High-order automatic gain control circuit applied to resonant MEMS device

Abstract

The invention discloses a high-order automatic gain control circuit applied to a resonant MEMS (Micro Electro Mechanical System) device, which is connected with the resonant MEMS device through a charge voltage converter, converts an initial signal input from the resonant MEMS device and outputs a signal to be processed; the peak detector performs peak sampling on the to-be-processed signal and outputs the amplitude of the to-be-processed signal; the error amplifier is used for subtracting the amplitude of the signal to be processed from an amplitude set value and outputting an amplitude error signal; and the high-order error controller processes the amplitude error signal according to a first preset configuration parameter, and outputs an amplitude control signal to control the harmonic amplitude of the resonant MEMS device. According to the invention, the z-domain transfer function of the amplitude control loop is expanded to a second order or higher order form, and the zero-pole configuration is optimized, so that the interference suppression capability limit of the traditional first-order amplitude control loop is broken through, and the improvement of the harmonic amplitude control precision is realized while the system stability is maintained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of micro-electro-mechanical system, and particularly relates to a high-order automatic gain control circuit applied to a resonant MEMS device. BACKGROUND

[0002] Resonant Micro ElectroMechanical System (MEMS) device is an important branch of micro-electro-mechanical system research and manufacturing field. The resonant MEMS device drives its sensitive unit to a stable resonant state through an interface circuit to realize the measurement of a corresponding physical quantity, for example, one axis of an amplitude modulation type MEMS gyroscope is in a resonant state, and the other axis realizes the measurement of angular rate by means of Coriolis effect. The resonant MEMS device has the advantages of small size, low cost, light weight and low power consumption, and has been widely applied in motion sensing, attitude control and vibration detection.

[0003] The interface circuit of the resonant MEMS device can be divided into an amplitude control circuit and a frequency control circuit according to functions. The amplitude control circuit maintains the stability of the vibration amplitude of the resonant MEMS device, and the frequency control circuit maintains the stability of the vibration frequency of the resonant MEMS device. The commonly used amplitude control circuit relies on automatic gain control (AGC) to realize. The current vibration amplitude information is obtained by detecting the resonant displacement peak value, and an error signal is generated after the difference between the current vibration amplitude information and the set value. The error signal is amplified by a proportional amplifier to generate an amplitude control voltage, so as to control the resonant amplitude near the set value. When considering the interference of noise and other factors on the resonant MEMS device and the circuit, the method of increasing the proportional control gain is usually adopted to suppress the interference to a greater extent, so as to realize the stable control of the resonant amplitude.

[0004] However, due to the discretization effect caused by peak value sampling, too high proportional control gain will cause the instability of the amplitude control loop. In the discretization analysis, the proportional control gain in the amplitude control loop has an upper limit, so the suppression ability of the proportional control gain to the interference has a limit, and the control precision of the resonant amplitude is limited by the stability of the loop. SUMMARY

[0005] In order to solve the above problems existing in the prior art, the application provides a high-order automatic gain control circuit applied to a resonant MEMS device.

[0006] The technical problem to be solved by the application is solved by the following technical scheme: The application provides a high-order automatic gain control circuit applied to a resonant MEMS device, which comprises a charge-voltage converter and a high-order automatic gain control module. The high-order automatic gain control module comprises a peak value detector, an error amplifier and a high-order error controller. The charge-voltage converter is used for connecting the resonant MEMS device and converting an initial signal input from the resonant MEMS device to output a to-be-processed signal. The peak detector is used for performing peak sampling on the to-be-processed signal to output an amplitude of the to-be-processed signal. The error amplifier is used for performing difference between the amplitude of the to-be-processed signal and an amplitude setting value to output an amplitude error signal. The high-order error controller is used for processing the amplitude error signal according to a first preset configuration parameter to output an amplitude control signal, and the amplitude control signal is used for controlling a resonance amplitude of the resonant MEMS device.

[0007] The high-order automatic gain control circuit applied to the resonant MEMS device comprises a charge-voltage converter and a high-order automatic gain control module, and the high-order automatic gain control module comprises a peak detector, an error amplifier and a high-order error controller.

