CN117691989A - Charge feedback MEMS capacitive sensor interface integrated circuit system - Google Patents
Charge feedback MEMS capacitive sensor interface integrated circuit system Download PDFInfo
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Abstract
An interface integrated circuit system of a charge feedback MEMS capacitive sensor belongs to the field of acceleration sensors. The invention aims at the problem of poor stability of a rear-stage interface circuit of the traditional capacitive sensor. The clock signal generating module generates a clock signal with set frequency and outputs the clock signal to the time sequence circuit control module and the driving signal generating module; the driving signal generating module generates a driving square wave signal and applies the driving square wave signal to the MEMS sensitive mechanical structure and the charge amplifier module; the time sequence circuit control module generates a switch control signal for controlling the charge amplifier module and the related double sampling module, and the charge amplifier module samples noise output by the charge amplifier module under a charge discharging reset phase; under the charge sampling phase and the feedback phase, the correlated double sampling module respectively samples a signal to be detected and a feedback signal output by the charge amplifier module; and obtaining an analog voltage signal through a proportional amplifying module. The invention is used for detecting the acceleration signal.
Description
Technical Field
The invention relates to a charge feedback MEMS capacitive sensor interface integrated circuit system, and belongs to the field of acceleration sensors.
Background
The MEMS capacitive sensor is a sensor which can be used for detecting various signals, can convert various physical signals into measurable electric signals, and is widely applied to the automobile industry, geological exploration, aerospace and consumer electronics.
Capacitive sensors are the most widely used MEMS sensors. For example, when the micro accelerometer is applied to an automobile safety airbag, whether the automobile has a safety accident or not can be judged through instantaneous acceleration change, the ejection of the safety airbag is controlled, and the safety of a driver and passengers is protected; in consumer electronics, accelerometers are used for camera stabilization, motion sensing game control in cell phones and gaming machines, personal computer hard disk protection, music player playback, song switching, etc., where the range is often ±1 g.
The capacitive sensor is divided into two parts, namely a sensitive structural unit and a rear-stage interface circuit. The sensitive structural unit is responsible for converting the input physical signal into an electrical signal that facilitates detection by the circuit. For capacitive sensitive structures, the input physical signal is converted to a small differential capacitance change, which in turn is converted to a change in charge. The interface circuit detects the change of the differential capacitance, converts the change into the change of the electrical quantity which is easier to process, amplifies the change of the electrical quantity according to a certain proportion, and is convenient for obtaining more visual physical signals, and the amplified proportion is also called the sensitivity of the sensor. Both determine the accuracy and other properties of the capacitive sensor.
Along with the improvement of the MEMS technology level, the precision and the stability of the sensitive structure are greatly improved, and the sensitive structure is widely applied, so that the performance requirement on a later-stage interface circuit is continuously improved, the structure is more reasonable, and the circuit structure with more ingenious design is also an important point of attention in the field of accelerometers. It is necessary to study and design the capacitive sensor interface circuit.
Disclosure of Invention
Aiming at the problem of poor stability of a rear-stage interface circuit of the traditional capacitive sensor, the invention provides a charge feedback MEMS capacitive sensor interface integrated circuit system.
The invention relates to a charge feedback MEMS capacitive sensor interface integrated circuit system, which comprises,
the clock signal generating module is used for generating a clock signal with set frequency and outputting the clock signal to the time sequence circuit control module and the driving signal generating module;
the driving signal generating module generates a driving square wave signal according to a clock signal with a set frequency, applies the driving square wave signal to the MEMS sensitive mechanical structure and the charge amplifier module, and the MEMS sensitive mechanical structure generates capacitance change according to a received signal to be detected and outputs a voltage signal to be detected to the charge amplifier module; the charge amplifier module simultaneously receives the analog voltage signal output by the proportional amplifying module as a feedback signal;
the time sequence circuit control module generates a switch control signal for controlling the charge amplifier module and the related double sampling module according to a clock signal with a set frequency, so that the charge amplifier module is provided with a charge release reset phase, a charge sampling phase and a feedback phase; in the charge discharging reset phase, the correlated double sampling module samples noise output by the charge amplifier module; under the charge sampling phase and the feedback phase, the correlated double sampling module respectively samples a signal to be detected and a feedback signal output by the charge amplifier module;
the proportional amplifying module is provided with different proportional amplifying times through switch control, and the sampling signals output by the related double sampling modules are amplified in proportion to obtain analog voltage signals under three phases of the charge amplifier module.
According to the charge feedback MEMS capacitive sensor interface integrated circuit system, a switch control signal of the proportional amplification module is output through the control unit and is transmitted to an amplification factor control signal input end of the proportional amplification module through the SPI communication module.
