Sensor data acquisition system with integrated power management

A microelectromechanical systems (MEMS) sensor with an integrated power management system that performs analog to digital conversion of weak signals is provided. The MEMs sensor can include a switching regulator that steps a supply voltage down to a voltage appropriate for an analog to digital converter (A/D converter). A timing circuit is provided to generate a clock frequency for the switching regulator and the A/D converter such that the clock frequencies are harmonically related. The frequency of the voltage ripples formed by the switching regulator will match the clock frequency provided to the switching regulator. When the sampling frequency of the A/D converter is harmonically related to the voltage ripple frequencies, the aliasing frequency will fall outside a range of frequencies associated with the analog signal.

TECHNICAL FIELD

The subject disclosure relates to microelectromechanical systems (MEMS), and more particularly, MEMS sensors with integrated power management systems.

BACKGROUND

As integrated systems reduce in size, low power consumption becomes increasingly important. For example, battery-operated devices such as mobile devices are required to have a long battery life. These devices can include power management systems that take an input voltage, and generate one or more supply voltages for different chips and components on the device. The sensors on the device are usually designed to operate over a wide supply range because the actual supply voltage used to operate the sensor may not be known to the manufacturer of the sensor. Also, different applications, designs or modes of operation may need a same sensor to operate at different voltage levels.

Linear regulator integrated with the sensors can assist with the large supply variation problem. Linear regulators provide a constant output voltage for stable operation of the sensor. Any voltage transients, due to the internal operation of the sensor or due to external disturbances, should be avoided to limit any performance degradation. Linear regulators have a low power efficiency however, particularly when there is a large difference between their input and output voltages. Switching regulators can achieve high power efficiencies while converting voltages, but switching regulators invariably introduce large voltage ripples that can be detrimental to sensor systems that are required to pick up very small signals. These signals can be one or more orders of magnitude smaller than the voltage ripples, thus the switching regulators can introduce noise that can drown out the desired signals.

SUMMARY

In a non-limiting example, an application specific integrated circuit (ASIC) can comprise a switching regulator that receives a power supply at a first voltage and outputs a power output at a second voltage different than the first voltage. The ASIC can also comprise an analog to digital converter that converts an analog electrical signal into a digital signal, wherein the analog to digital converter receives the power output via the switching regulator. The ASIC can also include a timing circuit that controls a switching frequency of the switching regulator and a sampling frequency of the analog to digital converter such that the switching frequency and sampling frequency are harmonically related.

In another non-limiting example, a method can comprise converting a voltage of a power input from a power supply that has a first voltage to a converted power output that has a second voltage, wherein the converting is based on a switching frequency. The method can also comprise generating an analog electrical signal based on input received via a transducer and sampling the analog electrical signal at a sampling frequency and generating a digital signal based on the sampling. The method can further comprise generating a timing signal that determines the switching frequency and the sampling frequency such that the switching frequency and the sampling frequency are harmonically related.

In another non-limiting example, a micro-electromechanical systems (MEMS) sensor can comprise a transducer that generates an analog electrical signal based on input energy. The MEMs sensor can also comprise a switching regulator that receives a power supply at a first voltage and outputs a power output at a second voltage different than the first voltage. The MEMs sensor can also include a timing circuit that controls a switching frequency of the switching regulator and generates a clock output for synchronous sampling, where a sampling frequency of the clock output is such that the switching frequency is an integer multiple of the sampling frequency. The MEMs sensor can also include a pair of ports to output the clock output and the analog electrical signal.

DETAILED DESCRIPTION

Overview

While a brief overview is provided, certain aspects of the subject disclosure are described or depicted herein for the purposes of illustration and not limitation. Thus, variations of the disclosed embodiments as suggested by the disclosed apparatuses, systems and methodologies are intended to be encompassed within the scope of the subject matter disclosed herein. For example, the various embodiments of the apparatuses, techniques and methods of the subject disclosure are described in the context of MEMS sensors. However, as further detailed below, various exemplary implementations can be applied to other areas of application specific integrated circuit board that perform analog to digital and digital to analog conversion of low amplitude signals, without departing from the subject matter described herein.

