Precision drive and sense operation for microelectromechanical systems devices

Abstract

A system includes a set of electrostatic actuators. Each electrostatic actuator of the set of electrostatic actuators includes a high-voltage side and a low-voltage side. The low-voltage side is configured to be driven by a time-varying voltage signal (TVVS). The system includes a set of drive-sense channels. A representative channel of the set of drive-sense channels includes a drive electrical link between (i) a corresponding drive circuit of a set of drive circuits and (ii) the high-voltage side of a corresponding electrostatic actuator of the set of electrostatic actuators. The representative channel is configured to carry, via the drive electrical link, a controllable drive voltage from the corresponding drive circuit to the high-voltage side of the corresponding electrostatic actuator. The representative channel includes a sense electrical link configured to carry a current generated by the TVVS to a sense-measurement circuit.

Description

Attorney Docket No. 52753-28PRECISION DRIVE AND SENSE OPERATION FOR MICROELECTROMECHANICALSYSTEMS DEVICESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 737,712 filed December 22, 2024. The entire disclosure of the above application is incorporated by reference.FIELD

[0002] The present disclosure relates to control systems for electromechanical devices and more particularly to control systems for arrays of optical elements.BACKGROUND

[0003] Microelectromechanical systems (MEMS) devices are used in a wide variety of applications such as medical applications, automotive applications, and precision measuring and instrumentation applications. Generally, the physical position of MEMS devices is controlled by a drive voltage. However, the physical position typically has a non-linear dependence on the drive voltage. Additionally, MEMS devices are often subjected to outside forces like shocks, vibrations, accelerations, and variation in environmental conditions like temperature, pressure, humidity and radiation. On top of these external influences, material property changes also occur in the devices. All of these effects (outside forces, environmental conditions, and material property changes, etc.) may cause a MEMS device to move to a position other than its indicated or commanded position. Some MEMS devices use open-loop control because there has been no reliable way to quickly and easily measure the location of the moving portion of the device in real time with a closed-loop control. Open-loop control can be inaccurate because of the outside forces on MEMS devices, which results in the actual position of the MEMS device differing significantly from its intended position.

[0004] These issues are particularly important when creating arrays of MEMS devices that must act in concert with one another because, when acting in concert, the arrays cannot tolerate significant performance differences between elements. These issues are emphasized in optical phase control MEMS devices because the positioning requirements for optical steering are very small (for example, much less than 1pm). In various implementations, MEMS devices must move to the correct position within nanometers of the target location to produce the desired optical phase, so any deviations can cause significant performance degradation of the optical output.

[0005] Additional challenges arise in applications with arrays of MEMS devices. For example, arrays of MEMS require a very large number of electrical contacts (for example hundreds, thousands, or hundreds of thousands) to manage all of the MEMS elements in each array. TheAttorney Docket No. 52753-28 parallelization of the electrical circuits creates significant issues with cross-coupling in areas where traces must be densely routed to support the arrays. The cross-coupling appears as capacitive coupling between traces, which causes adjacent neighboring traces to pick up a fraction of the drive and sense signals generated on the target trace. Such cross-coupling is a challenge to precision operation of MEMS devices. Shielding solutions can be implemented, however this further exacerbates the high-density trace issue. Shielding also increases parasitic capacitance (CP) between the traces and ground, adding to the capacitive load of the system and increasing the power consumption of both the drive and sense operation. Accordingly, systems and methods are desired for precisely and accurately detecting the real time position of elements in an array of MEMS devices, without the aforementioned limitations and drawbacks of an open-loop system.

[0006] The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.SUMMARY

[0007] A system includes a set of electrostatic actuators. Each electrostatic actuator of the set of electrostatic actuators includes a high-voltage side and a low-voltage side that is configured to be driven by a time-varying voltage signal (TVVS). The system includes a set of drive-sense channels. A representative channel of the set of drive-sense channels includes a drive electrical link between (i) a corresponding drive circuit of a set of drive circuits and (ii) the high-voltage side of a corresponding electrostatic actuator of the set of electrostatic actuators. The representative channel is configured to carry, via the drive electrical link, a controllable drive voltage from the corresponding drive circuit to the high-voltage side of the corresponding electrostatic actuator. The representative channel includes a sense electrical link configured to carry a current generated by the TVVS to a sense-measurement circuit.

[0008] In other features, the system includes a sense filter configured to translate the current generated by the TVVS into a position signal that corresponds to a position of the corresponding electrostatic actuator. In other features, the controllable drive voltage is based on the position signal. In other features, the position signal is sensed by a controller that controls the corresponding drive circuit. In other features, the sense-measurement circuit is configured to perform a sensing operation to measure a capacitance of the corresponding electrostatic actuator. In other features, each channel of the set of drive-sense channels includes an electrostatic actuator of the set of electrostatic actuators. In other features, each channel of the set of drivesense channels includes a drive circuit of the set of drive circuits.

[0009] In other features, the system includes the set of drive circuits. In other features, each channel of the set of drive-sense channels includes a drive filter configured to attenuate an effect of the TVVS on a voltage of the high-voltage side of the corresponding electrostatic actuator.Attorney Docket No. 52753-28

[0010] In other features, the drive filter for one of the set of drive-sense channels is an active circuit with one or more inputs including at least one of the controllable drive voltage, the TVVS, or a control input from a controller. In other features, the drive filter for the one of the set of drive-sense channels is a passive circuit. In other features, the corresponding drive circuit is configured to hold the controllable drive voltage steady for a threshold period of time. In other features, the corresponding electrostatic actuator and at least a second electrostatic actuator share a low-side node that is connected to the low-voltage side of each of the corresponding electrostatic actuator and the at least a second electrostatic actuator.

[0011] In other features, the representative channel includes a sense-modulation circuit. In other features, the sense-modulation circuit is connected to the low-side node of the corresponding electrostatic actuator. In other features, the sense-modulation circuit generates the TVVS.

[0012] In other features, the TVVS has an amplitude of 10 Volts or less. In other features, the sense electrical link connects the high-voltage side of the corresponding electrostatic actuator to the sense-measurement circuit. In other features, the sense electrical link connects a low-voltage side of the sense-modulation circuit and the sense-measurement circuit.

