MEMS silicon resonant pressure sensor and automatic gain control circuit single chip implementation method

Abstract

The application discloses a MEMS silicon resonance pressure sensor and a single-chip implementation method of an automatic gain control circuit, and relates to the technical field of pressure sensors.The pressure sensor comprises a silicon resonance pressure sensor sensitive structure and an AC-AGC (AC-Automatic Gain Control) circuit.The silicon resonance pressure sensor sensitive structure and the AC-AGC circuit constitute a closed-loop feedback control loop, and the detected sinusoidal signal is processed through band-pass filtering and square wave signal conversion, so that the conversion output of the pressure value and the frequency value is completed.Under the premise of meeting the high performance and high reliability requirements of the silicon resonance pressure sensor, the automatic gain control board-level circuit is designed at the chip level, so that the circuit is converted into a single chip, the types and quantities of the original circuit board components can be greatly reduced, the volume and weight of the control circuit and the pressure sensor whole meter are reduced, the power consumption and cost of the sensor whole meter are reduced, and the development requirements of the silicon resonance pressure sensor, such as light weight, small size, low price and low power consumption, are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of MEMS pressure sensor, in particular to a MEMS silicon resonant pressure sensor and an automatic gain control circuit single-chip implementation method. BACKGROUND

[0002] The MEMS silicon resonant pressure sensor and the automatic gain control single-chip circuit are a kind of high-precision pressure sensor for converting measured pressure into electrical signal, which is widely used in industrial field, meteorological environment monitoring and automobile electronics, such as hydraulic measurement, cabin pressure measurement, brake pressure measurement, oxygen detection, control system cooling gas pressure measurement, deicing system pressure measurement and tire pressure measurement. The MEMS silicon resonant pressure sensor based on the closed-loop control principle of resonator is currently the most comprehensive precision pressure sensor, which mostly adopts the mode of capacitance detection and electrostatic drive excitation, can directly output frequency electrical signal for representing measured pressure, and has the advantages of high precision, good stability and strong anti-interference ability of frequency output.

[0003] The MEMS silicon resonant pressure sensor generally consists of pressure sensor sensitive structure and interface circuit, wherein the interface circuit mostly adopts high-precision operational amplifier, comparator, resistor and capacitor and other discrete components, and is realized by building printed circuit board (PCB board). The analog control scheme has simple circuit structure and is easy to realize, but also has problems of large size, high power consumption, many discrete components and high cost. At the same time, the adaptability of analog circuit parameter index to pressure sensor sensitive structure, as well as the debugging, calibration and compensation of sensor whole table also have certain limitations, which causes difficulties for engineering production and application. SUMMARY

[0004] The main purpose of the present application is to provide a MEMS silicon resonant pressure sensor and an automatic gain control circuit single-chip implementation method, aiming at solving the existing technical problems.

[0005] To achieve the above purpose, the present application provides a MEMS silicon resonant pressure sensor, which comprises: a silicon resonant pressure sensor sensitive structure and an AC-AGC alternating current automatic gain control circuit, wherein the silicon resonant pressure sensor sensitive structure and the AC-AGC alternating current automatic gain control circuit constitute a closed-loop feedback control loop, and the detected sinusoidal signal is processed through band-pass filtering and square wave signal conversion to complete the detection pressure value-frequency value conversion output.

[0006] Further, the AC-AGC alternating current automatic gain control circuit comprises a weak capacitance detection circuit function module, the weak capacitance detection circuit function module adopts a CV conversion circuit, and the operational amplifier in the CV conversion circuit adopts a junction field effect transistor (JFET) as an input stage transistor.

[0007] Further, the CV conversion circuit employs a PMOS active resistor.

[0008] Further, the AC-AGC single-chip circuit employs and generates an amplitude modulation sine wave signal as a driving excitation signal, and utilizes a junction field effect transistor (JFET) operating in a linear region, whose source-drain effective resistance R DS is inversely proportional to the gate-source voltage V GS , to construct a driving excitation signal generation circuit, to perform amplitude negative feedback control on a detected sine wave signal, and to automatically control and adjust the overall loop gain.