As used herein, the terms MEMS sensor, MEMS acoustic sensor(s), MEMS audio sensor(s), and the like are used interchangeably unless context warrants a particular distinction among such terms. For instance, the terms can refer to MEMS devices or components that can measure a proximity, determine acoustic characteristics, generate acoustic signals, or the like.

Additionally, terms such as “at the same time,” “common time,” “simultaneous,” “simultaneously,” “concurrently,” “substantially simultaneously,” “immediate,” and the like are employed interchangeably throughout, unless context warrants particular distinctions among the terms. It should be appreciated that such terms can refer to times relative to each other and may not refer to an exactly simultaneously action(s). For example, system limitations (e.g., download speed, processor speed, memory access speed, etc.) can account for delays or unsynchronized actions. In other embodiments, such terms can refer to acts or actions occurring within a period that does not exceed a defined threshold amount of time.

Aspects of systems, apparatuses or processes explained in this disclosure can constitute machine-executable components embodied within machine(s), hardware components, or hardware components in combination with machine executable components, e.g., embodied in one or more computer readable mediums (or media) associated with one or more machines. Such components, when executed by the one or more machines, e.g., computer(s), computing device(s), virtual machine(s), etc., can cause the machine(s) to perform the operations described. While the various components are illustrated as separate components, it is noted that the various components can be comprised of one or more other components. Further, it is noted that the embodiments can comprise additional components not shown for sake of brevity. Additionally, various aspects described herein may be performed by one device or two or more devices in communication with each other.

Various embodiments provide for a MEMs sensor or ASIC, with an integrated power management system, that performs analog to digital conversion of weak signals. The MEMs sensor can include a switching regulator that steps a supply voltage down to a voltage appropriate for an analog to digital converter (A/D converter). A timing circuit is provided to generate a clock frequency for the switching regulator and the A/D converter such that the clock frequencies are harmonically related. The frequency of the voltage ripples formed by the switching regulator will match the clock frequency provided to the switching regulator. When the sampling frequency of the A/D converter is harmonically related to the voltage ripple frequencies, the aliasing frequency will fall outside a range of frequencies associated with the analog signal.

In an embodiment, the aliasing frequency will be a DC offset when the switching frequency is an integer multiple of the sampling frequency. In the case of an audio signal, the signal of interest can lie substantially above the DC offset, and the DC offset can be readily eliminated using a high pass filter. Making the A/D converter voltage ripple tolerant in this way allows the use of a switching regulator on the sensor circuit board while maintaining high sensitivity. Switching regulators used in conjunction with a low-dropout regulator (LDO) can provide efficient power management even when the supply voltage is much higher than the desired output voltage. By contrast, in traditional MEMs sensors as shown inFIG. 9, the MEMs sensor906includes just an LDO908and a sensor core910. The MEMs sensor906receives power from a power management component904and a battery902, and the LDO908converts the supply voltage to a voltage appropriate for the sensor core910. If there is a large difference between the supply voltage output by the power management component904and the sensor core910input voltage, the LDO908power conversion is inefficient, leading to power loss in the form of heat.

The systems and methods of the present invention can provide a closed feedback loop to efficiently convert the supply voltage to an output voltage. A controller can be provided to receive feedback based on the power output from the switching regulator, and can modulate the switching regulator to adjust the voltage of the power output. Similarly, the controller can also monitor the supply voltage and adjust the switching regulator to keep the output voltage within a predetermined range. In an embodiment the timing circuit of the MEMs sensor can act as a multiplexer which chooses between an external clock and an internal clock, depending on the mode of operation. The timing circuit may also include a frequency multiplier such as a PLL or DLL, generating multiple output clocks.

Various other configurations or arrangements are described herein. It is noted that the various embodiments can include other components and/or functionality. It is further noted that the various embodiments can be included in larger systems, including, smart televisions, smart phones or other cellular phones, wearables (e.g., watches, headphones, etc.), tablet computers, electronic reader devices (i.e., e-readers), laptop computers, desktop computers, monitors, digital recording devices, appliances, home electronics, handheld gaming devices, remote controllers (e.g., video game controllers, television controllers, etc.), automotive devices, personal electronic equipment, medical devices, industrial systems, cameras, and various other devices or fields.

