Capacitive MEMS sensing diagnostic mode

Abstract

The invention relates to a capacitive MEMS sensing diagnostic mode. A pressure sensor includes a micro-electro-mechanical system (MEMS) device having a first output pad, a second output pad, and a first voltage-sensitive capacitor element, a second voltage-sensitive capacitor element, a first reference capacitive element, and a second reference capacitive element arranged in a bridge configuration; and an application specific integrated circuit (ASIC) in electrical communication with the MEMS device, the ASIC has a first input pad and a second input pad, a measurement interface including a first input and a second input, a first switch coupled between the first input pad and the second input pad, and a second switch coupled between the second input of the measurement interface and the second input pad of the ASIC.

Description

Technical Field

[0001] The present invention generally relates to a capacitive micro-electromechanical system (MEMS) sensing diagnostic mode. Background Art

[0002] Capacitive pressure sensors can be implemented in a fully differential bridge configuration using a pressure-sensitive capacitor element and a reference capacitor element. This configuration measures the absolute pressure represented as a differential signal. In addition, by reconfiguring the bridge, diagnostic measurements can also be performed. The diagnostic mode measures the balance (matching) between the bridge elements, while the excitation effects of the measuring cell (e.g. air pressure) are strongly suppressed. An unbalanced bridge can be evidence of a defect (e.g. due to particle contamination) and can therefore be used to screen out such devices. In addition, diagnostic measurements allow continuous monitoring of the MEMS during the device lifetime.

[0003] Figure 1 A capacitive pressure sensor bridge 100A is depicted configured in normal operation and a capacitive pressure sensor bridge 100B is depicted configured in a diagnostic mode, but both use differential readout in accordance with the prior art.

[0004] Capacitive pressure sensor bridge 100A includes reference capacitor elements C1 and C4 and pressure-sensitive capacitor elements C2 and C3. Reference capacitor element C1 is coupled between terminal 102, indicated as VREF_P, and terminal 104, indicated as VOUT_N, and reference capacitor element C4 is coupled between terminal 108, indicated as VREF_N, and terminal 106, indicated as VOUT_P. Pressure-sensitive capacitor element C2 is coupled between terminal 102, indicated as VREF_P, and terminal 106, indicated as VOUT_P, and pressure-sensitive capacitor element C3 is coupled between terminal 108, indicated as VREF_N, and terminal 104, indicated as VOUT_N. A differential voltage between terminal 104 and terminal 106 provides a differential voltage representative of an input pressure, such as ambient air pressure.

[0005] Capacitive pressure sensor bridge 100B includes reference capacitor elements C1 and C4 and pressure sensitive capacitor elements C2 and C3. Reference capacitor element C1 is coupled between terminal 102, indicated as VREF_P, and terminal 104, indicated as VOUT_N, and reference capacitor element C4 is coupled between terminal 102, indicated as VOUT_N, and terminal 106, indicated as VOUT_P. Pressure sensitive capacitor element C2 is coupled between terminal 108, indicated as VREF_N, and terminal 106, indicated as VOUT_P, and pressure sensitive capacitor element C3 is coupled between terminal 108, indicated as VREF_N, and terminal 104, indicated as VOUT_N. The differential voltage between terminal 104 and terminal 106 provides a differential voltage representing an imbalance between a given capacitive element and the matching values ​​of the other three capacitive elements.

[0006] Although the capacitive pressure sensor bridge 100A is configured for normal operation and the capacitive pressure sensor 100B is configured for diagnostic mode, it is clear that additional switches are required to reconfigure the capacitive pressure sensor bridge 100A to assume the configuration of the capacitive pressure sensor bridge 100B. However, in MEMS technology, there are usually no CMOS devices for switches. Therefore, when communicating with a MEMS device, additional switches must be integrated into the corresponding application-specific integrated circuit (ASIC). Therefore, additional connections (bonding pads and bonding wires) are required between the MEMS device and the ASIC. Summary of the invention

[0007] According to one embodiment, a pressure sensor includes: a microelectromechanical system (MEMS) device, including: a first output pad, a second output pad, and a first pressure-sensitive capacitor element, a second pressure-sensitive capacitor element, a first reference capacitive element, and a second reference capacitive element arranged in a bridge configuration; and an application-specific integrated circuit (ASIC) that electrically communicates with the MEMS device, including: a first input pad and a second input pad, a measurement interface including a first input and a second input, a first switch coupled between the first input and the second input, and a second switch coupled between a second input of the measurement interface and a second input pad of the ASIC.