[0013] A method for controlling a set of electrostatic actuators includes driving a low-voltage side of a corresponding electrostatic actuator of the set of electrostatic actuators with a timevarying voltage signal (TVVS). The corresponding electrostatic actuator includes a high-voltage side. The method includes carrying, via a representative drive-sense channel of a set of drivesense channels, a controllable drive voltage from a corresponding drive circuit of a set of drive circuits to the corresponding electrostatic actuator. The representative drive-sense channel includes a drive electrical link between the corresponding drive circuit and the high-voltage side of the corresponding electrostatic actuator. The representative drive-sense channel includes a sense electrical link configured to carry a current generated by the TVVS to a sensemeasurement circuit.

[0014] In other features, the method includes translating, via a sense filter, the current generated by the TVVS into a position signal that corresponds to a position of the corresponding electrostatic actuator. In other features, the corresponding electrostatic actuator and at least a second electrostatic actuator share a low-side node that is connected to the low- voltage side of each of the corresponding electrostatic actuator and the at least a second electrostatic actuator. In other features, the representative drive-sense channel includes a sense-modulation circuit. In other features, the sense-modulation circuit is connected to the low-side node of the corresponding electrostatic actuator. In other features, the sense-modulation circuit generates the TVVS.

[0015] Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims, and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.Attorney Docket No. 52753-28BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present disclosure will become more fully understood from the detailed description and the accompanying drawings.

[0017] FIG. 1 is a block diagram of an example high-side drive-sense signal combination circuit.

[0018] FIG. 2 is a block diagram of an example high-side drive-sense signal combination circuit with a drive filter.

[0019] FIG. 3 is a block diagram of an example circuit with a sense circuit on the high-side of the electrostatic actuator.

[0020] FIG. 4 is a block diagram of an example circuit with a sense circuit between the electrostatic actuator and ground.

[0021] FIG. 5 is a block diagram of an example circuit with a sense electrical link connected to the high-voltage side of the electrostatic actuator.

[0022] FIG. 6 is a block diagram of an example circuit with a sense electrical link connected to a low-voltage side of a sense-modulation circuit.

[0023] FIG. 7 is a flowchart of an example method for operating a circuit with a closed-loop decoupled drive-sense topology.

[0024] In the drawings, reference numbers may be reused to identify similar and / or identical elements.DETAILED DESCRIPTIONINTRODUCTION

[0025] Precise position control in actuated arrays of MEMS devices faces several challenges, including environmental changes and inaccurate electrical measurements stemming from the size and proximity of the electrical components and traces of arrays of MEMS devices. The present disclosure resolves the various challenges and describes a decoupled drive-sense approach for electrostatically actuated arrays of MEMS devices that provides precise and accurate sensing. In various implementations, the solution is (i) parallelizable, (ii) integrated circuit (IC) miniaturizable, and (iii) having sub-stability threshold drive-sense coupling (DSC). The decoupled drive-sense approached relies on elements including:• An array of electrostatic actuators, which may share a common low-voltage node• An array of drive-sense channels, where each channel is designed to provide a controllable drive voltage to a specific electrostatic actuator and to carry out a sensing operation to measure the capacitance of that same electrostatic actuator• A sense time-varying voltage signal (TVVS) (usually with an amplitude less than 10 Volts) driving the low-voltage side of the electrostatic actuator, which generates a change in the voltage over the electrostatic actuator. In some implementations, all the electrostatic actuators share a common low-voltage node. In some implementations, the array ofAttorney Docket No. 52753-28 electrostatic actuators is separated into sub-groups of actuators (where each sub-group shares a common low-voltage node). For example, a shared common low-voltage node may be present for every 1, 2, 10, 100, or 1,000 electrostatic actuators• A drive electrical link from the drive circuit of the drive-sense channel to the high-side of the specific electrostatic actuator, which allows the drive circuit to apply a controlled voltage to the high-voltage side of the specific electrostatic actuator• A sense electrical link connecting the sense-measurement circuit to either: (i) the specific electrostatic actuator high-side (for example, if using a shared low-voltage node) or (ii) the low-voltage side (for example, via the sense-modulation circuit). The sense electrical link allows the sense-measurement circuit to measure the currents generated by the sense TV VS and, in doing so, measure the capacitance of the electrostatic actuator• A drive filter, whether active or passive, which attenuates the sense TVVS impact on the voltage of the high-side of the electrostatic actuator node• A sense filter in the sense-measurement circuit that translates the currents generated by the sense TVVS into a signal indicative of a position of the electrostatic actuatorCOMMON IMPLEMENTATIONS: CLOSED-LOOP SENSING AND ELECTROSTATIC ACTUATION

[0026] The present disclosure describes a sensing solution for electrostatically actuated arrays of optical MEMS devices. Electrostatic actuation provides a combination of a high force capacity for drive operation and a position-dependent capacitance that can be used as the sense signal. In some implementations, optical MEMS devices include arrays of active MEMS devices, driven by electrostatic actuation, where each element has feedback for closed-loop control of its position. Closed-loop control of each electrostatic actuator requires a dedicated drive and sense circuit channel for each actuator. The drivers for the array of MEMS devices are miniaturized via integrated circuit (IC) technology to make full use of the small size benefit of MEMS devices. A small MEMS device with an electronics box that is potentially several orders of magnitude larger fails to meet the needs of many MEMS applications. Electrostatically driven arrays of optical MEMS devices often have a shared low- voltage node for all the electrostatic actuators. Each actuator is driven by a command voltage applied to the high-voltage side of the actuator.

[0027] The array of optical MEMS devices is generally controlled by a digital controller which can interpret user commands into specific commands for each MEMS device and determine the correct signal to pass to each element in the array based on both the user command and the sense reading for each channel. An analog controller is possible but less flexible in terms of control strategies and thus less common.

[0028] Electrostatic actuators are capacitors that generate an oscillating current in response to an oscillating voltage (where the amplitude of the oscillating current is proportional to the capacitance and the frequency). A typical capacitance sensing approach relies on tracking the current response to a time-varying voltage signal (TVVS) across the capacitor (measuring the current provides a way to measure the capacitance, which then provides a measure ofAttorney Docket No. 52753-28 electrostatic actuator position). The sense TV VS is generally a specific frequency oscillation that is at a frequency much higher (for example, more than 10 times higher) than the mechanical resonance of the MEMS device. In various implementations, the sense TVVS is a pure- frequency signal while, in others, the sense TVVS has multiple frequency components. As a non-bounding example, square waves, sawtooth waves, and triangle waves with periodicity are broad frequency spectrum signals with multiple frequency components and would all be valid TVVS’s.