[0009] Further, the AC-AGC single-chip circuit further includes a peak detection circuit employing a full-wave rectification and a second-order low-pass filter circuit.

[0010] Further, the AC-AGC single-chip circuit further includes a high-voltage charge pump circuit employing a Dickson voltage multiplier structure, diodes of a buried layer type, and high-voltage interdigital capacitors.

[0011] Further, the AC-AGC single-chip circuit further includes a temperature sensor circuit designed based on the negative temperature characteristic of the base-emitter voltage V BE of the transistor Q1.

[0012] The MEMS silicon resonant pressure sensor automatic gain control circuit single-chip implementation method specifically includes the following steps,

[0013] The silicon resonant pressure sensor sensitive structure and the automatic gain control circuit form a closed-loop feedback loop. The pressure sensor sensitive structure is excited under the action of noise and electrostatic force, and converts a weak capacitance change into a sine wave voltage signal V

[0014] The first path of the sine wave voltage signal enters a driving excitation signal generation circuit module after phase adjustment, the second path enters a peak detection circuit module, and the third path enters a band-pass filter and square wave conversion after frequency output.

[0015] The sine wave voltage signal passes through the peak detection circuit, extracts the peak information of the amplitude of the sine wave voltage signal, and obtains a direct current voltage signal V

[0016] The sine wave voltage signal amplitude V PI enters a PI control module, is compared with a target amplitude value after proportional integral correction processing, and obtains a direct current correction voltage V PI . The PI control module can be adjusted according to the overall accuracy, start-up time, and other parameter indicators of the silicon resonant pressure sensor.

[0017] The direct current correction voltage V PIand the phase-adjusted sinusoidal voltage signal Vsin enters a driving excitation signal generating circuit to operate to generate a sinusoidal driving excitation voltage signal V EXC Then, feedback is applied to the silicon resonant pressure sensor sensitive structure, negative feedback closed-loop control of the detected sinusoidal signal Vsin amplitude is realized through automatic adjustment of loop gain, and stable amplitude-stable frequency control of the whole resonant closed loop is realized.

[0018] Further, the chip is integrated with an EEPROM-IP unit for adjusting and storing closed-loop gain and proportional coefficient electrical performance parameters.

[0019] Further, the MEMS silicon resonant pressure sensor is started by noise, the amplitude of the driving excitation voltage is adjusted through automatic control and adjustment of loop gain, negative feedback control of the detected sinusoidal voltage amplitude is realized, and after several cycles, the sensitive structure of the pressure sensor is realized at the resonant frequency point. The CV conversion circuit outputs a frequency and amplitude stable sinusoidal voltage signal, and after band-pass filtering and square wave conversion, a frequency voltage signal representing the size of the measured pressure value is output.

[0020] The beneficial effects of the present application are embodied in:

[0021] The present application meets the requirements of high performance and high reliability of the silicon resonant pressure sensor, and the automatic gain control board-level circuit is designed at the chip level, so as to be converted into a single chip, which can greatly reduce the types and quantities of original circuit board components, reduce the size and weight of the control circuit and the pressure sensor whole meter, and reduce the power consumption and cost of the sensor whole meter, which meets the development needs of the future "light weight, small size, low price and power saving" of the silicon resonant pressure sensor. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The present application is based on the integrated circuit BCD process of the silicon resonant pressure sensor whole meter function block diagram;

[0023] Figure 2 The present application is a CV conversion circuit (charge amplifier) chip-level implementation;

[0024] Figure 3 The present application is a PMOS active resistor R f Chip-level implementation;

[0025] Figure 4 The present application is a driving excitation signal generating circuit chip-level implementation;

[0026] Figure 5 The present application is a full-wave rectifier circuit implementation;

[0027] Figure 6For the temperature sensor implementation of the present application

[0028] Figure 7 For the high-voltage charge pump implementation of the present application. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The embodiments in the present application and the features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work under the premise that there is no conflict, belong to the scope of protection of the present application.