According to the charge feedback MEMS capacitive sensor interface integrated circuit system, an analog voltage signal output by a proportional amplification module is converted into a digital voltage signal through an analog-to-digital conversion module, and then the digital voltage signal is transmitted to a control unit through an SPI communication module;
the analog-to-digital conversion module converts an input analog voltage signal under the control of an AD control signal generated by the time sequence circuit control module according to a set frequency clock signal.
According to the charge feedback MEMS capacitive sensor interface integrated circuit system, a voltage reference module is adopted to provide a low-temperature drift stable voltage of 2.5V for a charge amplifier module, a correlated double sampling module, a proportional amplifying module and an analog-to-digital conversion module;
the voltage reference module is used for providing 2.5V and 5V high-low voltage reference signals for the driving signal generation module.
The charge feedback MEMS capacitive sensor interface integrated circuit system comprises a charge amplifier module, a charge amplifier module and a control module, wherein the charge amplifier module comprises an operational amplifier A1, a switch S2, a switch S3, a switch S4, a switch S5, a switch S6, a switch S7, a switch S8, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5 and a capacitor C6; the MEMS sensitive mechanical structure includes a variable capacitor Cs1 and a variable capacitor Cs2;
the connection relation between the MEMS sensitive mechanical structure and the charge amplifier module is as follows:
the positive electrode of the driving square wave signal Vs generated by the driving signal generating module is connected with one end of the capacitor C2 through the switch S2, the other end of the capacitor C2 is connected with the negative input end of the operational amplifier A1, the negative electrode of the driving square wave signal Vs generated by the driving signal generating module is connected with one end of the capacitor C1 through the switch S1, and the other end of the capacitor C1 is connected with the positive input end of the operational amplifier A1;
the positive electrode of the driving square wave signal Vs is connected with the movable electrode of the variable capacitor Cs2 through a switch S8, and the fixed electrode of the variable capacitor Cs2 is connected with the negative input end of the operational amplifier A1; the negative electrode of the driving square wave signal Vs is connected with the movable electrode of the variable capacitor Cs1 through a switch S7, and the fixed electrode of the variable capacitor Cs1 is connected with the positive input end of the operational amplifier A1;
a capacitor C3 and a switch S3 are sequentially connected between the positive input end of the operational amplifier A1 and the negative output end Voutn of the operational amplifier A1, and a capacitor C4 and a switch S4 are sequentially connected between the negative input end of the operational amplifier A1 and the positive output end Voutp of the operational amplifier A1; the negative output end Voutn of the operational amplifier A1 is used as the output negative end of the charge amplifier module, and the positive output end Voutp of the operational amplifier A1 is used as the output positive end of the charge amplifier module;
the positive input end of the operational amplifier A1 is connected with one end of a switch S5 through a capacitor C5, and the other end of the switch S5 is used as a feedback signal to be input into a positive end Vfbp; the negative input end of the operational amplifier A1 is connected with one end of a switch S6 through a capacitor C6, and the other end of the switch S6 is used as a feedback signal to be input into the negative end Vfbn.
According to the charge feedback MEMS capacitive sensor interface integrated circuit system, the corresponding switch control of the charge amplifier module under the charge release reset phase, the charge sampling phase and the feedback phase is as follows:
generating a switch control signal according to a set frequency clock signal, so that the switches S1 to S8 are all disconnected, and the charge amplifier module is in a charge discharging reset phase, so that the charge of each node in the module is discharged outwards;
the switch S2, the switch S7, the switch S3 and the switch S4 are closed, other switches are opened, the charge amplifier module is in a charge sampling phase, and a voltage signal to be detected, which is output by the MEMS sensitive mechanical structure, is sampled;
the switch S1, the switch S8, the switch S5 and the switch S6 are closed, other switches are opened, the charge amplifier module is in a feedback phase, and an analog voltage signal output by the proportional amplifying module is fed back to the charge amplifier module in a charge feedback mode, so that electrical feedback is realized.
According to the charge feedback MEMS capacitive sensor interface integrated circuit system, the related double sampling module comprises a capacitor C9, a capacitor C10, a capacitor C11, a capacitor C12, a switch S9, a switch S10, a switch S11 and a switch S12;
one end of the capacitor C9 is used as an input negative terminal inn of the related double-sampling module, the other end of the capacitor C9 is connected with one end of the switch S9, and the other end of the switch S9 is used as an output negative terminal outn of the related double-sampling module; one end of the capacitor C10 is used as an input positive end inp of the related double-sampling module, the other end of the capacitor C10 is connected with one end of the switch S10, and the other end of the switch S10 is used as an output positive end outp of the related double-sampling module;
a switch S11 is connected between the other end of the capacitor C9 and the ground voltage, and the capacitor C11 is connected between the ground voltage and the output negative terminal outn; the switch S12 is connected between the other end of the capacitor C10 and the ground voltage, and the capacitor C12 is connected between the ground voltage and the output positive end outp.
