Microelectromechanical gyroscope with resonant drive circuit for controlled oscillation amplitude and method for controlling microelectromechanical gyroscope

Abstract

This disclosure relates to a microelectromechanical gyroscope having a resonant drive circuit that achieves controlled oscillation amplitude, and a method for controlling the microelectromechanical gyroscope. A microelectromechanical gyroscope includes: a support structure; a drive block movable according to a drive shaft; and an oscillating microelectromechanical circuit. The microelectromechanical circuit has a resonant frequency and a circuit gain, and includes: the drive block, a sensing interface for sensing the position of the drive block, and a gain control stage that maintains the modulus of the circuit gain at a unit value at the resonant frequency. The gain control stage includes a sampler and a transconductance operational amplifier in an open-loop configuration. The sampler acquires samples of the circuit signal from the sensing interface under a first operating condition and passes them to the transconductance operational amplifier under a second operating condition. The sampler decouples the transconductance operational amplifier from the sensing interface under both the first and second operating conditions.

Description

Technical Field

[0001] This disclosure relates to a microelectromechanical gyroscope with a resonant drive circuit having a controlled oscillation amplitude, and to a method for controlling the microelectromechanical gyroscope. Background Technology

[0002] Microelectromechanical gyroscopes are known to be based on a microstructure comprising a support structure and a movable block or system of movable blocks. The movable blocks oscillate relative to the support structure along a drive axis at a controlled frequency and amplitude. If the microstructure rotates about a rotation axis perpendicular to the drive axis, the movable blocks are subjected to an apparent force, or Coriolis force, proportional to the rotational speed and perpendicular to both the drive axis and the rotation axis. The displacement of the movable blocks caused by the Coriolis force can be sensed relatively easily, for example, through a capacitively coupled system of fixed and movable sensing electrodes, and can be used to derive the angular velocity of the gyroscope. The same principle essentially applies to the case of multi-axis gyroscopes, where typically a common drive device provides the driven motion along one axis, and the connections and constraints between the movable blocks generate driven motion along one or more other axes.

[0003] To ensure oscillating motion with controlled frequency and amplitude, the drive device is based on a resonator ring, which includes a movable block and applies actuation force through capacitively coupled fixed and movable drive electrodes. To ensure oscillation conditions, the resonator ring satisfies Barkhausen's stability criterion, namely, at the resonant frequency, the modulus of the loop gain is equal to 1, and the phase of the loop gain is equal to 2π.

[0004] In known gyroscopes, the resonator loop is based on a phase-locked loop (PLL) circuit and a gain control stage. More specifically, a fully differential charge amplifier converts the read signal (typically in the form of charge packets) from the microstructure into a differential voltage signal indicating the capacitive coupling between the movable block and the supporting structure, thus indicating their relative position. Using a comparator, the differential signal is converted into a single-ended square wave signal, which is then fed to the PLL circuit. The PLL circuit locks the oscillation of the square wave signal, and a forcing stage applies a forcing signal to the microstructure such that the Barkhausen criterion regarding the loop phase is satisfied. Furthermore, a gain tuning stage reads the differential voltage at the output of the charge amplifier and generates a control signal, which is applied to the forcing stage to tune the amplitude of the forcing signal, ensuring unity-loop gain at the resonant frequency.

[0005] The limitations of a gyroscope are known to depend on the current consumption of its gain tuning stage, where a differential voltage signal provided by a charge amplifier is demodulated, filtered to remove high-frequency components, converted into a single-ended signal, and compared with a reference voltage to obtain the control voltage. The filters used are typically operational amplifier active filters, which offer advantages in reliability and accuracy on the one hand, and continuously draw current through a resistive feedback network with a defined transfer function on the other. The continuous current draw of the closed-loop operational amplifier may contrast with the increasingly frequent demands for reduced power consumption, especially when the gyroscope is used in portable or small devices, where autonomous and satisfactory energy storage may be important. Summary of the Invention

[0006] In various embodiments, this disclosure provides a microelectromechanical gyroscope and a method for controlling a microelectromechanical gyroscope, allowing for overcoming or at least mitigating the described limitations.

[0007] In at least one embodiment, a microelectromechanical gyroscope is provided, comprising: a support structure; a drive block capacitively coupled to the support structure and movable relative to the support structure according to a drive shaft; and an oscillating microelectromechanical circuit having a resonant frequency and a circuit gain, including the drive block, a sensing interface, and a gain control stage, the sensing interface for sensing the position of the drive block relative to the support structure, and the gain control stage for maintaining the modulus of the circuit gain at a unit value at the resonant frequency. The gain control stage includes a sampler and a transconductance operational amplifier in an open-loop configuration. The sampler is configured to: acquire samples of the circuit signal from the sensing interface under a first operating condition, and pass the samples to the transconductance operational amplifier under a second operating condition. The sampler is configured to: decouple the transconductance operational amplifier from the sensing interface under both the first and second operating conditions.