[0029] The sense solution for arrays of MEMS devices must not have any distortion due to the high-voltage or the distortion appears as an unacceptable coupling between the drive voltage and sense signal. Drive-sense coupling (DSC) is observed as sudden changes in the sense reading caused by sudden changes in the drive signal. DSC also causes instability in the feedback necessary for closed-loop control.

[0030] The importance of DSC is illustrated by following the feedback loop. As an example, the feedback compensator generates a command based on a sensed position error which is sent to the electrostatic actuator. Due to the undesirable DSC, a sensor instantly responds to the new command, which generates a sudden response in the feedback compensator output. The feedback loop rapidly drives the controller into uncontrollable oscillation (or in some systems into a hard stop). If DSC effects exceed a stability threshold, then closed-loop feedback operation fails. The stability threshold of the DSC is a function of the specific controller design, but generally is a very low value, such that the drive signal full scale swing generates much less than 1% of the full scale sensor swing.HIGH-VOLTAGE AND LOW- VOLTAGE

[0031] High-voltage refers to the amplitude of the voltage relative to the circuit ground voltage, as electrostatic actuators can be driven nearly identically with either positive or negative voltage. High-voltage is generally within the range of 100-300 Volts. The high-voltage side thus refers to the side of the electrostatic actuator that is controlled by the drive voltage and is controlled to charge the capacitor to a significant voltage (for example, greater than 200V) off the circuit ground voltage. The low-voltage side refers to the side of the electrostatic actuator which is kept near the circuit ground voltage. The low-voltage side of the actuators are generally linked to a shared node to minimize the number of traces on the MEMS device, and this node is often a conductive layer of silicon in the MEMS device.COMMON IMPLEMENTATIONS: VARIOUS IMPLEMENTATIONS OF MEMS CONTROL DESIGNS

[0032] In some implementations, MEMS control designs focus on shared high-side drive-sense approaches, where both the drive and the sense signal are passed to the electrostatic actuator using the same electrical link (or connection such as a wire), and going to the same (high) side of the electrostatic actuator (as seen in FIGS. 1-2). Different approaches are used to superimpose the signal. For example, the drive signal from drive circuit 104 and the sense signal from sense-modulation circuit 108 can be combined directly before being passed to theAttorney Docket No. 52753-28 electrostatic actuator (as seen in FIG. 1). Alternatively, a filter (such as drive filter 112) can be placed between the drive and sense signals (as seen in FIG. 2). In some cases, the drive and sense signals are superimposed on one another and passed through a shared electrical link (or an electrical connector such as a wire or trace) to the high-side of the electrostatic actuator.

[0033] In some implementations of MEMS control designs, there are several approaches for selecting the location of the sense-measurement circuit that samples the current (as seen in FIGS. 3-4). FIG. 3 uses an electrical link from the high-side of the electrostatic actuator to the sense-measurement circuit 304. FIG. 4 uses an electrical link from the low-side of the electrostatic actuator to the sense-measurement circuit 304 (which is between Cmand ground). In both cases, the designs are performing the same function of measuring the current response to the sense TV VS.

[0034] In some implementations, MEMS control designs use a grounded shared low- voltage node (as seen in FIGS. 3-4), which can pose an issue for high-side sense TVVS injection. The sense TVVS will appear on the shared ground node in an attenuated form because the ground has finite impedance. The current draw generated by the sense TVVS will act on the finite ground impedance (often approximately 10 ohms owing to the very small trace sizes on MEMS devices), resulting in a measurable TVVS which varies spatially across the array of MEMS devices. The attenuated TVVS on the low-side then generates a small-scale current signal in all other channels, which appears as cross-channel coupling. While this effect is not large, the effect scales with the size of the array to become a significant cross-channel coupling challenge. The issue can be resolved by differentiating the channels in the frequency domain. However, frequency differentiation does not scale to large arrays given the spectral band isolation filters which can be parallelized and integrated into IC designs. This lack of parallelizability is not immediately apparent when testing single element devices.

[0035] In some implementations, MEMS control designs utilize elements which are not IC compatible and thus cannot be miniaturized (such as inductors and lock-in amplifiers). These approaches work well for single element solutions to resolve the drive and sense signal coupling but cannot be scaled. For example, inductors cannot be fabricated on ICs for parallelization, and lock-in amplifiers (which are precision equipment that extract the exact response to voltage oscillations) are large, expensive, and cannot be effectively parallelized.

[0036] In some implementations, MEMS control designs use the high-side drive-sense approach for combined drive sense which uses a simpler circuitry than other types of configurations. Both the drive and sense signals are supplied by the same circuit, which imposes few limitations on the MEMS design and minimizes the number of traces to the MEMS. The drawbacks of shared high-side drive-sense approaches (lack of parallelizability, lack of IC miniaturizability, above-threshold DSC) are not immediately apparent when testing single element devices in open-loop mode.

[0037] DSC in currently-existing designs can come from many sources, including but not limited to: i) voltage-dependent sense TVVS generation, ii) coupled voltage and parameter changes in the system, and ii) voltage-dependent capacitances in the system.Attorney Docket No. 52753-28COMMON IMPLEMENTATIONS: VOLTAGE-DEPENDENT SENSE TVVS GENERATION

[0038] In some implementations, shared high-side drive-sense approaches have conflicting requirements that primarily appear as issues with parallelization, miniaturization, and DSC. A first requirement is that the drive signal must be high voltage and low frequency. In some implementations, the drive signal reaches voltages of more than 200V for electrostatic actuators. In some implementations, the drive signal is a steady state command if the MEMS devices need to be held in a specific position. A second requirement is that the sense TVVS must be low voltage and high frequency. The sense TVVS is often only a few volts (for example -10 to +10 Volts), but must generally change very quickly to elicit a significant current response from the electrostatic actuator. The combination of the drive high-voltage and the sense high frequency is a significant challenge for the drive electronics because the drive electronics must retain extreme stability during the operation to avoid distorting the sense TVVS. The sense circuit must not have any distortion due to the high voltage or DSC will occur, which is unacceptable for closed- loop operation.COMMON IMPLEMENTATIONS: COUPLED VOLTAGE AND PARAMETER CHANGES