According to the charge feedback MEMS capacitive sensor interface integrated circuit system, the switch control of the related double sampling module is as follows:
in a charge discharging reset phase of the charge amplifier module, a switch control signal is generated according to a clock signal with a set frequency, so that a switch S11 and a switch S12 are closed, a switch S9 and a switch S10 are opened, and the related double sampling module samples noise output by the charge amplifier module and stores the noise on a capacitor C9 and a capacitor C10 in a charge mode;
in the charge sampling phase and the feedback phase of the charge amplifier module, the switch S11 and the switch S12 are opened and the switch S9 and the switch S10 are closed, and the entire output of the charge amplifier module is sampled.
According to the charge feedback MEMS capacitive sensor interface integrated circuit system, a proportional amplification module comprises a resistor R0, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a switch S13, a switch S14, a switch S15, a switch S16, a switch S17, a switch S18, the same operational amplifier A2 and operational amplifier A3;
the positive input end of the operational amplifier A2 is used as the negative input end inn of the proportional amplifying module, and the output end of the operational amplifier A2 is used as the negative output end outn of the proportional amplifying module; a switch S13, a resistor R1, a resistor R2 and a resistor R3 are sequentially connected between the negative input end and the output end of the operational amplifier A2; one end of the switch S14 is connected with the negative input end of the operational amplifier A2, and the other end of the switch S14 is connected between the resistor R1 and the resistor R2; one end of the switch S15 is connected with the negative input end of the operational amplifier A2, and the other end of the switch S15 is connected between the resistor R2 and the resistor R3;
the positive input end of the operational amplifier A3 is used as the positive input end inp of the proportional amplifying module, and the output end of the operational amplifier A3 is used as the positive output end outp of the proportional amplifying module; a switch S16, a resistor R4, a resistor R5 and a resistor R6 are sequentially connected between the negative input end and the output end of the operational amplifier A3, one end of a switch S17 is connected with the negative input end of the operational amplifier A3, the other end of the switch S17 is connected between the resistor R4 and the resistor R5, one end of a switch S18 is connected with the negative input end of the operational amplifier A3, and the other end of the switch S18 is connected between the resistor R5 and the resistor R6;
a resistor R0 is connected between the switch S13 and the switch S16.
According to the charge feedback MEMS capacitive sensor interface integrated circuit system, the switch control method of the proportional amplifying module comprises the following steps:
the switch S13 and the switch S16 are closed, the switch S14, the switch S15, the switch S17 and the switch S18 are opened, and the proportional amplifying module has the maximum amplifying power;
the switch S14 and the switch S17 are closed, the switch S13, the switch S15, the switch S16 and the switch S18 are opened, and the proportional amplifying module has medium amplification factor;
the switch S15 and the switch S18 are closed, and the switch S13, the switch S14, the switch S16, and the switch S17 are opened, so that the proportional amplification module has an intermediate amplification factor.
The invention has the beneficial effects that: the system of the invention adopts discrete time sequence to work, the signal to be tested is converted into a plate capacitance difference value through the MEMS sensitive mechanical structure, the plate capacitance difference value is converted into a voltage signal through the driving signal modulation and the charge amplifier module, then the noise is introduced into the circuit through the related double sampling module, and the signal is further amplified by the proportional amplifying module to obtain analog output.
The system adopts a discrete time detection method, is matched with a correlated double sampling technology to improve the signal to noise ratio of system detection, and simultaneously utilizes the multi-phase working state of discrete time to realize feedback of the system in an electric closed loop mode, thereby improving the resolution of the system and increasing the linearity of the system. The system adopts an electric closed-loop feedback technology, realizes negative feedback through charge balance, does not need stability compensation, and ensures circuit precision and linearity to a certain extent.
Drawings
FIG. 1 is a schematic block diagram of a charge feedback MEMS capacitive sensor interface integrated circuit system in accordance with the present invention;
FIG. 2 is a circuit block diagram of a charge amplifier module;
FIG. 3 is a circuit block diagram of a correlated double sampling module;
fig. 4 is a circuit configuration diagram of the scaling-up module.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.
The invention is further described below with reference to the drawings and specific examples, which are not intended to be limiting.