Exemplary Embodiments

Accordingly,FIG. 1depicts a non-limiting schematic diagram100of an exemplary microelectromechanical systems (MEMS) sensor system102with an integrated power management system according to various non-limiting aspects of the subject disclosure. It is to be appreciated that system100can be used in connection with implementing one or more systems or components shown and described with reference to other figures disclosed herein. Further, it is noted that the embodiments can comprise additional components not shown for sake of brevity. Additionally, various aspects described herein may be performed by one device or two or more devices in communication with each other.

MEMS sensor system102can be an application specific integrated circuit that includes a sensor core108that receives input energy in one form and converts the energy into an electrical signal by way of a transducer. Energy types can include electrical, mechanical, electromagnetic, chemical, acoustic and thermal energy. Generally in this disclosure, reference will be made to a MEMS sensor system that converts acoustic waves into electric signal, but the principles disclosed in the subject matter herein can apply to sensors with various types of transducers. Exemplary sensors include accelerometers, gyroscope and pressure sensors.

The MEMs sensor102can include a switching regulator104that receives a power input from a power supply and converts the power to a power output at a different voltage than the power input. The switching regulator104can convert a power from power supply with a first voltage to a power output with a second voltage, where the second voltage is lower than a first voltage. The switching regulator104works by taking small chunks of energy, bit by bit, from the input voltage source, and moving them to the output. This is accomplished with the help of an electrical switch and a controller which regulates the rate at which energy is transferred to the output. Switching regulator104can supply a power output with relatively large voltage differentials compared to the power input at high efficiencies.

A linear regulator, in one embodiment a low dropout regulator106, can be provided to make small adjustments to the power output from the switching regulator104. LDO106can generally perform with good efficiency when the input-output voltage is around 100 mV, but larger voltage differences leads to power wasted in the form of heat. LDO106is therefore used to make small corrections to the power output from the switching regulator104.

The sensor core108can include an analog to digital (A/D) converter110that converts an analog electric signal produced by a transducer into a digital electric signal by sampling the analog electric signal at a sampling rate. The result is a sequence of digital values that have been converted from a continuous-time and continuous-amplitude analog signal to a discrete-time, discrete-amplitude digital signal. The A/D converter110samples the analog input at a sampling rate that is determined by a timing circuit112. The sampling rate is important since when an analog signal is sampled, and converted to digital by the A/D converter110at a sampling frequency fs, the signal spectrum undergoes aliasing, with spectral elements at an integer multiple of fsshifting to DC, providing a DC offset to the digital signal, and spectral elements at a non-integer multiple of fsproviding a frequency offset.

Inherent in the switching regulator104design however, voltage ripples are formed in the power output. Since the voltage ripples formed by the switching regulator104are spectrally rich, their presence can influence the aliasing of the A/D conversion and so the timing circuit112is provided to set the frequency of both the sampling frequency of the A/D converter and the switching regulator104so that the respective frequencies are harmonically related. The voltage ripples of the switching regulator104match the switching frequency determined by the timing circuit112. The switching regulator104ideally uses a constant frequency modulation scheme or a narrow band frequency modulation scheme to avoid causing additional interference. Since spectral elements at an integer multiple of fsshift to a DC offset, when the switching frequency is harmonically related to the sampling frequency, the voltage ripples will shift to DC when aliased. The signal of interest, which is being detected by the sensor core108, will likely lie substantially above the DC, the resulting offset does not cause degradation or interference with the signal of interest, and can be readily eliminated using a high pass filter. In an embodiment, the sensor core108can include the high pass filter that removes the offset in the signal produced by the A/D converter110, and provide a data output of the digital electric signal with the DC offset removed. In another embodiment, a digital high pass filter separate from the MEMs sensor102can remove the offset from the digital signal produced by the MEMs sensor102. In the embodiment shown inFIG. 1, the switching regulator is open loop in that the timing circuit112controls the switching frequency and the sampling frequency based solely on the clock signals from the oscillator114and/or the external clock, without any feedback from the output of the switching regulator104or the power supply. In other embodiments (e.g.,FIG. 2), a closed loop system can be provided.

In an embodiment, the sampling frequency and the switching frequency frcan be integer multiples of each other. In an embodiment, the aliasing frequency faliascan be provided by the following formula falias=kfs−mfr, where k,m=±1, ±2, . . . . In an embodiment when the sensor is a microphone, the sampling frequency and the switching frequency can be chosen such that that aliasing frequency is equal to zero, which corresponds to DC.