[0008] The high-order automatic gain control circuit breaks through the interference suppression capability limit of the traditional first-order amplitude control loop, improves the resonance amplitude control precision while maintaining the system stability by expanding the z-domain transfer function of the amplitude control loop to the second-order and above high-order form and optimizing the zero-pole configuration.

[0009] The application will be further described in detail below with reference to the accompanying drawings and the application. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a schematic diagram of a high-order automatic gain control circuit applied to a resonant MEMS device provided by an embodiment of the application; Figure 2 is a schematic diagram of converting a resonant MEMS device from a s-domain second-order model to a z-domain first-order model; Figure 3 is a transfer function model diagram and a zero-pole distribution schematic diagram of a traditional first-order amplitude control loop; Figure 4 is a circuit schematic diagram of a second-order automatic gain control module in the high-order automatic gain control circuit provided by the embodiment of the application; Figure 5is a transfer function model diagram and a zero pole distribution diagram of a second-order amplitude control loop provided by the embodiment of the present application; Figure 6 is a transfer function model diagram and a zero pole distribution diagram of a third-order amplitude control loop provided by the embodiment of the present application; Figure 7 is a circuit diagram of a third-order error controller in a high-order automatic gain control circuit provided by the embodiment of the present application; Figure 8 is a suppression limit and a time domain response diagram of a first-order, second-order and third-order amplitude control loop to amplitude interference provided by the embodiment of the present application; Figure 9 is a diagram of a high-order automatic gain control circuit applied to a resonant MEMS device applied to a digital signal processing scene provided by the embodiment of the present application.

[0011] Reference signs: 1, a resonant MEMS device; 2, a charge-voltage converter; 3, a high-order automatic gain control module; 31, a peak detector; 32, an error amplifier; 33, a high-order error controller; 331, a second-order error controller; 332, a third-order error controller; 34, a proportional error controller; 4, an amplitude automatic gain control circuit; 5, a frequency control circuit; 6, a driving output circuit; 7, an analog-digital converter; 8, a digital high-order automatic gain control module; 9, a digital-analog converter. DETAILED DESCRIPTION

[0012] The present application will be further described in detail below in conjunction with specific embodiments, but the embodiments of the present application are not limited thereto.

[0013] Reference signs: Figure 1 The embodiment of the present application provides a high-order automatic gain control circuit applied to a resonant MEMS device, which comprises a charge-voltage converter 2 and a high-order automatic gain control module 3, and the high-order automatic gain control module 3 comprises a peak detector 31, an error amplifier 32 and a high-order error controller 33.

[0014] The charge-voltage converter 2 is used for connecting the resonant MEMS device 1 and converting an initial signal input from the resonant MEMS device 1 to output a to-be-processed signal.

[0015] Exemplarily, the initial signal can be a charge signal containing interference noise, and the charge-voltage converter 2 converts the initial signal to obtain the to-be-processed signal, which can be a voltage signal.

[0016] In an alternative embodiment, the transfer function of the resonant MEMS device 1 in the z-domain of the present embodiment can be expressed as: ; wherein, Gz(s) represents the transfer function of the resonant MEMS device in the z-domain, ,Mz represents the equivalent mass of the resonant MEMS device, Qz represents the quality factor of the resonant MEMS device, fz represents the natural resonant frequency of the resonant MEMS device, Tz represents the period of the peak sampling, Kz represents the conversion factor of the resonant MEMS device from driving voltage to driving force, Xz(s) represents the z-domain variable of the resonant MEMS device, Pz represents the pole of the resonant MEMS device.