Detailed description of the inventionas shown in connection with fig. 1, the present invention provides a charge feedback MEMS capacitive sensor interface integrated circuit system comprising,
the clock signal generation module 107 is used for generating a clock signal with set frequency and outputting the clock signal to the time sequence circuit control module 106 and the driving signal generation module 109;
the driving signal generating module 109 generates a driving square wave signal according to a clock signal with a set frequency, applies the driving square wave signal to the MEMS sensitive mechanical structure and the charge amplifier module 101, and the MEMS sensitive mechanical structure generates capacitance change according to a received signal to be detected and outputs a voltage signal to be detected to the charge amplifier module 101; the charge amplifier module 101 receives the analog voltage signal output by the proportional amplifying module 103 as a feedback signal;
the time sequence circuit control module 106 generates a switch control signal for controlling the charge amplifier module 101 and the related double sampling module 102 according to the clock signal with the set frequency, so that the charge amplifier module 101 is provided with a charge release reset phase, a charge sampling phase and a feedback phase; in the charge-draining reset phase, the correlated double sampling module 102 samples noise output by the charge amplifier module 101; under the charge sampling phase and the feedback phase, the correlated double sampling module 102 respectively samples a signal to be detected and a feedback signal output by the charge amplifier module 101;
the proportional amplifying module 103 has different proportional amplifying times through switch control, and the sampling signals output by the related double sampling module 102 are subjected to proportional amplifying to obtain analog voltage signals under three phases of the charge amplifier module 101.
In this embodiment, the timing circuit control module 106 is configured to provide various control signals for discrete timing operation of the system.
The set frequency clock signal is a high frequency clock signal.
Further, as shown in fig. 1, the switch control signal of the proportional amplifying module 103 is output through the control unit and is transmitted to the amplification factor control signal input end of the proportional amplifying module 103 through the SPI communication module 105.
The control unit may be a computer, and outputs a switch control signal through a serial port of the computer, and transmits the switch control signal to the proportional amplifying module 103 through the SPI communication module 105 to control the amplification factor.
Still further, referring to fig. 1, the analog voltage signal output by the proportional amplifying module 103 is converted into a digital voltage signal by the analog-to-digital converting module 104, and then transmitted to the control unit by the SPI communication module 105;
the analog-to-digital conversion module 104 converts the input analog voltage signal under the control of the AD control signal generated by the timing circuit control module 106 according to the set frequency clock signal. The control signals generated by the timing circuit control module 106 are square wave signals with different frequencies and phases generated by the high-frequency clock signal through operations such as frequency division, logic operation, delay and the like.
The SPI communication module 105 can communicate with the control unit in both directions.
The analog voltage signal output by the proportional amplifying module 103 is output by the analog-to-digital conversion module 104. The SPI communication module 105, while configuring registers, uploads the received signals to the computer serial port.
In the embodiment, the system adopts external 5V power supply, and adopts a voltage reference module 100 to provide 2.5V low-temperature drift stable voltage for a charge amplifier module 101, a related double-sampling module 102, a proportional amplifying module 103 and an analog-to-digital conversion module 104;
the voltage reference module 100 is used to provide the 2.5V and 5V selectable high and low voltage reference signals to the drive signal generation module 109.
The embodiment further includes a temperature detection module 108, configured to monitor temperature changes during the system operation, convert the collected temperature analog signal into a temperature digital signal through the analog-to-digital conversion module 104, and transmit the temperature digital signal to the control unit through the SPI communication module 105.
The overall implementation process of the system in this embodiment is as follows: after the system is powered on, the voltage reference module 100 and the clock signal generation module 107 work first, wherein the voltage reference module 100 generates stable direct current voltages with different values required by each module and outputs the stable direct current voltages to each module; the clock signal generation module 107 generates a clock signal of a certain frequency and outputs the clock signal to the timing circuit control module 106 and the driving signal generation module 109; the timing circuit control module 106 is configured to generate control signals required for controlling the switches in the charge amplifier module 101, the related double sampling module 102 and the analog-to-digital conversion module 104, the driving signal generating module 109 generates a driving square wave signal applied to the MEMS sensitive mechanical structure, the MEMS sensitive mechanical structure sensitive signal to be tested generates a capacitance change, and under the condition of externally applying the driving square wave signal, a certain voltage signal is output, and the voltage signal obtains an analog voltage output result through the charge amplifier module 101, the related double sampling module 102 and the proportional amplifying module 103, and the result can be digitally output at the computer end through the analog-to-digital conversion module 104 and the SPI communication module 105, so that further signal processing is facilitated; the temperature detection module 108 always monitors the system temperature and performs real-time refreshing on the computer side through the analog-to-digital conversion module 104 and the SPI communication module 105.