[0039] The same challenge of output dependence on voltage observed in the drive electronics voltage circuitry can be observed in the dynamics of the passive electronic components. For example, the charge on a capacitor is proportional to the applied voltage, and this charge translates into a voltage-dependent current when the capacitance changes. The mapping of capacitance change to current flow is voltage dependent and more broadly, parameter variation in electrical components produces voltage-dependent behavior. This results in changes in the parameters of the electrical component in the circuit over large voltage ranges and the primary electrostatic actuator capacitance (represented by capacitance Cm) itself varies in time. The current flows generated by these parameter changes have two negative impacts: i) the current flows generate voltage drops throughout the circuit and ii) the current flows can directly add to the sensed current measurements to distort the sense-measurement process. Both effects appear as DSC to the sensing operation. Therefore, overlap of the regions of the circuit exposed to the sense TVVS with the regions of the circuit exposed to the high drive voltage must be mitigated. These overlap areas can create large unwanted voltage drops and large unwanted current flows, both of which will show up as DSC, which is unacceptable for closed-loop operation.COMMON IMPLEMENTATIONS: VOLTAGE-DEPENDENT CAPACITANCES

[0040] Drive circuits often utilize capacitors with voltage sensitivity (in other words, capacitors with a capacitance that can change significantly with voltage). In some implementations, the drive circuit capacitors are effectively in parallel with the electrostatic actuator capacitor and can easily affect the sense-measurement circuit. In other words, the drive circuit capacitors may be included as part of the total capacitance measurement unless special measures are taken which are not found in approaches like those described above. Overlap of the drive circuit capacitors and the electrostatic actuator capacitor results in the sense-measurementAttorney Docket No. 52753-28 acquiring a drive- voltage sensitivity (due to the voltage sensitivity of the drive capacitors), which results in unacceptable DSC.

[0041] In some implementations, MEMS control systems include drive filters between the sense-modulation and drive circuit. Drive filters between the sense-modulation and the drive circuit attenuate (but do not entirely remove) the effect of the sense TVVS on the drive circuit. The drive filter attenuation of the sense TVVS effects minimizes the drive circuit fighting the sense TVVS and reduces voltage-dependent capacitance in the drive circuit (which can cause DSC). In some designs, DSC is reduced but not fully resolved because the high-side of the electrostatic actuator is still subjected to the combination of the drive voltage and the sense TVVS, which can create DSC.

[0042] The conflicting requirements imposed by shared high-side drive-sense approaches on the drive circuit produce drive circuit designs which struggle to mitigate DSC. The shared high- side approach requires the drive circuit to hold a high-voltage drive signal while maintaining a small and distortion-free precise high-frequency signal superimposed on top of the high-voltage drive signal. As a result, the sense signal is subject to significant distortion from multiple sources including the applied frequency, the capacitive loading, and the applied drive voltage. All of these sources cause issues, as any distortion in the sense TVVS produces an equivalent distortion in the sense reading. In other words, shared high-side drive-sense approaches generally result in sense operations that lack precision and accuracy and have significant sensitivity to the conditions of the circuit including the drive voltage on the MEMS device which results in DSC. DSC is not a concern for open-loop systems or initial demonstrations, but it is unacceptable for closed-loop operation. Prior MEMS control system designs and approaches thus fail to meet the needs for a sensing solution for electrostatically actuated arrays of MEMS device which must be i) highly parallelizable, ii) IC miniaturizable and iii) showing minimal (sub-stability threshold) DSC to be compatible with closed-loop operation.CLOSED-LOOP DECOUPLED DRIVE-SENSE APPROACH

[0043] As stated previously, the present disclosure describes a decoupled drive-sense approach for electrostatically actuated arrays of MEMS devices that can provide precise and accurate sensing while also i) being parallelizable, ii) being IC miniaturizable, and iii) showing substability threshold DSC. This approach relies on several key elements described in greater detail below: i) a common low-voltage node, ii) a drive-sense channel, iii) a TVVS, iv) a drive electrical link, v) a sense electrical link, vi) a drive filter, and vii) a sense filter.SEPARATE DRIVE-SENSE CHANNELS

[0044] FIG. 5 is a functional block diagram of an example drive-sense channel 500 circuit. The decoupled drive-sense approach resolves the sense challenges for arrays of electrostatic actuators (where each actuator is treated as its own separate drive and sense channel). The decoupled drive-sense approach achieves the desired decoupling performance by physically separating the channels of the drive and sense signals. The decoupled approach shifts the senseAttorney Docket No. 52753-28TVVS 536 from the high-side 508 to the low-side 558 of the electrostatic actuator 532. With this change, the sense TVVS 536 can be generated independently of the drive signal and generated on a section of the electrical circuit whose voltage is not swinging over large changes.LOW-SIDE SENSE TVVS AND A COMMON LOW-VOLTAGE NODE

[0045] The low-side 558 sense TVVS 536 preferably connects to a shared low-voltage node 540 of the electrostatic actuators, as this significantly reduces the number of traces and thus reduces the trace density of the array of MEMS devices. Using a shared low- voltage node 540 avoids requiring a unique low-voltage trace for each electrostatic actuator 532 and instead replaces the separate low-voltage links with shared electrical link(s). Reducing the number of traces allows the traces to be further spaced apart from one another, reducing both crosscoupling and unwanted parasitic capacitance (represented by CP) coupling to ground. Active control of the low-side 558 voltage further aids the system by mitigating the channel coupling issues observed in high-side sense TVVS approaches.

[0046] The decoupled drive-sense approach is most efficient at solving the sense challenge for array MEMS when using a shared low-voltage node 540. However, the decoupled drive-sense approach does not specifically require a single shared low-voltage node 540, as the same TVVS 536 can be sent along multiple low-side traces to multiple different electrostatic actuators or sets of electrostatic actuators. The sense TVVS 536 is generally a specific frequency modulation that is at a frequency much higher (for example, more than 10 times higher) than the mechanical resonance of the MEMS device.

[0047] With the shared low-voltage node 540, the same sense TVVS 536 can be used to simultaneously modulate all the electrostatic actuators in the array. The simultaneous modulation further mitigates the cross-channel coupling issue as the TVVS 536 is equal on adjacent traces, so the capacitive coupling is not energized. The TVVS 536 is generated by sense-modulation circuit 544. In some implementations, the sense-modulation circuit 544 is controlled by a digital controller 552.DRIVE ELECTRICAL LINK AND SENSE ELECTRICAL LINK

[0048] The drive electrical link 512 for the drive circuit 504 provides a path for the drive circuit 504 to apply voltage to the high-side 508 of the electrostatic actuator 532. Drive circuit 504 applies a constant voltage for a threshold duration (for example, for a controller cycle from digital controller 552). In some implementations, drive circuit 504 is an op-amp or a pulse-width modulation circuit. This link is distinct from the sense electrical link 516 for the sensemeasurement circuit 520 to the high-side 508 of the electrostatic actuator 532.