[0008] In at least one embodiment, an electronic system is provided, including a microelectromechanical gyroscope and processing circuitry coupled to the microelectromechanical gyroscope.

[0009] In at least one embodiment, a method for controlling a microelectromechanical gyroscope is provided. The microelectromechanical gyroscope includes: a support structure; a drive block capacitively coupled to the support structure and movable relative to the support structure according to a drive axis; and a microelectromechanical circuit having a resonant frequency and a loop gain, and including the drive block. The method includes: placing the microelectromechanical circuit in an oscillation; sensing the position of the drive block relative to the support structure; and maintaining the modulus of the loop gain at a unit value at the resonant frequency. Maintaining the modulus of the loop gain includes: acquiring a sample of the loop signal indicating the position of the drive block relative to the support structure, and amplifying the sample in an open loop, wherein the acquisition and amplification are time-separated and do not overlap. Attached Figure Description

[0010] To better understand this disclosure, some embodiments thereof will now be described purely by way of non-limiting examples and with reference to the accompanying drawings, in which:

[0011] Figure 1 This is a simplified block diagram of a microelectromechanical gyroscope;

[0012] Figure 2 According to embodiments of this disclosure Figure 1 A more detailed block diagram of the microelectromechanical gyroscope;

[0013] Figure 3 It shows the relationship with Figure 1 A graph showing the quantities related to the microelectromechanical gyroscope;

[0014] Figure 4 Different embodiments according to this disclosure Figure 2 A more detailed block diagram;

[0015] Figure 5 According to another embodiment of this disclosure Figure 2 A more detailed block diagram; and

[0016] Figure 6 This is a simplified block diagram of an electronic system with an embedded microelectromechanical gyroscope according to the present disclosure. Detailed Implementation

[0017] refer to Figure 1 The microelectromechanical gyroscope 1 includes a microstructure 2 made of semiconductor material, a drive device 3, a readout generator 4, and a readout device 5.

[0018] Microstructure 2 is made of semiconductor material and, in one embodiment, includes a support structure 6, a drive block 7, and at least one sensing block 8. For simplicity, the embodiments described herein will refer to the case of a single-axis gyroscope, in which only one sensing block 8 exists. However, the following description also applies to the case of a multi-axis gyroscope, which includes two or more sensing blocks or block systems for sensing rotation along respective independent axes, such as pitch, roll, and yaw axes. Furthermore, the drive block 7 may coincide with the sensing block: in this case, in practice, a single block can move along both the vertical drive axis and the sensing axis, simultaneously performing the functions of driving and sensing angular velocity.

[0019] The drive block 7 is elastically constrained to the support structure 6 so that it can oscillate around the rest position according to the translational or rotational degrees of freedom.

[0020] Sensing block 8 is mechanically coupled to driving block 7 so as to be dragged along according to the same degree of freedom of driving block 7. Furthermore, sensing block 8 is elastically constrained to driving block 7 so as to oscillate relative to the same driving block 7, having a corresponding additional degree of freedom. In the embodiment described herein, specifically, driving block 7 is linearly movable along driving axis X, while sensing block 8 is movable relative to driving block 7 according to sensing axis Y perpendicular to driving axis X. However, it should be understood that the type of motion (translation or rotation) allowed by the degrees of freedom and the arrangement of driving and sensing axes can vary depending on the type of gyroscope.

[0021] Furthermore, the drive block 7 (and the sensing block 8) are connected to the support structure 6 to define a region with a resonant frequency f. R A resonant mechanical system (based on drive shaft X). As previously mentioned, drive block 7 and sensing block 8 can overlap.

[0022] The driving block 7 and the sensing block 8 are capacitively coupled to the support structure 6. More specifically, the first driving capacitive coupling is defined between the driving block 7 and the first driving terminal 7a of the microstructure 2 via a first set of fixed and movable driving electrodes, and the first set of fixed and movable driving electrodes are coupled to each other via a capacitor 7b. Figure 1 The diagram is schematically shown. A second driving capacitor coupling is defined between the driving block 7 and the second driving terminal 7c of the microstructure 2 via a second set of fixed and movable driving electrodes. The second set of fixed and movable driving electrodes are mutually coupled via capacitor 7d and... Figure 1 The diagram is schematically shown. Capacitive coupling is defined between the sensing block 8 and the sensing terminal 8a of the support structure 6 via a set of fixed and movable sensing electrodes, which are coupled to each other via a capacitor 8b. Figure 1 The diagram is used to represent this.

