Patent Publication Number: US-2023152393-A1

Title: Adaptive switching frequency selection

Description:
BACKGROUND 
     As is known, sensors are used to perform various functions in a variety of applications. Some sensors include one or more magnetic field sensing elements, such as a Hall effect element or a magnetoresistive element, to sense a magnetic field associated with proximity or motion of a target object, such as a ferromagnetic object in the form of a gear or ring magnet, or to sense a current, as examples. Sensor integrated circuits are widely used in automobile control systems and other safety-critical applications. There are a variety of specifications that set forth requirements related to permissible sensor quality levels, failure rates, and overall functional safety. 
     SUMMARY 
     According to aspects of the disclosure, a method is provided for use in a sensor, the method comprising: selecting a switching cycle for the sensor; transitioning the sensor into a state in which at least one component of the sensor is periodically turned on and off in accordance with the switching cycle; sampling an analog signal to generate a sampled signal, the analog signal being generated by at least one sensing element, the analog signal being sampled only during periods in which the at least one component of the sensor is turned on; and generating an output signal based, at least in part, on the sampled signal and outputting the output signal. 
     According to aspects of the disclosure, a sensor is provided, comprising: a sensing element; and a processing circuitry configured to: select a switching cycle for the sensor; and transition the sensor into a state in which at least one component of the sensor is periodically turned on and off in accordance with the switching cycle; sample an analog signal to generate a sampled signal, the analog signal being generated by at least one sensing element, the analog signal being sampled only during periods in which the at least one component of the sensor is turned on; and generate an output signal based, at least in part, on the sampled signal and output the output signal. 
     According to aspects of the disclosure, a non-transitory computer-readable medium that is configured to store one or more processor-executable instructions, which, when executed by a processing circuitry, cause the processing circuitry to perform the operations of: selecting a switching cycle for a sensor; and transitioning the sensor into a state in which at least one component of the sensor is periodically turned on and off in accordance with the switching cycle; sampling an analog signal to generate a sampled signal, the analog signal being generated by at least one sensing element, the analog signal being sampled only during periods in which the at least one component of the sensor is turned on;; and generating an output signal based, at least in part, on the sampled signal and outputting the output signal. 
     According to aspects of the disclosure, a sensor is provided comprising: means for selecting a switching cycle for the sensor; and means for transitioning the sensor into a state in which at least one component of the sensor is periodically turned on and off in accordance with the switching cycle; means for sampling an analog signal to generate a sampled signal, the analog signal being generated by at least one sensing element, the analog signal being sampled only during periods in which the at least one component of the sensor is turned on; means for; and means for generating an output signal based, at least in part, on the sampled signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing features may be more fully understood from the following description of the drawings in which: 
         FIG.  1    is a diagram of an example of a sensor, according to aspects of the disclosure; 
         FIG.  2    is a state diagram illustrating aspects of the operation of the sensor of  FIG.  1   , according to aspects of the disclosure; 
         FIG.  3    is a state diagram illustrating aspects of the operation of the sensor of  FIG.  1   , according to aspects of the disclosure; 
         FIG.  4    is a time-domain plot of an example of a signal that is configured to switch sampling circuitry on and off, according to aspects of the disclosure; 
         FIG.  5    is a frequency-domain plot of the signal that is configured to switch sampling circuitry on and off, according to aspects of the disclosure; 
         FIG.  6    is a plot illustrating aspects of the operation of the sensor of  FIG.  1   , according to aspects of the disclosure; 
         FIG.  7    is a plot illustrating aspects of the operation of the sensor of  FIG.  1   , according to aspects of the disclosure; 
         FIG.  8    is a plot illustrating aspects of the operation of the sensor of  FIG.  1   , according to aspects of the disclosure; 
         FIG.  9    is a flowchart of an example of a process, according to aspects of the disclosure; 
         FIG.  10    is a flowchart of an example of a process, according to aspects of the disclosure; and 
         FIG.  11    is a flowchart of an example of a process, according to aspects of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    is a diagram of an example of a system  100 , according to aspects of the disclosure. As illustrated, the system  100  includes a target  101  and a sensor  110  that is configured to detect a magnetic field  111  that is associated with the target. 