[0049] In some implementations (as shown in FIG. 6), a drive-sense channel 600 does not include a shared low-voltage node 540, which allows the sense electrical link 516 to connect the sense-measurement circuit 520 to the low-side 558 of the electrostatic actuator 532 via the low- voltage side of sense-modulation circuit 544 (instead of to the high-side 508 of electrostatic actuator 532 as seen in FIG. 5). The sense electrical link 516 connects to the electrostaticAttorney Docket No. 52753-28 actuator 532, whether via the high-side 508 or the low-side 558 (through the sense-modulation circuit 544). In both cases, the sense electrical link 516 passes the current (generated in response to the sense TVVS 536) to the sense-measurement circuit 520.

[0050] The sense TVVS 536 is injected on the low-side 558 of the electrostatic actuator array. Any capacitor whose voltage is altered (such as Cmof the electrostatic actuator 532) by the sense TVVS 536 will generate a current flow in response. These current flows all combine to create a net current flow, a portion (up to the entirety) of which passes through the sense-measurement circuit 520and creates a sense-measurement.HIGH-SIDE DRIVE FILTER

[0051] A high-side drive filter 548, composed of active and / or passive components, attenuates the impact of sense TVVS 536 on the voltage of the high-side 508 node of the electrostatic actuator 532. Active or passive electrical components can be used for this drive filter 548.

[0052] The drive filter 548 attenuation of the sense TVVS 536 impact on the voltage of the high-side 508 of the electrostatic actuator 532 node has two benefits. First, the drive filter 548 attenuates the DSC generated by voltage-dependent capacitance in the drive circuit 504. Since the drive circuit 504 is electrically linked (via drive electrical link 512) to the high-side 508 of the electrostatic actuator 532, the potentially voltage-dependent capacitance within the drive circuit 504 can observe some portion of the sense TVVS 536, resulting in current flow that contributes to the net current flow measured by the sense-measurement circuit 520. The voltage sensitivity of the drive circuit can thus contaminate the sense reading, causing unwanted DSC. The drive filter 548 attenuates this contribution, reducing DSC. Second, the drive filter 548 reduces the power consumption of the sensing operation. Voltage changes on the electrostatic actuator 532 high-side 508 node cause charging of the electrostatic actuator 532 (Cm), parasitic capacitances (Cp), and the drive circuit 504 capacitances. Charging the electrostatic actuator 532, parasitic capacitances, and the drive circuit 504 capacitances draws current onto the high-side 508 of the circuit which can consume significant power at high voltages. Attenuation of the sense TVVS 536 on the high-side 508 of the electrostatic actuator 532 attenuates this current demand, lowering power consumption of the sensing operation.

[0053] Several examples of drive filter 548 are provided. As an example, a passive drive filter 548 composed of a capacitance linked to the high-side 508 of the electrostatic actuator 532 provides charge to the high-side 508 node when the voltage drops. Providing charge to the high- side 508 node attenuates the sense TVVS 536 impact on the high-side 508 node, reducing the apparent scale of the sense TVVS 536 at the high-side 508 of the electrostatic actuator 532. A passive capacitance drive filter 548 increases the capacitive load on the drive circuit 504 as a tradeoff for sense TVVS 536 attenuation.

[0054] As another example, a frequency specific notch drive filter 548 tuned to have high capacitance at the primary frequency of the sense TVVS 536 can have a lower capacitance at low frequency as observed by the drive circuit 504. As another example, an active drive filter 548 composed of an op-amp provides a tuned response to a very low effective impedance at theAttorney Docket No. 52753-28 primary frequency of the sense TVVS 536 (so as to resist voltage changes of the high-side 508 of the electrostatic actuator 532) but to a much higher impedance at low frequency (so as to limit current draw when changing drive voltage). In some implementations, an active drive filter 548 is controlled by a digital controller 552. In some implementations, drive filter 548 has one or more inputs via electrical links to various points of drive-sense channel 500.SENSE FILTER AND DIGITIZATION ELEMENTS

[0055] The sense-measurement circuit 520 measures the current (amps) response to the sense TVVS 536. In some implementations, a sense-measurement circuit 520 is used on either the high-side 508 or low-side 558 of the electrostatic actuator 532. However, it is preferable that the sense-measurement circuit 520 is placed on the high-side 508 node because the sense TVVS 536 is supplied on the low-side 558 node. If the low-side 558 node is unique to each actuator (for example, when there is no shared low-voltage node 540, as seen in FIG. 6), the sensemeasurement circuit 520 can be placed on the low-voltage (for example, grounded) side of the sense-modulation circuit 544 (as seen in FIG. 6) or the high-side 508 node (as seen in FIG. 5). When the low-side 558 node is shared (as seen in FIG. 5), the shared low-side node 540 results in a mixture individual actuator responses that cannot be detangled from one another when measured from the same low-side. For this reason, the sense-measurement circuit 520 must be placed on the high-side 508 node.

[0056] The sense-measurement circuit 520 contains the sense filter 524 and optional digitization elements (such as sense digitization filter 528). The sense filter 524 translates the currents generated by the sense TVVS 536 into a signal approximately proportional to the electrostatic actuator 532 capacitance (Cm). The digitization element digitizes the filter output signal, so that the sense reading can be passed to a digital controller 552.

[0057] The sense filter 524 in the sense-measurement circuit 520 generates a signal (such as a voltage), in response to the current flow through the sense-measurement circuit 520. Many options exist for the sense filter 524 and a few examples are noted below. In some implementations, the sense filter 524 monitors voltage over a simple impedance, such as a resistance or capacitance. In the simple resistance impedance mode, the output voltage of sense filter 524 is proportional to the current flow. This is because resistors translate current flow into voltage. A sense TVVS 536 oscillation will thus generate a voltage oscillation output from the sense filter 524 which is proportional to the electrostatic actuator 532 capacitance. In some implementations, the sense filter 524 monitors voltage over a complex hybrid impedance. In some implementations, the complex hybrid impedance includes active elements. When using complex hybrid impedances, the sense filter 524 output voltage change can be proportional to the integral of the current flow and thus generates a voltage output from the sense filter 524 which is proportional to the electrostatic actuator 532 capacitance. In some implementations, the sense filter 524 includes a capacitor in a trans -impedance amplifier at the low-side 558 of the electrostatic actuator 532 to integrate the current flow into a voltage output. In the various examples mentioned above, the designs are performing the same function of transforming theAttorney Docket No. 52753-28 current response to the sense TVVS 536 into a signal which is indicative of the electrostatic actuator 532 capacitance and thus the electrostatic actuator 532 position.