[0017] Exemplarily, referring to Figure 2 ,Figure 1 is a schematic diagram of the resonant MEMS device 1 converted from a s-domain second-order model to a z-domain first-order model when analyzing the amplitude control loop characteristics. Figure 2 The left half of Figure 1 is an interface circuit diagram of the resonant MEMS device 1, which includes an amplitude control circuit composed of a charge-voltage converter 2 and an amplitude automatic gain control circuit 4, a frequency control circuit 5, and a driving output circuit 6. The amplitude control circuit is used to maintain the stability of the vibration amplitude of the resonant MEMS device, the frequency control circuit is used to maintain the stability of the vibration frequency of the resonant MEMS device, and the driving output circuit combines the driving voltage amplitude and the driving voltage frequency to generate a driving voltage for driving. Figure 2

[0018] The full response model of the resonant MEMS device is a model with a s-domain second-order transfer function, and the corresponding transfer function (the input is the equivalent driving voltage of the resonant MEMS device, and the output is the equivalent driving displacement of the resonant MEMS device) is expressed as:

[0019] wherein, G(s) represents the transfer function of the resonant MEMS device in the s-domain, s represents the Laplace variable.

[0020] Referring to Figure 2Right half, in the analysis of the amplitude characteristics of the loop, due to the discretization effect of peak sampling, the resonant MEMS device 1 is amplitude reduced and discretized, and is modeled as a lossy integrator. The transfer function of the resonant MEMS device 1 in the z domain (the input is the equivalent driving voltage amplitude of the resonant MEMS device, and the output is the equivalent driving displacement amplitude of the resonant MEMS device) is represented as:

[0021] wherein, represents the transfer function of the resonant MEMS device in the z domain, represents the pole of the resonant MEMS device, , , represents the equivalent vibration mass of the resonant MEMS device, represents the quality factor of the resonant MEMS device, represents the natural resonant frequency of the resonant MEMS device, represents the period of peak sampling, represents the conversion coefficient of the resonant MEMS device driving voltage to driving force, represents the z domain variable of the resonant MEMS device.

[0022] Before detailing the high-order automatic gain control module 3 of the present embodiment, for the convenience of clearly understanding the present application, the limited disturbance suppression capability of the traditional first-order amplitude control loop due to the loop stability limitation is simply described.

[0023] Referring to Figure 3 , a traditional first-order amplitude control loop is shown, including a resonant MEMS device 1, a charge-voltage converter 2, a peak detector 31, an error amplifier 32, and a proportional error controller 34. In z domain analysis, the resonant MEMS device 1 can be modeled as a lossy integrator, and the corresponding transfer function is The charge-voltage converter 2 can be modeled as a gain stage with a gain equal to The peak detector 31 can be modeled as a gain stage with a gain equal to The error amplifier 32 can be modeled as a gain stage with a gain equal to The proportional error controller 34 can be modeled as a gain stage with a gain equal to The transfer function from the amplitude disturbance injection to the actual displacement output amplitude of the resonant MEMS device can be written as:

[0024] wherein, represents the transfer function of the first-order amplitude control loop, .

[0025] From the transfer function of the traditional first order amplitude control loop, it can be seen that there is a zero point and a pole in the loop. The zero point is determined by the parameters of the resonant MEMS device 1, and the pole is determined by the parameters of the entire circuit and the resonant MEMS device 1.

[0026] Referring to Figure 3 the right half, the gain of the proportional error controller 34 is increased , and the pole position moves to the negative direction of the real axis. The limit position is the intersection point of the unit circle and the real axis (-1, 0). According to the geometric evaluation method of the z-domain transfer function, when the pole is at the limit position, the loop has the maximum degree of suppression to the direct current (low frequency) interference, and the suppression coefficient is . This reflects the limited interference suppression capability of the first order amplitude control loop containing the proportional error controller 34 due to the stability limitation of the loop.

[0027] In combination with the above description, the high order automatic gain control module 3 of the present embodiment will be described in detail.

[0028] The peak detector 31 is used for peak sampling of the to-be-processed signal, and outputs the amplitude of the to-be-processed signal.

[0029] In an alternative embodiment, the peak detector 31 is composed of a third sampling capacitor, a feedback capacitor, a holding capacitor, an operational amplifier, a voltage buffer and corresponding switches connected thereto; the gain of the peak detector is 1.