[0030] Please refer to Figure 1 The present application provides a MEMS silicon resonant pressure sensor, comprising: a silicon resonant pressure sensor sensitive structure and an AC-AGC alternating current automatic gain control circuit, the silicon resonant pressure sensor sensitive structure and the AC-AGC alternating current automatic gain control circuit constitute a closed loop feedback control loop, and the sine wave signal is detected to pass through band pass filtering and square wave signal conversion processing, and the detection pressure value-frequency value conversion output is completed.

[0031] The MEMS silicon resonant pressure sensor generally consists of a pressure sensor sensitive structure and an interface circuit. The present application is based on the integrated circuit BCD (Bipolar-CMOS-DMOS) process, adopts the resonator alternating current-automatic gain control scheme AC-AGC (Alternating Current-Automatic Gain Control), combines analog and digital circuit design, integrates the non-volatile storage unit EEPROM-IP in the chip, is used for adjusting and storing the circuit electrical parameters, and calibrates, compensates and stores the key indicators of the pressure sensor, such as the sensor key indicators of the pressure sensor, temperature characteristics, comprehensive accuracy, and the like, so as to realize the single-chip design and function integration of the silicon resonant pressure sensor automatic gain control circuit.

[0032] The single-chip design of the automatic gain control circuit adopts an AC-AGC scheme, that is, the driving excitation signal (electrostatic force) adopts a form of fixed DC voltage combined with an amplitude-modulated sine wave. Under the action of noise excitation and continuous driving excitation signal (electrostatic force), the sensitive structure of the capacitive silicon resonant pressure sensor converts the weak capacitance change generated by the sensitive structure of the pressure sensor into a detectable voltage through a CV conversion circuit (charge amplifier), and performs peak detection on the detected and amplified sine wave signal, extracts the sine wave peak value information, and performs PI control (proportional-integral correction) to adjust the amplitude of the sine wave signal, thereby generating an amplitude-modulated sine wave driving excitation signal, and feeding back the signal to the sensitive structure of the pressure sensor. When the circuit detects that the amplitude of the sine wave signal decreases, the electrostatic driving force can be increased by increasing the amplitude of the driving excitation signal, thereby increasing the amplitude of the detected sine wave signal; on the contrary, when the amplitude of the sine wave signal is detected to increase, the electrostatic driving force can be reduced by reducing the amplitude of the driving excitation signal, thereby suppressing the increase of the amplitude of the sine wave signal, achieving the purpose of automatic control and adjustment of the loop gain, and realizing the negative feedback amplitude-stable and frequency-stable closed-loop control of the entire sensor system, as shown in Figure 1 .

[0033] The sensitive structure of the silicon resonant pressure sensor is mostly a capacitive structure, which has the advantages of high precision, low noise, low drift, small temperature sensitivity, simple structure and the like. When external pressure is applied to the sensitive structure of the pressure sensor, the detection capacitance of the sensor sensitive structure will change. Since the capacitance change of the sensor sensitive structure is relatively weak (the minimum capacitance change is of the order of aF), the signal-to-noise ratio of the weak capacitance detection single-chip circuit needs to be improved, and factors such as temperature characteristics, linearity and stability of the signal detection also need to be considered.