[0023] The drive device 3 is connected to the first drive terminal 7a and the second drive terminal 7c to form an oscillating microelectromechanical circuit 10 with the drive block 7. The oscillating microelectromechanical circuit 10 has a resonant frequency f. R It is configured to keep the drive block 7 (and the sensing block 8 connected thereto) at a controlled amplitude and close to the resonant frequency f. R driving frequency f D Oscillation. The oscillation amplitude is programmed during the design phase according to preferences.

[0024] In one embodiment, the driving device 3 includes a charge amplifier 12, a comparator 13, a phase-locked stage or PLL (phase-locked loop) stage 15, an actuation stage 17, and a gain control stage 18.

[0025] The components of the drive device 3 coordinate to control the phase and oscillation amplitude of the microelectromechanical circuit 10.

[0026] The charge amplifier 12 is fully differential, and its input is connected to the first drive terminal 7a of the microstructure 2. The charge amplifier 12 also defines the sensing interface and provides the sensing voltage V. O The sensing voltage V O It indicates the position of the drive block 7 relative to the support structure 6 along the drive shaft X.

[0027] Comparator 13 has an input that is connected to the output of charge amplifier 12 and a sense voltage V present therebetween. O It switches at each zero-crossing point, thus operating as a frequency detector device. In practice, converter 13 provides a single-ended square wave signal to PLL stage 15 at the oscillation frequency of microelectromechanical circuit 10. PLL stage 15 locks the oscillation of the single-ended square wave signal and, through actuator stage 17, transmits the differential drive signal V... D1 V D2 The second drive terminal 7c of the microstructure 2 is applied such that the Barkhausen criterion regarding the loop phase is satisfied, i.e. (at the resonant frequency f) R Below, the resonant frequency f R Basically equal to the driving frequency f D G LOOP (This is the loop gain of the microelectromechanical circuit 10).

[0028] Actuation stage 17 has an output connected to a second drive terminal 7c of microstructure 2 to provide drive voltages VD1 and VD2 and maintain microelectromechanical circuit 10 at drive frequency f. D The oscillation is caused by the gain control stage 17, which is controlled by the gain control stage 18 via a sense voltage V that oscillates at the output of the charge amplifier 12. O The control signal V generated by the function C To determine. Specifically, the gain of actuator 17 is determined in the following manner: satisfying the condition that the microelectromechanical circuit 10 is at its resonant frequency f. R Oscillation condition |G LOOP |=1.

[0029] Figure 2 The gain control stage 18 is shown in more detail, which in one embodiment includes a sampler 20, a transconductance operational amplifier (OTA) 21, and a buffer 22.

[0030] Sampler 20 has differential inputs coupled to the corresponding outputs of charge amplifier 12 and outputs coupled to the inputs of transconductance operational amplifier 21.

[0031] Sampler 20 is configured to sense voltage V in a subsequent step. O Sample V O*Passed to transconductance operational amplifier 21, and there is no direct coupling between the input and output.

[0032] The transconductance operational amplifier 21 is in an open-loop configuration and is connected to the sampler 20 to receive the sensed voltage V. O Sample V O The first input of * is connected to the second input of the reference voltage generator 24, which provides the reference voltage V. R The transconductance operational amplifier 21 also provides a control voltage V. C And it is connected to the output of the control input 17a of the actuator stage 17 via buffer 22, which facilitates driving. Control voltage V C It is used as a reference voltage V R The comparison function is generated, and the reference voltage V is selected. R To ensure the oscillation conditions of the microelectromechanical circuit 10, especially regarding the modulus |G of the circuit gain. LOOP The condition |=1, and the oscillation amplitude of the drive block 7 programmed during the design phase.

[0033] Specifically, the sampler 20 includes a data acquisition circuit 25 and an output circuit 26.

[0034] The acquisition circuit 25 further includes an acquisition and storage component 27 (e.g., a component with an acquisition capacitor C). A The acquisition capacitor is defined by the acquisition circuitry 28. In one embodiment, the acquisition connection circuitry 28 includes two three-way selectors 30 and 31, each having a corresponding input 30a and 31a connected to a corresponding output of the charge amplifier 12. Three-way selector 30 has a first output 30b and a second output 30c connected to a first terminal and a second terminal of the acquisition storage component 27, respectively, and a suspended third output 30d. Three-way selector 31 has a first output 31b and a second output 31c connected to a second terminal and a first terminal of the acquisition storage component 27, respectively, and a suspended third output 31d.