[0008] According to another embodiment, a pressure sensor includes: a microelectromechanical system (MEMS) device, including: a first output pad, a second output pad, and a first pressure-sensitive capacitor element, a second pressure-sensitive capacitor element, a first reference capacitive element, and a second reference capacitive element arranged in a bridge configuration; and an application-specific integrated circuit (ASIC) that electrically communicates with the MEMS device, including: a first input pad and a second input pad, a measurement interface including a first input and a second input, a first switch coupled between the first input of the measurement interface and the second input of the measurement interface, a second switch coupled between the second input of the measurement interface and the second input pad of the ASIC, and a third switch coupled between the first input of the measurement interface and the first input pad of the ASIC.

[0009] According to one embodiment, a pressure sensor includes: a microelectromechanical system (MEMS) device, including: a first output pad, a second output pad, and a first pressure-sensitive capacitor element, a second pressure-sensitive capacitor element, a first reference capacitive element, and a second reference capacitive element arranged in a bridge configuration; and an application-specific integrated circuit (ASIC) in electrical communication with the MEMS device, including: a first input pad and a second input pad, a measurement interface including a first input and a second input, a first switch coupled between the second input pad of the ASIC and a bias voltage source, a second switch coupled between the second input pad of the ASIC and a second input of the measurement interface, a third switch coupled between the first input pad of the ASIC and the bias voltage source, and a fourth switch coupled between the first input pad of the ASIC and the first input of the measurement interface. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] For a more complete understanding of the present invention and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0011] Figure 1 is a schematic diagram of a capacitive pressure sensor bridge configured in a normal operating mode with differential readout and a capacitive pressure sensor bridge configured in a diagnostic operating mode with differential readout;

[0012] Figure 2 is a schematic diagram of a capacitive pressure sensor bridge configured in a normal operating mode with differential readout and a capacitive pressure sensor bridge configured in a diagnostic operating mode with common mode readout;

[0013] Figure 3 is a block diagram of a pressure sensor according to a first embodiment;

[0014] Figure 4A , Figure 4B and Figure 4C According to the embodiment, it is suitable for Figure 3Block diagram of the measurement interface of the pressure sensor;

[0015] Figure 5A and Figure 5B is a block diagram of a pressure sensor according to a second embodiment;

[0016] Figure 5C is with Figure 5A and Figure 5B A timing diagram associated with a pressure sensor;

[0017] Fig. 6A is a block diagram of a pressure sensor according to a third embodiment;

[0018] Figure 6B is with Fig. 6A a timing diagram associated with a pressure sensor; and

[0019] Figure 7 is a flow chart of a method of operating a pressure sensor according to an embodiment. DETAILED DESCRIPTION

[0020] The making and use of the currently preferred embodiments are discussed in detail below. However, it should be understood that the present invention provides many applicable inventive concepts that can be embodied in various specific contexts. The specific embodiments discussed only illustrate the specific ways to make and use the present invention, and do not limit the scope of the present invention.

[0021] In the following detailed description, reference is made to the accompanying drawings which form a part thereof, and in these drawings, specific examples in which the present invention can be practiced are shown by way of illustration. It should be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. For example, features illustrated or described for one embodiment may be used for other embodiments or used in combination with other embodiments to produce another embodiment. The present disclosure is intended to include such modifications and variations. Examples are described using specific language, which should not be interpreted as limiting the scope of the appended claims. The drawings are not necessarily drawn to scale and are for illustrative purposes only. For clarity, the same or similar elements are designated by corresponding reference numerals in different drawings unless otherwise specified.

[0022] According to the following embodiments, the diagnostic mode of a pressure-sensitive capacitive (or resistive) MEMS device in a pressure sensor is achieved by shorting the differential output of a bridge inside the MEMS device and measuring the corresponding signal in a single-ended (common mode) configuration. This configuration advantageously avoids the need for any additional connections (such as additional bonding pads and additional bonding wires) between the MEMS device and the accompanying ASIC. The following pressure sensor embodiments can also be applied to a full-bridge configuration, where all elements are sensitive to the measurement unit. In addition, capacitive sensor elements can also be used interchangeably with other pressure-sensitive elements (e.g., resistive elements, such as piezoresistance elements).