[0058] In some implementations, the sense filter 524 includes several filters in series and can be used to attenuate sensitivities in the signal. As an example, a frequency filter such as a notch filter or anti-aliasing filter can be used to properly condition the signal prior to transfer into the controller.

[0059] An optional digitization element (such as sense digitization filter 528) reads in the signal from the sense filter 524 and turns sense filter output into a digital signal for use in a digital controller 552. Array MEMS devices will generally be run via a digital controller 552, but this is not strictly necessary, because it is possible for the analog sense signal to be used in an analog closed-loop controller (which can replace digital controller 552).

[0060] In the decoupled design of the present disclosure, the sense filter 524 and optional sense digitization filter 528 can be made IC compatible because the decoupled approach separates the drive and sense signal, allowing the remaining issues to be resolved with simple IC-compatible RC filters instead of inductors or lock-in amplifiers. The low-side 558 sense TVVS 536 generates a uniform signal without DSC for all electrostatic actuators which produces a unique sense reading without DSC for each actuator that is transformed into the desired signal through miniaturizable and parallelizable circuitry.FLOWCHART

[0061] FIG. 7 is an example method of operation for a drive-sense channel as depicted in FIGS. 5 and 6. Control begins at 704 and determines whether a new cycle has begun (in other words, whether a threshold period of time has elapsed). If a new cycle has not begun, control remains at 704. If a new cycle has begun, control transfers to 708. In some implementations, the cycle and / or threshold period of time is defined by a controller clock cycle. At 708, the sensemodulation circuit modulates (generates a change in voltage) which causes a current change in the electrostatic actuator. At 712, control detects the change in current to determine the voltage of the electrostatic actuator. At 716, control translates the voltage of the electrostatic actuator into a position signal. At 720, control uses the position signal to determine whether the electrostatic actuator is at the desired position. If not, control transfers to 724 and the drive signal is adjusted and control continues to 728. If the electrostatic actuator is at the desired position, control continues to 728 and the drive signal is sent (for example, by the drive circuit). Control then returns to 704.CONCLUSION

[0062] The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. In the writtenAttorney Docket No. 52753-28 description and claims, one or more steps within a method may be executed in a different order (or concurrently) without altering the principles of the present disclosure. Similarly, one or more instructions stored in a non-transitory computer-readable medium may be executed in a different order (or concurrently) without altering the principles of the present disclosure. Unless indicated otherwise, numbering or other labeling of instructions or method steps is done for convenient reference, not to indicate a fixed order.

[0063] Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and / or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure.

[0064] Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship encompasses a direct relationship where no other intervening elements are present between the first and second elements as well as an indirect relationship where one or more intervening elements are present between the first and second elements.

[0065] As noted below, the term “set” generally means a grouping of one or more elements. However, in various implementations a “set” may, in certain circumstances, be the empty set (in other words, the set has zero elements in those circumstances). As an example, a set of search results resulting from a query may, depending on the query, be the empty set. In contexts where it is not otherwise clear, the term “non-empty set” can be used to explicitly denote exclusion of the empty set — that is, a non-empty set will always have one or more elements.

[0066] A “subset” of a first set generally includes some of the elements of the first set. In various implementations, a subset of the first set is not necessarily a proper subset: in certain circumstances, the subset may be coextensive with (equal to) the first set (in other words, the subset may include the same elements as the first set). In contexts where it is not otherwise clear, the term “proper subset” can be used to explicitly denote that a subset of the first set must exclude at least one of the elements of the first set. Further, in various implementations, the term “subset” does not necessarily exclude the empty set. As an example, consider a set of candidates that was selected based on first criteria and a subset of the set of candidates that was selected based on second criteria; if no elements of the set of candidates met the second criteria, the subset may be the empty set. In contexts where it is not otherwise clear, the term “non-empty subset” can be used to explicitly denote exclusion of the empty set.

[0067] In the figures, the direction of an arrow, as indicated by the arrowhead, generally demonstrates the flow of information (such as data or instructions) that is of interest to the illustration. For example, when element A and element B exchange a variety of information butAttorney Docket No. 52753-28 information transmitted from element A to element B is relevant to the illustration, the arrow may point from element A to element B. This unidirectional arrow does not imply that no other information is transmitted from element B to element A. Further, for information sent from element A to element B, element B may send requests for, or receipt acknowledgements of, the information to element A.

[0068] In this application, including the definitions below, the term “module” can be replaced with the term “controller” or the term “circuit.” In this application, the term “controller” can be replaced with the term “module.” The term “module” may refer to, be part of, or include: an Application Specific Integrated Circuit (ASIC); a digital, analog, or mixed analog / digital discrete circuit; a digital, analog, or mixed analog / digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); processor hardware (shared, dedicated, or group) that executes code; memory hardware (shared, dedicated, or group) that is coupled with the processor hardware and stores code executed by the processor hardware; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip.

[0069] The module may include one or more interface circuits. In some examples, the interface circuit(s) may implement wired or wireless interfaces that connect to a local area network (LAN) or a wireless personal area network (WPAN). Examples of a LAN are Institute of Electrical and Electronics Engineers (IEEE) Standard 802.11-2020 (also known as the WIFI wireless networking standard) and IEEE Standard 802.3-2018 (also known as the ETHERNET wired networking standard). Examples of a WPAN are IEEE Standard 802.15.4 (including the ZIGBEE standard from the ZigBee Alliance) and, from the Bluetooth Special Interest Group (SIG), the BLUETOOTH wireless networking standard (including Core Specification versions 3.0, 4.0, 4.1, 4.2, 5.0, and 5.1 from the Bluetooth SIG).

[0070] The module may communicate with other modules using the interface circuit(s). Although the module may be depicted in the present disclosure as logically communicating directly with other modules, in various implementations the module may actually communicate via a communications system. The communications system includes physical and / or virtual networking equipment such as hubs, switches, routers, and gateways. In some implementations, the communications system connects to or traverses a wide area network (WAN) such as the Internet. For example, the communications system may include multiple LANs connected to each other over the Internet or point-to-point leased lines using technologies including Multiprotocol Label Switching (MPLS) and virtual private networks (VPNs).