In an embodiment, the switching regulator104can use a constant frequency modulation scheme such as digital capacitance modulation. In other embodiments, the switching regulator104can use a narrow band frequency modulation scheme such as pulse width modulation. Constant frequency modulation schemes and narrow band frequency modulation schemes are preferable as frequency modulation can cause interference with the signal of interest.

In an embodiment, timing circuit112can receive a clock signal from an external source. In other embodiments, timing circuit112can receive a clock signal from an oscillator114on the MEMs sensor system102. The timing circuit112can multiplex the timing signals from the external clock and the oscillator114and the timing circuit112or the switching regulator104can choose between the signals from the oscillator114or the external clock depending on the mode of operation. The timing circuit112may also include a frequency multiplier such as a phase-locked loop (PLL) or delay-locked loop (DLL), generating multiple output clocks. A PLL is a control system that generates an output signal whose phase is related to the phase of an input signal and a DLL is similar to the PLL but doesn't have an internal voltage controlled oscillator, which is replaced by a delay line.

Turning now toFIG. 2, illustrated is a schematic diagram200of an exemplary MEMS sensor system202with a closed loop integrated power management system according to various non-limiting aspects of the subject disclosure. It is to be appreciated that system200can be used in connection with implementing one or more systems or components shown and described with reference to other figures disclosed herein. Further, it is noted that the embodiments can comprise additional components not shown for sake of brevity. Additionally, various aspects described herein may be performed by one device or two or more devices in communication with each other.

MEMS sensor system202can include a sensor core208that receives input energy in one form and converts the energy into an electrical signal using a transducer. Energy types can include electrical, mechanical, electromagnetic, chemical, acoustic and thermal energy. The MEMs sensor202can include a switching regulator204that receives a power input from a power supply and converts the power to a power output at a different voltage than the power input. The switching regulator204can convert a power from power supply with a first voltage to a power output with a second voltage.

An LDO206, can be provided to make small adjustments to the power output from the switching regulator204. LDO206can generally perform with good efficiency when the input-output voltage is around 100 mV, but larger voltage differences leads to power wasted in the form of heat. LDO206is therefore used to make small corrections to the power output from the switching regulator204.

The sensor core208can include an analog to digital (A/D) converter210that converts an analog electric signal produced by a transducer into a digital electric signal by sampling the analog electric signal at a sampling rate. The sampling rate is determined by a timing circuit212that bases the timing signals on either a oscillator214or an external clock.

In an embodiment, the sampling frequency and the switching frequency frcan be integer multiples of each other or otherwise harmonically related. In an embodiment, the aliasing frequency faliascan be provided by the following formula falias=kfs−mfr, where k,m=±1, ±2, . . . . In an embodiment when the sensor is a microphone, the sampling frequency and the switching frequency can be chosen such that that aliasing frequency is equal to zero, which corresponds to a DC offset.

In an embodiment, a controller216can be provided to receive feedback based on the power output and manage the switching regulator to adjust the second voltage of the power output. In an embodiment, the controller216can also monitor the power supply, and adjust a conversion ratio of the switching regulator based on the power supply. The switching regulator204can convert the incoming power supply into a power output in a number of different conversion ratios based on the internal configuration of the switching regulator. If the voltage of the power supply changes, the controller can adjust the switching regulator204configuration as needed.

Environmental conditions such as temperature in addition to load current and other factors may have an effect on the switching regulator204's efficiency and voltage conversion. The controller216can monitor the output of the switching regulator204and make corrections to the switching regulator204in response to the output changing.

In some embodiments, the controller216can also monitor the frequency of voltage ripples, and adjust the switching frequency so that the voltage ripple frequency is harmonically related to the sampling frequency. This is particularly useful when there may be factors which cause the frequency of the voltage ripples to differ from the switching frequency. In this case, the switching frequency can be adjusted so that voltage ripple frequency is harmonically related (e.g., an integer multiple of) to the sampling frequency, even if the switching frequency is not directly harmonically related to the sampling frequency. In an embodiment, the controller216can send an instruction to the timing circuit212to adjust the switching frequency based on the feedback received from the output of the switching regulator204.