     The target  101  according to the present example includes a permanent magnet. However alternative implementations are possible in which the target  101  includes a metal object (e.g., a gear, a metal wire, etc.) and/or any other suitable type of target  101 . The magnetic field  111  may include one or more of a magnetic field that is generated by the target  101 , a magnetic field that is induced in the target  101  by a coil, and or a magnetic field that is produced by a back bias magnet and subsequently modulated by the target  101 . The sensor  110  may include an angle sensor, a speed sensor, a current sensor, and/or any other suitable type of magnetic field sensor. The sensor  110  may be configured to generate an output signal  116 , as shown. The output signal  116  may include any suitable type of output signal, such as a signal that is indicative of the position of the target  101 , a signal that is indicative of the speed of the target  101 , and/or any other suitable type of signal. 
     The sensor  110  may include a sensing module  102 , sampling circuitry  104 , and processing circuitry  106 . The sensing module  102  may include one or more magnetic field sensing elements. In some implementations, the sensing module  102  may include a bridge circuit that is formed by using magnetic field sensing elements. In some implementations, any of the magnetic field sensing elements in the sensing module  102  may include a giant magentoresistor (GMR), a tunnel magentoresistor (TMR), a Hall effect element, a receiving coil, and/or any other suitable type of magnetic field sensing element. The sampling circuitry  104  may include one or more analog-to-digital converters. The processing circuitry  106  may include any electronic circuitry that is part of the sensor  110 . For example, the processing circuitry may include one or more of digital logic, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a general-purpose processor, a CORDIC processor, and/or any other suitable type of electronic circuitry that is arranged to process digital signals. Additionally, or alternatively, in some implementations, the processing circuitry  106  may include a power controller. Additionally, or alternatively, in some implementations, the processing circuitry  106  may include a memory controller. 
     In operation, the sensing module  102  may generate at least a signal  112 . According to the present example, signal  112  is an analog signal. The sampling circuitry  104  may sample the signal  112  to produce a signal  114 . According to the present example, the signal  114  is a digital signal. The processing circuitry  106  may process the signal  114  to produce the output signal  116 . Furthermore, the processing circuitry  106  may be configured to produce a signal  301  and provide the signal  301  to the sampling circuitry  104 . The signal  301  may be a signal that is configured to turn the sampling circuitry on and off. Although in the example of  FIG.  1   , the signal  301  is configured to turn the sampling circuitry  104  on and off, alternative implementations are possible in which the signal  301  is configured to turn on and off any other component or components of the sensor  110  in addition (or instead of) the sampling circuitry  104 . Examples of components that may be turned on and off with the signal  301  include an amplifier, a frequency chopper (that is part of the sensing module  102 ), an analog filter circuit, a memory module, and/or any component of the processing circuitry  106  and/or sensor  110 . 
     The signal  301  may be used to operate the sensor  110  is in a low-power mode. In low-power mode, the signal  301  may alternate between a logic-high and a logic-low value. When the signal  301  is at logic-high, one or more components of the sensor  110  (e.g., the sampling circuitry  104 , etc.) may be turned on. When the signal  301  is at logic-low, one or more components of the sensor  110  may be turned off. In some implementations, a component may be turned off when the component is powered off. Additionally, or alternatively, in some implementations, a component may be turned off when current flow to the component is interrupted by means of an independent control system. The frequency of the signal  301  is herein referred to as “switching frequency.” As used throughout the disclosure, the term “switching frequency of a sensor” shall refer to a frequency at which at least one component of a sensor is turned on and off. Under the nomenclature of the present disclosure, the component of the sensor that is being turned on and off may be referred to as a “power-cycled component.” 
     The processing circuitry  106  is configured to execute a process for the selection of a switching frequency, which results in a favorable distribution of harmonic components of the signal  114 . The switching frequency of the sensor  110  determines (at least partially) the rate at which the signal  112  is sampled. Consequently, the switching frequency of the sensor  110  determines the positions of different harmonic components of the signal  114  in the frequency spectrum. As is discussed further below, the processing circuitry  106  is configured to select the switching frequency of the sensor  110  such that the harmonic components of the signal  114  are staggered away from out-of-band interference signals that are present in the environment of the sensor  110 . This is advantageous because it enables the signal  114  to be filtered aggressively to remove the out-of-band interference signals. 
