Patent Description:
The sensing of environmental parameters in the ambient atmosphere, such as noise, sound, temperature, etc., as well as the monitoring the direct environment of a mobile device for implementing, for example, a touchless gesture recognition, efficient proximity sensing, ambient temperature sensing, under-water communication, etc., gets more and more attention and importance in the implementation of appropriate sensors within mobile devices. In particular, on this field of sensors a low power consumption, portability and a small size has to be achieved for an implementation in portable and wearable applications for mobile devices.

<CIT> relates to an acoustic apparatus with ultrasonic detector. The acoustic apparatus includes a transducer, a signal generator, a buffering module, and a proximity detection module. A switching module is coupled to the transducer, signal generator, the buffering module, and the proximity detection module.

XP <NUM><NUM><NUM> ("<NPL>") relates to interface electronics for ultrasonic transducers. Section <NUM> relates to a chip architecture of a single <NUM> V-supply ultrasonic interface ASIC design.

Thus, in the field of sensors there is a constant need for sensor elements that detect their desired measurement variables, such as e.g., various ambient conditions of a mobile device, with a sufficiently high accuracy but with a low additional technical expenditure.

Such a need can be met by the subject matter of the present independent claims.

Embodiments and further implementations of the present concept are defined in the dependent claims.

Any embodiments and examples of the description not falling within the scope of the claims do not form part of the invention and are provided for illustrative purposes only.

In the following, embodiments of the present disclosure are described in detail with respect to the figures, in which:.

In the following description, embodiments are discussed in further detail using the figures, wherein in the figures and the specification identical elements and elements having the same functionality and/or the same technical or physical effect are provided with the same reference numbers or are identified with the same name. Thus, the description of these elements and of the functionality thereof as illustrated in the different embodiments are mutually exchangeable or may be applied to one another in the different embodiments.

In the following description, embodiments are discussed in detail, however, it should be appreciated that the embodiments provide many applicable concepts that can be embodied in a wide variety of semiconductor devices. The specific embodiments discussed are merely illustrative of specific ways to make and use the present concept, and do not limit the scope of the embodiments. In the following description of embodiments, the same or similar elements having the same function have associated therewith the same reference signs or the same name, and a description of such elements will not be repeated for every embodiment. Moreover, features of the different embodiments described hereinafter may be combined with each other, unless specifically noted otherwise.

It is understood that when an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or intermediate elements may be present. Conversely, when an element is referred to as being "directly" connected to another element, "connected" or "coupled," there are no intermediate elements. Other terms used to describe the relationship between elements should be construed in a similar fashion (e.g., "between" versus "directly between", "adjacent" versus "directly adjacent", and "on" versus "directly on", etc.).

<FIG> shows a schematic block diagram of a MEMS device <NUM> with the different functional blocks according to an embodiment.

According to an embodiment, the MEMS device <NUM> comprises a MEMS sound transducer <NUM> and a control circuitry <NUM>. The control circuitry <NUM> comprises a supply signal provider <NUM> for providing a high-level supply signal S1, a read-out circuitry <NUM> for receiving an output signal SOUT from the MEMS sound transducer <NUM>, and a switching arrangement <NUM> for selectively connecting the MEMS sound transducer <NUM> to the supply signal provider <NUM>, and for selectively connecting the MEMS sound transducer <NUM> to the read-out circuitry <NUM> based on a control signal S2. The control circuitry <NUM> is configured to provide the control signal S2 having an ultrasonic actuation pattern P to the switching arrangement <NUM> during a first condition TX of the control signal S2, wherein the ultrasonic actuation pattern P of the control signal S2 triggers the switching arrangement <NUM> for alternately coupling the high-level supply signal S1 to the MEMS sound transducer <NUM>.

According to an embodiment, the first condition TX of the control signal S2 enables a transmission mode of the MEMS sound transducer <NUM>, and wherein a second condition RX of the control signal S2 enables a sense mode of the MEMS sound transducer <NUM>.

Thus, the control signal S2 has the first condition or first signal portion TX defining an ultrasonic transmission mode of the MEMS device <NUM>, and the second condition or second signal portion RX defining an acoustic reception mode RX of the MEMS device <NUM>, wherein the control signal S2 has only in the first condition TX the ultrasonic actuation pattern P.

The first condition TX of the control signal S2 enables the transmission mode of the MEMS sound transducer <NUM>, wherein the ultrasonic actuation pattern P of the control signal S2 triggers the switching arrangement <NUM> for alternately coupling the high-level supply signal S1 to the MEMS sound transducer <NUM>, and wherein the switching arrangement <NUM> electrically disconnects the MEMS sound transducer <NUM> from the read-out circuitry <NUM>.

The second condition RX of the control signal S2 enables a sense mode (= reception mode) RX of the MEMS sound transducer <NUM>, wherein in the sense mode the switching arrangement <NUM> electrically disconnects the MEMS sound transducer <NUM> from the supply signal provider <NUM> and electrically connects the acoustic output signal SOUT of the MEMS sound transducer <NUM> to the read-out circuitry <NUM>.

According to an embodiment, the supply signal provider <NUM> may optionally comprise a hold capacitor for storing the high-level supply signal S1 and for providing the high-level supply signal S1 during the transmission mode TX to the MEMS sound transducer <NUM>.

According to an embodiment, the supply signal provider <NUM> may be configured to charge the hold capacitor during the sense mode RX with the high-level supply signal S1.

According to an embodiment, the switching arrangement <NUM> is configured to decouple the supply signal provider <NUM> and the (optional) hold capacitor during the sense mode from the MEMS sound transducer <NUM> and the read-out circuitry <NUM>.

According to an embodiment, the supply signal provider <NUM> may be configured to provide the high-level supply signal S1 in a low-ohmic configuration, wherein the signal (voltage) level V1 of the high-level supply signal S1 is higher than a common supply signal VDD of the MEMS device <NUM>.

According to an embodiment, the supply signal provider <NUM> may comprise a charge pump arrangement <NUM>-<NUM> for providing the high-level supply signal S1 to the MEMS sound transducer <NUM>, wherein the voltage level V1 of the high-level supply signal S1 is higher than a common supply signal VDD of the MEMS device <NUM>.

According to an embodiment, the supply signal provider <NUM> may comprise a further charge pump arrangement <NUM>-<NUM> wherein the further charge pump arrangement <NUM>-<NUM> is configured to provide a further high-level supply signal S1' during the sense mode or the transmission mode to the MEMS sound transducer <NUM>. The supply signal provider <NUM> is further configured to provide the high-level supply signal S1 during the transmission mode to the MEMS sound transducer <NUM>.

According to a further embodiment, the supply signal provider <NUM> may generally comprise any circuit block <NUM>-<NUM>, <NUM>-<NUM> that is able to generate the low-ohmic high-level voltages V1, V1' (e.g. >10V).

According to an embodiment, the MEMS sound transducer <NUM> may comprises a membrane structure and a counter electrode structure, wherein the membrane structure and the counter electrode structure are arranged to provide a differential excitation and differential read-out configuration of the MEMS sound transducer <NUM> or to provide a single-ended (= common mode) excitation and single-ended read-out configuration of the MEMS sound transducer <NUM>.

According to an embodiment, the switching arrangement <NUM> may comprises (at least) four switches for the differential excitation and differential read-out configuration of the MEMS sound transducer <NUM> for alternately coupling the high-level supply signal S1 of the supply signal provider <NUM> to the MEMS sound transducer <NUM> during the ultrasonic transmission mode TX.

According to an embodiment, wherein the switching arrangement <NUM> may comprises (at least) two switches for the single-ended excitation and single-ended read-out configuration of the MEMS sound transducer <NUM> for alternately coupling the high-level supply signal S1 of the supply signal provider <NUM> to the MEMS sound transducer <NUM> during the ultrasonic transmission mode TX.

According to an embodiment, the switching arrangement <NUM> is connected between the MEMS sound transducer <NUM>, the supply signal provider <NUM> and the read-out circuitry <NUM> for selectively connecting the MEMS sound transducer <NUM> to the supply signal provider <NUM> during the ultrasonic transmission mode TX, and for selectively connecting the acoustic output signal SOUT of the MEMS sound transducer <NUM> to the read-out circuitry <NUM> during the sense mode RX. The switching arrangement may comprise PMOS switches between the supply signal provider <NUM> and the MEMS sound transducer <NUM>, and NMOS switches between the MEMS sound transducer <NUM> and the read-out circuitry <NUM>.

According to an embodiment, the read-out circuitry <NUM> may comprise an operational amplifier for receiving and amplifying the acoustic (= audio and/or ultrasonic range) output signal SOUT from the MEMS sound transducer <NUM>, e.g. in a high-impedance read-out configuration.

The audio frequency range may be between approximately <NUM> and <NUM> or between <NUM> and <NUM>, wherein the ultrasonic frequency range between <NUM> and <NUM>, between <NUM> and <NUM>, between <NUM> and <NUM> or between <NUM> and <NUM>.

According to an embodiment, a first portion (low sens) RX1 of the sense mode RX following the transmission mode TX forms a recovery period of the MEMS sound transducer <NUM>, wherein the control circuitry <NUM> may provide a low-ohmic interface during the recovery period. The low-ohmic recovery mode enables a bypass switch across the high-ohmic blocks at the ASIC <NUM> input.

According to an embodiment, the control signal S2 may be based on a combination of a first control signal component S2-<NUM> and a second control signal component S2-<NUM>, and wherein the control circuitry <NUM> is configured to provide the second control signal component S2-<NUM> having the ultrasonic actuation pattern P to the switching arrangement <NUM> only during a first condition (= first logic value) of the first control signal component S2-<NUM>, wherein the second control signal component S2-<NUM> triggers the switching arrangement <NUM> for alternately coupling the high-level supply signal S1 to the MEMS sound transducer <NUM> based on the ultrasonic actuation pattern P.