[0035] Output circuit 26 includes output storage component 35 (e.g., composed of an output capacitor C). O The output capacitor is defined by the output capacitor (and the output connection circuit 36). In one embodiment, the output capacitor C O Greater than the sampling capacitor C A The output connection circuit 36 ​​includes a switch 37 (connected between the first terminal of the acquisition storage component 27 and the first terminal of the output storage component 35) and a switch 38 (connected between the second terminal of the acquisition storage component 27 and the second terminal of the output storage component 35). The first terminal of the output storage component 35 defines the output of the sampler.

[0036] The acquisition connection circuit 28 and the output connection circuit 36 ​​are controlled by a selection signal generated by the PLL stage 15, and are therefore synchronized with the oscillation of the microelectromechanical loop 10. Specifically, the acquisition connection circuit 28 receives a first selection signal S that is inversely phase to each other. SEL1 Second selection signal S SEL2 Simultaneously, the output connection circuit 35 receives the third selection signal S. SEL3 Select signal S SEL1 S SEL2 S SEL3 It has the selection value SEL and the deselection value DESEL, such as Figure 3 As shown, and with timing defined such that there is never a direct connection between the input and output storage components (i.e., in fact, between the output of charge amplifier 12 and the input of transconductance operational amplifier 21).

[0037] Three-way selectors 30 and 31 will output the corresponding inputs 30a and 31a:

[0038] When the first selection signal S SEL1 When the selection value SEL is present, connect to the corresponding first outputs 30b and 31b respectively;

[0039] When the second selection signal S SEL2 When the selection value SEL is available, connect to the corresponding second outputs 30c and 31c respectively;

[0040] When the first selection signal S SEL1 Second selection signal S SEL2 When both have the deselect value DESEL, connect them to the corresponding third outputs 30d and 31d respectively.

[0041] Therefore, the three-way selectors 30 and 31 have:

[0042] In the first state, the acquisition and storage component 27 is connected to the output of the charge amplifier 12 with a first polarity;

[0043] In the second state, the acquisition and storage component 27 is connected to the output of the charge amplifier 12 with a second polarity opposite to the first polarity (i.e., the first and second terminals of the acquisition and storage component 27 are connected to the output of the charge amplifier 12 (opposite to the first state)); and

[0044] In the third state, the acquisition and storage component 27 is disconnected from the output of the charge amplifier 12.

[0045] When the third selection signal S SEL3When the selection value SEL is present, switches 37 and 38 are closed; otherwise, they are open. Therefore, output storage component 35 is only connected to acquisition storage component 27 (transfer state) when acquisition storage component 27 is disconnected from charge amplifier 12; otherwise, it is decoupled (cutoff state).

[0046] Regarding timing, the first selection signal S SEL1 Second selection signal S SEL2 In each cycle, the sensing voltage V is respectively used O The maximum and minimum values ​​are collected at the interval T. A The selection signal SEL is maintained within the selected value. For the remaining time of each cycle, the first selection signal S... SEL1 Second selection signal S SEL2 It has a deselect value, DESEL. The third selection signal, S. SEL3 Provided to output connection circuit 35 and only when the first selection signal S SEL1 Second selection signal S SEL2 The selection value SEL is only available when both are in the deselection state (DESEL). In fact, the third selection signal S... SEL3 In each half-cycle, during the transmission interval T T The value SEL is maintained within the selected range, without being affected by the previous and next acquisition intervals T. A Overlap (transmission interval T) T With the acquisition interval T A Alternating). For example, transmission interval T T With the acquisition interval T A Separated stable interval T S Stable interval T S Transient termination caused by switching of three-way selectors 30, 31 and / or switches 37, 38 is permitted.

[0047] Therefore, in each cycle, the acquisition and storage component 27 acquires data at intervals T up to the positive and negative peak values ​​(the first and second states of the three selectors 30 and 31, respectively). A The signal is connected to the output of charge amplifier 12 for the duration of the signal, and during each acquisition interval T A The connection to charge amplifier 12 is disconnected. Since in each cycle, the three selectors 30 and 31 are set to the first state (up to the positive peak) and the second state (up to the negative peak) as described above, the connection to charge amplifier 12 is reversed twice, and the sample V stored in the acquisition storage component 27 is... O * Always have the same symbol. Therefore, the acquisition connection circuit 28 also functions as a rectifier circuit.