Still further, as shown in connection with fig. 2, the charge amplifier module 101 includes an operational amplifier A1, a switch S2, a switch S3, a switch S4, a switch S5, a switch S6, a switch S7, a switch S8, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, and a capacitor C6; the MEMS sensitive mechanical structure is a variable capacitance structure formed by fixed comb teeth and movable comb teeth and comprises a variable capacitor Cs1 and a variable capacitor Cs2;
the connection relationship between the MEMS sensitive mechanical structure and the charge amplifier module 101 is:
the positive electrode of the driving square wave signal Vs generated by the driving signal generating module 109 is connected with one end of the capacitor C2 through the switch S2, the other end of the capacitor C2 is connected with the negative input end of the operational amplifier A1, the negative electrode of the driving square wave signal Vs generated by the driving signal generating module 109 is connected with one end of the capacitor C1 through the switch S1, and the other end of the capacitor C1 is connected with the positive input end of the operational amplifier A1;
the positive electrode of the driving square wave signal Vs is connected with the movable electrode of the variable capacitor Cs2 through a switch S8, and the fixed electrode of the variable capacitor Cs2 is connected with the negative input end of the operational amplifier A1; the negative electrode of the driving square wave signal Vs is connected with the movable electrode of the variable capacitor Cs1 through a switch S7, and the fixed electrode of the variable capacitor Cs1 is connected with the positive input end of the operational amplifier A1;
a capacitor C3 and a switch S3 are sequentially connected between the positive input end of the operational amplifier A1 and the negative output end Voutn of the operational amplifier A1, and a capacitor C4 and a switch S4 are sequentially connected between the negative input end of the operational amplifier A1 and the positive output end Voutp of the operational amplifier A1; the negative output end Voutn of the operational amplifier A1 is used as the output negative end of the charge amplifier module 101, and the positive output end Voutp of the operational amplifier A1 is used as the output positive end of the charge amplifier module 101;
the positive input end of the operational amplifier A1 is connected with one end of a switch S5 through a capacitor C5, and the other end of the switch S5 is used as a feedback signal to be input into a positive end Vfbp; the negative input end of the operational amplifier A1 is connected with one end of a switch S6 through a capacitor C6, and the other end of the switch S6 is used as a feedback signal to be input into the negative end Vfbn.
Still further, as shown in conjunction with fig. 1 and 2, the corresponding switching control of the charge amplifier module 101 in the charge-draining reset phase, the charge sampling phase, and the feedback phase is:
the working process of the charge amplifier module 101 is not continuously performed, but discrete sampling is performed by switch control for detection; generating a switch control signal according to the set frequency clock signal, so that the switches S1 to S8 are all disconnected, and the charge amplifier module 101 is in a charge discharging reset phase, so that the charge of each node in the module is discharged outwards;
the switch S2, the switch S7, the switch S3 and the switch S4 are closed, other switches are opened, the charge amplifier module 101 is in a charge sampling phase, and a voltage signal to be detected, which is output by the MEMS sensitive mechanical structure, is sampled;
the switch S1, the switch S8, the switch S5 and the switch S6 are closed, the other switches are opened, the charge amplifier module 101 is in a feedback phase, and an analog voltage signal output by the proportional amplifying module 103 is fed back to the charge amplifier module 101 in a charge feedback mode, so that electrical feedback is realized. The three phases reciprocate back and forth to realize the sampling and detection of the previous stage signals, and the control signals for controlling the switches S1-S8 are generated by the time sequence circuit control module 106.
Referring to fig. 3, the correlated double sampling module 102 includes a capacitor C9, a capacitor C10, a capacitor C11, a capacitor C12, a switch S9, a switch S10, a switch S11, and a switch S12;
one end of the capacitor C9 is used as an input negative terminal inn of the related double-sampling module 102, the other end of the capacitor C9 is connected with one end of the switch S9, and the other end of the switch S9 is used as an output negative terminal outn of the related double-sampling module 102; one end of the capacitor C10 is used as an input positive end inp of the related double-sampling module 102, the other end of the capacitor C10 is connected with one end of the switch S10, and the other end of the switch S10 is used as an output positive end outp of the related double-sampling module 102;
a switch S11 is connected between the other end of the capacitor C9 and the ground voltage, and the capacitor C11 is connected between the ground voltage and the output negative terminal outn; the switch S12 is connected between the other end of the capacitor C10 and the ground voltage, and the capacitor C12 is connected between the ground voltage and the output positive end outp.