In various embodiments, the MEMs sensor systems202and102can employ power/energy harvesting to provide power for the sensor systems202and102. Power can be picked up from the environment, and can be supplied as an input to switching regulator204and/or104. A charge bump can also be included to increase the voltage of the power supply in cases when the power supply has a voltage lower than the voltage required by the sensor core208.

Turning now toFIG. 3, illustrated is a schematic diagram300of an exemplary MEMS sensor system302with a closed loop integrated power management system according to various non-limiting aspects of the subject disclosure.

MEMS sensor system302can include a sensor core308that receives input energy in one form and converts the energy into an electrical signal using a transducer. The MEMs sensor302can include a switching regulator, in this case a switched capacitor voltage converter304, that receives a power input from a power supply and converts the power to a power output at a different voltage than the power input. The switched capacitor voltage converter304can convert a power from power supply with a first voltage to a power output with a second voltage. An LDO306, can be provided to make small adjustments to the power output from the switched capacitor voltage converter304.

The sensor core308can include an analog to digital (A/D) converter310that converts an analog electric signal produced by a transducer into a digital electric signal by sampling the analog electric signal at a sampling rate. The sampling rate is determined by a timing circuit312that bases the timing signals on either an oscillator314or an external clock.

In an embodiment, a controller316can be provided to receive feedback based on the power output and manage the switched capacitor voltage converter304to adjust the second voltage of the power output. In an embodiment, the controller316can also monitor the power supply, and adjust a conversion ratio of the switching regulator based on the power supply. The switched capacitor voltage converter304can convert the incoming power supply into a power output in a number of different conversion ratios based on the internal configuration of the switched capacitor voltage converter304. If the voltage of the power supply changes, the controller can adjust the switched capacitor voltage converter304configuration as needed.

Environmental conditions such as temperature in addition to load current and other factors may have an effect on the switched capacitor voltage converter304's efficiency and voltage conversion. The controller316can monitor the output of the switched capacitor voltage converter304and make corrections to the switched capacitor voltage converter304in response to the output changing.

In an embodiment, the switched capacitor voltage converter304can use a constant frequency modulation scheme such as digital capacitance modulation. In other embodiments, the switched capacitor voltage converter304can use a narrow band frequency modulation scheme such as pulse width modulation. Constant frequency modulation schemes and narrow band frequency modulation schemes are preferable as frequency modulation can cause interference with the signal of interest.

Turning now toFIG. 4, illustrated is a schematic diagram400of an exemplary MEMS sensor system402with a closed loop integrated power management system according to various non-limiting aspects of the subject disclosure.

MEMS sensor system402can include a sensor core408that receives input energy in one form and converts the energy into an electrical signal using a transducer. The MEMs sensor402can include a switching regulator, in this case a inductive switching regulator404, that receives a power input from a power supply and converts the power to a power output at a different voltage than the power input. The inductive switching regulator404can convert a power from power supply with a first voltage to a power output with a second voltage. An LDO406can be provided to make small adjustments to the power output from the switched capacitor voltage converter404. The inductive switching regulator404can include an induction loop418

The sensor core408can include an analog to digital (A/D) converter410that converts an analog electric signal produced by a transducer into a digital electric signal by sampling the analog electric signal at a sampling rate. The sampling rate is determined by a timing circuit412that bases the timing signals on either an oscillator414or an external clock.

In an embodiment, a controller416can be provided to receive feedback based on the power output and manage the inductive switching regulator404to adjust the second voltage of the power output. In an embodiment, the controller416can also monitor the power supply, and adjust a conversion ratio of the switching regulator based on the power supply. The inductive switching regulator404can convert the incoming power supply into a power output in a number of different conversion ratios based on the internal configuration of the inductive switching regulator404. If the voltage of the power supply changes, the controller416can adjust the inductive switching regulator404configuration as needed.

In an embodiment, the inductive switching regulator404can use a narrow band frequency modulation scheme such as pulse width modulation. Nearly constant frequency modulation schemes or narrow band frequency modulation schemes are preferable as frequency modulation can cause interference with the signal of interest.

It is to be appreciated that in the open and closed loop systems shown inFIGS. 1-4, an LDO is present in each of the MEMs sensors. In other embodiments, the MEMs sensors and ASICs can perform the power management with just a switching regulator and no LDO.

