 and a voltage regulator V1, and the capacitor C2 has a capacitance of 100pF.

[0074] This invention proposes a built-in IEPE circuit for a piezoelectric shock wave pressure sensor, comprising a high-gain amplifier 1, a feedback capacitor 5, and a constant current source 10. The high-gain amplifier 1 consists of an N-channel enhancement-mode MOSFET 7, a P-channel enhancement-mode MOSFET 9, resistors R16 and R23, a feedback resistor R32, and a resistor R48. The high-gain amplifier 1 is used to convert the current signal and amplify the converted voltage signal multiple times. In use, its input terminal is connected to the sensitive element 4 of the piezoelectric sensor to receive the charge signal generated by it, as detailed below:

[0075] Resistors R16 and R23 are connected in series to the constant current source 10, thus generating a bias voltage at point A. The gate of the N-channel enhancement-mode MOSFET 7 is connected to point A through resistor R32. The bias voltage is applied to the gate of the N-channel enhancement-mode MOSFET 7 through the high-value resistor R32, thus providing it with a bias voltage. Therefore, by changing the ratio of resistors R16 and R23, the static operating voltage can be controlled, that is, the voltage across the constant current source 10 can be controlled when there is no signal input.

[0076] The relationship between the circuit's static operating voltage VS and resistors R16 and R23 is given by the following formula:

[0077]

[0078] Among them, V T R1 is the turn-on voltage of the N-channel enhancement-mode MOSFET 7, R2 is the resistance of resistor R16, and R2 is the resistance of resistor R23.

[0079] The drain of the N-channel enhancement-mode MOSFET 7 is connected to the positive terminal of the constant current source 10 through resistor R48. Resistor R48 converts the current signal in the N-channel enhancement-mode MOSFET 7 into a voltage signal, realizing the first-stage amplification of the voltage signal. For the AC signal input voltage ΔV... IN Voltage ΔV between the drain of N-channel enhancement-mode MOSFET 7 and the drain G1 The relationship can be expressed by the following formula.

[0080]

[0081] Where k1 is a constant related to the N-channel enhancement-mode MOSFET 7.

[0082] The drain of the N-channel enhancement-mode MOSFET 7 is connected to the gate of the P-channel enhancement-mode MOSFET 9. A voltage signal, amplified by one stage, is input to the gate of the P-channel enhancement-mode MOSFET 9, controlling the current ΔI flowing through the P-channel enhancement-mode MOSFET 9. D2 This achieves two-stage amplification of the voltage signal, and for the AC signal, the current ΔI in the P-channel enhancement-mode MOSFET 9... D2 Voltage ΔV between gate and source G2 The relationship can be represented as:

[0083] ΔI D2 =k2ΔV G2 (3)

[0084] Where k2 is an arbitrary constant related to the P-channel enhancement-mode MOSFET 9.

[0085] This invention connects an N-channel enhancement-mode field-effect transistor 7 and a P-channel enhancement-mode field-effect transistor 9 together to form a two-stage amplification, thereby achieving high-gain amplification. For AC signals, its amplification factor K can be expressed by the following formula:

[0086]

[0087] Where V IN Input voltage, V O R4 represents the output voltage of the circuit, and R4 represents the resistance value of resistor R48.

[0088] By adding a feedback capacitor 5 between the input and output terminals to form negative feedback, a charge amplifier circuit can be constructed. The amplification capability of the charge amplifier circuit is determined by the capacitance value of the feedback capacitor 5. The relationship between the output charge Q of the piezoelectric sensor sensitive element 4 and the output voltage can be expressed by the following formula.

[0089]

[0090] Where Q is the charge input to the circuit, C F The resistance value of feedback capacitor 5

[0091] To further reduce the size of the circuit, such as Figure 2 As shown, this utility model packages resistor R16, resistor R23, feedback resistor R32, N-channel enhancement-mode field-effect transistor 7 and P-channel enhancement-mode field-effect transistor 9 on a wafer to form an independent chip 11, and forms a charge amplification circuit by adding external feedback resistor R32 and feedback capacitor 5.

[0092] In summary:

[0093] This invention constructs a complete IEPE circuit using a small number of electronic components, which has the advantages of high integration, small size and strong anti-interference ability. It can be integrated into the sensor to amplify the charge signal.

[0094] This invention generates a bias voltage by connecting resistors R16 and R2 in series with a constant current source 10. This bias voltage is then applied to the gate of the N-channel enhancement-mode MOSFET 7 through a high-resistance resistor. The static operating point (the voltage across the constant current source 10 when there is no signal input) can be controlled by changing the ratio of the two voltage divider resistors.

[0095] This invention uses resistor R48 to convert current signals into voltage signals and achieves a first-stage amplification. Then, by connecting the drain of the N-channel enhancement-mode field-effect transistor 7 to the gate of the P-channel enhancement-mode field-effect transistor 9, the first-stage amplified voltage signal generated in the previous stage is converted into a current signal in the P-channel enhancement-mode field-effect transistor 9, thus achieving a second-stage amplification of the signal.