As shown in fig. 1 and fig. 3, the correlated double sampling module 102 may implement double sampling on the previous signal, and implement a result of reducing signal noise, where the switching control of the correlated double sampling module 102 is:
in the charge discharging reset phase of the charge amplifier module 101, a switch control signal is generated according to a set frequency clock signal, so that a switch S11 and a switch S12 are closed, a switch S9 and a switch S10 are opened, and the correlated double sampling module 102 samples noise output by the charge amplifier module 101 and stores the noise on a capacitor C9 and a capacitor C10 in a charge mode;
in the charge sampling phase and the feedback phase of the charge amplifier module 101, the switch S11 and the switch S12 are opened and the switch S9 and the switch S10 are closed, sampling the overall output of the charge amplifier module 101; noise charges in the two samplings are counteracted to a certain extent, and the purpose of reducing signal noise is achieved. The control signals for switches S9-S11 are also generated by the timing circuit control module 106.
Still further, referring to fig. 4, the proportional amplifying module 103 includes a resistor R0, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a switch S13, a switch S14, a switch S15, a switch S16, a switch S17, a switch S18, and the same operational amplifier A2 and operational amplifier A3;
the positive input end of the operational amplifier A2 is used as the negative input end inn of the proportional amplifying module 103, and the output end of the operational amplifier A2 is used as the negative output end outn of the proportional amplifying module 103; a switch S13, a resistor R1, a resistor R2 and a resistor R3 are sequentially connected between the negative input end and the output end of the operational amplifier A2; one end of the switch S14 is connected with the negative input end of the operational amplifier A2, and the other end of the switch S14 is connected between the resistor R1 and the resistor R2; one end of the switch S15 is connected with the negative input end of the operational amplifier A2, and the other end of the switch S15 is connected between the resistor R2 and the resistor R3;
the positive input end of the operational amplifier A3 is used as the positive input end inp of the proportional amplifying module 103, and the output end of the operational amplifier A3 is used as the positive output end outp of the proportional amplifying module 103; a switch S16, a resistor R4, a resistor R5 and a resistor R6 are sequentially connected between the negative input end and the output end of the operational amplifier A3, one end of a switch S17 is connected with the negative input end of the operational amplifier A3, the other end of the switch S17 is connected between the resistor R4 and the resistor R5, one end of a switch S18 is connected with the negative input end of the operational amplifier A3, and the other end of the switch S18 is connected between the resistor R5 and the resistor R6;
a resistor R0 is connected between the switch S13 and the switch S16.
As shown in fig. 1 and 4, the switch control method of the proportional amplifying module 103 is as follows:
different proportional amplification can be realized by controlling the closing state of the switch S13-the switch S18; under different amplification factors, only one pair of switches in the two groups of switches S13-S15 and S16-S18 is closed; the method comprises the following steps:
switch S13 and switch S16 are closed, switch S14, switch S15, switch S17 and switch S18 are opened, and the scaling module 103 has the maximum amplification factor;
switch S14 and switch S17 are closed, switch S13, switch S15, switch S16 and switch S18 are opened, and the proportional amplification module 103 has a medium amplification factor;
the switch S15 and the switch S18 are closed, and the switch S13, the switch S14, the switch S16, and the switch S17 are opened, so that the proportional amplification module 103 has an intermediate amplification factor.
The switch control signals of the proportional amplifying module 103 are transmitted by the SPI communication module 105, and the switches of the proportional amplifying module 103 can be controlled by a control unit, for example, by a computer input mode.
In conclusion, the system can realize low-noise and high-linearity detection and amplification of the acceleration signal, and then the acceleration signal is cascaded to a subsequent analog-to-digital conversion module and an SPI communication module, so that the measurement signal can be transmitted to a computer for signal processing and utilization.
Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the different dependent claims and the features described herein may be combined in ways other than as described in the original claims. It is also to be understood that features described in connection with separate embodiments may be used in other described embodiments.
Claims (10)
1. A charge feedback MEMS capacitive sensor interface integrated circuit system, comprising,
a clock signal generating module (107) is adopted to generate a clock signal with set frequency and output the clock signal to a time sequence circuit control module (106) and a driving signal generating module (109);
the driving signal generation module (109) generates a driving square wave signal according to a clock signal with a set frequency, applies the driving square wave signal to the MEMS sensitive mechanical structure and the charge amplifier module (101), and the MEMS sensitive mechanical structure generates capacitance change according to a received signal to be detected and outputs a voltage signal to be detected to the charge amplifier module (101); the charge amplifier module (101) simultaneously receives an analog voltage signal output by the proportional amplification module (103) as a feedback signal;
the time sequence circuit control module (106) generates a switch control signal for controlling the charge amplifier module (101) and the related double sampling module (102) according to a clock signal with a set frequency, so that the charge amplifier module (101) is provided with a charge release reset phase, a charge sampling phase and a feedback phase; in a charge discharging reset phase, a correlated double sampling module (102) samples noise output by a charge amplifier module (101); under the charge sampling phase and the feedback phase, the correlated double sampling module (102) respectively samples a signal to be detected and a feedback signal output by the charge amplifier module (101);
the proportional amplification module (103) has different proportional amplification factors through switch control, and the sampling signals output by the related double sampling module (102) are subjected to proportional amplification to obtain analog voltage signals under three phases of the charge amplifier module (101).