According to an embodiment, the first control signal component S2-<NUM> and the second control signal component S2-<NUM> may be standard digital signals, wherein the control circuitry <NUM> may configured to gate, e.g. with a logical AND conjunction, the second control signal component S2-<NUM> having the ultrasonic actuation pattern P to the switching arrangement <NUM> for triggering the switching operation only during the presence of the predefined first logic level of the first control signal component S2-<NUM>, wherein the actuation pattern P provides and defines the ultrasonic excitation frequency of the MEMS sound transducer <NUM>.

According to an embodiment, the control circuitry <NUM> may be part of an ASIC for providing an integrated on-chip implementation of the signal generation for controlling the operations modes of the MEMS sound transducer <NUM> of the MEMS device <NUM>.

According to the present embodiments, the present concept for a MEMS device <NUM> allows to add a ultrasound transducer feature to a (standard) MEMS microphone functionality with no size increase needed and without adding system complexity or assembly/package/system modifications.

Thus, the implementation of the MEMS device <NUM> according to the above embodiments is an inexpensive but effective way of implementing the MEMS device <NUM> having a fully integrated ultra-sound transceiver (differential or single-ended) without losing the standard microphone functionality, all-in-one. The control signal S2, e.g. two added control signal components S2-<NUM>, S2-<NUM> (standard digital), allow to switch from microphone RX to ultra-sound transmission TX and to adjust the excitation ultrasonic frequency, e.g. eventually tuning it to the system resonances.

Embodiments of the MEMS device <NUM> achieve an implementation of a fully integrated ultrasonic transducer with differential/single-ended excitation method or configuration, controllable with two standard digital input signals (signal components) S2-<NUM>, S2-<NUM>. Such a solution offers the standard audio performance of MEMS microphones combined with the ultrasonic transducer capabilities all-in-one. This specific solution ensures the maximum ultrasonic power transmitted by the specific MEMS used, in addition to an effective and inexpensive integration due to the simplicity of the standard digital control signals.

The MMES device <NUM> has two main operation modes and only needs an additional control signal (or two additional control signal components) with respect to a standard MEMS microphone that allow to switch from standard audio (receive - RX) mode to ultrasonic signal transmission mode (send - TX) with a tuneable frequency (= tuneable ultrasonic actuation frequency) of the actuation pattern P.

During audio mode (RX) the audio performance of the MEMS sound transducer <NUM> (MEMS microphone) is unchanged. During transmission (TX), the MEMS sound transducer <NUM> is excited with the ultrasonic actuation pattern P at the (tuned) ultrasound frequency with an internal voltage generator (= the supply signal provider <NUM>) that brings the membrane of the MEMS sound transducer <NUM> to its maximum displacement on both gaps alternatively, based on the ultrasound signal pattern P and generating the ultrasound transmission signal pattern. At the end of the excitation the MEMS device <NUM> switches back to receive mode RX and starts sensing the returning ultrasound waves (in addition to the standard audio signals) during RX2 after a short recovery time RX1 (low sens.

<FIG> shows an exemplary illustration of the temporal course of the control signal S2 for the MEMS device <NUM> as provided by the control circuitry <NUM> to the switching arrangement <NUM> according to an embodiment. The control signal S2 has the ultrasonic actuation pattern P (e.g. only) during the ultrasonic transmission mode TX (send mode) of the MEMS sound transducer <NUM> of the MEMS device <NUM>.

According to an embodiment, the control signal S2 may be based on a logical combination of a first control signal component S2-<NUM> and a second signal component S2-<NUM>. The control circuitry <NUM> may be configured to provide the second control signal component S2-<NUM> having the ultrasonic actuation pattern P to the switching arrangement <NUM> only during a first condition TX (= first logic value) of the first control signal component S2-<NUM>, wherein the second control signal component S2-<NUM> triggers the switching arrangement for alternately coupling the high-level supply signal S1 to the MEMS sound transducer <NUM> based on the ultrasonic actuation pattern P. Thus, the ultrasonic actuation pattern P of the second control signal component S2-<NUM> triggers the switching arrangement for alternately coupling the high-level supply signal S1 to the MEMS sound transducer <NUM>.

According to an embodiment, the first control signal component S2-<NUM> and the second control signal component S2-<NUM> may be standard digital signals (having two logic levels), wherein the control circuitry <NUM> is configured to gate, e.g. in form of a logical AND conjunction, the second control signal component S2-<NUM> having the ultrasonic actuation pattern P to the switching arrangement <NUM> for triggering the switching operation only during the presence of the predefined first logic level of the first control signal component S2-<NUM>, wherein the actuation pattern P defines the ultrasonic excitation frequency of the MEMS sound transducer <NUM>.

According to an embodiment, the second control signal component <NUM>-<NUM> may comprise the ultrasonic actuation pattern P as a continuous pattern, for example. The set or adjusted frequency of the actuation pattern P corresponds to the transmitted ultrasonic signal of the MEMS sound transducer <NUM>. Thus, an arbitrary actuation pattern in frequency may be provided to the switching arrangement <NUM>.

Therefore, the provided control signal S2 defines the operation of the MEMS sound transducer <NUM> with respect to a send mode (transmission mode = the first portion TX of the control signal S2) and a receive mode (= the second portion RX of the control signal S2). As further shown in <FIG>, the receive mode RX comprises a region RX1 with a low reception sensitivity (immediately subsequent to the send mode) and a region RX2 with a high reception sensitivity timely subsequent to the low sensitivity region T2-<NUM>. The periods RX1 and RX2 having different reception sensitivities for an ultrasonic echo signal result from the structure of the MEMS sound transducer <NUM> and will be described in more detail below with respect to <FIG>.

According to an embodiment, the control signal S2 may be provided from an external circuit element and/or processing device to the control circuitry <NUM> or may be generated by the control circuitry <NUM>. Further, the first control signal component S2-<NUM> and a second signal component S2-<NUM> may be provided from an external circuit element and/or processing device to the control circuitry <NUM>, wherein the control circuitry <NUM> generates the control signal S2 and provides the control signal S2 to the switching arrangement <NUM>.

According to the above evaluations, the control signal S2 is the trigger signal for the switches of the switching arrangement <NUM> to switch the supply signal provider <NUM> (e.g. the charge pumps or other high-voltage elements) on and off at the excitation frequency of the MEMS sound transducer <NUM>, wherein the frequency of the actuation pattern P of the control signal S2 may be set or tuned to the resonance frequency or one of the resonance frequencies of the MEMS sound transducer <NUM> (MEMS microphone).

According to an embodiment, the actuation pattern P can be a continuous pattern of the second control signal component S2-<NUM>, wherein the resulting control signal S2 is enabled (gated) by the digital (<NUM>-<NUM>) switch-on signal (= the first control signal component S2-<NUM>), the switch-on signal S2-<NUM> toggling (switching) "globally" between the send mode TX and receive mode RX. In the "low sens" (low sensitivity) range RX1, the MEMS interface (= MEMS sound transducer <NUM> interface = the terminals of the MEMS sound transducer <NUM>) is in a low-ohmic state in order to make the recovery period as short as possible, since the following applies: the shorter the recovery period, the shorter distances can be detected in the ultrasonic mode. The low-ohmic recovery mode enables a bypass switch across the high-ohmic blocks at the ASIC <NUM> input, for example.

With respect to an exemplary implementation of the bypass switch(es) according to an embodiment, it is referred to <FIG> and the associated specification, for example.

During the recovery period RX1, the oscillation of the MEMS microphone <NUM> will abate or fade away (= ringing), with the MEMS microphone <NUM> returning to normal sound reception mode. Due to the low-resistance or low-resistance state of the MEMS interface, short time constants can be achieved in order to be able to achieve the receive mode RX as quickly as possible.

In the present concept, the entire signal generation may be carried out in the ASIC, which enables complete integration of the control electronics or the entire system. In addition, both modes of operation (single-ended mode - differential mode) are improved, whereby the integration of the MEMS system <NUM> can also be simplified.

<FIG> show a schematic cross-sectional views of the MEMS sound transducer <NUM> in different configurations, such as in a single membrane and single backplate (= counter-electrode) configuration, in a (e.g. sealed) dual membrane configuration and in a dual-backplate configuration.

<FIG> shows a schematic cross-sectional view of the MEMS sound transducer <NUM> in single membrane and single backplate configuration. As shown in <FIG>, the MEMS sound transducer <NUM> has the membrane structure <NUM> and the counter electrode structure <NUM>. The term "structure" is intended to illustrate that the membrane and the counter-electrode, respectively, can comprise a semi-conductive layer or, also, a layer sequence or layer stack having a plurality of different layers, wherein at least one of the layers is electrically conductive.

The layer arrangement may be positioned on a carrier substrate <NUM> (see <FIG>), wherein the membrane structure <NUM> and the counter electrode structure <NUM> are separated and spaced apart from one another. The counter electrode structure <NUM>, which is generally configured to be more rigid than the deflectable membrane structure <NUM>, is spaced apart at a distance D from the membrane structure, with the result that a capacitance C<NUM> (= MEMS capacitance = capacitance of the MEMS sound transducer <NUM>) can form between the counter electrode structure <NUM> and the membrane structure <NUM> and can be sensed by the readout circuitry <NUM> of the control circuitry <NUM>. The non-clamped region of the membrane structure <NUM> (with respect to the counter electrode structure <NUM>) is referred to as the deflectable (= displaceable) or movable region (= active region) of the membrane structure <NUM>. A deflection Δx of the membrane structure <NUM> relative to the counter electrode structure <NUM> can then be detected and read out as a capacitance change ΔC by means of the readout circuitry <NUM> in order to provide a corresponding (analog or AD-converted digital) output signal Sout of the MEMS sound transducer <NUM>. The deflection of the membrane structure <NUM> is (generally) caused by an acoustic sound pressure change in the environment.