[0030] Exemplarily, referring to Figure 4 , the peak detector 31 is composed of a third sampling capacitor , a feedback capacitor , a holding capacitor , an operational amplifier, a voltage buffer and corresponding switches. In the sampling stage, the switch controlled by the sampling control signal is closed, the differential input end of the operational amplifier is connected to the output end, the input end voltage of the operational amplifier is set to the common mode value, one end of the third sampling capacitor is connected to the input to-be-processed signal, and the other end is connected to the common mode potential, and the differential mode value of the input to-be-processed signal is saved in the form of charge. In the holding stage, the switch controlled by the holding control signal is closed, and both ends of the third sampling capacitor are connected to the common mode potential, and the charge obtained in the sampling stage is transferred to the feedback capacitor , and a voltage proportional to the sampled input to-be-processed signal is generated at the output end of the operational amplifier, and the holding capacitor The voltage connected to one end of the operational amplifier is equal to this voltage value, thus completing the peak sampling of the input signal to be processed. Alternatively, the input signal to be processed can be selected The peak detector 31 is equivalent to a gain stage with a gain of 1 in the transfer function of the high-order automatic gain control circuit.

[0031] The error amplifier 32 is used to subtract the amplitude set value from the amplitude of the signal to be processed, and output an amplitude error signal.

[0032] Exemplarily, with reference to Figure 4 The error amplifier 32 is composed of an input device , a feedback device and an operational amplifier. Alternatively, the input device and the feedback device can also be implemented by capacitors. The error amplifier 32 subtracts the amplitudes of the differential input signals and corresponding to the signal to be processed from the corresponding amplitude set values and respectively, to obtain an amplitude error signal. Alternatively, the error amplifier 32 can be selected to be equivalent to a gain stage with a gain of in the transfer function of the high-order automatic gain control circuit.

[0033] The high-order error controller 33 is used to process the amplitude error signal according to a first preset configuration parameter, and output an amplitude control signal, which is used to control the resonance amplitude of the resonant MEMS device 1.

[0034] In an alternative embodiment, the transfer function of the high-order amplitude control loop composed of the high-order automatic gain control circuit and the resonant MEMS device is represented as: (4) wherein, represents the transfer function of the high-order amplitude control loop, represents the gain of the charge-voltage converter, represents the gain of the error amplifier, represents the transfer function of the high-order error controller, represents the order of the high-order amplitude control loop, .

[0035] Exemplarily, according to the zero-pole distribution, the high-order transfer function of the high-order amplitude control loop in the z domain (the input is the noise affecting the displacement amplitude of the resonant MEMS device, and the output is the actual displacement amplitude of the resonant MEMS device) can also be represented as:

[0036] wherein, , It is the zero point in the higher-order amplitude control loop. It is a pole in a higher-order amplitude control loop. The zeros and poles are introduced by the resonant MEMS device 1 through the loop (which are also the poles of the resonant MEMS device). The remaining zeros and poles are introduced by the high-order automatic gain control module 3 through the loop. Under the premise of satisfying the loop stability, the zeros and poles of the transfer function are configured by the first preset configuration parameters to improve the loop's ability to suppress interference at the frequency of interest, thereby improving the accuracy of the resonant amplitude control.

[0037] Reference Figure 5 , Figure 5 The left half is the transfer function model of the second-order amplitude control loop, which includes the second-order error controller 331. The transfer function from the amplitude interference injection point to the actual displacement output amplitude of the resonant MEMS device, i.e., the second-order amplitude control loop transfer function, can be expressed as:

[0038] in, , This represents the transfer function of a second-order error controller.

[0039] Figure 5 The right half shows a schematic diagram of the zero-pole distribution of a second-order amplitude control loop including a second-order error controller 331. The second-order error controller 331 introduces one zero and two poles into the loop. Optionally, to improve the loop's ability to suppress low-frequency interference while ensuring stability, the zeros of the second-order amplitude control loop... Must get close ,pole It must be located inside the unit circle and close to The extreme position of the pole is Based on the zero-pole distribution, we can write: Another form is as follows:

[0040] Reference Figure 6 , Figure 6 The left half is the transfer function model of the third-order amplitude control loop, which includes the third-order error controller 332. The transfer function from the amplitude disturbance injection point to the actual displacement output amplitude of the resonant MEMS device, i.e., the transfer function of the third-order amplitude control loop, can be expressed as:

[0041] in, This represents the transfer function of the third-order error controller 342.