[0071] In various implementations, the functionality of the module may be distributed among multiple modules that are connected via the communications system. For example, multiple modules may implement the same functionality distributed by a load balancing system. In a further example, the functionality of the module may be split between a server (also known as remote, or cloud) module and a client (or, user) module. For example, the client module may include a native or web application executing on a client device and in network communication with the server module.Attorney Docket No. 52753-28

[0072] Some or all hardware features of a module may be defined using a language for hardware description, such as IEEE Standard 1364-2005 (commonly called “Verilog”) and IEEE Standard 1076-2008 (commonly called “VHDL”). The hardware description language may be used to manufacture and / or program a hardware circuit. In some implementations, some or all features of a module may be defined by a language, such as IEEE 1666-2005 (commonly called “SystemC”), that encompasses both code, as described below, and hardware description.

[0073] The term code, as used above, may include software, firmware, and / or microcode, and may refer to programs, routines, functions, classes, data structures, and / or objects. Shared processor hardware encompasses a single microprocessor that executes some or all code from multiple modules. Group processor hardware encompasses a microprocessor that, in combination with additional microprocessors, executes some or all code from one or more modules. References to multiple microprocessors encompass multiple microprocessors on discrete dies, multiple microprocessors on a single die, multiple cores of a single microprocessor, multiple threads of a single microprocessor, or a combination of the above.

[0074] The memory hardware may also store data together with or separate from the code. Shared memory hardware encompasses a single memory device that stores some or all code from multiple modules. One example of shared memory hardware may be level 1 cache on or near a microprocessor die, which may store code from multiple modules. Another example of shared memory hardware may be persistent storage, such as a solid state drive (SSD) or magnetic hard disk drive (HDD), which may store code from multiple modules. Group memory hardware encompasses a memory device that, in combination with other memory devices, stores some or all code from one or more modules. One example of group memory hardware is a storage area network (SAN), which may store code of a particular module across multiple physical devices. Another example of group memory hardware is random access memory of each of a set of servers that, in combination, store code of a particular module. The term memory hardware is a subset of the term computer-readable medium.

[0075] The apparatuses and methods described in this application may be partially or fully implemented by a special -purpose computer created by configuring a general-purpose computer to execute one or more particular functions embodied in computer programs. Such apparatuses and methods may be described as computerized or computer-implemented apparatuses and methods. The functional blocks and flowchart elements described above serve as software specifications, which can be translated into the computer programs by the routine work of a skilled technician or programmer.

[0076] The computer programs include processor-executable instructions that are stored on at least one non-transitory computer-readable medium. The computer programs may also include or rely on stored data. The computer programs may encompass a basic input / output system (BIOS) that interacts with hardware of the special-purpose computer, device drivers that interact with particular devices of the special-purpose computer, one or more operating systems, user applications, background services, background applications, etc.Attorney Docket No. 52753-28

[0077] The computer programs may include: (i) descriptive text to be parsed, such as HTML (hypertext markup language), XML (extensible markup language), or JSON (JavaScript Object Notation), (ii) assembly code, (iii) object code generated from source code by a compiler, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. As examples only, source code may be written using syntax from languages including C, C++, C#, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, JavaScript®, HTML5 (Hypertext Markup Language 5th revision), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, Visual Basic®, Lua, MATLAB, SIMULINK, and Python®.

[0078] The term non-transitory computer-readable medium does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave). Non-limiting examples of a non-transitory computer-readable medium are nonvolatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape or a hard disk drive), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc).

[0079] The term “set” generally means a grouping of one or more elements. The elements of a set do not necessarily need to have any characteristics in common or otherwise belong together. The phrase “at least one of A, B, and C” should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.” The phrase “at least one of A, B, or C” should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR.CLAUSES

[0080] Various example embodiments of the invention are described in the following clauses.

[0081] Clause 1: A system comprising: a set of electrostatic actuators, wherein each electrostatic actuator of the set of electrostatic actuators includes: a high-voltage side, and a low-voltage side that is configured to be driven by a time- varying voltage signal (TVVS), and a set of drive-sense channels, wherein a representative channel of the set of drive-sense channels: includes a drive electrical link between (i) a corresponding drive circuit of a set of drive circuits and (ii) the high-voltage side of a corresponding electrostatic actuator of the set of electrostatic actuators,Attorney Docket No. 52753-28 is configured to carry, via the drive electrical link, a controllable drive voltage from the corresponding drive circuit to the high-voltage side of a corresponding electrostatic actuator, and includes a sense electrical link configured to carry a current generated by the TVVS to a sense-measurement circuit.

[0082] Clause 2: The system of clause 1 further comprising a sense filter configured to translate the current generated by the TVVS into a position signal that corresponds to a position of the corresponding electrostatic actuator.

[0083] Clause 3: The system of clause 2 wherein the controllable drive voltage is based on the position signal.

[0084] Clause 4: The system of clause 2 wherein the position signal is sensed by a controller that controls the corresponding drive circuit.

[0085] Clause 5: The system of any one of clauses 1-4 wherein the sense- measurement circuit is configured to perform a sensing operation to measure a capacitance of the corresponding electrostatic actuator.

[0086] Clause 6: The system of any one of clauses 1-5 wherein each channel of the set of drive-sense channels includes an electrostatic actuator of the set of electrostatic actuators.

[0087] Clause 7: The system of any one of clauses 1-6 wherein each channel of the set of drive-sense channels includes a drive circuit of the set of drive circuits.

[0088] Clause 8: The system of any of clauses 1-7 further comprising the set of drive circuits.

[0089] Clause 9: The system of any one of clauses 1-7 wherein each channel of the set of drive-sense channels includes a drive filter configured to attenuate an effect of the TVVS on a voltage of the high-voltage side of the corresponding electrostatic actuator.

[0090] Clause 10: The system of clause 8 wherein the drive filter for one of the set of drivesense channels is an active circuit with one or more inputs including at least one of: the controllable drive voltage, the TVVS, or a control input from a controller.

[0091] Clause 11 : The system of clause 9 wherein the drive filter for the one of the set of drive-sense channels is a passive circuit.

[0092] Clause 12: The system of any one of clauses 1-11 wherein the corresponding drive circuit is configured to hold the controllable drive voltage steady for a threshold period of time.