[0023] Figure 2 is a schematic diagram of a capacitive pressure sensor bridge 100A configured in a normal operating mode with differential readout and a capacitive pressure sensor bridge 100C configured in a diagnostic operating mode with single-ended (common mode) readout. Figure 1 A capacitive pressure sensor bridge 100A is shown and described. A capacitive pressure sensor bridge 100C is shown and described with respect to Figure 1 The capacitive pressure sensor bridge 100B shown and described has the same capacitive elements in the same configuration. However, the capacitive pressure sensor bridge 100C has a short circuit between terminal 104 (VOUT_N) and terminal 106 (VOUT_P) to form a common mode terminal 110 indicated as VOUT_CM. In operation, a diagnostic mode using a single-ended readout at the common mode terminal 110 allows the balance (matching) between the bridge elements in the capacitive pressure sensor bridge 100C to be measured while the excitation effects of the measurement (e.g., air pressure) are strongly suppressed.

[0024] Figure 3 is a block diagram of a pressure sensor 300 according to the first embodiment. Figure 3 Depicted is a combination of a MEMS device 302, such as a capacitive pressure sensor bridge 100A and a corresponding ASIC 304, which implements a diagnostic mode using a single-ended (common mode) readout.

[0025] The switches on ASIC 304 are used to short the MEMS device 302 output signals and combine them into a single-ended signal. This signal is then connected to the input of the measurement interface 306 in a single-ended configuration by disconnecting one of the inputs. In the balanced MEMS device 302, the single-ended signal is close to zero volts and can therefore be processed using the same differential measurement interface that is used for differential signals in normal operating mode. (The small common-mode portion is handled by the differential measurement interface without degrading performance.) Pressure sensor 300 is also described in detail below.

[0026] The pressure sensor 300 includes a MEMS device 302, which includes a capacitive pressure sensor bridge 100A, which is coupled to a terminal 102 (first reference pad), a terminal 108 (second reference pad), a terminal 106 (first output pad), and a terminal 104 (second output pad). The MEMS device 302 is typically manufactured as a single packaged integrated circuit using a process specifically adapted for MEMS devices. The pressure sensor 300 also includes an ASIC 304, which includes a measurement interface 306 having a first reference output (REF_P) coupled to a first reference pad 312, a second reference output (REF_N) coupled to a second reference pad 318, a first input (IN_P) coupled to a first input pad 316, and a second input (IN_N) coupled to a second input pad 314. In an embodiment, the MEMS device 302 and the ASIC 304 are in electrical communication via a plurality of bonding wires 320. In Figure 3 As can be seen in FIG, each of the reference pads of the MEMS device 302 and the ASIC 304 are coupled together with two bonding wires, and each of the signal pads of the MEMS device 302 and the ASIC 304 are also coupled together with two bonding wires. In the first embodiment, only a total of 8 bonding pads and 4 bonding wires are required to implement a pressure sensor device having a normal operating mode and a diagnostic operating mode. The measurement interface 306 is in electrical communication with a control / post-processing component 308, which includes a microprocessor or a state machine or other suitable control component. The control / post-processing component 308 includes an output 310 indicated as SW_CON, which provides control signals for switches S1 and S2, which will be described in detail below.

[0027] ASIC 304 includes a first switch S1 coupled between the first input (IN_P) and the second input (IN_N) and a second switch S2 coupled between the second input (IN_N) of the measurement interface 306 and the second input pad 314 of ASIC 304. Switch S1 and switch S2 allow for implementation of a normal operating mode (to act as a forward pressure sensing device) as well as a diagnostic operating mode (to detect an imbalance in the capacitive pressure sensor bridge).

[0028] Table 1 shows the switch configuration of the first embodiment in the normal operation mode and the diagnostic operation mode.

[0029] Switch S1 Switch S2 Normal Mode disconnect closure Diagnostic Mode closure disconnect

[0030] Table 1

[0031] Figure 4A , Figure 4B and Figure 4C According to the embodiment, it is suitable for Figure 3Block diagram of the pressure sensor measurement interface.