[0042] Figure 6The right half shows a zero-pole distribution diagram of the third order amplitude control loop including the third order error controller 332. The third order error controller 332 introduces two zero points and three pole points in the loop. Optionally, to improve the ability of the loop to suppress low frequency interference while ensuring stability, the zero points of the amplitude control loop must be close to must be close to , the pole points must be located in the unit circle and close to , the limit position of the pole points is , according to the zero-pole distribution, another form of

[0043] In an optional embodiment, the high-order error controller is composed of a target number of switched-capacitor integrators in cascade, the target number being the order of the high-order amplitude control loop minus one.

[0044] For example, if the order of the high-order amplitude control loop is 2, the target number is 1, that is, the second order error controller includes 1 switched-capacitor integrator; if the order of the high-order amplitude control loop is 3, the target number is 2, that is, the third order error controller can be composed of 2 switched-capacitor integrators in cascade; if the order of the high-order amplitude control loop is 4, the target number is 3, that is, the fourth order error controller can be composed of 3 switched-capacitor integrators in cascade. By analogy, the high-order error controller can be flexibly set by those skilled in the art according to actual conditions.

[0045] In an optional embodiment, the switched-capacitor integrator includes a sampled delay input branch composed of a first sampling capacitor and a switch connected thereto, a non-sampled delay input branch composed of a second sampling capacitor and a switch connected thereto, an integral loss branch composed of a loss capacitor and a switch connected thereto, an integral feedback branch composed of an integral capacitor, a DC feedback branch composed of a feedback resistor, and an operational amplifier; The preset configuration parameters include configuration parameters corresponding to the first sampling capacitor, the second sampling capacitor, the loss capacitor, and the integral capacitor, and the preset configuration parameters are determined according to the transfer function of the high-order error controller.

[0046] In an optional embodiment, if the high-order error controller is a second order error controller, the second order error controller includes one switched-capacitor integrator; The transfer function of the second order error controller is represented as: ; Wherein, represents the transfer function of the second order error controller, represents the configuration parameter of the first sampling capacitor, represents the configuration parameter of the second sampling capacitor,​​ This indicates the configuration parameters of the loss capacitor. This indicates the configuration parameters of the integrating capacitor.

[0047] For example, refer to Figure 4 The second-order error controller 331 includes: a first sampling capacitor The circuit consists of a sampling delay input branch and a second sampling capacitor, along with the switches connected to it. The input branch consisting of the switch connected to it and the input branch with no sampling delay, and the loss capacitor The integral loss branch consisting of the switches connected to it, and the integral capacitor The integral feedback branch consists of a feedback resistor. This consists of a DC feedback branch and an operational amplifier. Wherein, V inp V represents the positive input signal of the peak detector 31. inn V represents the negative input signal of peak detector 31. CM V represents the common-mode voltage of the circuit. REFD V represents the negative amplitude setting value. REFU This indicates the positive amplitude setting value.

[0048] The input-output differential signal of the upper half of the second-order error controller 331 and Analysis yields the following difference equation:

[0049] in, Indicates the order of a time series.

[0050] Performing a z-transform on equation (10), the z-domain transfer function of the second-order error controller 331 is obtained as follows:

[0051] Based on the equality of equations (6) and (7), another form of the transfer function of the second-order error controller 331 is derived from the distribution of the zeros and poles of the second-order amplitude control loop, which is expressed as:

[0052] Based on the equality of equations (11) and (12), optionally, the first preset configuration parameter corresponding to the second-order error controller 331 is: (13) in, This indicates that any settable capacitance value is possible.