Turning now toFIG. 5illustrated is a circuit diagram500of an exemplary switched capacitors voltage converter according to various non-limiting aspects of the subject disclosure. In particular,FIG. 5displays a switched capacitors voltage converter at different conversion ratios. At502, the conversion ratio is n=½, where the output voltage is half the supply voltage. At504, the conversion ratio is n=⅔, where the output voltage is ⅔ the supply voltage, and at506, the conversion ratio is n=⅓, where the output voltage is ⅓ the supply voltage. These different conversion ratios are reached by modulating which switches are open and closed. Specifically, in each of the images, the switches that are dotted are open, while the other switches are closed.

In an embodiment, the switched capacitors voltage converter can change the conversion ratio from a first ratio to a second ratio. This can be done in response to a changing supply voltage, or a changing desired output voltage. For instance, if the external supply is between 1.8V and 2.4V, the controller may choose a conversion ratio of ⅔ to generate an output of at least 1.2V, and if the external voltage exceeds 2.4V, it may use a ratio of ½ to achieve the 1.2V. If the external voltage is 2.6V, the ratio of ½ can be applied, and an LDO can be used to convert the 1.3V to 1.2V as needed. In some embodiments, the conversion ratio can be selected to output a voltage under the input voltage, while in other embodiments, the conversion ratio can be selected to output a voltage that is above the input voltage. In these embodiments, charge pumps, which are switched capacitors switching regulators that increase voltage, and boost regulators, which are inductive switching regulators that increase voltage, can be used.

In an embodiment, the switched capacitors voltage converter can adjust the conversion ratio in response to determining that the supply voltage has changed, and in other embodiments, a controller can monitor the supply voltage and the output voltage and send an instruction to the switched capacitors voltage converter to change the conversion ratio accordingly.

Turning now toFIG. 6, illustrated is a schematic diagram600of an exemplary MEMS sensor system602with a closed loop integrated power management system according to various non-limiting aspects of the subject disclosure. InFIG. 6, an embodiment of the subject disclosure is shown where the MEMs sensor602and sensor core608output an analog electric signal without sampling. The sensor core608can include the transducer which converts acoustic energy into an electric signal, but then outputs the resulting analog signal without A/D conversion. The timing circuit612still sends a clock signal with a switching frequency to the controller616and switching regulator604, but can output a clock with the sampling frequency. An external A/D converter (not shown) can then receive the sampling frequency from the timing circuit612and the analog electric signal from the sensor core608and perform the sampling with the correctly calibrated aliasing frequency resulting in a DC offset. The oscillator614, controller616, switching regulator604, and LDO606can perform the same or similar functions as described in earlier embodiments, (e.g.,FIG. 2).

While several example embodiments are provided, it is noted that aspects of this disclosure are not limited to the exemplary embodiments. As such, the various embodiments disclosed herein can be applied to numerous applications. In exemplary embodiments, systems and methods described herein can be applied to smart phones, hand held gaming devices, hand held electronics, notebook computers, desktop computers, and the like. Such systems can utilize aspects disclosed herein to determine characteristics associated with acoustic signals, such as for speech recognition, pressure detection, or the like.

In view of the subject matter described supra, methods that can be implemented in accordance with the subject disclosure will be better appreciated with reference to the flowcharts ofFIGS. 7-8. While for purposes of simplicity of explanation, the methods are shown and described as a series of blocks, it is to be understood and appreciated that such illustrations or corresponding descriptions are not limited by the order of the blocks, as some blocks may occur in different orders and/or concurrently with other blocks from what is depicted and described herein. Any non-sequential, or branched, flow illustrated via a flowchart should be understood to indicate that various other branches, flow paths, and orders of the blocks, can be implemented which achieve the same or a similar result. Moreover, not all illustrated blocks may be required to implement the methods described hereinafter.

Exemplary Methods

FIG. 7depicts an exemplary flowchart of non-limiting methods associated with a performing analog to digital conversion in a MEMS sensor according to various non-limiting aspects of the disclosed subject matter. As a non-limiting example, exemplary method700can facilitate performing analog to digital conversions of electric signals in MEMS sensors with integrated power management systems (e.g., system100,200, etc.).