[0093] Clause 13: The system of any one of clauses 1-12 wherein the corresponding electrostatic actuator and at least a second electrostatic actuator share a low-side node that is connected to the low-voltage side of each of the corresponding electrostatic actuator and the at least a second electrostatic actuator.Attorney Docket No. 52753-28

[0094] Clause 14: The system of clause 13 wherein: the representative channel includes a sense-modulation circuit, the sense-modulation circuit is connected to the low-side node of the corresponding electrostatic actuator, and the sense- modulation circuit generates the TVVS.

[0095] Clause 15: The system of any one of clauses 1-14 wherein the TVVS has an amplitude of 10 Volts or less.

[0096] Clause 16: The system of any one of clauses 1-15 wherein the sense electrical link connects the high-voltage side of the corresponding electrostatic actuator to the sensemeasurement circuit.

[0097] Clause 17: The system of any one of clauses 1-15 wherein the sense electrical link connects a low-voltage side of the sense-modulation circuit and the sense-measurement circuit.

[0098] Clause 18: A method for controlling a set of electrostatic actuators, the method comprising: driving a low- voltage side of a corresponding electrostatic actuator of the set of electrostatic actuators with a time-varying voltage signal (TVVS), wherein the corresponding electrostatic actuator includes a high-voltage side; and carrying, via a drive electrical link of a representative drive-sense channel of a set of drive-sense channels, a controllable drive voltage from a corresponding drive circuit of a set of drive circuits to the corresponding electrostatic actuator, wherein the representative drive-sense channel includes: the drive electrical link between (i) the corresponding drive circuit and (ii) the high-voltage side of the corresponding electrostatic actuator, and a sense electrical link configured to carry a current generated by the TVVS to a sense-measurement circuit.

[0099] Clause 19: The method of clause 18 further comprising translating, via a sense filter, the current generated by the TVVS into a position signal that corresponds to a position of the corresponding electrostatic actuator.

[0100] Clause 20: The method of clause 18 wherein: the corresponding electrostatic actuator and at least a second electrostatic actuator share a low-side node that is connected to the low-voltage side of each of the corresponding electrostatic actuator and the at least a second electrostatic actuator, the representative drive-sense channel includes a sense-modulation circuit, the sense-modulation circuit is connected to the low-side node of the corresponding electrostatic actuator, and the sense-modulation circuit generates the TVVS.

Claims

Attorney Docket No. 52753-28CLAIMS1. A system comprising: a set of electrostatic actuators, wherein each electrostatic actuator of the set of electrostatic actuators includes: a high-voltage side, and a low-voltage side that is configured to be driven by a time- varying voltage signal (TVVS), and a set of drive-sense channels, wherein a representative channel of the set of drive-sense channels: includes a drive electrical link between (i) a corresponding drive circuit of a set of drive circuits and (ii) the high-voltage side of a corresponding electrostatic actuator of the set of electrostatic actuators, is configured to carry, via the drive electrical link, a controllable drive voltage from the corresponding drive circuit to the high-voltage side of the corresponding electrostatic actuator, and includes a sense electrical link configured to carry a current generated by the TVVS to a sense-measurement circuit.

2. The system of claim 1 further comprising a sense filter configured to translate the current generated by the TVVS into a position signal that corresponds to a position of the corresponding electrostatic actuator.

3. The system of claim 2 wherein the controllable drive voltage is based on the position signal.

4. The system of claim 2 wherein the position signal is sensed by a controller that controls the corresponding drive circuit.

5. The system of claim 1 wherein the sense-measurement circuit is configured to perform a sensing operation to measure a capacitance of the corresponding electrostatic actuator.

6. The system of claim 1 wherein each channel of the set of drive-sense channels includes an electrostatic actuator of the set of electrostatic actuators.

7. The system of claim 1 wherein each channel of the set of drive-sense channels includes a drive circuit of the set of drive circuits.

8. The system of claim 1 further comprising the set of drive circuits.

9. The system of claim 1 wherein each channel of the set of drive-sense channels includes a drive filter configured to attenuate an effect of the TVVS on a voltage of the high-voltage side of the corresponding electrostatic actuator.Attorney Docket No. 52753-2810. The system of claim 9 wherein the drive filter for one of the set of drive-sense channels is an active circuit with one or more inputs including at least one of: the controllable drive voltage, the TV VS, or a control input from a controller.

11. The system of claim 9 wherein the drive filter for one of the set of drive-sense channels is a passive circuit.

12. The system of claim 1 wherein the corresponding drive circuit is configured to hold the controllable drive voltage steady for a threshold period of time.

13. The system of claim 1 wherein: the corresponding electrostatic actuator and a second electrostatic actuator of the set of electrostatic actuators share a low-side node, and the low-side node is connected to the low-voltage side of the corresponding electrostatic actuator and the low-voltage side of the second electrostatic actuator.

14. The system of claim 13 wherein: the representative channel includes a sense-modulation circuit, the sense-modulation circuit is connected to the low-side node, and the sense- modulation circuit generates the TVVS.

15. The system of claim 1 wherein the TVVS has an amplitude of 10 Volts or less.

16. The system of claim 1 wherein the sense electrical link connects the high-voltage side of the corresponding electrostatic actuator to the sense-measurement circuit.

17. The system of claim 14 wherein the sense electrical link connects a low- voltage side of the sense-modulation circuit and the sense-measurement circuit.

18. A method for controlling a set of electrostatic actuators, the method comprising: driving a low- voltage side of a corresponding electrostatic actuator of the set of electrostatic actuators with a time-varying voltage signal (TVVS), wherein the corresponding electrostatic actuator includes a high-voltage side; and carrying, via a drive electrical link of a representative drive-sense channel of a set of drive-sense channels, a controllable drive voltage from a corresponding drive circuit of a set of drive circuits to the corresponding electrostatic actuator, wherein the representative drive-sense channel includes: the drive electrical link between (i) the corresponding drive circuit and (ii) the high-voltage side of the corresponding electrostatic actuator, and a sense electrical link configured to carry a current generated by the TVVS to a sense-measurement circuit.Attorney Docket No. 52753-2819. The method of claim 18 further comprising translating, via a sense filter, the current generated by the TVVS into a position signal that corresponds to a position of the corresponding electrostatic actuator.

20. The method of claim 18 wherein: the corresponding electrostatic actuator and a second electrostatic actuator of the set of electrostatic actuators share a low-side node, the low-side node is connected to the low-voltage side of the corresponding electrostatic actuator and the low-voltage side of the second electrostatic actuator, the representative drive-sense channel includes a sense-modulation circuit, the sense- modulation circuit is connected to the low-side node, and the sense- modulation circuit generates the TVVS.

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