[0048] Sampler 20 provides sample V to transconductance operational amplifier 21 in a sufficiently stable manner. O*To prevent interference (such as interference related to switching or from the sampling process of the output signal of charge amplifier 12) from degrading the operation of transconductance operational amplifier 21, which is in an open-loop configuration. Specifically, sampler 20 will acquire sample V O The steps of * are separated from the steps leading to the output, avoiding a direct connection between the input of the transconductance operational amplifier 21 and the output of the charge amplifier under any operating condition. This is achieved through synchronization of: on the one hand, the selection of the states of the three-way selectors 30, 31, in which the acquisition storage component 27 is connected to at least one state (first or second) of the charge amplifier 12, and the state in which the acquisition storage component 27 is disconnected from the charge amplifier 12; and on the other hand, the switches 37, 38, which are in an open or closed state when any of the three-way selectors 30, 31 is in the first or second state. Therefore, the first and second states of the three-way selectors 30, 31 and the closed or open states of the switches 37, 38 do not overlap in time (except for auxiliary operations of the gyroscope 1, such as for example, for equalization nodes).

[0049] The sensed voltage V is measured in two time-different and non-overlapping steps. O Sampling allows sample V O * It possesses sufficient stability to enable the use of transconductance operational amplifier 21 in an open-loop configuration. The rectifier function of sampler 20 assists sampling in this sense, further improving the obtained results. In turn, the open-loop configuration of transconductance operational amplifier 21 allows for significant current savings due to the absence of a resistive feedback network, making gyroscope 1 particularly suitable for very low-power applications.

[0050] The described configuration also allows for component savings compared to known solutions that use closed-loop operational amplifiers. In fact, the sampler and transconductance operational amplifier in the open loop perform essentially the same function, requiring or utilizing a demodulator based on a closed-loop operational amplifier, an active low-pass filter, and a variable gain amplifier in a known gyroscope.

[0051] Buffer 22 is advantageous because it facilitates driving the capacitive load downstream of transconductance operational amplifier 21. However, it is not necessary and can be omitted, for example, in [the following context is missing from the original text]. Figure 4 In the embodiments described above.

[0052] The rectifier function of the sampler is not required and is related to the sampling of the two peaks of the output sine wave of stage 12. In fact, the rectifier function can be omitted by sampling only the positive peak. For example, in Figure 5In the embodiment, where the same reference numerals are used to denote the same parts as those already shown, the sampler, referred to herein as 120, in gain control stage 118 includes the described acquisition circuit 125 and output circuit 26, wherein the output storage component 35 and the output connection circuit 36 ​​are defined by switches 37 and 38.

[0053] The acquisition circuit 125 further includes an acquisition storage component 27 and an acquisition connection circuit 128. The acquisition connection circuit 128 includes two switches 130 and 131, each connected between a corresponding output of the charge amplifier 12 and a corresponding terminal in the first and second terminals of the acquisition storage component 27. Similarly, in this case, sampling is performed in two steps. The acquisition circuit 125 and the output circuit 26 are controlled so that the output storage component 35 is never directly connected to the charge amplifier 12. In practice, switches 37 and 38 close only after switches 130 and 131 have been opened and reopen before switches 130 and 131 close. The time intervals for switches 130 and 131 and switches 37 and 38 to remain closed are different and do not overlap, ensuring that switches 130, 131, 37, and 38 will never close simultaneously.

[0054] Figure 6 The illustration shows an electronic system 200 that can be of any type, particularly but not limited to wearable devices such as watches, smart bracelets, or wristbands; computers such as mainframes, personal computers, laptop computers, or tablet computers; smartphones; digital music players, digital cameras, or any other device for processing, storing, sending, or receiving information. The electronic system 200 can be a general-purpose or device-embedded processing system, apparatus, or other system.

[0055] Electronic system 200 includes processing circuitry system 202 (which may be referred to herein as processing unit 202), memory device 203, and a microelectromechanical gyroscope according to the present disclosure, such as... Figure 1 The electronic system 200 includes a microelectromechanical gyroscope 1 and may also be provided with input / output (I / O) devices 205 (e.g., a keyboard, pointer, or touchscreen), a wireless interface 206, peripheral devices 207.1, ..., 207.N, and possibly other auxiliary devices (not shown here). Components of the electronic system 200 may be directly and / or indirectly coupled to each other via a bus 208. The electronic system 200 may also include a battery 209. It should be noted that the scope of this disclosure is not limited to embodiments that must have one or all of the listed devices.

[0056] Depending on design preferences, the processing unit 202 may include, for example, one or more microprocessors, microcontrollers, etc.

[0057] Storage device 203 may include various types of volatile and non-volatile memory devices, such as SRAM and / or DRAM memory for volatile and solid-state memory, and disk and / or optical disk for non-volatile types.

[0058] Finally, it is obvious that modifications and variations can be made to the microelectromechanical gyroscope and the described method without departing from the scope of this disclosure as defined by the appended claims.