Method700can begin at702, where the method includes converting a voltage of a power input from a power supply that has a first voltage to a converted power output that has a second voltage (e.g., by switching regulator104,204, etc), wherein the converting is based on a switching frequency. The switching frequency can be received from a timing circuit that generates a clock signal based on an external clock or an oscillator on the ASIC. The switching regulator can convert the supply voltage into an output voltage based on a selected conversion ratio. The conversion ratio can be adjusted in response to a change in a desired output voltage, or a change in the supply voltage.

The method can continue at704, where the method includes generating an analog electrical signal based on input received via a transducer (e.g., by sensor core108,208, etc.) The transducer works by receiving input energy in one form and converts the energy into an electrical signal. Energy types can include electrical, mechanical, electromagnetic, chemical, acoustic and thermal energy.

The method can continue at706, where the method includes sampling the analog electrical signal at a sampling frequency and generating a digital signal based on the sampling (e.g., by A/D converter110,210, etc.). The A/D converter converts an analog electrical signal produced by the transducer into a digital electric signal by sampling the analog electrical signal at a sampling rate. The result is a sequence of digital values that have been converted from a continuous-time and continuous-amplitude analog signal to a discrete-time, discrete-amplitude digital signal.

The method can continue at708, where the method includes generating a timing signal that determines the switching frequency and the sampling frequency such that the switching frequency and the sampling frequency are harmonically related (e.g., by timing circuit112,212, etc.). The sampling rate is important since when an analog signal is sampled, and converted to digital by the A/D converter at a sampling frequency fs, the signal spectrum undergoes aliasing, with spectral elements at an integer multiple of fsshifting to DC, providing a DC offset to the digital signal, and spectral elements at a non-integer multiple of fsproviding a frequency offset. Since the voltage ripples formed by the switching regulator are spectrally rich, their presence can influence the aliasing of the A/D conversion and so the timing circuit is provided to set the frequency of both the sampling frequency of the A/D converter and the switching regulator so that the respective frequencies are harmonically related. The voltage ripples of the switching regulator match the switching frequency determined by the timing circuit. Since spectral elements at an integer multiple of fsshift to a DC offset, when the switching frequency is harmonically related to the sampling frequency, the voltage ripples will offset to DC when aliased.

Exemplary Operating Environment

With reference toFIG. 8, a suitable environment800for implementing various aspects of the claimed subject matter includes a computer802. The computer802includes a processing unit804, a system memory806, sensor(s)835(e.g., the MEMS sensor system102,202, etc.), and a system bus808. The system bus808couples system components including, but not limited to, the system memory806to the processing unit804. The processing unit804can be any of various available processors. Dual microprocessors and other multiprocessor architectures also can be employed as the processing unit804.

The system memory806includes volatile memory810and non-volatile memory812. The basic input/output system (BIOS), containing the basic routines to transfer information between elements within the computer802, such as during start-up, is stored in non-volatile memory812. In addition, according to present innovations, sensor(s)835may include at least one audio sensor (e.g., sensor core108,208, etc.). In an embodiment, the processing unit804and or system memory can process and/or receive a digital signal received from the sensor835(e.g., from MEMs sensor102,202, etc.). In other embodiments, the processing unit804can perform sampling on an analog signal received from the sensor835(e.g., MEMs sensor602) using a clock signal received from the sensor835. By way of illustration, and not limitation, non-volatile memory812can include read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory810includes random access memory (RAM), which acts as external cache memory. According to present aspects, the volatile memory may store the write operation retry logic (not shown inFIG. 8) and the like. By way of illustration and not limitation, RAM is available in many forms such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), and enhanced SDRAM (ESDRAM).

Computer802may also include removable/non-removable, volatile/non-volatile computer storage medium.FIG. 8illustrates, for example, disk storage814. Disk storage814includes, but is not limited to, devices like a magnetic disk drive, solid state disk (SSD) floppy disk drive, tape drive, Jaz drive, Zip drive, LS-100 drive, flash memory card, or memory stick. In addition, disk storage814can include storage medium separately or in combination with other storage medium including, but not limited to, an optical disk drive such as a compact disk ROM device (CD-ROM), CD recordable drive (CD-R Drive), CD rewritable drive (CD-RW Drive) or a digital versatile disk ROM drive (DVD-ROM). To facilitate connection of the disk storage devices814to the system bus808, a removable or non-removable interface is typically used, such as interface816. It is appreciated that storage devices814can store information related to a user. Such information might be stored at or provided to a server or to an application running on a user device. In one embodiment, the user can be notified (e.g., by way of output device(s)836) of the types of information that are stored to disk storage814and/or transmitted to the server or application. The user can be provided the opportunity to control having such information collected and/or shared with the server or application (e.g., by way of input from input device(s)828).