[0053] In the embodiment, the amplitude control loop is extended from a first-order z-domain transfer function to a second-order z-domain transfer function by the second-order error controller 331, and the zero-pole of the transfer function is configured by the first preset configuration parameter to improve the suppression ability of the amplitude control loop to the interference at the frequency of interest by two times (for example, the suppression ability is improved from -15 dB to -30 dB) in the dB scale, and then the resonance amplitude control precision is improved.

[0054] In an optional embodiment, if the high-order error controller is a third-order error controller, the third-order error controller is composed of two cascaded switched-capacitor integrators, and the two switched-capacitor integrators are respectively a first switched-capacitor integrator and a second switched-capacitor integrator. The transfer function of the third-order error controller is represented as: ; Among them, The transfer function of the third-order error controller is represented as, The configuration parameter of the first sampling capacitor in the first switched-capacitor integrator is represented as, The configuration parameter of the second sampling capacitor in the first switched-capacitor integrator is represented as, The configuration parameter of the loss capacitor in the first switched-capacitor integrator is represented as, The configuration parameter of the integration capacitor in the first switched-capacitor integrator is represented as; The configuration parameter of the first sampling capacitor in the second switched-capacitor integrator is represented as, The configuration parameter of the second sampling capacitor in the second switched-capacitor integrator is represented as, The configuration parameter of the loss capacitor in the second switched-capacitor integrator is represented as, The configuration parameter of the integration capacitor in the second switched-capacitor integrator is represented as.

[0055] Exemplarily, referring to Figure 7 , Figure 7 is a circuit diagram of a third-order error controller 332 provided by an embodiment of the present application. The third-order error controller 332 is composed of two cascaded switched-capacitor integrators, and the two switched-capacitor integrators are respectively a first switched-capacitor integrator and a second switched-capacitor integrator. Each switched-capacitor integrator includes: a sampling delay input branch composed of ( ) and switches connected thereto, a non-sampling delay input branch composed of ( ) and switches connected thereto, an integration loss branch composed of ( ) and switches connected thereto, an integration feedback branch composed of ( ), and an output branch composed of The direct current feedback branch and the operational amplifier are composed. Similar to the second-order error controller 331, the z-domain transfer function of the third-order error controller 332 is:

[0056] According to the equality of formula (8) and formula (9), the transfer function of another form of the third-order error controller 332 is derived from the distribution of the zero-pole of the third-order amplitude control loop, which is expressed as:

[0057] The numerator of formula (15) is factorized as follows (the factorization is required for , and the factorized is required to be a non-negative real number): According to the equality of formula (14) and formula (16), the first preset configuration parameter corresponding to the third-order error controller 332 is expressed as:

[0058] (17) The embodiment extends the amplitude control loop from a first-order z-domain transfer function to a third-order z-domain transfer function through the third-order error controller 332, and under the premise of meeting the loop stability, the zero-pole of the transfer function is configured through the first preset configuration parameter to make the suppression ability of the amplitude control loop to the interference of the concerned frequency increase by three times (for example, the suppression ability is improved from-15 dB to-45 dB) in the dB scale, and then the resonance amplitude control precision is improved. It should be noted that the high-order automatic gain control circuit applied to the resonant MEMS device of the application can be applied to an analog signal processing scene, and can also be applied to a digital signal processing scene.

[0059] In the digital signal processing scene, the high-order automatic gain control circuit applied to the resonant MEMS device can include an analog-digital converter 7, a digital high-order automatic gain control module 8 and a digital-analog converter 9.

[0060] Figure 9 The analog-digital converter is used to connect the resonant MEMS device 1, and to perform analog-digital conversion on the initial signal input from the resonant MEMS device 1, and to output a digital signal to be processed.

[0061] The digital high-order automatic gain control module 8 has the same function as the high-order automatic gain control module 3, and the parameters of the digital high-order automatic gain control module 8 are configured through the second preset configuration parameter, so that the z-domain transfer function of the amplitude control loop corresponding to the digital high-order automatic gain control module is ​​Z-domain transfer function of amplitude control loop corresponding to high-order automatic gain control module The same. Thus, the functions including peak detection, error amplification, and high-order error control can be realized on the digital signal to be processed, and a digital amplitude control signal is output.