[0032] Figure 4A 4 is a detailed view of the capacitive measurement interface 304A, which includes an analog-to-digital converter (ADC) 406, the ADC 406 having a first input and a second input, which are coupled to the first output and the second output of the programmable gain amplifier (PGA) 404 in the measurement block 408. The output of the ADC 406 includes an N-bit digital output (DOUT) that represents the pressure signal in the normal operating mode and the diagnostic signal in the diagnostic operating mode. The first input of the PGA 404 is coupled to the first input (IN_P) of the capacitive measurement interface 304A, and the second input of the PGA 404 is coupled to the second input (IN_N) of the capacitive measurement interface 304A. The PGA 404 includes a first feedback capacitor C1 and a second feedback capacitor C2, which are configured to amplify the signal ( Figure 4A ). The capacitive measurement interface 304A further comprises a reference modulator 402 for generating a first reference signal at a first reference output (REF_P) and for generating a second reference signal at a second reference output (REF_N), the reference modulator 402 being configured for proper operation of the capacitive element in the MEMS device 302. The reference modulator has an input for receiving an input reference signal VREF, which may be a DC voltage or a square wave signal depending on the circuit design used.

[0033] Figure 4B is a detailed view of the capacitive measurement interface 304B, which includes an analog-to-digital converter (ADC) 406 and a reference modulator 402, both of which are shown above with respect to Figure 4A In the capacitive measurement interface 304B, the output of the ADC 406 is directly coupled to the first input (IN_P) of the capacitive measurement interface 304B, and is coupled to the second input (IN_N) of the capacitive measurement interface 304B. Figure 4B The programmable gain amplifier (PGA) 404 in the measurement block 408 is omitted.

[0034] Figure 4C 4 is a detailed view of a resistive measurement interface 304C, which includes a reference modulator 402 for generating a DC reference voltage at a first reference output (REF_P) and a second reference output (REF_N). The measurement block 408 is substantially the same as previously described with respect to Figure 4AHowever, the feedback capacitor C1 is replaced with a feedback resistor R1, and the feedback capacitor C2 is replaced with a feedback resistor R2. The replacement of the DC reference voltage and feedback resistors R1 and R2 allows the resistive measurement interface 304C to operate with resistive MEMS devices (preferably in Figure 5B and described below).

[0035] According to the second embodiment, Figure 5A is a block diagram of a capacitive pressure sensor 500A, and Figure 5B is a block diagram of a resistive pressure sensor 500B. Specifically, a second switch is added to the other differential input of the measurement interface to allow diagnostic mode measurements to be performed sequentially to obtain higher accuracy. Therefore, Figure 5A and Figure 5B A combination of a MEMS device and an ASIC is depicted that implements a diagnostic mode using single-ended (common mode) readout for both measurement interface inputs.

[0036] Figure 5A A capacitive pressure sensor 500A is shown, which includes a MEMS device 502A, which includes the capacitive pressure sensor bridge 100A described previously, which is coupled to the reference pad and output pad also described previously. The capacitive pressure sensor 500A also includes an ASIC 504, which includes a first reference pad 512, a second reference pad 518, a first input pad 516 and a second input pad 514, similar to the previously described capacitive pressure sensor bridge 100A. Figure 3 ASIC 504 includes a measurement interface 506 and a control / post-processing component 508 having an output 510, similar to that previously described in Figure 3 The measurement interface and control / processing components described in the first embodiment are shown. The MEMS device 502 and the ASIC 504 are in electrical communication via a plurality of bond wires 520 .

[0037] Specifically, the ASIC 504 includes a first switch S1, a second switch S2, and a third switch S3, the third switch S3 implementing a sequential diagnostic mode for measuring a single-ended output signal from the capacitive pressure sensor bridge 100A, and implementing a normal operation mode for measuring a differential signal from the capacitive pressure sensor bridge 100A. The ASIC 504 includes: a first switch S1 coupled between a first input (IN_P) of the measurement interface 506 and a second input (IN_N) of the measurement interface 506, a second switch S2 coupled between the second input (IN_N) of the measurement interface 506 and a second input pad 514 of the ASIC, and a third switch coupled between the first input (IN_P) of the measurement interface 506 and a first input pad 516 of the ASIC.