2. The charge feedback MEMS capacitive sensor interface integrated circuit system of claim 1,
the switch control signal of the proportional amplifying module (103) is output through the control unit and is transmitted to the amplifying factor control signal input end of the proportional amplifying module (103) through the SPI communication module (105).
3. The charge feedback MEMS capacitive sensor interface integrated circuit system of claim 2, wherein the analog voltage signal output by the proportional amplification module (103) is converted into a digital voltage signal by the analog-to-digital conversion module (104), and then transmitted to the control unit by the SPI communication module (105);
the analog-to-digital conversion module (104) converts an input analog voltage signal under the control of an AD control signal generated by the time sequence circuit control module (106) according to a set frequency clock signal.
4. A charge feedback MEMS capacitive sensor interface integrated circuit system according to claim 3, characterized in that a voltage reference module (100) is employed to provide a low temperature drift stable voltage of 2.5V for the charge amplifier module (101), the correlated double sampling module (102), the proportional amplifying module (103) and the analog-to-digital conversion module (104);
a voltage reference module (100) is used for providing 2.5V and 5V high-low voltage reference signals for a driving signal generation module (109).
5. The charge feedback MEMS capacitive sensor interface integrated circuit system of claim 4, wherein the charge amplifier module (101) comprises an op-amp A1, a switch S2, a switch S3, a switch S4, a switch S5, a switch S6, a switch S7, a switch S8, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, and a capacitor C6; the MEMS sensitive mechanical structure includes a variable capacitor Cs1 and a variable capacitor Cs2;
the connection relation between the MEMS sensitive mechanical structure and the charge amplifier module (101) is as follows:
the positive electrode of the driving square wave signal Vs generated by the driving signal generating module (109) is connected with one end of the capacitor C2 through the switch S2, the other end of the capacitor C2 is connected with the negative input end of the operational amplifier A1, the negative electrode of the driving square wave signal Vs generated by the driving signal generating module (109) is connected with one end of the capacitor C1 through the switch S1, and the other end of the capacitor C1 is connected with the positive input end of the operational amplifier A1;
the positive electrode of the driving square wave signal Vs is connected with the movable electrode of the variable capacitor Cs2 through a switch S8, and the fixed electrode of the variable capacitor Cs2 is connected with the negative input end of the operational amplifier A1; the negative electrode of the driving square wave signal Vs is connected with the movable electrode of the variable capacitor Cs1 through a switch S7, and the fixed electrode of the variable capacitor Cs1 is connected with the positive input end of the operational amplifier A1;
a capacitor C3 and a switch S3 are sequentially connected between the positive input end of the operational amplifier A1 and the negative output end Voutn of the operational amplifier A1, and a capacitor C4 and a switch S4 are sequentially connected between the negative input end of the operational amplifier A1 and the positive output end Voutp of the operational amplifier A1; the negative output end Voutn of the operational amplifier A1 is used as the output negative end of the charge amplifier module (101), and the positive output end Voutp of the operational amplifier A1 is used as the output positive end of the charge amplifier module (101);
the positive input end of the operational amplifier A1 is connected with one end of a switch S5 through a capacitor C5, and the other end of the switch S5 is used as a feedback signal to be input into a positive end Vfbp; the negative input end of the operational amplifier A1 is connected with one end of a switch S6 through a capacitor C6, and the other end of the switch S6 is used as a feedback signal to be input into the negative end Vfbn.
6. The charge feedback MEMS capacitive sensor interface integrated circuit system of claim 5, wherein the corresponding switching control of the charge amplifier module (101) in the charge-bleeding reset phase, the charge sampling phase, and the feedback phase is:
generating a switch control signal according to a set frequency clock signal, so that the switches S1 to S8 are all disconnected, and the charge amplifier module (101) is in a charge discharging reset phase, so that the charge of each node in the module is discharged outwards;
the switch S2, the switch S7, the switch S3 and the switch S4 are closed, other switches are opened, the charge amplifier module (101) is in a charge sampling phase, and a voltage signal to be detected, which is output by the MEMS sensitive mechanical structure, is sampled;
the switch S1, the switch S8, the switch S5 and the switch S6 are closed, other switches are opened, the charge amplifier module (101) is in a feedback phase, and an analog voltage signal output by the proportional amplifying module (103) is fed back to the charge amplifier module (101) in a charge feedback mode, so that electrical feedback is realized.