[0059] A microelectromechanical gyroscope can be summarized as including: a support structure (6); at least one drive block (8) capacitively coupled to the support structure (6) and movable relative to the support structure (6) according to the drive axis (X); and an oscillating microelectromechanical circuit (10) having a resonant frequency (f). R ) and loop gain (G LOOP ), and includes a drive block (7), a sensing interface (12) configured to sense the position of the drive block (7) relative to the support structure (6), and a sensor interface (12) configured to sense the position of the drive block (7) relative to the support structure (6) at a resonant frequency (f R The loop gain (G) will be reduced. LOOP The modulus of ) (|G) LOOP |) A gain control stage (18; 118) is maintained at a unit value; wherein the gain control stage (18; 118) includes a sampler (20; 120) and a transconductance operational amplifier (21) in an open-loop configuration; wherein the sampler (20; 120) is configured to: acquire a loop signal (V) from the sensing interface (12) under a first operating condition O ) samples (V) O *), and under the second operating condition, the sample (V) O *) is passed to the transconductance operational amplifier (21); and the sampler (20; 120) is configured to decouple the transconductance operational amplifier (21) from the sensing interface (12) under a first operating condition and a second operating condition.

[0060] The sampler (20; 120) may include an acquisition stage (25; 125) and an output stage (26); the acquisition stage (25; 125) may include an acquisition storage component (27) and an acquisition connection circuit (28; 128), the acquisition connection circuit (28; 128) having at least one connected state and a disconnected state, in at least one connected state the acquisition connection circuit (28; 128) couples the acquisition storage component (27) to the sensing interface (12), and in the disconnected state the acquisition connection circuit (28; 128) connects the acquisition storage component (27) to the sensing interface (12). Decoupling; the output stage (26) may include an output storage component (35) and an output connection circuit (36), the output connection circuit (36) having a pass state and a cut-off state, in the pass state the output connection circuit (36) couples the output storage component (35) to the acquisition storage component (27), and in the cut-off state the output connection circuit (36) decouples the output storage component (35) from the acquisition storage component (27); and the pass state of the output connection circuit (36) may be time-separated from at least one connection state of the acquisition connection circuit (28; 128).

[0061] The acquisition storage component (27) may include a first capacitor having a first capacitance, and the output storage component (35) may include a second capacitor having a second capacitance.

[0062] The acquisition connection circuit (28) can be configured to rectify the loop signal (VO).

[0063] The acquisition connection circuit (28) may have a first connection state and a second connection state. In the first connection state, the acquisition connection circuit (28) couples the acquisition storage component (27) to the sensing interface (12) with a first polarity. In the second connection state, the acquisition connection circuit (28) couples the acquisition storage component (27) to the sensing interface (12) with a second polarity opposite to the first polarity.

[0064] The acquisition connection circuit (28) may include: a first selector (30) having a first output (30b) and a second output (30c) respectively connected to a first terminal and a second terminal of the acquisition storage component (27), and a third output (30d) that may be suspended; and a second selector (31) having a first output (31b) and a second output (30c) respectively connected to a second terminal and a first terminal of the acquisition storage component (27), and a third output (31d) that is suspended.

[0065] The microelectromechanical circuit (10) may include a phase-locked stage (15) configured to generate a selection signal (S) synchronized with the oscillation of the microelectromechanical circuit (10). SEL1 S SEL2 S SEL3), and the acquisition connection circuit (28) and the output connection circuit (36) can be selected by the selection signal (S SEL1 S SEL2 S SEL3 )control.

[0066] In the loop signal (V) O In each cycle of ), through the first selection signal (S) SEL1 S SEL2 The acquisition connection circuit (28) can be used until the loop signal (V) O The maximum value of the sampling time interval (T) A It is set to the first connection state within ) and until the loop signal (V) O The minimum value of the sampling time interval (T) A It is set to the second connection state.

[0067] Through the second selection signal (S) SEL3 ), in the interval between the previous and next acquisitions (T) A The propagation time interval (T) of the separate stable interval (Ts) T Within the circuit (35), the output connection circuit can be connected to the loop signal (V). O It is set to the transmission state in each half-cycle.

[0068] The microelectromechanical circuit (10) may include an actuator stage (17) configured to apply drive signals (VD1, VD2) to a drive block (7), and wherein a transconductance operational amplifier (21) may be configured to provide a control signal (VD1, VD2) to the actuator stage (17). C Furthermore, the gain of the actuator stage (17) can be controlled by the control signal (V). C ) is determined such that at the resonant frequency (f R Under these conditions, the loop gain (G) LOOP The modulus of (10) can have a unit value, and the microelectromechanical circuit (10) can have a controlled oscillation amplitude.