[0038] Figure 5B is a block diagram of a resistive pressure sensor 500B which is similar in topology and operation to the previously described resistive pressure sensor 500B. Figure 5A The capacitive pressure sensor 500A shown is similar to that described. However, the capacitive pressure sensor bridge 100A is replaced with a resistive pressure sensor bridge 100D. The pressure-sensitive capacitor element is replaced with a pressure-sensitive resistor element, and the reference capacitor element is replaced with a reference resistor element in the resistive pressure sensor bridge 100D.

[0039] Table 2 shows the switch configuration of the second embodiment in normal operating mode in a first measuring step (diagnostic mode A) and in a second measuring step (diagnostic mode B) in the diagnostic operating mode.

[0040] Switch S1 Switch S2 Switch S3 Diagnostic Mode A closure disconnect closure Diagnostic Mode B closure closure disconnect Normal Mode disconnect closure closure

[0041] Table 2

[0042] Figure 5C is with Figure 5A and Figure 5B 5, illustrates sequential steps A and B in the diagnostic mode. In a first time period 532, the switches are arranged as described above in diagnostic mode A, and the results are stored in the control / post-processing component 508. In a second time period 534, the switches are arranged as described above in diagnostic mode B, and the results are stored in the control / post-processing component 508. In a third time period, post-processing is performed in the control / post-processing component 508 to calculate a final result by, for example, subtracting the first measurement during diagnostic mode A from the second measurement during diagnostic mode B. The final result advantageously doubles the signal amplitude and eliminates non-idealities of the ASIC.

[0043] Fig. 6Ais a block diagram of a pressure sensor 600 according to a third embodiment. Unlike the differential output short-circuiting that short-circuits the capacitive pressure sensor bridge in the first two embodiments, the two differential outputs of the MEMS device are disconnected from the measurement interface and connected to a bias voltage vbias (where the bias voltage vbias may be a common mode voltage vss) in two sequential measurement steps also described below. The results of the two sequential measurements may then be subtracted to obtain a measure of the balance of the bridge.

[0044] Fig. 6A A pressure sensor 600 is shown, which includes a MEMS device 602, which includes the capacitive pressure sensor bridge 100A described previously, which is coupled to the reference pad and output pad also described previously. The pressure sensor 600 also includes an ASIC 604, which includes a first reference pad 612, a second reference pad 618, a first input pad 616, and a second input pad 614, similar to the reference pads and input pads described previously. The ASIC 604 includes a measurement interface 606 and a control / post-processing component 608 with an output 610, similar to the measurement interface and control / processing component described previously. The MEMS device 602 and the ASIC 604 are in electrical communication through a plurality of bonding wires 620.

[0045] Specifically, the ASIC 604 includes a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4, the fourth switch S4 also implementing a sequential diagnostic mode for measuring a differential output signal from the capacitive pressure sensor bridge 100A, and implementing a normal operation mode for measuring a differential signal from the capacitive pressure sensor bridge 100A. The ASIC 604 includes: a first switch S1 coupled between a second input pad 614 of the ASIC and a bias voltage (vbias) source, a second switch S2 coupled between the second input pad 614 of the ASIC and a second input IN_N of the measurement interface 606, a third switch S3 coupled between a first input pad 616 of the ASIC and a bias voltage (vbias) source, and a fourth switch S4 coupled between the first input pad 616 of the ASIC and a first input (IN_P) of the measurement interface 606.

[0046] Table 3 shows the switch configuration of the third embodiment in the normal operating mode in the first measuring step (diagnostic mode A) and in the second measuring step (diagnostic mode B) in the diagnostic operating mode.

[0047]

[0048] Table 3

[0049] Figure 6B is with Fig. 6A6, illustrates sequential steps A and B in the diagnostic mode. In a first time period 632, the switches are arranged as described above in diagnostic mode A, and the results are stored in the control / post-processing component 608. In a second time period 634, the switches are arranged as described above in diagnostic mode B, and the results are stored in the control / post-processing component 608. In a third time period, post-processing is performed in the control / post-processing component 608 to calculate a final result by, for example, subtracting the first measurement during diagnostic mode A from the second measurement during diagnostic mode B. The final result advantageously doubles the signal amplitude and eliminates non-idealities of the ASIC.