As shown in <FIG>, the MEMS sound transducer <NUM> having a dual membrane MEMS configuration (or sealed dual membrane configuration) comprises the first membrane structure <NUM> and a further (second) membrane structure <NUM>-<NUM> spaced apart therefrom with the counter electrode structure <NUM> arranged there between, wherein the counter electrode structure <NUM> is spaced apart each from the first and second membrane structures <NUM>, <NUM>-<NUM>. Furthermore, at least one or a plurality mechanical connection elements <NUM> can be provided between the first and second membrane structures <NUM>, <NUM>-<NUM>, wherein the mechanical connection element(s) is mechanically coupled between the first and second membrane structures <NUM>, <NUM>-<NUM> and is mechanically decoupled from the counter electrode structure <NUM>.

In a sealed dual membrane configuration, the first and second membrane structures <NUM>, <NUM>-<NUM> are arranged in a hermetically sealed configuration, and a cavity <NUM> may be formed between the first and the second membrane structure <NUM>, <NUM>-<NUM>, wherein the counter electrode structure <NUM> is arranged in the cavity <NUM>, e.g. when compared to the environmental atmosphere. The cavity <NUM> may comprise a reduced atmospheric pressure, e.g., a "vacuum" with an atmospheric pressure of about or below <NUM> Torr, <NUM> Torr, <NUM> Torr or <NUM> Torr.

Upon a deflection of the first and second (mechanically coupled) membrane structures <NUM>, <NUM>-<NUM> relative to the counter electrode structure <NUM>, that deflection or displacement can in turn be read out capacitively, for example, by the readout circuitry <NUM> in order to provide the output signal SOUT dependent on the deflection (gap change) with respect to the counter electrode structure <NUM>. The deflection of the membrane structure <NUM> is caused by an acoustic sound pressure change in the environment. In case of the dual-membrane arrangement as shown in <FIG>, the read-out circuitry <NUM> can be configured to read out the MEMS sound transducer <NUM> in a "single-ended" (common-mode) or differential configuration.

According to a further configuration of the MEMS sound transducer <NUM> as a MEMS microphone as shown in <FIG>, the MEMS sound transducer <NUM> may comprise a dual-counter electrode configuration (dual backplate configuration), wherein the MEMS sound transducer <NUM> may comprise a first counter-electrode structure <NUM> and a further (second) counter-electrode structure <NUM>-<NUM>, such that the membrane structure <NUM> is arranged between the first and second counter electrode structures <NUM>, <NUM>-<NUM>. In case of the dual-counter electrode arrangement as shown in <FIG>, the read-out circuitry <NUM> can be configured to read out the MEMS sound transducer <NUM> in a "single-ended" (common-mode) or differential configuration.

In case of the dual-backplate configuration, the read-out circuitry <NUM> may be configured to detect the deflection or displacement Δx of the membrane structure <NUM> relative to the counter electrode structure <NUM> and/or relative to the further (second) counter electrode structure <NUM>-<NUM>, depending on the single-ended (common mode) or differential readout configuration. The deflection of the membrane structure <NUM> is again caused by an acoustic sound pressure change in the environment.

In the following, the electrostatic actuation principle is discussed. The electrostatic forces in a differential MEMS sound transducer, e.g. a dual backplate (DBP) device, can be described as follows:.

wherein the signal Vup is the voltage at the first counter electrode structure <NUM>, the signal Vdown is the voltage at the second counter electrode structure <NUM>-<NUM>, and the signal VMEM is the voltage at the interposed membrane structure <NUM> (in case of a dual backplate configuration). Furthermore, the term "gapup" is the distance between the membrane <NUM> and the first counter electrode <NUM> and the term "gapdown" is the distance between the membrane structure <NUM> and the second counter electrode structure <NUM>-<NUM>.

The same assumptions are correspondingly applicable to a MEMS sound transducer <NUM> in a "sealed" dual membrane (SDM) configuration.

In the microphone mode, both electrostatic forces are balanced, i.e. VMEM = VMIC, and Vup = Vdown = Vsens, and also in the presence of a DC configuration, i.e. DC signals (DC = direct current). Consequently, the membrane structure <NUM> is only moved by incident sound pressure, wherein the amplitude of deflection of the membrane structure <NUM> depends on the incident sound pressure level (SPL).

According to embodiments, for an ultrasound emission of the MEMS sound transducer <NUM>, AC voltages (AC = alternating current) can be superimposed to drive the membrane structure <NUM> electrostatically, however, with respect to the actuation voltage it is referred to that:.

However, the MEMS device <NUM> according to the present embodiment allows using a differential driving voltage for ultrasound actuation of the MEMS sound transducer <NUM>, wherein the actuation signal may be internally provided by the control circuitry <NUM> which may be implemented as a part of the ASIC of the MEMS device <NUM>. Based on a differential driving voltage for ultrasound emission, the membrane <NUM> (in a dual backplate configuration) moves from a top pull-in condition to a bottom pull-in condition.

<FIG> shows a schematic cross-sectional view of the MEMS device <NUM> having the MEMS sound transducer <NUM> and the control circuitry <NUM> (the ASIC or at least a part of the ASIC) in a packaged (housed) configuration according to an embodiment. The MEMS sound transducer <NUM> has a first, second and third connection terminal <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>. As shown in <FIG>, the MEMS device <NUM> may be arranged in a housing <NUM> having an interior volume VC, wherein the housing <NUM> has an access opening or sound port <NUM> to the interior volume VC of the MEMS device <NUM>. The MEMS sound transducer <NUM> is arranged in the housing <NUM>, for example, adjacent to the sound opening <NUM>. The housing <NUM> may then comprise, for example, a substrate <NUM> and an optional cap element <NUM>, which can be at least partially or completely electrically conductive. In an exemplary arrangement, the MEMS sound transducer <NUM> (MEMS microphone) can subdivide the interior volume VC into a front volume VF and a back volume VB, wherein the front volume VF is situated in the region between the sound port <NUM> and the MEMS microphone <NUM>, and wherein the back volume VB is situated on the opposite side of the MEMS sound transducer <NUM> with respect thereto in the interior volume VC of the housing <NUM>. In this context, reference is made to the exemplary illustration of the different MEMS sound transducer arrangements in <FIG>, which illustrate different exemplary embodiments of the MEMS sound transducer or MEMS microphone <NUM>.

According to an embodiment, the control signal S2 may be provided from an external circuit element and/or processing device to the control circuitry <NUM> or may be generated by the control circuitry <NUM>. According to a further embodiment, the first control signal component S2-<NUM> and a second signal component S2-<NUM> may be provided from an external circuit element and/or processing device to the control circuitry <NUM>, wherein the control circuitry <NUM> generates the control signal S2 and provides the control signal S2 to the switching arrangement <NUM>.

According to an embodiment, the control circuitry <NUM> may an ASIC (ASIC = application specific integrated circuit) or may be part of an ASIC of the MEMS device <NUM> for providing an integrated on-chip implementation of the signal generation (e.g. the control signal and high-level supply signal generation) and for controlling the operations modes of the MEMS sound transducer <NUM>. As exemplarily shown in <FIG>, the control circuitry <NUM> (ASIC) may be arranged to receive the control signal S2 or the control signal components S2-<NUM>, S2-<NUM>, the common supply signal or voltage VDD, and a reference potential Vref, e.g. ground potential, and to provide the output signal SOUT.

<FIG> show exemplary illustrations of the time course of the ultrasonic pulses/signals STX transmitted from the MEMS sound transducer <NUM> and the received signals (echo signals) reflected from objects (to be detected) and sensed/measured from the MEMS sound transducer <NUM>.

<FIG> shows a transmitted ultrasonic signal with a frequency of about <NUM> with a reception bandpass filter for a bandpass frequency range between <NUM> and <NUM>. <FIG> shows the resulting transmission and reception signals for a <NUM> ultrasonic signals with a reception bandpass filter for a bandpass frequency range between <NUM> and <NUM>.

<FIG> exemplarily show the signal profile of an ultrasonic transmission signal STX and the signal profile temporarily offset with respect thereto of an ultrasonic reception signal SRX of the MEMS sound transducer <NUM>. As shown in <FIG>, during a first duration (time interval), the ultrasonic pattern P having the ultrasonic frequency is applied to the MEMS sound transducer <NUM>. This is referred to as loudspeaker activation pulse (speaker actuation pulse). The direct reaction of the MEMS sound transducer <NUM> to the ultrasonic transmission pulse occurs in the form of a strong oscillating excitation of the MEMS sound transducer <NUM>, which is also referred as "ringing". When the loudspeaker activation pulse P is ended, this "ringing" decays relatively rapidly during the following time interval SRX1. The ultrasonic reception signal of the MEMS sound transducer <NUM>, i.e., the reflection echo signal, can then be detected and read out during the following time interval SRX2, i.e. when the ringing is sufficiently decreased.

As shown in <FIG>, the echo signals can be associated to different objects in the range of the ultrasonic transmission signal depending on the arrival time of the respective echo signal. The nearer the object is located, the earlier the echo signal arrives at the MEMS sound transducer <NUM>. Based on the time interval (run time) until reception of the echo signal, the distance of the respective object is derivable.

The duration of the excited "ringing" of the MEMS sound transducer <NUM> on account of the ultrasonic transmission signal (ultrasonic actuation pulses) predefines the minimum distance that can be detected by the MEMS sound transducer <NUM> during the ultrasonic reception operation (receive mode), i.e., as soon as the undesired excitation of the MEMS sound transducer <NUM> has decayed to a sufficient extent, the acoustic signal can be reliably detected. The time duration for the ringing, which corresponds to the low sensitivity region during the receive mode of <FIG>, can lie e.g., in a range of <NUM> to <NUM>, such that the minimum propagation distance for the ultrasonic signal can be in the order of a few centimeters, for example <NUM> to <NUM>, in order to be able to detect the reflected ultrasonic reception signal.