       FIG.  1    is provided as an example only. Although in the example of  FIG.  1   , the sensor  110  is a magnetic field sensor, alternative implementations are possible in which the sensor  110  is a different type of sensor. For example, the sensor  110  may be an optical sensor, a pressure sensor, a humidity sensor, a temperature sensor, and/or any other suitable type of sensor. Although in the example of  FIG.  1   , the sensing module  102  includes one or more magnetic field sensing elements, alternative implementations are possible in which the sensing module  102  includes a light sensing element, a pressure sensing element, a temperature sensing element, a humidity sensing element, and/or any other suitable type of sensing element. Although the sensor  110  is depicted as including only one channel, it will be understood that alternative implementations are possible in which the sensor  110  includes multiple channels. Stated succinctly, the present disclosure is not limited to any specific implementation of the sensor  110 . 
       FIG.  2    is a state diagram illustrating aspects of the operation of the sensor  110 . As illustrated, during its operation, the sensor  110  may be in one of an inactive mode  201 , a calibration mode  202 , and a low-power mode  204 . 
     When the sensor  110  is the inactive mode  201 , the sensor  110  may be powered off or otherwise inactive. That is, all components of the sensor  110  may be turned off or otherwise rendered inactive. When the sensor  110  is in the calibration mode  202 , the processing circuitry  106  may execute a process for determining the switching frequency of the sensor  110  (e.g., determine the frequency of the signal  301 , etc.). For example, in some implementations, when the sensor  110  is in the calibration mode  202 , the sensor  110  may execute one of processes  1000 - 1100 , which are discussed further below with respect to  FIGS.  10  and  11   , respectively. 
     When the sensor  110  is in the low-power mode  204 , one or more components of the sensor  110  may be turned on and off periodically, as discussed above with respect to  FIG.  1   . In other words, the one or more components may be power-cycled. Furthermore, when the sensor is in the low-power mode  204 , the processing circuitry  106  (or only a portion of the processing circuitry which controls the power-cycling of the one or more components) may be continuously turned on. This is in contrast to the inactive mode  201 , in which the processing circuitry  106  (or only the portion of the processing circuitry which controls the power-cycling) may be turned off. 
     In some implementations, the sensor  110  may transition from the inactive mode  201  to the calibration mode  202  when the sensor  110  is powered on. The sensor  110  may transition from the calibration mode  202  to the low-power mode  204  after the processing circuitry  106  has determined a switching frequency for the sensor  110 . For example, the sensor  110  may transition from the calibration mode  202  to the low-power mode after the processor  120  has finished executing one of processes  1000 - 1100  (shown in  FIGS.  10 - 11   ). The sensor  110  may transition from the low-power mode  204  to the inactive mode  201  when the sensor  110  is powered off. 
     Although in the example of  FIG.  2    the sensor  110  is configured to operate in low-power mode only, alternative implementations are possible in which the sensor  110  is configured to operate in both low-power mode  204  and a normal operating mode (not shown). When the sensor  110  is running in the normal operating mode, the one or more components of the sensor  110 , which are periodically turned on and off when the sensor  110  is in low-power mode, may be turned on all the time. Stated succinctly, the present disclosure is not limited to any specific configuration of the sensor  110 , as long as the sensor  110  is configured to operate in low-power mode. 
       FIG.  3    is a state diagram illustrating the operation of the sensor  110  when the sensor  110  is in the low-power mode  204 . As illustrated, when the sensor  110  is operating in the low-power mode  204 , the sensor  110  may be in one of a state  212  and a state  214 . When the sensor  110  is in the state  212 , one or more components of the sensor  110  may be turned off. When the sensor  110  in the state  214 , the same one or more components of the sensor  110  may be turned on. The sensor  110  may transition out of the state  212  and into the state  214  on the rising edge of the signal  301 . The sensor  110  may transition out of state  214  and into  212  on the falling edge of the signal  301 . 