[0062] The digital-to-analog converter 9 is used for analog-to-digital conversion of the digital amplitude control signal, and outputs an amplitude control signal used for controlling the resonance amplitude of the resonant MEMS device 1.

[0063] The application of the high-order automatic gain control circuit for the resonant MEMS device provided by the application is further described below through simulation results.

[0064] Referring to Figure 8 , Figure 8 is a schematic diagram of the suppression limit of a first-order, second-order, and third-order amplitude control loop to amplitude interference (left) and a time-domain response schematic diagram (right). The z-domain transfer function of the first-order amplitude control loop is formula (3), and there is a zero point close to in the loop and a pole close to the limit position in the unit circle, and the suppression ability of the first-order loop to low-frequency interference is ; the z-domain transfer function of the second-order amplitude control loop is formula (6) and formula (7), and the second-order error controller acts on the loop to introduce a zero point and two poles. There are two zero points close to in the loop and two poles close to the limit position in the unit circle, and according to the geometric evaluation method of the z-domain transfer function, the suppression ability to the interference of the frequency of interest is improved by about two times in the dB scale, which is (such as the suppression ability is improved from -15 dB to -30 dB). The z-domain transfer function of the third-order amplitude control loop is formula (8) and formula (9), and the third-order error controller acts on the loop to introduce two zero points and three poles. There are three zero points close to in the loop and three poles close to the limit position in the unit circle, and according to the geometric evaluation method of the z-domain transfer function, the suppression ability to the interference of the frequency of interest is improved by about three times in the dB scale, which is (such as the suppression ability is improved from -15 dB to -45 dB).

[0065] Figure 8The right half part shows a schematic diagram of the first, second and third order amplitude control loop for the interference suppression when a sine type amplitude interference is injected. With the increase of the order, the amplitude interference is suppressed more strongly. The high order automatic gain control circuit proposed in the application breaks through the interference suppression capability limit of the traditional first order amplitude control loop by extending the z-domain transfer function of the amplitude control loop to the second order and above high order form and optimizing the zero pole configuration, while maintaining the system stability, the resonance amplitude control precision is greatly improved.

[0066] The embodiment considers the discretization effect caused by the peak sampling in the amplitude control loop of the resonant MEMS device. Too high increase of the proportional control gain will cause instability of the amplitude control loop, which is limited by the loop stability. The proportional control gain in the amplitude control loop has an upper limit, so its interference suppression capability has a limit, and the amplitude control precision is limited by the loop stability. The high order automatic gain control circuit of the embodiment breaks through the interference suppression capability limit of the traditional first order amplitude control loop by extending the z-domain transfer function of the amplitude control loop to the second order and above high order form and optimizing the zero pole configuration, while maintaining the system stability, the resonance amplitude control precision is greatly improved.

[0067] It should be noted that the terms "first", "second", and so on are used to distinguish similar objects, and do not necessarily mean a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the application described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of devices and methods consistent with some aspects of the present application.

[0068] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present specification.

[0069] Although the present application has been described in connection with certain embodiments, persons skilled in the art will understand and appreciate that many modifications can be made to the described embodiments and these modifications can be made without departing from the scope of the application in its broader aspects. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality, and the

[0070] The above description is further detailed in connection with specific preferred embodiments of the application, and it is not to be construed that the specific implementation of the application is limited to these descriptions. For those skilled in the art, without departing from the concept of the application, a number of simple deductions or substitutions can be made, and all of these should be considered as falling within the scope of protection of the application.

Claims

1. A high order automatic gain control circuit applied to a resonant MEMS device, characterized by, The charge-voltage converter and a high-order automatic gain control module including a peak detector, an error amplifier and a high-order error controller are included. The charge-voltage converter is used to connect a resonant MEMS device and convert an initial signal input from the resonant MEMS device to output a to-be-processed signal. The peak detector is used to perform peak sampling on the to-be-processed signal to output an amplitude value of the to-be-processed signal. The error amplifier is used to subtract the amplitude value of the to-be-processed signal from an amplitude setting value to output an amplitude error signal. The high-order error controller is used to process the amplitude error signal according to a first preset configuration parameter to output an amplitude control signal, which is used to control a resonant amplitude of the resonant MEMS device.