<FIG> describe different use cases at different frequencies, which represent, for example, different resonance frequencies of the MEMS sound transducer <NUM>. Different resonances can lead to a different directivity of the MEMS sound transducer <NUM>. Furthermore, the recovery periods of the MEMS sound transducer <NUM> can be changed or be set by the ASIC <NUM> due to different resonance frequencies. A higher frequency may lead to a shorter mechanical recovery. As shown in the lower figure of <FIG>, an increased frequency of the control signal S2 (e.g. matched to a resonance frequency of the MEMS sound transducer <NUM>) can result in a shorter excitation period TX, which can also lead to shorter "ringing" of the MEMS microphone <NUM>.

In the following, exemplary implementations of the MEMS device <NUM> and, in particular, different exemplary implementations of the supply signal provider <NUM> and the switching arrangement <NUM> of the control circuitry <NUM> are explained in detail.

<FIG> shows a schematic view of the MEMS device <NUM> with a schematic cross-sectional view of the MEMS sound transducer <NUM> together with a schematic block diagram of the control circuitry <NUM> in a differential excitation and read-out configuration of the MEMS sound transducer <NUM> according to an embodiment.

As shown in <FIG>, the MEMS device <NUM> comprises the MEMS sound transducer <NUM> and the control circuitry <NUM>. As exemplarily shown in <FIG>, the MEMS sound transducer <NUM> is a dual membrane microphone (or a sealed dual membrane microphone), which can be differentially actuated with the ultrasonic actuation signal P of the control signal S2 and differentially read out. The following evaluations are equally applicable to a MEMS sound transducer <NUM> in a dual backplate configuration which can also be differentially actuated and differentially read out.

As shown in <FIG>, the supply signal provider <NUM> for providing a high-level supply signal S1 may be configured to provide the high-level supply signal in a low-ohmic configuration, wherein the voltage level V1 of the high-level supply signal S1 is higher than a common supply signal VDD of the MEMS device <NUM>.

Typical (absolute) voltage values V1 of the high-level supply signal S1 may be in a voltage between <NUM> and <NUM> V. Typical (absolute) voltage values VDD of the common supply signal SDD may be in a voltage between <NUM> and <NUM> V. The voltage values VDD may form the to the supply voltage of the ASIC <NUM> (= the control circuitry). Thus, typical values for the voltage VDD may be <NUM>. 8V for a digital control circuitry and <NUM>. 75V for analog control circuitry with allowed +-<NUM>% variations, for example.

To be more specific, the voltage values V1 may depend on the specific MEMS device wherein lower voltages and considerably higher voltages are also possible. The voltage V1 needs to be high enough to bring the sensor <NUM> (the MEMS sound transducer) to its maximum displacement at the interesting frequencies of excitation.

According to an embodiment, the supply signal provider <NUM> may comprise a charge pump arrangement <NUM>-<NUM> (= ultrasonic send charge pump) for providing the high-level supply signal S1 to the MEMS sound transducer <NUM>.

According to a further embodiment, the supply signal provider <NUM> may comprise a hold capacitor <NUM> for storing the high-level supply signal S1 and for providing the high-level supply signal S1 during the ultrasonic transmission mode to the MEMS sound transducer <NUM>. The supply signal provider <NUM> may be further configured to charge the hold capacitor <NUM> during the sense mode with the high-level supply signal S1. During the sense mode, the switching arrangement <NUM> is configured to decouple the supply signal provider <NUM> and the hold capacitor <NUM> from the MEMS sound transducer <NUM> and the read-out circuitry <NUM>.

According to an embodiment, the switching arrangement <NUM> comprises (at least) four switches <NUM>-<NUM>,. , <NUM>-<NUM> for the differential excitation and differential read-out configuration of the MEMS sound transducer <NUM> for alternately coupling the high-level supply signal V1 of the supply signal provider <NUM> to the MEMS sound transducer <NUM> during the ultrasonic transmission mode TX.

Thus, the switching arrangement <NUM> is connected between the MEMS sound transducer <NUM>, the supply signal provider <NUM> and the read-out circuitry <NUM> for selectively connecting the MEMS sound transducer <NUM> to the supply signal provider <NUM> during the ultrasonic transmission mode TX, and for selectively connecting the acoustic output signal SOUT of the MEMS sound transducer <NUM> to the read-out circuitry <NUM> during the sense mode RX.

In the first condition TX of the control signal S2, which enables the transmission mode TX of the MEMS sound transducer <NUM>, the ultrasonic actuation pattern P of the control signal S2 triggers the switching arrangement <NUM> for alternately coupling the high-level supply signal S1 to the first and second terminal <NUM>-<NUM>, <NUM>-<NUM> of the MEMS sound transducer <NUM>, wherein the switching arrangement <NUM> electrically disconnects the MEMS sound transducer <NUM> from the read-out circuitry <NUM>.

In the second condition RX of the control signal S2, which enables the sense mode (= reception mode) of the MEMS sound transducer <NUM>, the switching arrangement <NUM> electrically disconnects the MEMS sound transducer <NUM> from the supply signal provider <NUM> and electrically connects the acoustic output signal SOUT of the MEMS sound transducer <NUM> to the read-out circuitry <NUM>.

shows the MEMS device <NUM> with a relatively inexpensive and compact "single charge pump concept (configuration)". As exemplarily shown in <FIG>, the switching arrangement <NUM> may comprise a first switch element <NUM>-<NUM>, which is electrically connected between the terminal (= connection pin) <NUM>-<NUM> of the first membrane structure <NUM> (<NUM>-<NUM> = the first terminal of the MEMS sound transducer <NUM>) and the first terminal <NUM>-<NUM> of the read-out circuitry <NUM>, wherein a second switch element <NUM>-<NUM> is electrically connected between the terminal <NUM>-<NUM> of the second membrane element <NUM>-<NUM> (<NUM>-<NUM> = the second terminal of the MEMS sound transducer <NUM>) and the second terminal <NUM>-<NUM> of the read-out circuitry <NUM>. A third switch element <NUM>-<NUM> is electrically connected between the terminal <NUM>-<NUM> of the first membrane structure <NUM> and the terminal (= output pin) <NUM>-1a of the supply signal provider <NUM>, wherein a fourth switching element <NUM>-<NUM> is electrically connected between the terminal <NUM>-<NUM> of the second membrane structure <NUM>-<NUM> and the output pin <NUM>-1a of the supply signal provider <NUM>. Furthermore, the hold capacitor <NUM> is connected between the output terminal <NUM>-1a of the supply signal provider <NUM> and a reference potential, e.g. ground potential. The terminal <NUM>-1a of the signal provider <NUM> is electrically connected to the terminal <NUM>-<NUM> of the counter electrode structure <NUM> (<NUM>-<NUM> = the third terminal of the MEMS sound transducer <NUM>) to provide the high level supply signal V1 to the counter electrode structure <NUM> of the MEMS sound transducer <NUM>.

The hold capacitor <NUM> may comprise a capacitance CH which can be about <NUM> pF or at least 20pF, e.g. in a range between <NUM> pF and <NUM> pF. Generally, the capacitance CH of the hold capacitor <NUM> may be about <NUM>-times of C<NUM> (~ <NUM> x C<NUM>, with C<NUM> is the capacitance of the MEMS sound transducer <NUM>) or may be in a range between <NUM>- and <NUM>-times or <NUM> and <NUM>-times of C<NUM>. Generally, the capacitance CH of the hold capacitor <NUM> may depend on the capacitance C<NUM> of the MEMS sound transducer <NUM> and on the number of excitation cycles needed versus the recovery time between two excitations. Moreover, the switch elements have the capability of switching high-level signals, i.e. to reliable block or conduct the high-level signals V1 based on the adjusted operation condition. According to an embodiment, the switching arrangement <NUM> may comprise PMOS switches <NUM>-<NUM>, <NUM>-<NUM> between the supply signal provider <NUM> and the MEMS sound transducer <NUM>, and NMOS switches <NUM>-<NUM>, <NUM>-<NUM> between the MEMS sound transducer <NUM> and the read-out circuitry <NUM>.

In the following, an exemplary arrangement and functionality of the blocks of the MEMS device <NUM> is described.

The differential implementation includes four high-voltage switches <NUM>-<NUM>,. , <NUM>-<NUM> at the input of the MEMS interface, i.e. at the terminals <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> of the MEMS sound transducer <NUM>, that switch at ultrasound frequency during the send mode TX and bringing the two membranes <NUM>, <NUM>-<NUM> of the MEMS sound transducer <NUM> to pull-in alternatively. The on-chip ultrasound charge-pump <NUM>-<NUM> plus hold capacitor <NUM> deliver the excitation voltage S1 that is alternatively connected to the two sides <NUM>, <NUM>-<NUM> of the MEMS sound transducer. The excitation mode TX is followed by a recovery period RX1 in which the MEMS interface is low-ohmic, the length of such period RX1 is fixed but can also be made adjustable, as the audio sensitivity of the microphone is reduced during this period. The resulting choice of the length of the recovery period RX1 depends on the distances to be covered by the ultrasound signal required by the application, usually a few cm to about <NUM>.

While in sensing mode RX the ultrasonic charge-pump <NUM>-<NUM> loads the hold capacitor <NUM> for the following excitation period, in this phase, both components <NUM>, <NUM> are decoupled from the rest of the circuit by steadily opening the relative high-voltage PMOS switches <NUM>-<NUM>, <NUM>-<NUM>. Still during the sense mode RX, the signal path is re-established by steadily closing the two high-voltage NMOS switches <NUM>-<NUM>, <NUM>-<NUM>, which connect the MEMS sound transducer <NUM> to the read-out path <NUM>.

According to a further embodiment, the charge-pump <NUM>-<NUM> (as the supply signal provider) used for excitation of the MEMS sound transducer <NUM> can be substituted by another circuit block that is able to generate the low-ohmic high voltages V1 (>10V). This could provide to a potential extension of the duration of the excitation period, if the designed high-voltage generator is able to drive the MEMS-load efficiently and with a low ohmic-coupling.

The MEMS device <NUM> with MEMS sound transducer <NUM> in a differential excitation and read-out configuration using internal actuation signals provides a number of technical effects:.