[0034] Specifically, the function module of the weak capacitance detection circuit in the present application is designed to adopt a CV conversion circuit (charge amplifier) structure. When the voltage across the detection capacitance of the sensitive structure remains unchanged, the capacitance value changes and generates excess charge. The charge generated by the capacitance change is converted into a voltage signal, thereby realizing the detection function of the sensitive weak capacitance signal, and the chip-level implementation is as shown in Figure 2 . The feedback resistor R f provides a stable DC operating point for the input node of the operational amplifier, and the resistance value is relatively large, which can be approximately considered as all the detection current (charge) flowing through the feedback capacitor C f Therefore, the resistance value of the feedback resistor needs to satisfy the following relationship:

[0035]

[0036] The output voltage of the CV conversion circuit (charge amplifier) is:

[0037]

[0038] V OUT = V CM + ΔCC f * V CM

[0039] Generally, the amount of change in capacitance detected by a capacitive sensor is very small, in order to improve the gain of the CV conversion circuit, theoretically, the common-mode voltage V CM of the operational amplifier and the capacitance value of the feedback capacitor C f may be increased, but in practice, the capacitance value of the feedback capacitor C f cannot be infinitely small. If the capacitance value of the feedback capacitor C f is small to a certain extent, the white noise of the circuit may cause the operational amplifier to produce self-oscillation, and the common-mode voltage V CM is also limited by the power supply voltage and the input range of the operational amplifier.

[0040] Specifically, the CV conversion circuit (charge amplifier) in the present application can set the size of the capacitance value of the feedback capacitor C f , that is, the gain of the CV conversion circuit (charge amplifier) by the combination of the opening and closing of the switches S1, S2 and S3. The feedback capacitor C f has a total of 8 capacitance values to choose from, that is, the 8-gear gain setting of the CV conversion circuit (charge amplifier) can be performed by 3-bit switches, and the switch control signal can be configured and stored by the EEPROM-IP in the chip.

[0041] Specifically, the operational amplifier design in the CV conversion circuit (charge amplifier) in the present application adopts a junction field effect transistor JFET as an input stage transistor, which not only avoids the problem that the input impedance of a bipolar transistor is small and there is a large bias current at the base, so that weak current signal detection cannot be performed, but also avoids the hidden danger of current leakage at the gate input end due to the need for an ESD static protection unit when a field effect transistor MOSFET is used. In addition, the junction field effect transistor JFET can also provide good noise characteristics, so that a single-chip design of a low-noise, weak capacitance signal detection circuit can be realized.

[0042] The feedback capacitor C f in the CV conversion circuit (charge amplifier) is generally a pF-level capacitor, and the resonant frequency of the sensitive structure is about 30 kHz, so the resistance value of the feedback resistor R f needs to be greater than 100MΩ. Since the resistance value is large, if a polysilicon resistor is used in the chip, it will occupy a large chip area and cause cost waste, and also generate a large noise, therefore, the CV conversion circuit (charge amplifier) in the present application adopts a PMOS active resistor design to realize a high-resistance, low-noise feedback resistor Rf function.

[0043] As Figure 3 shown, the A port and the B port are equivalent to two ends of a PMOS active resistor R f . The circuit design of the PMOS active resistor R f adopts an operational amplifier negative feedback technology for stabilizing the resistance value of the PMOS active resistor R f , so that the resistance value does not change with the change of the input signal voltage amplitude of the A port and the B port. The PMOS transistor M1, the PMOS transistor M6, the NMOS transistor M2, the NMOS transistor M4, the NMOS transistor M10 and the NMOS transistor M7 constitute a simple operational amplifier circuit, wherein the NMOS transistor M2 and the NMOS transistor M4 are input stages of the operational amplifier, and IB_10uA is a bias current provided for the internal operational amplifier. The PMOS transistor M9 and the bias current IB_CTRL jointly provide a gate bias voltage for the active resistance PMOS transistor M8 and the PMOS transistor M5. When the input signal voltage amplitude of the A port or the B port increases, the source voltage of the PMOS transistor M5 and the PMOS transistor M8 increases, which causes the gate voltage of the input stage NMOS transistor M2 of the operational amplifier to increase, thereby increasing the current size of the NMOS transistor M2 and the PMOS transistor M1 branch. According to the current mirror relationship of the PMOS transistor M1 and the PMOS transistor M6, the current flowing through the PMOS transistor M6 increases, while the tail current source current size of the operational amplifier itself does not change, thus causing the source voltage of the PMOS transistor M9 to increase. Meanwhile, the current size of IB_CTRL remains unchanged, and the gate voltages of the PMOS transistor M9, the PMOS transistor M5 and the PMOS transistor M8 also increase, thereby ensuring that the gate-source voltage of the PMOS transistor M5 and the PMOS transistor M8 is fixed and does not change, that is, the resistance value of the PMOS active resistor does not change and is irrelevant to the change of the input signal voltage amplitude of the A port and the B port. When designing the circuit chip, the width-length ratio and the gate-source voltage of the PMOS transistor M5 and the PMOS transistor M8 can be designed to realize a PMOS active resistor of not less than 100MΩ.