7. The charge feedback MEMS capacitive sensor interface integrated circuit system of claim 6, wherein the correlated double sampling module (102) comprises a capacitor C9, a capacitor C10, a capacitor C11, a capacitor C12, a switch S9, a switch S10, a switch S11, and a switch S12;
one end of the capacitor C9 is used as an input negative terminal inn of the related double-sampling module (102), the other end of the capacitor C9 is connected with one end of the switch S9, and the other end of the switch S9 is used as an output negative terminal outn of the related double-sampling module (102); one end of the capacitor C10 is used as an input positive end inp of the related double-sampling module (102), the other end of the capacitor C10 is connected with one end of the switch S10, and the other end of the switch S10 is used as an output positive end outp of the related double-sampling module (102);
a switch S11 is connected between the other end of the capacitor C9 and the ground voltage, and the capacitor C11 is connected between the ground voltage and the output negative terminal outn; the switch S12 is connected between the other end of the capacitor C10 and the ground voltage, and the capacitor C12 is connected between the ground voltage and the output positive end outp.
8. The charge feedback MEMS capacitive sensor interface integrated circuit system of claim 7, wherein the switching control of the correlated double sampling module (102) is:
in a charge discharging reset phase of the charge amplifier module (101), a switch control signal is generated according to a clock signal with a set frequency, so that a switch S11 and a switch S12 are closed, a switch S9 and a switch S10 are opened, and a correlated double sampling module (102) samples noise output by the charge amplifier module (101) and stores the noise on a capacitor C9 and a capacitor C10 in a charge mode;
in the charge sampling phase and the feedback phase of the charge amplifier module (101), the switch S11 and the switch S12 are opened and the switch S9 and the switch S10 are closed, and the entire output of the charge amplifier module (101) is sampled.
9. The charge feedback MEMS capacitive sensor interface integrated circuit system of claim 8, wherein the proportional amplification module (103) comprises a resistor R0, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a switch S13, a switch S14, a switch S15, a switch S16, a switch S17, a switch S18, the same op-amp A2 and op-amp A3;
the positive input end of the operational amplifier A2 is used as the negative input end inn of the proportional amplifying module (103), and the output end of the operational amplifier A2 is used as the negative output end outn of the proportional amplifying module (103); a switch S13, a resistor R1, a resistor R2 and a resistor R3 are sequentially connected between the negative input end and the output end of the operational amplifier A2; one end of the switch S14 is connected with the negative input end of the operational amplifier A2, and the other end of the switch S14 is connected between the resistor R1 and the resistor R2; one end of the switch S15 is connected with the negative input end of the operational amplifier A2, and the other end of the switch S15 is connected between the resistor R2 and the resistor R3;
the positive input end of the operational amplifier A3 is used as the positive input end inp of the proportional amplifying module (103), and the output end of the operational amplifier A3 is used as the positive output end outp of the proportional amplifying module (103); a switch S16, a resistor R4, a resistor R5 and a resistor R6 are sequentially connected between the negative input end and the output end of the operational amplifier A3, one end of a switch S17 is connected with the negative input end of the operational amplifier A3, the other end of the switch S17 is connected between the resistor R4 and the resistor R5, one end of a switch S18 is connected with the negative input end of the operational amplifier A3, and the other end of the switch S18 is connected between the resistor R5 and the resistor R6;
a resistor R0 is connected between the switch S13 and the switch S16.
10. The charge feedback MEMS capacitive sensor interface integrated circuit system of claim 9, wherein the switch control method of the proportional amplifying module (103) is:
the switch S13 and the switch S16 are closed, the switch S14, the switch S15, the switch S17 and the switch S18 are opened, and the proportional amplifying module (103) has the maximum amplifying power;
the switch S14 and the switch S17 are closed, the switch S13, the switch S15, the switch S16 and the switch S18 are opened, and the proportional amplification module (103) has medium amplification factor;
the switch S15 and the switch S18 are closed, the switch S13, the switch S14, the switch S16 and the switch S17 are opened, and the proportional amplification module (103) is provided with an intermediate amplification factor.
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| CN202311701690.9A CN117691989A (en) | 2023-12-12 | 2023-12-12 | Charge feedback MEMS capacitive sensor interface integrated circuit system |
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| CN202311701690.9A CN117691989A (en) | 2023-12-12 | 2023-12-12 | Charge feedback MEMS capacitive sensor interface integrated circuit system |
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