It is to be appreciated thatFIG. 8describes software that acts as an intermediary between users and the basic computer resources described in the suitable operating environment800. Such software includes an operating system818. Operating system818, which can be stored on disk storage814, acts to control and allocate resources of the computer system802. Applications820take advantage of the management of resources by operating system818through program modules824, and program data826, such as the boot/shutdown transaction table and the like, stored either in system memory806or on disk storage814. It is to be appreciated that the claimed subject matter can be implemented with various operating systems or combinations of operating systems.

A user enters commands or information into the computer802through input device(s)828. Input devices828include, but are not limited to, a pointing device such as a mouse, trackball, stylus, touch pad, keyboard, microphone, joystick, game pad, satellite dish, scanner, TV tuner card, digital camera, digital video camera, web camera, and the like. These and other input devices connect to the processing unit804through the system bus808via interface port(s)830. Interface port(s)830include, for example, a serial port, a parallel port, a game port, and a universal serial bus (USB). Output device(s)836use some of the same type of ports as input device(s)828. Thus, for example, a USB port may be used to provide input to computer802and to output information from computer802to an output device836. Output adapter834is provided to illustrate that there are some output devices836like monitors, speakers, and printers, among other output devices836, which require special adapters. The output adapters834include, by way of illustration and not limitation, video and sound cards that provide a means of connection between the output device836and the system bus808. It should be noted that other devices and/or systems of devices provide both input and output capabilities such as remote computer(s)838.

Computer802can operate in a networked environment using logical connections to one or more remote computers, such as remote computer(s)838. The remote computer(s)838can be a personal computer, a server, a router, a network PC, a workstation, a microprocessor based appliance, a peer device, a smart phone, a tablet, or other network node, and typically includes many of the elements described relative to computer802. For purposes of brevity, only a memory storage device840is illustrated with remote computer(s)838. Remote computer(s)838is logically connected to computer802through a network interface842and then connected via communication connection(s)844. Network interface842encompasses wire and/or wireless communication networks such as local-area networks (LAN) and wide-area networks (WAN) and cellular networks. LAN technologies include Fiber Distributed Data Interface (FDDI), Copper Distributed Data Interface (CDDI), Ethernet, Token Ring and the like. WAN technologies include, but are not limited to, point-to-point links, circuit switching networks like Integrated Services Digital Networks (ISDN) and variations thereon, packet switching networks, and Digital Subscriber Lines (DSL).

Communication connection(s)844refers to the hardware/software employed to connect the network interface842to the bus808. While communication connection844is shown for illustrative clarity inside computer802, it can also be external to computer802. The hardware/software necessary for connection to the network interface842includes, for exemplary purposes only, internal and external technologies such as, modems including regular telephone grade modems, cable modems and DSL modems, ISDN adapters, and wired and wireless Ethernet cards, hubs, and routers.

Moreover, it is to be appreciated that various components described herein can include electrical circuit(s) that can include components and circuitry elements of suitable value in order to implement the embodiments of the subject innovation(s). Furthermore, it can be appreciated that many of the various components can be implemented on one or more integrated circuit (IC) chips. For example, in one embodiment, a set of components can be implemented in a single IC chip. In other embodiments, one or more of respective components are fabricated or implemented on separate IC chips.

What has been described above includes examples of the embodiments of the present disclosure. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the claimed subject matter, but it is to be appreciated that many further combinations and permutations of the subject innovation are possible. Accordingly, the claimed subject matter is intended to embrace all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims. Moreover, the above description of illustrated embodiments of the subject disclosure, including what is described in the Abstract, is not intended to be exhaustive or to limit the disclosed embodiments to the precise forms disclosed. While specific embodiments and examples are described herein for illustrative purposes, various modifications are possible that are considered within the scope of such embodiments and examples, as those skilled in the relevant art can recognize. Moreover, use of the term “an embodiment” or “one embodiment” throughout is not intended to mean the same embodiment unless specifically described as such.