[0044]

[0045] Specifically, the silicon resonance pressure sensor in the application adopts an AC automatic gain control scheme AC-AGC, and an amplitude-modulated sinusoidal signal is generated in the single-chip circuit and used as a driving excitation signal. A junction field effect transistor JFET working in a linear region is used, and the source-drain effective resistance R DS of the JFET is inversely proportional to the gate-source voltage V GS (V GS increases, R DSThe amplitude of the detection sinusoidal signal is controlled by the negative feedback control, and the whole loop gain is automatically controlled and adjusted. When the amplitude of the detection sinusoidal signal exceeds the amplitude setting target value, the amplitude of the driving excitation signal is reduced; when the amplitude of the detection sinusoidal signal is less than the amplitude setting target value, the amplitude of the driving excitation signal is increased, and the loop phase relationship is adjusted to meet the requirement of the loop phase difference 2nπ, so that the sensitive structure of the silicon resonant pressure sensor is stably oscillated at the resonant frequency point.

[0046] The implementation mode of the driving excitation signal generation circuit is shown in Figure 4 . PI VPI is a direct current voltage signal after PI correction, sin V is a sinusoidal detection signal after phase adjustment, EXC V is a driving excitation signal applied to the sensitive structure of the pressure sensor.

[0047]

[0048] I DSS V is the saturation drain current of the junction field effect transistor (V GS =0), and V GS(off) is the pinch-off voltage of the junction field effect transistor, which are determined by the selected integrated circuit BCD process. Similarly, the CV conversion circuit (charge amplifier) can also be controlled by switches to adjust the resistance value of the resistor R2 to select the multi-gear amplification gain. Therefore, during the whole table debugging of the silicon resonant pressure sensor, the amplitude of the driving excitation signal can be set according to the structure parameters of the sensitive structure, and the resonant frequency stability, oscillation nonlinearity and detection sensitivity are comprehensively considered to select the best working state, so that the silicon resonant pressure sensor can be stably frequency-stable and amplitude-stable.

[0049] Specifically, the peak detection circuit in the application adopts a full-wave rectification and a second-order low-pass filter circuit, and the implementation mode of the full-wave rectification circuit is shown in Figure 5 .

[0050] V out =|V sin |

[0051] Specifically, the temperature sensor circuit in the application is designed by using the negative temperature characteristic of the base-emitter voltage V BE of the transistor Q1. The output voltage V T of the temperature sensor circuit is inversely proportional to the temperature, and the specific implementation mode is shown in Figure 6 .

[0052]

[0053] Transistor Q1 base-emitter voltage V BE determined by the selected integrated circuit BCD process, and can be determined by adjusting the resistance value ratio of resistor R2 and resistor R3 T .

[0054] Specifically, the high-voltage charge pump circuit in the application adopts a Dickson voltage multiplier structure, the diodes are selected to be of the type with buried layers (to reduce leakage current), and high-voltage interdigital capacitors are used, and the implementation is as shown in Figure 7 .

[0055] V H = VDD + N * (V clk -V t )- V t

[0056] CLK and / CLK are a pair of complementary overlapping clock signals, V clk is a high-level voltage value, V t is a diode voltage drop, and N is a multiplication number of stages.