     According to the present example, the processing circuitry  106  samples the signal  112  only when the sensor  110  is in the state  214 . When the sensor  110  is in the state  212 , no samples of the signal  112  are obtained by the processing circuitry  106 . It will be understood that the number of samples captured by the processing circuitry  106  when the sensor  110  is in the state  212  may vary. For example, the processing circuitry  106  may capture only one sample of signal  112  every time the sensor  110  is in state  214  or, alternatively, the processing circuitry  106  may capture multiple samples of the signal  112  every time the sensor  110  is in state  214 . Irrespective of how many samples are taken during each on-period of the sensor  110  (i.e., each time when the sensor  110  is in the state  214 ), the fundamental frequency at which the signal  112  is sampled depends on the switching frequency of the sensor  110 . Under the present arrangement, it is the switching frequency of the signal  301  that (at least in part) determines the spectral distribution of the harmonic components of the signal  114 . As used throughout the disclosure, the term “distribution of harmonic components of a signal” refers to the pattern in which the frequencies of some (or all) harmonic components of the signal are spaced apart from one another (or otherwise distributed) in the frequency spectrum. 
       FIG.  4    is a plot of the signal  301 , according to aspects of the disclosure. The signal  301  may have a square waveform that is characterized by a switching cycle. The switching cycle of the signal  301  may be equal to the time period between two successive rising edges of the signal  301 . However, it will be clear to those of ordinary skill in the art, after reading this disclosure, that the switching cycle of the signal  301  may be defined as the time period between two successive falling edges of the signal  301  or in any other suitable manner. 
       FIG.  5    is a plot of the signal  114  illustrating different harmonic components of the signal  114 . The Y-axis of the plot represents the amplitude of each of the frequency harmonics that comprise the signal  114 . The X-axis of the plot represents normalized frequency, which is calculated by dividing frequency by the switching cycle of the signal  301 .  FIG.  5    illustrates that different harmonic components  501  of the signal  114  can be spaced apart from one another along the frequency spectrum (assuming the Nyquist criterion is satisfied). 
       FIG.  6    is a plot of the signal  114  when the signal  114  is sampled in accordance with a first switching frequency of the signal  301 . The Y-axis of the plot represents the amplitude of each of the frequency harmonics that comprise the signal  114 . The X-axis of the plot represents normalized frequency, which is calculated by dividing frequency by the switching cycle of the signal  301 . Further shown in the plot of  FIG.  6    are the frequencies of out-of-band interference signals  601  that are present in the environment of the sensor  110 .  FIG.  6    illustrates that when the signal  114  is sampled in accordance with the first switching frequency, the out-of-band interference signals  601  may overlap with the harmonic components  501  of the signal  114 . In other words, the frequency (e.g., fundamental tone) of each out-of-band interference signal  601  may be the same as (or within predetermined distance from) the frequency as a respective one of the harmonic components  501  of the signal  114 . 
       FIG.  7    is a plot of the signal  114  when the signal  114  is sampled in accordance with a second switching frequency of the signal  301 . The Y-axis of the plot represents the amplitude of each of the frequency harmonics that comprise the signal  114 . The X-axis of the plot represents normalized frequency, which is calculated by dividing frequency by the switching cycle of the signal  301 . Further shown in the plot of  FIG.  7    are the frequencies of out-of-band interference signals  601  that are present in the environment of the sensor  110 .  FIG.  7    illustrates that when the signal  114  is sampled in accordance with the second switching frequency, the out-of-band interference signals  601  would not overlap with the harmonic components  501  of the signal  114 . In other words, in comparison to the example of  FIG.  6   , none (or fewer) of the harmonic components  501  of the signal  114  may overlap with the frequencies (e.g., fundamental tones) of the out-of-band interference signals  601 . 
       FIG.  8    is a plot of the signal  114  when the signal  114  is sampled in accordance with a second switching frequency of the signal  301 . The Y-axis of the plot represents the amplitude of each of the frequency harmonics that comprise the signal  114 . The X-axis of the plot represents normalized frequency, which is calculated by dividing frequency by the switching cycle of the signal  301 . Further shown in  FIG.  8    is the envelope of a filter  801  that is used to filter the signal  114 .  FIG.  8    illustrates that a selection of a switching frequency (i.e., second switching frequency), which prevents the harmonic components  501  of the signal  114  from overlapping with out-of-band interference signals  601  allows the out-of-band interference signal  601  to be removed (from the signal  114 ) by the application of (aggressive) filtering. By contrast, as illustrated in the example of  FIG.  6   , if the first switching frequency is used, the application of aggressive filtering to remove the out-of-band interference signals  601  would not be feasible. 