[0050] Figure 7 is a flowchart 700 of a method of operating a pressure sensor, the pressure sensor including a pressure sensitive bridge coupled to a measurement interface via a first switch, a second switch, a third switch, and a fourth switch, the method comprising: at step 702, during a first sequential step of a diagnostic mode, selectively coupling the pressure sensitive bridge to the measurement interface in a first switch configuration; at step 704, during a second sequential step of the diagnostic mode, selectively coupling the pressure sensitive bridge to the measurement interface in a second switch configuration; and at step 706, during a normal operating mode, selectively coupling the pressure sensitive bridge to the measurement interface in a third switch configuration. The method also includes post-processing the results of the first sequential step and the results of the second sequential step to provide a diagnostic mode result. Other methods of operating a pressure sensor may include the aforementioned two or three switches.

[0051] The pressure embodiments described herein advantageously implement a diagnostic mode of a MEMS device without requiring additional connections (such as external bonding pads and external bonding wires) between the MEMS device and the associated ASIC. Additional switches may be added on the ASIC side at low cost or reduced performance. For example, the switches of the second and third embodiments may be combined into a total of five switches to provide maximum flexibility in normal and diagnostic modes. In addition, any of the embodiments described herein may use a resistive or capacitive pressure-sensitive bridge, and any suitable version of the measurement interface may be used. In some embodiments, the control / post-processing component may be external to the ASIC. In some embodiments, the switch may be implemented as an NMOS or PMOS transistor switch or a combination thereof.

[0052] Example embodiments of the invention are summarized here. Other embodiments may also be understood from the overall description and claims submitted herein.

[0053] Example 1. According to one embodiment, a pressure sensor includes:

[0054] a microelectromechanical system (MEMS) device comprising a first output pad, a second output pad, and a first pressure-sensitive capacitor element, a second pressure-sensitive capacitor element, a first reference capacitive element, and a second reference capacitive element arranged in a bridge configuration; and

[0055] An application specific integrated circuit (ASIC) in electrical communication with the MEMS device includes a first input pad and a second input pad, a measurement interface including a first input and a second input, a first switch coupled between the first input pad and the second input pad, and a second switch coupled between a second input of the measurement interface and the second input pad of the ASIC.

[0056] Example 2. The pressure sensor of Example 1, wherein the first pressure-sensitive capacitor element and the first reference capacitive element are coupled to a first reference pad of the MEMS device, and wherein the second pressure-sensitive capacitor element and the second reference capacitive element are coupled to a second reference pad of the MEMS device.

[0057] Example 3. A pressure sensor according to any of the above examples, wherein the first pressure-sensitive capacitor element and the second reference capacitive element are coupled to a first output pad of the MEMS device, and wherein the second pressure-sensitive capacitor element and the first reference capacitive element are coupled to a second output pad of the MEMS device.

[0058] Example 4. A pressure sensor according to any of the above examples, wherein the measurement interface includes a differential amplifier.

[0059] Example 5. A pressure sensor according to any of the above examples, wherein the measurement interface includes an analog-to-digital converter (ADC).

[0060] Example 6. The pressure sensor of any of the above examples, wherein the measurement interface comprises a first reference voltage source coupled to a first reference pad of the ASIC and a second reference voltage source coupled to a second reference pad of the ASIC.

[0061] Example 7. According to an embodiment, a pressure sensor including a micro-electromechanical system (MEMS) device includes:

[0062] a first output pad, a second output pad, and a first voltage sensitive capacitor element, a second voltage sensitive capacitor element, a first reference capacitive element, and a second reference capacitive element arranged in a bridge configuration; and

[0063] An application specific integrated circuit (ASIC) in electrical communication with a MEMS device includes a first input pad and a second input pad, a measurement interface including a first input and a second input, a first switch coupled between the first input pad of the measurement interface and the second input pad of the measurement interface, a second switch coupled between the second input of the measurement interface and the second input pad of the ASIC, and a third switch coupled between the first input of the measurement interface and the first input pad of the ASIC.

[0064] Example 8. The pressure sensor of Example 7, wherein the first pressure-sensitive capacitor element and the first reference capacitive element are coupled to a first reference pad of the MEMS device, and wherein the second pressure-sensitive capacitor element and the second reference capacitive element are coupled to a second reference pad of the MEMS device.