2. The high-order automatic gain control circuit for a resonant MEMS device according to claim 1, wherein A transfer function of the resonant MEMS device in a z domain is represented as: ； wherein, represents a transfer function of the resonant MEMS device in the z-domain, , represents an equivalent mass of the resonant MEMS device, represents a quality factor of the resonant MEMS device, represents a natural resonant frequency of the resonant MEMS device, represents a period of peak sampling, represents a conversion factor of the resonant MEMS device drive voltage to drive force, represents a z-domain variable of the resonant MEMS device, represents a pole of the resonant MEMS device; A transfer function of a high-order amplitude control loop composed of the high-order automatic gain control circuit and the resonant MEMS device is represented as: ； wherein, represents a transfer function of the high order amplitude control loop, represents a gain of the charge-voltage converter, represents a gain of the error amplifier, represents a transfer function of the high order error controller, represents an order of the high order amplitude control loop, .

3. The high-order automatic gain control circuit for a resonant MEMS device according to claim 2, wherein The high-order error controller is composed of a target number of switched-capacitor integrator cascades, and the target number is one less than an order of the high-order amplitude control loop.

4. The high-order automatic gain control circuit for a resonant MEMS device according to claim 3, wherein The switched-capacitor integrator includes a sampled-delay input branch composed of a first sampling capacitor and a connected switch, an unsampled-delay input branch composed of a second sampling capacitor and a connected switch, an integral loss branch composed of a loss capacitor and a connected switch, an integral feedback branch composed of an integral capacitor, a DC feedback branch composed of a feedback resistor and an operational amplifier. The preset configuration parameter includes configuration parameters corresponding to the first sampling capacitor, the second sampling capacitor, the loss capacitor and the integral capacitor, and the preset configuration parameter is determined according to a transfer function of the high-order error controller.

5. The high-order automatic gain control circuit for a resonant MEMS device according to claim 4, wherein If the high-order error controller is a second-order error controller, the second-order error controller includes one switched-capacitor integrator. A transfer function of the second-order error controller is represented as: ； wherein, G2(s) represents a transfer function of the second order error controller, G1(s) represents a configuration parameter of the first sampling capacitor, G2(s) represents a configuration parameter of the second sampling capacitor, G3(s) represents a configuration parameter of the loss capacitor, G4(s) represents a configuration parameter of the integration capacitor.

6. The high-order automatic gain control circuit for a resonant MEMS device according to claim 4, wherein If the high-order error controller is a third-order error controller, the third-order error controller is composed of two switched-capacitor integrators, which are a first switched-capacitor integrator and a second switched-capacitor integrator. A transfer function of the third-order error controller is represented as: ； wherein, G3(z) represents a transfer function of the third order error controller, G1(z) represents a configuration parameter of a first sampling capacitor in the first switched-capacitor integrator, G2(z) represents a configuration parameter of a second sampling capacitor in the first switched-capacitor integrator, G3(z) represents a configuration parameter of a loss capacitor in the first switched-capacitor integrator, G4(z) represents a configuration parameter of an integration capacitor in the first switched-capacitor integrator; G1(z) represents a configuration parameter of a first sampling capacitor in the second switched-capacitor integrator, G2(z) represents a configuration parameter of a second sampling capacitor in the second switched-capacitor integrator, G3(z) represents a configuration parameter of a loss capacitor in the second switched-capacitor integrator, G4(z) represents a configuration parameter of an integration capacitor in the second switched-capacitor integrator.

7. The high-order automatic gain control circuit for a resonant MEMS device according to claim 1, wherein The peak detector is composed of a third sampling capacitor, a feedback capacitor, a holding capacitor, an operational amplifier, a voltage buffer and corresponding connected switches, and a gain of the peak detector is 1.

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