     In some respects,  FIGS.  6 - 8    illustrate that the selection of a switching frequency for the sensor  110  may affect the effectiveness of any subsequent filtering that is applied on a signal that is sampled in accordance with the switching frequency. As used throughout the disclosure, the phrase “signal sampled in accordance with a switching frequency of a sensor” may refer to a signal that is sampled only when a power-cycled component is turned on, wherein the power-cycled component is a component that is turned on and off at the switching frequency. 
       FIG.  9    is a flowchart of an example of a process  900 , according to aspects of the disclosure. 
     At step  902 , the processing circuitry  106  selects a switching frequency for the sensor  110 . As used throughout the disclosure, the phrase “selecting a switching frequency for a sensor” may refer to at least one of: (1) selecting a frequency at which at least one component of the sensor is turned on and off, (2) selecting a duration for which the at least one component of the sensor is turned off periodically, and/or (3) selecting a duration for which the at least one component of the sensor is turned on periodically. In the implementation of the sensor  110 , which is shown in  FIG.  1   , selecting the switching frequency for the sensor  110  includes selecting a frequency (and/or a specific duty cycle) for the signal  301 . For instance, the processing circuitry  106  may select one or more of: (i) the switching frequency of the signal  301 , (ii) the duration for which the signal  301  remains at logic-high during each switching cycle of the signal  301 , and/or (iii) the duration for which the signal  301  remains at logic low during each switching cycle of the signal  301 . In some implementations, the switching frequency may be in the range of 1 Hz-1000 Hz. However, it will be understood that the present disclosure is not limited to any specific switching frequency being selected. 
     In some implementations, a switching frequency may be selected for the sensor  110  at step  902 , which prevents one or more harmonic components  501  of the signal  114  from overlapping with the frequency (e.g., fundamental tone, etc.) of at least one out-of-band interference signal  601  that is present in the environment of the sensor  110 . In some implementations, step  902  may be executed when the sensor  110  is in the calibration mode  202  (shown in  FIG.  2   ). In some implementations, step  902  may be executed in accordance with one of processes  1000  and  1100 , which are discussed further below with respect to  FIGS.  10 - 11   , respectively. 
     At step  904 , the processing circuitry  106  transitions the sensor  110  into a state in which at least one component of the sensor  110  is turned on and off based on the switching frequency (selected at step  902 ). According to the present example, the processing circuitry  106  transitions the sensor  110  into the low-power mode  204 . As noted above, the at least one component of the sensor  110  that is turned on and off may be referred to as a “power-cycled component”. 
     At step  906 , the processing circuitry  106  samples the signal  112  with the sampling circuitry  104  to produce the signal  114 . As noted above, the signal  112  is sampled only when the power-cycled component is turned on, such that no samples of the signal  112  are obtained when the power-cycled component is turned off. In other words, the signal  112  is sampled in accordance with the switching frequency of the sensor  110 , the respective frequencies of any harmonic components  501  of signal  114  are determined by the switching frequency. As noted above, the switching frequency is selected (at step  902 ) in a way that reduces (or ideally eliminates) the degree to which the harmonic components  501  of the signal  114  overlap with out-of-band interference signals  601 . 
     More specifically, in one example, at step  906 , a switching frequency may be selected which produces a distribution of harmonic components of the signal  114  that has the least amount of overlap with the out-of-band interference signals  601 . In another example, at step  906 , a switching frequency may be selected which produces a distribution of harmonic components of the signal  114  that has no overlap with the out-of-band interference signals  601 . For example, the degree of overlap between a distribution of harmonic components of a signal and out-of-band interference signals may be equal to (or otherwise based on) a count of harmonic components in the distribution that have the same frequency as the frequency (e.g., fundamental tone, etc.) of any of the interference signals. Additionally or alternatively, the degree of overlap between a distribution of harmonic components of a signal and out-of-band interference signals may be equal to (or otherwise based on) a count of harmonic components in the distribution whose frequency is within a predetermined distance from the frequency (e.g., fundamental tone, etc.) of any of the interference signals. The distribution of harmonic components of a signal may include all harmonic components of the signal or only the first N harmonic components of the signal, where N is an integer greater than 1. 