The above evaluations of a MEMS sound transducer <NUM> in a dual membrane configuration are equally applicable to a MEMS sound transducer <NUM> in a dual backplate configuration, wherein the first (top) counter electrode structure <NUM> is associated to the first terminal <NUM>-<NUM> and the second (bottom) counter electrode structure <NUM>-<NUM> is associated to the second terminal <NUM>-<NUM>, and wherein the membrane structure <NUM> is associated to the third terminal <NUM>-<NUM>. Thus, the control circuitry <NUM> can equally couple the supply signal provider <NUM> to the MEMS sound transducer <NUM> using the same terminals <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, i.e. in the dual membrane configuration or in the dual backplate configuration, wherein the same technical effects of the MEMS device <NUM> can be achieved during the operation with the control circuitry <NUM>.

In the following, a number of different possible implementations of the functional blocks of the MEMS device <NUM> are exemplarily described.

In the present description of embodiments, the same or similar elements having the same structure and/or function are provided with the same reference numbers or the same name, wherein a detailed description of such elements will not be repeated for every embodiment. Thus, the above description with respect to <FIG> is equally applicable to the further embodiments as described below. In the following description, essentially the differences, e.g. additional, changed or replaced elements, to the embodiment as shown in <FIG> and the technical effect(s) resulting therefrom are discussed in detail.

<FIG> show a schematic view of the MEMS device <NUM> with a schematic cross-sectional view of the MEMS sound transducer <NUM> together with a schematic block diagram of the control circuitry <NUM> of the MEMS device <NUM> in a differential excitation and read-out configuration of the MEMS sound transducer <NUM> according to a further embodiment.

As exemplarily shown in <FIG>, the MEMS sound transducer <NUM> is a dual membrane microphone (or a sealed dual membrane microphone), which can be differentially actuated with the ultrasonic actuation signal P and differentially read out. The following evaluations are equally applicable to a MEMS sound transducer <NUM> in a dual backplate configuration which can also be differentially actuated and differentially read out.

The switching arrangement <NUM> is connected between the MEMS sound transducer <NUM>, the supply signal provider <NUM> and the read-out circuitry <NUM> for selectively connecting the MEMS sound transducer <NUM> to the supply signal provider <NUM> during the ultrasonic transmission mode TX, and for selectively connecting the acoustic output signal SOUT of the MEMS sound transducer <NUM> to the read-out circuitry <NUM> during the sense mode RX.

Thus, <FIG> show the MEMS device <NUM> with a "mode-dedicated charge pump concept / configuration". According to the embodiment of <FIG> the supply signal provider <NUM> comprises a charge pump arrangement <NUM>-<NUM> for providing the high-level supply signal S1 to the MEMS sound transducer <NUM>, wherein the voltage level V1 of the high-level supply signal S1 is higher than a common supply signal VDD of the MEMS device <NUM>.

Moreover, the supply signal provider <NUM> of the MEMS device <NUM> comprises a further charge pump arrangement <NUM>-<NUM>, wherein the further charge pump arrangement <NUM>-<NUM> is configured to provide a further high-level supply signal S1', e.g. during the sense mode RX to the MEMS sound transducer <NUM>, and wherein the charge pump arrangement <NUM>-<NUM> of the supply signal provider <NUM> is configured to provide the high-level supply signal S1 during the transmission mode TX to the MEMS sound transducer <NUM>, i.e. alternately to the first and second terminal <NUM>-<NUM>, <NUM>-<NUM> of the MEMS sound transducer <NUM>.

Typical (absolute) voltage values V1 of the high-level supply signal S1 may be in a voltage between <NUM> and <NUM> V. Typical (absolute) voltage values V1' of the further high-level supply signal S1' may be in a voltage between <NUM> and <NUM> V. Typical (absolute) voltage values VDD of the common supply signal SDD may be in a voltage between <NUM> and <NUM> V. The voltage values VDD may form the to the supply voltage of the ASIC <NUM> (the control circuitry).

Thus, typical values for the voltage VDD may be <NUM>. 8V for a digital control circuitry and <NUM>. 75V for analog control circuitry with allowed +-<NUM>% variations, for example.

To be more specific, the voltage values V1 may depend on the specific MEMS device (the MEMS sound transducer <NUM>) wherein lower voltages and considerably higher voltages are also possible. The voltage V1 needs to be high enough to bring the MEMS sound transducer <NUM> to its maximum displacement at the interesting frequencies of excitation.

According to an embodiment, the high-level voltages V1, V1' may be chosen to be equal or essentially equal so that the resulting electrostatic forces are zero or essentially zero on that (voltage supplied) side of the MEMS sound transducer <NUM> when the high-level voltage V1 is connected.

Furthermore, the high-level voltage V1 may indicate or define the useful range of high-level voltage V1', as the high-level voltage V1' may be chosen to comprise a voltage value which is by some (e.g. <NUM>, <NUM> or <NUM>) Volts above the voltage value of the high-level voltage V1 to account also for the discharging of the hold capacitor <NUM> (CH).

As exemplarily shown in <FIG>, the switching arrangement <NUM> may comprise the first switch element <NUM>-<NUM>, which is electrically connected between the terminal <NUM>-<NUM> of the first membrane structure <NUM> and the first terminal <NUM>-<NUM> of the read-out circuitry <NUM>, wherein a second switch element <NUM>-<NUM> is electrically connected between the terminal <NUM>-<NUM> of the second membrane element <NUM>-<NUM> and the second terminal <NUM>-<NUM> of the read-out circuitry <NUM>. A third switch element <NUM>-<NUM> is electrically connected between the terminal <NUM>-<NUM> of the first membrane structure <NUM> and the output terminal <NUM>-1a of the supply signal provider <NUM> (of the first charge pump arrangement <NUM>-<NUM>), wherein a fourth switching element <NUM>-<NUM> is electrically connected between the terminal <NUM>-<NUM> of the second membrane structure <NUM>-<NUM> and the output terminal <NUM>-1a of the supply signal provider <NUM>.

Furthermore, the hold capacitor <NUM> is connected between the output terminal <NUM>-1a of the supply signal provider <NUM> and a reference potential, e.g. ground potential.

Thus, the MEMS device <NUM> of <FIG> differs from the MEMS device of <FIG> in that the MEMS device of <FIG> comprises the further signal provider <NUM>-<NUM>, e.g. in form of a further charge pump arrangement <NUM>-<NUM>, wherein the output terminal <NUM>-2a of the further signal provider <NUM>-<NUM> is electrically connected to the terminal <NUM>-<NUM> of the counter electrode structure <NUM> to provide the further high level supply signal V1' to the terminal <NUM>-<NUM> of the counter electrode structure <NUM> of the MEMS sound transducer <NUM>, e.g. during the sense mode of the MEMS sound transducer <NUM>.

The implementation of the MEMS device according to <FIG> provides a high audio performance and a fast switching between the two modes RX, TX, wherein a considerable discharge of the hold capacitor <NUM> can be avoided during the transmission mode TX. Moreover, a low parasitic capacitance at the excitation node may be achieved.

According to an embodiment, the switching conditions (phases) φ1, φ2 in <FIG> indicate that, during an excitation mode, the two phases φ1, φ2 follow the timing of the excitation signal and connect alternatively each one of the MEMS sides (i.e. alternatively the first membrane structure <NUM> and the further (second) membrane structure <NUM>-<NUM> "or" alternatively the first counter-electrode structure <NUM> and the further (second) counter-electrode structure <NUM>-<NUM>) to the reference signal (reference voltage) of the amplifier <NUM> (= read-out circuitry) or to the high voltage V1 provided by the charge pump arrangement <NUM>. In this manner, each side experiences respectively high or almost-zero electrostatic forces.

<FIG> shows the schematic cross-sectional view of the MEMS sound transducer of <FIG> together with a schematic implementation of bypass switch(es) according to an embodiment. The schematic implementation of the bypass switch(es) as exemplarily shown in <FIG>, is correspondingly applicable to all embodiments of the present description.

The MEMS device <NUM> of <FIG> differs from the MEMS device of <FIG> in that the MEMS device of <FIG> comprises the further bypass switches (bypass switch arrangement) <NUM>, <NUM> and <NUM> and a further hold capacitor <NUM>-<NUM> at the terminal <NUM>-<NUM> of the counter electrode structure <NUM>.

As shown in <FIG>, the first bypass switch arrangement <NUM> is electrically connected between the first terminal <NUM>-<NUM> of the read-out circuitry <NUM> and ground potential (reference potential). The first bypass switch arrangement <NUM> comprises a voltage source <NUM>-<NUM> and a high impedance element <NUM>-<NUM> (high-resistance element) in a serial connection. The serial connection of the voltage source <NUM>-<NUM> and the high impedance element <NUM>-<NUM> is coupled between the first terminal <NUM>-<NUM> of the read-out circuitry <NUM> and the ground terminal. Furthermore, a first switching element <NUM>-<NUM> is parallel connected to the voltage source <NUM>-<NUM>, and a second switching element <NUM>-<NUM> is parallel connected to the high-impedance element <NUM>-<NUM>. The voltage source <NUM>-<NUM> may provide an amplifier common mode reference voltage, wherein the switching elements <NUM>-<NUM>, <NUM>-<NUM> may provide the excitation low-Z-mode switching elements (Z = impedance) of the bypass switch arrangement <NUM>.

The second bypass switch arrangement <NUM> is electrically connected between the second terminal <NUM>-<NUM> of the read-out circuitry <NUM> and ground potential. The second bypass switch arrangement <NUM> comprises a voltage source <NUM>-<NUM> and a high impedance element <NUM>-<NUM> (high-resistance element) in a serial connection. The serial connection of the voltage source <NUM>-<NUM> and the high impedance element <NUM>-<NUM> is coupled between the second terminal <NUM>-<NUM> of the read-out circuitry <NUM> and the ground terminal. Furthermore, a first switching element <NUM>-<NUM> is parallel connected to the voltage source <NUM>-<NUM>, and a second switching element <NUM>-<NUM> is parallel connected to the high-impedance element <NUM>-<NUM>. The voltage source <NUM>-<NUM> may provide an amplifier common mode reference voltage, wherein the switching elements <NUM>-<NUM>, <NUM>-<NUM> may provide the excitation low-Z-mode switching elements of the bypass switch arrangement <NUM>.