[0057] As shown in Figure 1 , the application further provides a MEMS silicon resonant pressure sensor automatic gain control circuit single-chip implementation method. The MEMS silicon resonant pressure sensor core circuit is an automatic gain control circuit, which mostly uses discrete components such as operational amplifiers, comparators, resistors, and capacitors, and is implemented by building a PCB circuit board. Therefore, there are problems such as large volume, large weight, high power consumption, and high cost. At the same time, the adaptability of the pure analog scheme circuit board to the silicon resonant pressure sensor sensitive structure and the whole table adjustability also have limitations. Therefore, the sensor automatic gain control circuit function is integrated on the same chip, and the EEPROM-IP unit is integrated on the chip for adjusting and storing the closed-loop gain, the proportional coefficient, and other electrical performance parameters, so that it matches the silicon resonant pressure sensor sensitive structure parameters, thereby realizing the whole silicon resonant pressure sensor automatic gain closed-loop control function, and ensuring that the pressure sensor sensitive structure continuously oscillates at the resonant frequency point with stable amplitude and frequency.

[0058] S1, the whole MEMS silicon resonant pressure sensor includes a silicon resonant pressure sensor sensitive structure and an AC-AGC AC automatic gain control circuit. The silicon resonant pressure sensor sensitive structure and the AC-AGC AC automatic gain control circuit form a closed-loop feedback control loop, and the detected sinusoidal signal is processed through band-pass filtering and square wave signal conversion, and the detection pressure value-frequency value conversion output is completed.

[0059] S2, the silicon resonant pressure sensor sensitive structure and the automatic gain control circuit constitute a closed loop feedback loop, the pressure sensor sensitive structure is excited under the action of noise and electrostatic force. The weak capacitance detection single chip circuit design needs to improve the signal to noise ratio of detection, and selects the CV conversion circuit (charge amplifier) structure by combining the temperature characteristics, linearity and stability of weak capacitance detection and other factors, to convert the weak capacitance change into a sinusoidal voltage signal Vsin. The sinusoidal voltage signal is connected to the drive excitation signal generation circuit module after phase adjustment, and is connected to the peak detection circuit module after band pass filtering and square wave conversion, and is connected to the frequency output.

[0060] In order to save the chip area and reduce the circuit noise, the feedback resistor R f in the CV conversion circuit (charge amplifier) of the application is designed by using PMOS active resistor.

[0061] S3, the sinusoidal voltage signal passes through the peak detection circuit, that is, full wave / half wave rectification and low pass filtering link, extracts the peak value information of the amplitude of the sinusoidal voltage signal, and obtains a direct current voltage signal Vdc.

[0062] S4, the amplitude Vdc of the sinusoidal voltage signal enters the PI control module, and after difference comparison and proportional integral correction processing with the amplitude target value, a direct current correction voltage V PI is obtained. The PI control module can also be adjusted according to the parameters such as the overall accuracy of the silicon resonant pressure sensor, the starting time and other parameter index requirements, and only the proportional P link can be selected.

[0063] S5, the direct current correction voltage V PI and the sinusoidal voltage signal Vsin after phase adjustment enter the drive excitation signal generation circuit, and after operation to generate a sinusoidal drive excitation voltage signal V EXC , the feedback is applied to the silicon resonant pressure sensor sensitive structure, and through the automatic adjustment loop gain, the negative feedback closed loop control of the amplitude of the detection sinusoidal signal V EXC is realized, so that the stable amplitude-stable frequency control of the whole resonant closed loop is realized. That is, when the amplitude of the sinusoidal signal V EXC is less than the target set value, the amplitude of the drive excitation voltage signal V EXC is increased, and when the amplitude of the sinusoidal signal V EXC is greater than the target set value, the amplitude of the drive excitation voltage signal V EXC is increased.