     At step  908 , the processing circuitry  106  filters the signal  114  to remove one or more out-of-band interference signals  601  from the signal  114 . In some implementations, the signal  114  may be filtered with the filter  801 , which is discussed above with respect to  FIG.  8   . The switching frequency, as noted above, may be selected to reduce (or ideally eliminate) the degree to which the harmonic components  501  of the signal  114  overlap with out-of-band interference signals  601 . Such selection is advantageous because it permits the application of aggressive filtering to remove (fully or partially) the out-of-band interference signals  601  from the signal  114 . 
     At step  910 , the processing circuitry  106  generates the output signal  116  based on the signal  114 . Those of ordinary skill in the art will readily recognize, after reading this disclosure, that there are various ways to generate an output signal (such as the output signal  116 ) based on a signal that is generated by at least one sensing element (such as the signal  114 ). In this regard, it will be understood that the present disclosure is not limited to any specific method for generating the signal  116 . 
       FIG.  10    is a flowchart of an example of a process  1000  for selecting a switching cycle for the sensor  110 , as specified by step  902  of the process  900 . 
     At step  1002 , frequencies of one or more out-of-band interference signals  601  are identified that are incident on the sensor  110 . The identified set may include one or more frequencies, wherein each frequency corresponds to a different one of the out-of-band interference signals  601 . For example, the frequencies of the out-of-band interference signals  601  may be identified by turning the sensing module  102 , sampling the signal  112  at a high enough frequency to be able to capture out-of-band interference signals , and performing a Fourier transform of the sampled signal. However, it will be understood that the present disclosure is not limited to any specific method for identifying the frequencies of the out-of-band interference signals  601 . 
     At step  1004 , a switching frequency is identified based on the frequencies of the out-of-band interference signals  601 . For example, in some implementations, a switching frequency may be selected that results in harmonic components  501  of the signal  114  which do not overlap with the out-of-band interference signals  601 . As another example, a set of candidate switching frequencies may be retrieved from a memory, and a selection may be performed from the set of the switching frequency that results in the least amount of overlap between the harmonic components  501  of the signal  114  and the out-of-band interference signals  601 . It will be understood that the present disclosure is not limited to any specific method for obtaining (or calculating) a switching frequency of the sensor  110  which eliminates (or reduces) the overlap between the frequencies of harmonic components  501  of the signal  114  and the frequencies (e.g., fundamental tones) of out-of-band interference signals  601 . 
       FIG.  11    is a flowchart of an example of a process  1100  for selecting a switching frequency for the sensor  110 , as specified by step  902  of the process  900 . At step  1102 , a first switching frequency is selected for the sensor  110 . At step  1104 , the signal  112  is sampled in accordance with the first switching frequency to produce a first copy of the signal  112 , after which the filtered copy is filtered with a filter that corresponds to the first sampling frequency (i.e. filter that is configured to pass through frequencies where harmonic components resulting from the first sampling frequency are expected to be, etc.). At step  1106 , a second switching cycle is selected for the sensor  110 . The second switching frequency may be different from the first switching cycle. At step  1108 , the signal  112  is sampled in accordance with the second switching cycle to produce a second copy of the signal  112 , after which second copy is filtered with a filter that corresponds to the second sampling frequency (i.e. filter that is configured to pass through frequencies where harmonic components resulting from the second sampling frequency are expected to be, etc.). At step  1110 , the first filtered copy of the signal  112  is compared to the second filtered copy of the signal  112  to determine if they match. If the second filtered copy and the first filtered copy match, the process  1100  proceeds to step  1112 . If the second filtered copy and the first filtered copy do not match, the process  1100  returns to step  1102  and another set of first and second switching frequency is selected. At step  1112 , one of the first switching frequency and the second switching frequency is selected as the switching frequency for the sensor  110 . In most instances, if the first filtered copy and the second filtered copy match, this is an indication that the harmonic series produced by either one of the first switching frequency and the second switching frequency do not overlap with the frequencies of out-of-band interference signals. 