The third bypass switch arrangement <NUM> comprises a parallel connection of a high-impedance element <NUM>-<NUM> and a switching element <NUM>-<NUM>, which are electrically connected between the output terminal <NUM>-2a of the further signal provider <NUM>-<NUM> and the third terminal <NUM>-<NUM> of the counter electrode structure <NUM>. Further, the optional hold capacitor <NUM>-<NUM> is connected between the output terminal <NUM>-2a of the further signal provider <NUM>-<NUM> and ground potential. The switching element <NUM>-<NUM> may provide the excitation low-Z-mode switching elements of the bypass switch arrangement <NUM>.

As already discussed above, the first portion (low sens) RX1 of the sense mode RX following the transmission mode TX forms a recovery period of the MEMS sound transducer <NUM>, wherein the control circuitry <NUM> may provide a low-ohmic interface during the recovery period by means of the bypass switch arrangements <NUM>, <NUM>, <NUM>. In the low-ohmic recovery mode, the bypass switch arrangements <NUM>, <NUM>, <NUM> are enabled across the high-ohmic blocks as the ASIC <NUM> input. During the recovery period RX1, the oscillation of the MEMS microphone <NUM> will abate or fade away (= ringing), with the MEMS microphone <NUM> returning to normal sound reception mode. Due to the low-resistance or low-resistance state of the MEMS interface, short time constants can be achieved in order to be able to achieve the receive mode RX as quickly as possible, since the following applies: the shorter the recovery period, the shorter distances can be detected in the ultrasonic mode. The low-ohmic recovery mode enables the bypass switches across the high-ohmic blocks at the ASIC <NUM> input, for example.

As exemplarily shown in <FIG>, the optional hold capacitor <NUM>-<NUM> may be arranged for storing and providing the further high-level supply signal S1', e.g., provided by the further charge pump arrangement <NUM>-<NUM> during the sense mode RX, to the MEMS sound transducer <NUM>.

According to the different embodiments of the present specification, a hold capacitor <NUM>-<NUM> may be arranged at the output terminal <NUM>-2a of the further signal provider <NUM>-<NUM> for storing and providing the further high-level supply signal S1', i.e. the hold capacitor <NUM>-<NUM> may be connected between the output terminal <NUM>-2a of the further signal provider <NUM>-<NUM> and ground potential.

<FIG> shows a schematic view of the MEMS device <NUM> with a schematic cross-sectional view of the MEMS sound transducer <NUM> together with a schematic block diagram of the control circuitry <NUM> of the MEMS device in a differential excitation and read-out configuration of the MEMS sound transducer according to a further embodiment.

Thus, <FIG> also shows the MEMS device <NUM> with a "mode-dedicated charge pump concept (configuration)". As exemplarily shown in <FIG>, the switching arrangement <NUM> may comprise the first switch element <NUM>-<NUM>, which is electrically connected between the terminal <NUM>-<NUM> of the first membrane structure <NUM> and the first terminal <NUM>-<NUM> of the read-out circuitry <NUM>, wherein a second switch element <NUM>-<NUM> is electrically connected between the terminal <NUM>-<NUM> of the second membrane element <NUM>-<NUM> and the second terminal <NUM>-<NUM> of the read-out circuitry <NUM>. A third switch element <NUM>-<NUM> is electrically connected between the terminal <NUM>-<NUM> of the first membrane structure <NUM> and the output terminal <NUM>-1a of the supply signal provider <NUM>, wherein a fourth switching element <NUM>-<NUM> is electrically connected between the terminal <NUM>-<NUM> of the second membrane structure <NUM>-<NUM> and the output terminal <NUM>-1a of the supply signal provider <NUM>. Furthermore, the hold capacitor <NUM> is connected between the output terminal <NUM>-1a of the supply signal provider <NUM> and a reference potential, e.g. ground potential.

When compared to the MEMS device <NUM> as shown in <FIG>, the MEMS device <NUM> of <FIG> further comprises a fifth and sixth switching element <NUM>-<NUM>, <NUM>-<NUM>. The fifth switching element <NUM>-<NUM> is electrically connected between the terminal <NUM>-<NUM> of the counter electrode structure <NUM> and the output terminal <NUM>-1a of the supply signal provider <NUM>. The sixth switching element <NUM>-<NUM> is electrically connected between the output terminal <NUM>-2a of the further signal provider <NUM>-<NUM> and the terminal <NUM>-<NUM> of the counter electrode structure <NUM> to provide the further high level supply signal V1' to the terminal <NUM>-<NUM> of the counter electrode structure <NUM> of the MEMS sound transducer <NUM>, e.g. during the sense mode of the MEMS sound transducer <NUM>.

The implementation of the MEMS device according to <FIG> also provides a high audio performance and a fast switching between the two modes RX, TX, wherein a considerable discharge of the hold capacitor <NUM> can be avoided during the transmission mode TX.

According to an embodiment, the switching conditions (phases) φ1, φ2 in <FIG> indicate that, during an excitation mode, the two phases φ1, φ2 follow the timing of the excitation signal and connect alternatively each one of the MEMS sides (i.e. alternatively the first membrane structure <NUM> and the further (second) membrane structure <NUM>-<NUM> "or" alternatively the first counter-electrode structure <NUM> and the further (second) counter-electrode structure <NUM>-<NUM>) to the reference signal (reference voltage) of the amplifier <NUM> (= read-out circuitry) or to the high voltage V1 provided by the charge pump arrangement <NUM>.

As exemplarily shown in <FIG>, the first switching element <NUM>-<NUM> follows the condition φ1, the second switching element <NUM>-<NUM> follows the condition φ2, the third switching element <NUM>-<NUM> follows the condition φ2, the fourth switching element <NUM>-<NUM> follows the condition φ1, the fifth switching element <NUM>-<NUM> follows the condition "φ1 OR φ2" (logic OR), the sixth switching element <NUM>-<NUM> follows the condition "φ1 NOR φ2" (logic NOR). Thus, the sixth switching element <NUM>-<NUM> ensures that the further signal provider <NUM>-<NUM> provides the further high-level supply signal V1' to the terminal <NUM>-<NUM> of the counter electrode structure <NUM> of the MEMS sound transducer <NUM> (only) during the sense mode of the MEMS sound transducer <NUM>.

Even if the RX charge pump <NUM>-<NUM> (= the (first) supply voltage provider <NUM>-<NUM>) is isolated from the system while transmitting /TX mode), for avoiding the situation that the "VMIC" node (at the terminal <NUM>-<NUM>) of the MEMS sound transducer <NUM> would follow the excitation charge-pump node <NUM>-1a during the transmission mode TX, the "VMIC" node <NUM>-<NUM> is subject to a strong excitation (at discharge) leading to a bigger drift of the VMIC node and a slower recovery after the excitation that has to be driven by the sense charge pump <NUM>-<NUM>. Therefore, in a technology having hi-V MOS switches (hi-V = high-Volt) between two charge pumps (which may be designed as only hi-side or only low-side, i.e. with only one of the two junctions available to stand high voltages), reverse voltages can be avoided which otherwise might damage the devices.

<FIG> shows a schematic view of the MEMS device <NUM> with a schematic cross-sectional view of the MEMS sound transducer <NUM> together with a schematic block diagram of the control circuitry of the MEMS device <NUM> (in a differential excitation and read-out configuration of the MEMS sound transducer) according to a further embodiment.

As exemplarily shown in <FIG>, a first capacitor <NUM> (as a DC-blocking and AC-coupling capacitor) is electrically coupled between the first terminal <NUM>-<NUM> of the MEMS sound transducer <NUM> (= the terminal <NUM>-<NUM> of the first membrane structure <NUM>) and the first terminal <NUM>-<NUM> of the readout circuitry <NUM>. The second terminal <NUM>-<NUM> of the MEMS sound transducer <NUM> (= the terminal <NUM>-<NUM> of the second membrane structure <NUM>-<NUM>) is electrically connected to the second terminal <NUM>-<NUM> of the read out circuitry <NUM>.

A first switch element <NUM>-<NUM> is electrically connected between the third terminal <NUM>-<NUM> of the MEMS sound transducer <NUM> (= the terminal <NUM>-<NUM> of the backplate structure <NUM>) and the output terminal <NUM>-1a of the (first) supply voltage provider <NUM>-<NUM> (e.g. a first change pump arrangement <NUM>-<NUM>). A first terminal <NUM>-2a of a further (second) supply signal provider <NUM>-<NUM> (e.g. a second charge pump arrangement <NUM>-<NUM>) is electrically connected to the first terminal <NUM>-<NUM> of the MEMS sound transducer <NUM> (= the terminal <NUM>-<NUM> of the membrane structure <NUM>). A second switch element <NUM>-<NUM> is electrically connected between a second terminal <NUM>-2b of the further supply signal provider <NUM>-<NUM> and the third terminal <NUM>-<NUM> of the MEMS sound transducer <NUM> (= the terminal <NUM>-<NUM> of the backplate structure <NUM>). Further, a third switch element <NUM>-<NUM> is electrically connected between the third terminal <NUM>-<NUM> of the MEMS sound transducer <NUM> and a reference potential, e.g., ground potential.

<FIG> further shows a timing diagram of the different conditions of the control signal S2, such as the control signal components S2-<NUM>, S2-<NUM>, and the associated and resulting signal values (voltage values) at the different elements of the MEMS sound transducer <NUM>.