[0065] Example 9. A pressure sensor according to any of the above examples, wherein the first pressure-sensitive capacitor element and the second reference capacitive element are coupled to a first output pad of the MEMS device, and wherein the second pressure-sensitive capacitor element and the first reference capacitive element are coupled to a second output pad of the MEMS device.

[0066] Example 10. The pressure sensor of any of the above examples, wherein the measurement interface comprises a differential amplifier.

[0067] Example 11. A pressure sensor according to any of the above examples, wherein the measurement interface includes an analog-to-digital converter (ADC).

[0068] Example 12. The pressure sensor of any of the above examples, wherein the measurement interface comprises a first reference voltage source coupled to a first reference pad of the ASIC and a second reference voltage source coupled to a second reference pad of the ASIC.

[0069] Example 13. According to one embodiment, a pressure sensor includes:

[0070] a microelectromechanical system (MEMS) device comprising a first output pad, a second output pad, and a first pressure-sensitive capacitor element, a second pressure-sensitive capacitor element, a first reference capacitive element, and a second reference capacitive element arranged in a bridge configuration; and

[0071] An application specific integrated circuit (ASIC) in electrical communication with a MEMS device includes a first input pad and a second input pad, a measurement interface including a first input and a second input, a first switch coupled between the second input pad of the ASIC and a bias voltage source, a second switch coupled between the second input pad of the ASIC and a second input of the measurement interface, a third switch coupled between the first input pad of the ASIC and the bias voltage source, and a fourth switch coupled between the first input pad of the ASIC and the first input of the measurement interface.

[0072] Example 14. The pressure sensor of Example 13, further comprising a fifth switch coupled between the first output pad of the ASIC and the second output pad of the ASIC.

[0073] Example 15. A pressure sensor according to any of the above examples, wherein the first pressure-sensitive capacitor element and the first reference capacitive element are coupled to a first reference pad of the MEMS device, and wherein the second pressure-sensitive capacitor element and the second reference capacitive element are coupled to a second reference pad of the MEMS device.

[0074] Example 16. A pressure sensor according to any of the above examples, wherein the first pressure-sensitive capacitor element and the second reference capacitive element are coupled to a first output pad of the MEMS device, and wherein the second pressure-sensitive capacitor element and the first reference capacitive element are coupled to a second output pad of the MEMS device.

[0075] Example 17. A pressure sensor according to any of the above examples, wherein the measurement interface includes a differential amplifier.

[0076] Example 18. A pressure sensor according to any of the above examples, wherein the measurement interface includes an analog-to-digital converter (ADC).

[0077] Example 19. The pressure sensor of any of the above examples, wherein the measurement interface comprises a first reference voltage source coupled to a first reference pad of the ASIC and a second reference voltage source coupled to a second reference pad of the ASIC.

[0078] Example 20. A pressure sensor according to any of the above examples, wherein the first switch, the second switch, the third switch and the fourth switch are set to be in a first configuration for a normal operating mode, and wherein the first switch, the second switch, the third switch and the fourth switch are set to be in a second configuration for a diagnostic operating mode.

[0079] Although the present invention has been described with reference to illustrative embodiments, this description is not intended to be interpreted in a limited sense. Various modifications and combinations of the illustrative embodiments and other embodiments of the present invention will be apparent to those skilled in the art when referring to the description. Therefore, it is apparent that the attached claims include any such modifications or embodiments.

Claims

1. A pressure sensor comprising: A micro-electromechanical system MEMS device comprising a first output pad, a second output pad, and a first pressure-sensitive capacitor element, a second pressure-sensitive capacitor element, a first reference capacitive element, and a second reference capacitive element arranged in a bridge configuration; as well as An application specific integrated circuit ASIC in electrical communication with the MEMS device comprises a first input pad and a second input pad, a measurement interface comprising a first input and a second input, a first switch coupled between the first input pad and the second input pad, and a second switch coupled between the second input of the measurement interface and the second input pad of the ASIC.

2. The pressure sensor according to claim 1, wherein the first pressure sensitive capacitor element and the first reference capacitive element are coupled to a first reference pad of the MEMS device, and Wherein the second pressure sensitive capacitor element and the second reference capacitive element are coupled to a second reference pad of the MEMS device.