[0064] S6, the high voltage charge pump and the temperature sensor provide the direct current high voltage and the temperature information of the sensor working, which are used to improve the detection sensitivity of the pressure sensor, and to calibrate and compensate the temperature coefficient.

[0065] S7, the EEPROM-IP module integrated in the chip can complete the adjustment and storage of the parameter indexes of each functional module of the automatic gain control circuit, including loop gain (10 times to 200 times), loop phase compensation (0° to 90°), filter characteristic (low-pass filter cutoff frequency range 10Hz to 10kHz), excitation voltage amplitude (2V to 3.3V) and proportional integral coefficient (proportional coefficient 1 times to 20 times) and the like. At the same time, the calibration, compensation and coefficient storage of the key indexes of the silicon resonant pressure sensor, such as linearity, temperature characteristic and comprehensive accuracy of the whole meter, can also be completed.

[0066] S8, the MEMS silicon resonant pressure sensor starts to work normally.

[0067] The automatic gain control circuit of the silicon resonant pressure sensor can realize the automatic control of the loop gain of the whole meter of the sensor, that is, when the amplitude of the detected sinusoidal signal is reduced, the amplitude of the driving excitation voltage is increased to increase the electrostatic force, so as to increase the amplitude of the detected sinusoidal signal and complete the negative feedback function; on the contrary, when the amplitude of the detected sinusoidal signal is increased, the amplitude of the driving excitation voltage is reduced to reduce the electrostatic force, so as to suppress the increase of the amplitude of the detected sinusoidal signal, and finally realize the stable frequency and amplitude oscillation of the sensitive structure of the silicon resonant pressure sensor at the resonance frequency point. The single-chip implementation method of the present application is used to design the sensor control circuit at the chip level, so that the types and quantities of components used in the original control circuit board are reduced, the volume and weight of the control circuit and the whole meter of the sensor are reduced, and the power consumption and cost of the whole meter of the sensor are reduced.

[0068] The beneficial effect of the present application is that the single-chip implementation method of the MEMS silicon resonant pressure sensor automatic gain control circuit ensures the high performance and high reliability requirements of the original silicon resonant pressure sensor, and based on the integrated circuit BCD (Bipolar-CMOS-DMOS) process, the traditional board-level control circuit which mainly uses operational amplifiers, comparators, EEPROM memories and discrete components such as resistance and capacitance is designed as a single-chip at the chip level, and the non-volatile storage unit EEPROM-IP is integrated on the chip for adjusting and storing the closed-loop gain, proportional coefficient and other electrical performance parameters of the single-chip circuit, and storing the calibration and compensation coefficients of the sensor whole meter, so that the single-chip circuit of the silicon resonant pressure sensor is matched with the sensitive structure parameters, thereby realizing the automatic gain closed-loop control of the whole silicon resonant pressure sensor. The single-chip implementation method of the MEMS silicon resonant pressure sensor automatic gain control circuit can reduce the original PCB circuit board to a single chip, greatly reduce the types and quantities of components on the original circuit board, reduce the volume and weight of the control circuit and the whole pressure sensor, and reduce the power consumption and cost of the whole pressure sensor.

[0069] It should be noted that if the present application embodiments involve directional indications such as up, down, left, right, front, back, etc., the directional indications are only used to explain the relative position relationship, motion condition, etc. between the components in a certain specific posture as shown in the drawings, and if the specific posture changes, the directional indications will also change accordingly.

[0070] In addition, if the present application embodiments involve descriptions such as "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first" and "second" can explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes, for example, "A and / or B" includes A scheme, or B scheme, or A and B simultaneously meet the scheme. In addition, "multiple" means two or more. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist.