[0069] The gain control stage (18; 118) may include a reference voltage generator (24) that provides a reference voltage (VR), wherein the transconductance operational amplifier (21) may be coupled to a sampler (20; 120) to receive a loop signal (V). O ) samples (V) O The first input of *) is coupled to the reference voltage generator (24) to receive the reference voltage (V R The second input, and the one that provides the control signal (V) C The output of ) and the reference voltage (V R ) can be selected such that the control signal (V)C The loop gain (G) is caused by the programmed amplitude. LOOP The unit value of the modulus and the controlled oscillation amplitude of ).

[0070] The gain control stage (18; 118) may include a buffer (22) between the transconductance operational amplifier (21) and the actuation stage (17).

[0071] The sensing interface (12) may include a fully differential charge amplifier, and the microelectromechanical circuit (10) may include a comparator (13) having an input that is connected to a corresponding output of the charge amplifier.

[0072] The electronic system can be summarized as including a processing unit (202) and a gyroscope (1).

[0073] A method for controlling a microelectromechanical gyroscope, the microelectromechanical gyroscope being generally defined as including: a support structure (6); at least one drive block (7) capacitively coupled to the support structure (6) and movable relative to the support structure (6) according to a drive axis (X); and a microelectromechanical circuit (10) having a resonant frequency (f). R ) and loop gain (G LOOP The method includes: placing the microelectromechanical circuit (10) in an oscillating state; sensing the position of the drive block (7) relative to the support structure (6); and at the resonant frequency (f R The loop gain (G) will be reduced. LOOP The modulus of ) (|G) LOOP |) Maintain a unit value; wherein maintaining includes: acquiring a loop signal (V) indicating the position of the drive block (7) relative to the support structure (6). O ) samples (V) O *), and amplifying the sample in the open loop (V) O *), and the acquisition and amplification steps are separate in time and do not overlap.

[0074] The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments based on the detailed description above. Generally, the terminology used in the following claims should not be construed as limiting the claims to the specific embodiments disclosed in the specification and claims, but should be interpreted to include all possible embodiments and the full scope of equivalents claimed by those claims. Therefore, the claims are not limited to this disclosure.

Claims

1. A microelectromechanical gyroscope, comprising: Support structure; The drive block is capacitively coupled to the support structure and is movable relative to the support structure according to the drive shaft; as well as An oscillating microelectromechanical circuit has a resonant frequency and a loop gain, and includes: the driving block; a sensing interface configured to sense the position of the driving block relative to the support structure; and a gain control stage configured to maintain the modulus of the loop gain at a unit value at the resonant frequency. The gain control stage includes a sampler and a transconductance operational amplifier in an open-loop configuration. The sampler is configured to: acquire samples of the loop signal from the sensing interface under a first operating condition, and pass the samples to the transconductance operational amplifier under a second operating condition. The sampler is configured to decouple the transconductance operational amplifier from the sensing interface under the first operating condition and the second operating condition.

2. The gyroscope according to claim 1, wherein: The sampler includes an acquisition stage and an output stage. The acquisition stage includes an acquisition and storage component and an acquisition connection circuit. The acquisition connection circuit has at least one connected state and a disconnected state. In the at least one connected state, the acquisition connection circuit couples the acquisition and storage component to the sensing interface. In the disconnected state, the acquisition connection circuit decouples the acquisition and storage component from the sensing interface. The output stage includes an output storage component and an output connection circuit. The output connection circuit has a pass-through state and a cut-off state. In the pass-through state, the output connection circuit couples the output storage component to the acquisition storage component. In the cut-off state, the output connection circuit decouples the output storage component from the acquisition storage component. The transmission state of the output connection circuit and the at least one connection state of the acquisition connection circuit are separated in time.

3. The gyroscope according to claim 2, wherein the acquisition and storage component includes a first capacitor having a first capacitance, and the output storage component includes a second capacitor having a second capacitance.

4. The gyroscope according to claim 2, wherein the acquisition connection circuit is configured to rectify the loop signal.

5. The gyroscope according to claim 2, wherein the acquisition connection circuit has a first connection state and a second connection state, wherein in the first connection state the acquisition connection circuit couples the acquisition storage component to the sensing interface with a first polarity, and in the second connection state the acquisition connection circuit couples the acquisition storage component to the sensing interface with a second polarity opposite to the first polarity.

6. The gyroscope according to claim 5, wherein the acquisition connection circuit comprises: The first selector has a first output and a second output that are respectively connected to a first terminal and a second terminal of the acquisition and storage component, and a suspended third output; and The second selector has a first output and a second output that are respectively connected to the second terminal and the first terminal of the acquisition and storage component, and a suspended third output.

7. The gyroscope of claim 5, wherein the microelectromechanical circuit includes a phase-locked stage configured to generate a selection signal synchronized with the oscillation of the microelectromechanical circuit, and wherein the acquisition connection circuit and the output connection circuit are controlled by the selection signal.