As shown in <FIG>, the first charge pump arrangement <NUM>-<NUM> is arranged to provide a high-level supply signal S1 having a voltage value V1, wherein the second charge pump arrangement <NUM>-<NUM> is arranged to provide a further high-level supply signal S1' having a further voltage value V1'. According to an embodiment, the second charge pump arrangement <NUM>-<NUM> is arranged to provide a high-level supply signal S1' having a higher voltage value V1', e.g., a double voltage value V1' = <NUM>*V1, when compared to the signal level V1 of the high-level supply signal S1 of the first charge pump arrangement <NUM>-<NUM>. Thus, the signal level V1' of the further high-level supply signal S1' may be in a range of <NUM> to <NUM> times higher than the signal level V1 of the high-level supply signal S1, e.g. V1' = <NUM> to <NUM>,<NUM>*V1 or about V1' = <NUM>*V1.

According to the timing diagram of <FIG>, the first switching element <NUM>-<NUM> is closed (= conducting), and the second and third switching elements <NUM>-<NUM> and <NUM>-<NUM> are open (= non-conducting) during the sense mode RX (= condition M1) with a first (low = "<NUM>") logical level of the control signal S2 and of the first control signal component S2-<NUM>. In the transmission mode TX of the MEMS sound transducer <NUM>, the control signal S2 provides the actuation pattern P which switches with the actuation frequency between the first (low = <NUM>) logic level and the second (high = <NUM>) logic level. Thus, in the second condition M2, the actuation pattern P (= the control signal S2) has a high logic level, e.g. as the logic AND combination of the high logic level of the first control signal component S2-<NUM> and the high logic level of the second control signal component S2-<NUM>, wherein the second switching element <NUM>-<NUM> is closed, and the first and third switching elements <NUM>-<NUM> and <NUM>-<NUM> are open. In the third condition M3, the alternating actuation pattern P (= the control signal S2) has s a low logic level, e.g. as the logic AND combination of the high logic level of the first control signal component S2-<NUM> and the low logic level of the second control signal component S2-<NUM>, wherein the third switching element <NUM>-<NUM> is closed, and the first and second switching elements <NUM>-<NUM>, <NUM>-<NUM> are open.

The resulting voltage levels during the different operating conditions of the MEMS device <NUM> are indicated in the timing diagram of <FIG>.

To be more specific, the first membrane structure <NUM> comprises during all conditions M1-M3 the voltage to V1' provided by the second charge pump arrangement <NUM>-<NUM>. The second membrane structure <NUM>-<NUM> is during all conditions M1-M3 connected with the second input terminal <NUM>-<NUM> of the readout circuitry <NUM> and comprises, for example, a constant voltage of about <NUM> V or e.g. <NUM> - <NUM> V. The backplate <NUM> (stator) comprises during the first condition M1 the voltage V1, during the second condition M2 the voltage V1', and during the third condition M3, the reference potential, e.g., ground potential = 0V.

As shown in <FIG> the hold capacitor <NUM> can be omitted, for example, if the high-voltage generators (e.g. the charge-pumps) <NUM>-<NUM>, <NUM>-<NUM> have an output that is low-ohmic enough, i.e. is able to drive the involved loads and quickly recover the nodes at the excitation frequencies. Thus, if the series resistance of the supply signal providers <NUM>-<NUM>, <NUM>-<NUM> has a sufficiently low value, the supply signal providers <NUM>-<NUM>, <NUM>-<NUM> can drive the MEMS nodes <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> at ultra-sound frequencies. Otherwise, the provision of the hold capacitor <NUM>, <NUM>-<NUM> may be necessary to sustain the excitation phase.

<FIG> shows a schematic view of the MEMS device <NUM> with a schematic cross-sectional view of the MEMS sound transducer together with a schematic block diagram of the control circuitry of the MEMS device (in a differential excitation and read-out configuration of the MEMS sound transducer) according to a further embodiment.

As exemplarily shown in <FIG>, a first capacitor <NUM> (as a DC-blocking and AC-coupling capacitor) is electrically coupled between the first terminal <NUM>-<NUM> of the MEMS sound transducer <NUM> (= the terminal <NUM>-<NUM> of the first membrane structure <NUM>) and the first terminal <NUM>-<NUM> of the readout circuitry <NUM>. A second capacitor <NUM> (as a DC-blocking and AC-coupling capacitor) is electrically coupled between the second terminal <NUM>-<NUM> of the MEMS sound transducer <NUM> (= the terminal <NUM>-<NUM> of the second membrane structure <NUM>-<NUM>) and the second terminal <NUM>-<NUM> of the readout circuitry <NUM>.

A first switching element <NUM>-<NUM> is electrically connected between the third terminal <NUM>-<NUM> of the MEMS sound transducer <NUM> (= the terminal <NUM>-<NUM> of the backplate structure <NUM>) and the first output terminal <NUM>-1a of the first supply voltage provider <NUM>-<NUM> (e.g. a positive change pump arrangement). A second output terminal <NUM>-1b of the first supply voltage provider <NUM>-<NUM> is electrically connected to the second terminal <NUM>-<NUM> of the MEMS sound transducer <NUM> (= the terminal <NUM>-<NUM> of the second membrane structure <NUM>-<NUM>).

A first output terminal <NUM>-2a of a further (second) supply signal provider <NUM>-<NUM> (e.g. a second negative charge pump arrangement) is electrically connected to the first terminal <NUM>-<NUM> of the MEMS sound transducer <NUM> (= the terminal <NUM>-<NUM> of the membrane structure <NUM>). A second switching element <NUM>-<NUM> is electrically connected between a second output terminal <NUM>-2a of the further supply signal provider <NUM>-<NUM> and the third terminal <NUM>-<NUM> of the MEMS sound transducer <NUM> (= the terminal <NUM>-<NUM> of the backplate structure <NUM>). Further, a third switching element <NUM>-<NUM> is electrically connected between the third terminal <NUM>-<NUM> of the MEMS sound transducer <NUM> and a reference potential, e.g., ground potential.

<FIG> further shows a timing diagram of the different conditions of the control signal S2, such as the control signal components S2-<NUM>, S2-<NUM>, and the associated and resulting signal values (voltage values V1, V1') at the different elements of the MEMS sound transducer <NUM>.

As shown in <FIG>, the first charge pump arrangement <NUM>-<NUM> is arranged to provide a high-level supply signal S1 having a voltage value V1, wherein the second charge pump arrangement <NUM>-<NUM> is arranged to provide a further high-level supply signal S1' having a further voltage value V1'. According to an embodiment, the second charge pump arrangement <NUM>-<NUM> is arranged to provide a high-level supply signal S1' having a negative voltage value V1', e.g., a voltage value V1' = -V1, when compared to the signal level V1 of the high-level supply signal S1 of the first charge pump arrangement <NUM>-<NUM>. Thus, the signal level V1' of the further high-level supply signal S1' may be in a range of V1' = -<NUM> to -<NUM>,<NUM>*V1 or about V1' = -V1.

According to the timing diagram of <FIG>, the third switching element <NUM>-<NUM> is closed (= conducting), and the first and second switching elements <NUM>-<NUM> and <NUM>-<NUM> are open (= non-conducting) during the sense mode RX (= condition M1). In the second condition M2, the actuation pattern P (= the control signal S2) has a high logic level, wherein the second switching element <NUM>-<NUM> is closed, and the first and third switching elements <NUM>-<NUM> and <NUM>-<NUM> are open. In the third condition M3, the alternating actuation pattern P (= the control signal S2) has s a low logic level wherein the third switching element <NUM>-<NUM> is closed, and the first and second switching elements <NUM>-<NUM>, <NUM>-<NUM> are open.

The resulting voltage levels during the different operating conditions of the MEMS device <NUM> are indicated in the timing diagram of <FIG>. To be more specific, the first membrane structure <NUM> comprises during all conditions M1 to M3 the voltage to V1' provided by the second charge pump arrangement <NUM>-<NUM>. The second membrane structure <NUM>-<NUM> is during all conditions M1 to M3 connected with the second terminal <NUM>-1b of the first charge pump arrangement <NUM>-<NUM> and comprises, for example, a signal level V1. The backplate <NUM> (stator) comprises during the first condition M1 the reference voltage, e.g., ground potential = 0V, during the second condition M2 the voltage V1, and during the third condition M3, the voltage level V1', e.g., V1' = -V1.

The above evaluations in <FIG> of a MEMS sound transducer <NUM> in a dual membrane configuration are equally applicable to a MEMS sound transducer <NUM> in a dual backplate configuration, wherein the first (top) counter electrode structure <NUM> comprises the first terminal <NUM>-<NUM> and the second (bottom) counter electrode structure <NUM>-<NUM> comprises a second terminal <NUM>-<NUM>, and wherein the membrane structure <NUM> comprises the third terminal <NUM>-<NUM>. Thus, the control circuitry <NUM> can equally couple the supply signal provider <NUM> to the MEMS sound transducer <NUM> using the same terminals <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> i.e., in the dual membrane configuration or in the dual backplate configuration, wherein the same technical effects of the MEMS device <NUM> can be achieved during the operation with the control circuitry <NUM>.

<FIG> shows a schematic view of the MEMS device <NUM> with a schematic cross-sectional view of the MEMS sound transducer <NUM> together with a schematic block diagram of the control circuitry <NUM> of the MEMS device <NUM> in a single-ended excitation and read-out configuration of the MEMS sound transducer <NUM> according to a further embodiment. As exemplarily shown in <FIG>, the MEMS sound transducer <NUM> is a single membrane microphone in a single-ended (common mode) ultrasonic actuation and read-out configuration.

Thus, <FIG> shows the MEMS device <NUM> with a "mode-dedicated charge pump concept". According to the embodiment of <FIG> the supply signal provider <NUM> comprises a first charge pump arrangement <NUM>-<NUM> for providing the high-level supply signal S1 to the MEMS sound transducer <NUM>, wherein the voltage level V1 of the high-level supply signal S1 is higher than a common supply signal VDD of the MEMS device <NUM>.