[0071] The above only describes the preferred embodiments of the present application and does not limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A MEMS silicon resonant pressure sensor, characterized in that... It includes: a silicon resonant pressure sensor sensitive structure and an AC-AGC automatic gain control single-chip circuit. The silicon resonant pressure sensor sensitive structure and the AC-AGC automatic gain control single-chip circuit form a closed-loop feedback control loop. At the same time, the detected sine wave signal is processed by bandpass filtering and square wave signal conversion to complete the conversion output of the detected pressure value to the frequency value. The AC-AGC automatic gain control single-chip circuit includes a weak capacitance detection circuit functional module, which adopts a CV conversion circuit. In the CV conversion circuit, the operational amplifier uses a junction field-effect transistor (JFET) as the input stage transistor. The CV conversion circuit uses a PMOS active resistor; The AC-AGC automatic gain control single-chip circuit uses and generates an amplitude-modulated sine wave signal as the driving excitation signal, and utilizes a junction field-effect transistor (JFET) operating in the linear region, whose effective source-drain resistance R... DS With gate-source voltage V GS Based on the inverse proportional relationship, a driving excitation signal generation circuit is constructed to control the amplitude of the detected sine wave signal through negative feedback, as well as to automatically control and adjust the gain of the entire loop. The AC-AGC automatic gain control single-chip circuit also includes a peak detection circuit, which uses full-wave rectification and second-order low-pass filter circuit. The AC-AGC automatic gain control single-chip circuit also includes a high-voltage charge pump circuit, which adopts a Dickson voltage multiplier structure, and uses buried layer diodes and high-voltage interdigitated capacitors. The AC-AGC automatic gain control single-chip circuit also includes a temperature sensor circuit, which uses the base-emitter voltage V of transistor Q1 to control the temperature sensor circuit. BE Designed with negative temperature characteristics; The chip integrates an EEPROM-IP unit for adjusting and storing closed-loop gain, proportional coefficient, and electrical performance parameters.

2. A single-chip implementation method for automatic gain control circuit of MEMS silicon resonant pressure sensor, characterized in that: Specifically, it includes the following steps: The silicon resonant pressure sensor’s sensitive structure and automatic gain control circuit form a closed-loop feedback loop. The pressure sensor’s sensitive structure oscillates under the influence of noise and electrostatic force, converting the weak capacitance change into a sinusoidal voltage signal Vsin. The sinusoidal voltage signal enters the drive excitation signal generation circuit module after phase adjustment in the first path, enters the peak detection circuit module in the second path, and enters the frequency output after bandpass filtering and square wave conversion in the third path. The sinusoidal voltage signal passes through a peak detection circuit to extract the peak value information of the sinusoidal voltage signal amplitude, thus obtaining the DC voltage signal Vdc. The amplitude Vdc of the sinusoidal voltage signal enters the PI control module, where it is compared with the target amplitude value and subjected to proportional-integral correction to obtain the DC correction voltage V. PI The PI control module can be adjusted according to the overall accuracy, start-up time and other parameters of the silicon resonant pressure sensor. DC correction voltage V PI The phase-adjusted sinusoidal voltage signal Vsin enters the drive excitation signal generation circuit, which calculates and generates a sinusoidal drive excitation voltage signal V. EXC Then, feedback is applied to the sensitive structure of the silicon resonant pressure sensor. By automatically adjusting the loop gain, the amplitude of the detected sinusoidal signal Vsin is controlled by negative feedback closed loop, thereby achieving amplitude-frequency stability control of the entire resonant closed loop.

3. The single-chip implementation method of the automatic gain control circuit for a MEMS silicon resonant pressure sensor as described in claim 2, characterized in that: The MEMS silicon resonant pressure sensor relies on noise to start oscillating. Through automatic control and adjustment of loop gain, the amplitude of the driving excitation voltage is adjusted. The negative feedback control of the amplitude of the detected sinusoidal voltage is achieved. After several cycles, the pressure sensor's sensitive structure achieves stable frequency and amplitude continuous oscillation at its resonant frequency point. The CV conversion circuit outputs a sinusoidal voltage signal with stable frequency and amplitude. After bandpass filtering and square wave conversion, a frequency voltage signal representing the magnitude of the pressure value to be measured is output.

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