     In some implementations, comparing the first copy of the signal  114  with the second copy may include subtracting the first copy of the signal from the second copy (or vice versa) to determine the difference between the first copy and the second copy. In some implementations, the first copy of the signal and the second copy of the signal may match only when the difference is less than or equal to a predetermined threshold. 
     Sampling the signal  112  in accordance with the first switching frequency may include obtaining samples of the signals  112  which are spaced in time according to a pattern that is consistent with the first switching frequency - i.e., which are taken at times when the power-cycled component would be turned on if the sensor  110  were operated in accordance with the first switching frequency. Sampling the signal  112  in accordance with the second switching frequency may include obtaining samples of the signals  112  which are spaced in time according to a pattern that is consistent with the second switching frequency - i.e., which are taken at times when the power-cycled component would be turned on if the sensor  110  were operated in accordance with the second switching frequency. In other words, steps  1104  and  1108  may be executed by a sampling the signal  112  at a high rate to obtain a set of samples, and then identifying proper subsets of the set, which correspond to the first and second switching frequencies. 
     The concepts and ideas described herein may be implemented, at least in part, via a computer program product, (e.g., in a non-transitory machine-readable storage medium such as, for example, a non-transitory computer-readable medium), for execution by, or to control the operation of, data processing apparatus (e.g., a programmable processor, a computer, or multiple computers). Each such program may be implemented in a high-level procedural or object-oriented programming language to work with the rest of the computer-based system. However, the programs may be implemented in assembly, machine language, or Hardware Description Language. The language may be a compiled or an interpreted language, and it may be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or another unit suitable for use in a computing environment. A computer program may be deployed to be executed on one computer or multiple computers at one site or distributed across multiple sites and interconnected by a communication network. A computer program may be stored on a non-transitory machine-readable medium that is readable by a general or special purpose programmable computer for configuring and operating the computer when the non-transitory machine-readable medium is read by the computer to perform the processes described herein. For example, the processes described herein may also be implemented as a non-transitory machine-readable storage medium, configured with a computer program, where upon execution, instructions in the computer program cause the computer to operate in accordance with the processes. A non-transitory machine-readable medium may include but is not limited to a hard drive, compact disc, flash memory, non-volatile memory, or volatile memory. The term unit (e.g., an addition unit, a multiplication unit, etc.), as used throughout the disclosure may refer to hardware (e.g., an electronic circuit) that is configured to perform a function (e.g., addition or multiplication, etc.), software that is executed by at least one processor, and configured to perform the function, or a combination of hardware and software. 
     According to the present disclosure, a magnetic field sensing element can include one or more magnetic field sensing elements, such as Hall effect elements, magnetoresistance elements, or magnetoresistors, and can include one or more such elements of the same or different types. As is known, there are different types of Hall effect elements, for example, a planar Hall element, a vertical Hall element, and a Circular Vertical Hall (CVH) element. As is also known, there are different types of magnetoresistance elements, for example, a semiconductor magnetoresistance element such as Indium Antimonide (InSb), a giant magnetoresistance (GMR) element, for example, a spin valve, an anisotropic magnetoresistance element (AMR), a tunneling magnetoresistance (TMR) element, and a magnetic tunnel junction (MTJ). The magnetic field sensing element may be a single element or, alternatively, may include two or more magnetic field sensing elements arranged in various configurations, e.g., a half-bridge or full (Wheatstone) bridge./. Depending on the device type and other application requirements, the magnetic field sensing element may be a device made of a type IV semiconductor material such as Silicon (Si) or Germanium (Ge), or a type III.-V. semiconductor material like Gallium-Arsenide (GaAs) or an Indium compound, e.g., Indium-Antimonide (InSb). 
     Having described preferred embodiments, which serve to illustrate various concepts, structures and techniques, which are the subject of this patent, it will now become apparent that other embodiments incorporating these concepts, structures and techniques may be used. Accordingly, it is submitted that the scope of the patent should not be limited to the described embodiments but rather should be limited only by the spirit and scope of the following claims.