Moreover, the MEMS device <NUM> comprises a further (second) charge pump arrangement <NUM>-<NUM>, wherein the further charge pump arrangement <NUM>-<NUM> is configured to provide a further high-level supply signal S1' during the sense mode RX to the MEMS sound transducer <NUM>, and wherein the charge pump arrangement <NUM>-<NUM> of the supply signal provider <NUM> is configured to provide the high-level supply signal S1 during the transmission mode TX to the MEMS sound transducer <NUM>.

As exemplarily shown in <FIG>, the switching arrangement <NUM> may comprise a first switch element <NUM>-<NUM>, which is electrically connected between the terminal <NUM>-<NUM> of the MEMS sound transducer <NUM> (= of the backplate (stator) <NUM> and the terminal <NUM>-<NUM> of the read-out circuitry <NUM>. A further (second) switch element <NUM>-<NUM> is electrically connected between the terminal <NUM>-<NUM> of the backplate <NUM> and the terminal (= output pin) <NUM>-1a of the supply signal provider <NUM>-<NUM> (e.g. e first charge pump arrangement). A hold capacitor <NUM> is connected between the output terminal <NUM>-1a of the supply signal provider <NUM>-<NUM> and a reference potential VREF, e.g. ground potential. The MEMS device <NUM> comprises the further signal provider <NUM>-<NUM>, e.g. in form of a further charge pump arrangement, wherein the output terminal <NUM>-2a of the further signal provider <NUM>-<NUM> is electrically connected to the terminal <NUM>-<NUM> of the membrane structure <NUM> (= the first terminal <NUM>-1of the MEMS sound transducer <NUM>) to provide the further high-level supply signal V1' to the terminal <NUM>-<NUM> of the membrane structure <NUM> of the MEMS sound transducer <NUM>, e.g. during the sense mode of the MEMS sound transducer <NUM>.

The single-ended implementation of <FIG> includes two high-voltage switches <NUM>-<NUM>, <NUM>-<NUM> at the input of the MEMS interface, i.e. at the terminals <NUM>-<NUM>, <NUM>-2of the MEMS sound transducer <NUM>, that switch at ultrasound frequency during the send mode TX and bringing the membrane <NUM> of the MEMS sound transducer <NUM> to pull-in alternatively. The on-chip ultrasound charge-pump <NUM>-<NUM> plus hold capacitor <NUM> deliver the excitation voltage S1 that is alternatively connected to the membrane <NUM> of the MEMS sound transducer.

In above evaluations of <FIG> of a MEMS device <NUM>, the signal provider <NUM> comprises for example a first and (optionally) a second charge pump arrangement <NUM>-<NUM>, <NUM>-<NUM>. According to the described embodiments, the charge-pumps <NUM>-<NUM>, <NUM>-<NUM> (as supply signal provider) used for excitation of the MEMS sound transducer <NUM> can be substituted by a circuit block that is able to generate the low-ohmic high voltages V1, V1' ( with an absolute value >10V).

According to the different embodiments of the present specification as described above, a hold capacitor <NUM>-<NUM> may be arranged at the output terminal <NUM>-2a or <NUM>-2b (or at each of the output terminals <NUM>-2a, <NUM>-2b) of the further signal provider <NUM>-<NUM> for storing and providing the further high-level supply signal S1', i.e. the optional hold capacitor <NUM>-<NUM> may be connected between the respective output terminal <NUM>-2a, <NUM>-2b of the further signal provider <NUM>-<NUM> and ground potential.

In the following, <FIG> show an illustration of the temporal course of the different ultrasonic and audio operation modes of the MEMS device <NUM> and the resulting signals at the different elements of the MEMS device <NUM> having the MEMS sound transducer <NUM> and the control circuitry <NUM>.

Thus, <FIG> shows the ultrasonic operation modes of the MEMS device based on the different conditions TX, RX (RX with RX1 and RX2) of the control signal S2, i.e., the different conditions of the first and second control signal components S2-<NUM>, S2-<NUM> in the sense mode RX and the excitation mode TX, for example. Furthermore, <FIG> shows a possible time duration (= recovery period) of the low impedance mode (low Z mode = low-ohmic mode) of the interface (= terminals <NUM>-<NUM>,. , <NUM>-<NUM>) of the MEMS sound transducer <NUM>.

As exemplarily shown in <FIG>, the recovery period may have a duration of about <NUM> based on a clock frequency of <NUM> and <NUM>,<NUM> periods. Thus, a recovery time duration of <NUM> corresponds to the nearest range for detecting an objection (= nearest detectable object) in the sense mode RX of about <NUM> (= <NUM>/s * <NUM>)/<NUM>, with the speed of sound = <NUM>/s. Based on a possible variation of the oscillator frequency in a range from about <NUM> to <NUM> and a recovery duration RX1 of about <NUM>,<NUM> periods, the nearest detection range (= nearest detectable objects in the sense mode RX) can be adjusted between <NUM> to <NUM>, for example.

The number of actuation cycles during the send mode TX may be limited, to about <NUM> (or between <NUM> and <NUM>), to avoid an excessive discharge of the ultrasonic charge pump node, e.g., having the hold capacitor <NUM>.

<FIG> shows a temporal illustration (of the charge and discharge conditions) of the high-level supply signal at the hold capacitor <NUM> and the sensed signal of the MEMS device <NUM> according to an embodiment. To be more specific, <FIG> shows the signal levels (voltages) of the two charge pump arrangements <NUM>-<NUM>, <NUM>-<NUM> during the initial excitation phase TX followed by the recovery RX1 and the following sense mode RX2 of the ultrasonic excitation mode.

<FIG> shows the temporal illustration of the (sense) signals at the nodes for the top and bottom electrodes of the MEMS sound transducer <NUM> (MEMS microphone) according to an embodiment.

<FIG> shows the temporal illustration of the MEMS pull-in signal (voltage) of the top-bottom-electrode resulting from the MEMS sound transducer gaps during actuation according to an embodiment.

<FIG> provide the same considerations for the MEMS nodes (first to third terminals <NUM>-<NUM>,. , <NUM>-<NUM> of the MEMS sound transducer) and their excitation pattern P with alternating high and low voltages and the effects of the actuation on the MEMS displacement (gaps) in <FIG>.

<FIG> shows a temporal illustration of the amplitude of the echo signal (received signal) of the MEMS device (when compared to a single ended implementation) according to an embodiment; and.

<FIG> shows a graphical illustration of the un-weighted spectral density measurement of the MEMS device according to an embodiment.

Based on the illustrations in <FIG> and <FIG>, it can be seen that the above-described MEMS device <NUM> according to the different embodiments shows excellent characteristics with respect to its audio performance of the MEMS sound transducer <NUM>, to the resulting object detection and the provided ultrasound signal strength.

Embodiments of the present disclosure may provide a so-called combo-sensor solution of an audio microphone and an ultrasonic transducer. Such a solution can be, for example, used for gesture recognition and proximity sensor applications, etc. Embodiments of the MEMS device <NUM> provide additionally ultrasonic functionality to a MEMS microphone, wherein the efforts for the integration of the MEMS sound transducer for audio and ultrasonic applications, such as additionally circuit components, are relatively low, wherein essentially no changes in the packaging or added hardware are needed.

Additional embodiments and aspects are described which may be used alone or in combination with the features and functionalities described herein.

Although some aspects have been described as features in the context of an apparatus it is clear that such a description may also be regarded as a description of corresponding features of a method. Although some aspects have been described as features in the context of a method, it is clear that such a description may also be regarded as a description of corresponding features concerning the functionality of an apparatus.

Depending on certain implementation requirements, embodiments of the control circuitry can be implemented in hardware or in software or at least partially in hardware or at least partially in software. Generally, embodiments of the control circuitry can be implemented as a computer program product with a program code, the program code being operative for performing one of the methods when the computer program product runs on a computer.

In the foregoing detailed description, it can be seen that various features are grouped together in examples for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed examples require more features than are expressly recited in each claim. Rather, as the following claims reflect, subject matter may lie in less than all features of a single disclosed example. Thus the following claims are hereby incorporated into the detailed description, where each claim may stand on its own as a separate example. While each claim may stand on its own as a separate example, it is to be noted that, although a dependent claim may refer in the claims to a specific combination with one or more other claims, other examples may also include a combination of the dependent claim with the subject matter of each other dependent claim or a combination of each feature with other dependent or independent claims. Such combinations are proposed herein unless it is stated that a specific combination is not intended. Furthermore, it is intended to include also features of a claim to any other independent claim even if this claim is not directly made dependent to the independent claim.

Claim 1:
A MEMS device (<NUM>) comprising:
A MEMS sound transducer (<NUM>), wherein the MEMS sound transducer (<NUM>) comprises a membrane structure (<NUM>, <NUM>-<NUM>) and a counter electrode structure (<NUM>), and
a control circuitry (<NUM>) comprising:
a supply signal provider (<NUM>) for providing a high-level supply signal (S1, S1'),
a read-out circuitry (<NUM>) for receiving an output signal from the MEMS sound transducer (<NUM>), and
a switching arrangement (<NUM>) for selectively connecting the MEMS sound transducer (<NUM>) to the supply signal provider (<NUM>), and for selectively connecting the MEMS sound transducer (<NUM>) to the read-out circuitry (<NUM>) based on a control signal (S2),
wherein the control signal (S2) is based on a first control signal component (S2-<NUM>) and a second control signal component (S2-<NUM>); wherein a first condition (TX) of the first control signal component (S2-<NUM>) enables a transmission mode of the MEMS sound transducer (<NUM>), and wherein a second condition (RX) of the first control signal component (S2-<NUM>) enables a sense mode of the MEMS sound transducer (<NUM>); and
wherein the control circuitry (<NUM>) is configured to provide the second control signal component (S2-<NUM>) having an ultrasonic actuation pattern (P) to the switching arrangement (<NUM>) only during the first condition of the first control signal component (S2-<NUM>), wherein the second control signal component (S2-<NUM>) triggers the switching arrangement (<NUM>) for alternately coupling the high-level supply signal (S1, S1') to the MEMS sound transducer (<NUM>) based on the ultrasonic actuation pattern (P).