[0096] This invention constructs a charge amplifier circuit by adding a feedback capacitor 5 between the input terminal (gate of the N-channel enhancement-mode MOSFET 7) and the output terminal (positive terminal of the constant current source 10) to form negative feedback. The charge amplification factor can be adjusted by adjusting the size of the feedback capacitor 5.

[0097] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any other way. Any modifications or equivalent changes made based on the technical essence of the present utility model shall still fall within the scope of protection claimed by the present utility model.

Claims

1. A built-in IEPE circuit for a piezoelectric shock wave pressure sensor, characterized in that: The system includes a high-gain amplifier (1), a feedback capacitor (5), and a constant current source (10). The high-gain amplifier (1) is composed of an N-channel enhancement-mode field-effect transistor (7), a P-channel enhancement-mode field-effect transistor (9), resistors R1 (6), R2 (3), a feedback resistor R3 (2), and R4 (8). The constant current source (10) is connected to both ends of the high-gain amplifier (1). The gate of the N-channel enhancement-mode MOSFET (7) is the input terminal of the circuit. The resistors R1 (6) and R2 (3) are connected in series to the constant current source (10) to generate a bias voltage at point A. The gate of the N-channel enhancement-mode MOSFET (7) is connected to point A through resistor R3 (2). The static operating voltage V of the circuit is... S The relationship between resistors R1(6) and R2(3) is given by the following formula: （1） Among them, V T R1 is the turn-on voltage of the N-channel enhancement-mode MOSFET (7), R2 is the resistance value of resistor R1 (6), and R2 is the resistance value of resistor R2 (3). The drain of the N-channel enhancement-mode field-effect transistor (7) is connected to the positive terminal of the constant current source (10) through resistor R4 (8). Resistor R4 (8) converts the current signal in the N-channel enhancement-mode field-effect transistor (7) into a voltage signal, realizing the first-stage amplification of the voltage signal. The voltage at the input terminal is... Voltage between the drain of the N-channel enhancement-mode MOSFET (7) The relationship can be expressed by the following formula: （2） Where k1 is an arbitrary constant related to the N-channel enhancement-mode field-effect transistor (7), The drain of the N-channel enhancement-mode field-effect transistor (7) is connected to the gate of the P-channel enhancement-mode field-effect transistor (9). The voltage signal, after being amplified by one stage, is input to the gate of the P-channel enhancement-mode field-effect transistor (9), thereby controlling the current ΔI flowing through the P-channel enhancement-mode field-effect transistor (9). D2 This achieves two-stage amplification of the voltage signal, and for the AC signal, the current ΔI in the P-channel enhancement-mode MOSFET (9) D2 Voltage ΔV between gate and source G2 The relationship can be represented as: （3） Where k2 is an arbitrary constant related to the P-channel enhancement-mode field-effect transistor (9), The P-channel enhancement-mode field-effect transistor (9) is connected to the N-channel enhancement-mode field-effect transistor (7). For AC signals, its amplification factor K can be expressed by the following formula: （4） Where V IN Input voltage, V O R4 represents the output voltage of the circuit, and R4 represents the resistance value of resistor R4(8). The positive terminal of the constant current source (10) is the output terminal, and the constant current source (10) is connected to the P-channel enhancement-mode field-effect transistor (9); It also includes a piezoelectric sensor sensing element (4), which is connected to the input terminal and receives the charge signal generated by it through the input terminal; The feedback capacitor (5) is installed between the input and output terminals to form negative feedback, constituting a charge amplification circuit. The relationship between the output charge Q of the piezoelectric sensor sensing element (4) and the output voltage can be expressed by the following formula: （5） Where Q is the amount of charge input to the circuit. The resistance value of the feedback capacitor (5) is given.

2. The built-in IEPE circuit for a piezoelectric shock wave pressure sensor according to claim 1, characterized in that: The resistors R1 (6), R2 (3), R3 (2), N-channel enhancement field-effect transistor (7) and P-channel enhancement field-effect transistor (9) are packaged on a wafer to form an independent chip (11).

3. The built-in IEPE circuit for a piezoelectric shock wave pressure sensor according to claim 1, characterized in that: The high-gain amplifier (1) has a gain greater than 80dB.

4. The built-in IEPE circuit for a piezoelectric shock wave pressure sensor according to claim 1, characterized in that: The feedback capacitor (5) is C1, and the feedback capacitor (5) is 100pF.

5. The built-in IEPE circuit for a piezoelectric shock wave pressure sensor according to claim 1, characterized in that: The piezoelectric sensor sensing element (4) includes a capacitor C2 and a voltage regulator V1, wherein the capacitor C2 is 100pF.

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