8. The gyroscope of claim 7, wherein in each cycle of the loop signal, the acquisition connection circuit is set to the first connection state for an acquisition time interval up to the maximum value of the loop signal, and is set to the second connection state for an acquisition time interval up to the minimum value of the loop signal, by means of a first selection signal.

9. The gyroscope of claim 8, wherein, by means of a second selection signal, the output connection circuit is set to the transmission state in each half-cycle of the loop signal during a transmission time interval that is a stable interval separate from the previous and subsequent acquisition intervals.

10. The gyroscope of claim 1, wherein the microelectromechanical circuit includes an actuation stage configured to apply a drive signal to the drive block, and wherein the transconductance operational amplifier is configured to provide a control signal to the actuation stage, and the gain of the actuation stage is determined by the control signal such that the modulus of the circuit gain has a unit value at the resonant frequency, and the microelectromechanical circuit has a controlled oscillation amplitude.

11. The gyroscope of claim 10, wherein the gain control stage includes a reference voltage generator providing a reference voltage, wherein the transconductance operational amplifier has a first input coupled to the sampler to receive a sample of the loop signal, a second input coupled to the reference voltage generator to receive the reference voltage, and an output providing the control signal, and wherein the reference voltage is selected such that the control signal causes a unit value of the modulus of the loop gain and a controlled oscillation amplitude according to a programmed amplitude.

12. The gyroscope of claim 10, wherein the gain control stage includes a buffer between the transconductance operational amplifier and the actuation stage.

13. The gyroscope of claim 1, wherein the sensing interface comprises a fully differential charge amplifier, and the microelectromechanical circuit comprises a comparator having an input connected to a corresponding output of the charge amplifier.

14. An electronic system comprising: Microelectromechanical gyroscopes include: Support structure; A drive block, capacitively coupled to the support structure, and movable relative to the support structure according to the drive shaft; and An oscillating microelectromechanical circuit, having a resonant frequency and a loop gain, includes: the driving block; a sensing interface configured to sense the position of the driving block relative to the support structure; and a gain control stage configured to maintain the modulus of the loop gain at a unit value at the resonant frequency; and The processing circuitry is coupled to the microelectromechanical gyroscope. The gain control stage includes a sampler and a transconductance operational amplifier in an open-loop configuration. The sampler is configured to: acquire samples of the loop signal from the sensing interface under a first operating condition, and pass the samples to the transconductance operational amplifier under a second operating condition. The sampler is configured to decouple the transconductance operational amplifier from the sensing interface under the first operating condition and the second operating condition.

15. The electronic system according to claim 14, wherein: The sampler includes an acquisition stage and an output stage. The acquisition stage includes an acquisition and storage component and an acquisition connection circuit. The acquisition connection circuit has at least one connected state and a disconnected state. In the at least one connected state, the acquisition connection circuit couples the acquisition and storage component to the sensing interface. In the disconnected state, the acquisition connection circuit decouples the acquisition and storage component from the sensing interface. The output stage includes an output storage component and an output connection circuit. The output connection circuit has a pass-through state and a cut-off state. In the pass-through state, the output connection circuit couples the output storage component to the acquisition storage component. In the cut-off state, the output connection circuit decouples the output storage component from the acquisition storage component. The transmission state of the output connection circuit and the at least one connection state of the acquisition connection circuit are separated in time.

16. The electronic system of claim 15, wherein the acquisition and storage component includes a first capacitor having a first capacitance, and the output storage component includes a second capacitor having a second capacitance.

17. The electronic system of claim 15, wherein the acquisition connection circuit is configured to rectify the loop signal.

18. The electronic system of claim 15, wherein the acquisition connection circuit has a first connection state and a second connection state, wherein in the first connection state the acquisition connection circuit couples the acquisition storage component to the sensing interface with a first polarity, and in the second connection state the acquisition connection circuit couples the acquisition storage component to the sensing interface with a second polarity opposite to the first polarity.

19. A method for controlling a microelectromechanical gyroscope, the microelectromechanical gyroscope comprising: Support structure; The drive block is capacitively coupled to the support structure and is movable relative to the support structure according to the drive shaft; And a microelectromechanical circuit having a resonant frequency and a circuit gain, and including the driving block, the method comprising: The microelectromechanical circuit is placed in an oscillating state; Sensing the position of the drive block relative to the support structure; and The modulus of the loop gain is maintained at a unit value at the resonant frequency. The modulus for maintaining the loop gain includes: acquiring a sample of the loop signal indicating the position of the drive block relative to the support structure, and amplifying the sample in an open loop, wherein the acquisition and amplification are time-separated and do not overlap.

20. The method of claim 19, further comprising: The circuit signal is rectified by acquiring the connection circuit.

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