3. The pressure sensor according to claim 1, wherein the first pressure sensitive capacitor element and the second reference capacitive element are coupled to the first output pad of the MEMS device, and Wherein the second pressure sensitive capacitor element and the first reference capacitive element are coupled to the second output pad of the MEMS device. The pressure sensor of claim 1 , wherein the measurement interface comprises a differential amplifier. The pressure sensor according to claim 1 , wherein the measurement interface comprises an analog-to-digital converter (ADC).

6. The pressure sensor according to claim 1, wherein the measurement interface comprises: a first reference voltage source coupled to a first reference pad of the ASIC; as well as A second reference voltage source is coupled to a second reference pad of the ASIC.

7. A pressure sensor comprising: A micro-electromechanical system MEMS device comprising a first output pad, a second output pad, and a first pressure-sensitive capacitor element, a second pressure-sensitive capacitor element, a first reference capacitive element, and a second reference capacitive element arranged in a bridge configuration; as well as An application specific integrated circuit ASIC in electrical communication with the MEMS device comprises a first input pad and a second input pad, a measurement interface comprising a first input and a second input, a first switch coupled between the first input pad of the ASIC and the second input pad of the ASIC, a second switch coupled between the second input of the measurement interface and the second input pad of the ASIC, and a third switch coupled between the first input of the measurement interface and the first input pad of the ASIC.

8. The pressure sensor according to example 7, wherein the first pressure sensitive capacitor element and the first reference capacitive element are coupled to a first reference pad of the MEMS device, and Wherein the second pressure sensitive capacitor element and the second reference capacitive element are coupled to a second reference pad of the MEMS device.

9. The pressure sensor according to example 7, wherein the first pressure sensitive capacitor element and the second reference capacitive element are coupled to the first output pad of the MEMS device, and Wherein the second pressure sensitive capacitor element and the first reference capacitive element are coupled to the second output pad of the MEMS device.

10. The pressure sensor of Example 7, wherein the measurement interface comprises a differential amplifier.

11. The pressure sensor of Example 7, wherein the measurement interface comprises an analog-to-digital converter (ADC).

12. The pressure sensor of example 7, wherein the measurement interface comprises: a first reference voltage source coupled to a first reference pad of the ASIC; as well as A second reference voltage is coupled to a second reference pad of the ASIC.

13. A pressure sensor, comprising: A micro-electromechanical system MEMS device comprising a first output pad, a second output pad, and a first pressure-sensitive capacitor element, a second pressure-sensitive capacitor element, a first reference capacitive element, and a second reference capacitive element arranged in a bridge configuration; as well as An application specific integrated circuit ASIC in electrical communication with the MEMS device comprises a first input pad and a second input pad, a measurement interface comprising a first input and a second input, a first switch coupled between the second input pad of the ASIC and a bias voltage source, a second switch coupled between the second input pad of the ASIC and the second input of the measurement interface, a third switch coupled between the first input pad of the ASIC and the bias voltage source, and a fourth switch coupled between the first input pad of the ASIC and the first input of the measurement interface.

14. The pressure sensor of example 13, further comprising a fifth switch coupled between the first output pad of the ASIC and the second output pad of the ASIC.

15. The pressure sensor according to example 13, wherein the first pressure sensitive capacitor element and the first reference capacitive element are coupled to a first reference pad of the MEMS device, and Wherein the second pressure sensitive capacitor element and the second reference capacitive element are coupled to a second reference pad of the MEMS device.

16. The pressure sensor according to example 13, wherein the first pressure sensitive capacitor element and the second reference capacitive element are coupled to the first output pad of the MEMS device, and Wherein the second pressure sensitive capacitor element and the first reference capacitive element are coupled to the second output pad of the MEMS device.

17. The pressure sensor of Example 13, wherein the measurement interface comprises a differential amplifier.

18. The pressure sensor of Example 13, wherein the measurement interface comprises an analog-to-digital converter (ADC).

19. The pressure sensor of example 13, wherein the measurement interface comprises: a first reference voltage source coupled to a first reference pad of the ASIC; as well as A second reference voltage source is coupled to a second reference pad of the ASIC.

20. A pressure sensor according to Example 13, wherein the first switch, the second switch, the third switch, and the fourth switch are set in a first configuration for a normal operating mode, and wherein the first switch, the second switch, the third switch, and the fourth switch are set in a second configuration for a diagnostic operating mode.

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