Data integration circuit and system for low quality factor sensors

Abstract

The techniques described herein relate to data integration circuits and systems for low quality factor sensors. An example circuit for interrogating a sensor to output a decaying signal is disclosed. The example circuit includes a resonant circuit configured to receive a wirelessly transmitted sensor signal as feedback from the sensor, and oscillate the sensor signal at an oscillation frequency. The example circuit further includes a phase shift circuit configured to provide a phase shift to the sensor signal to sustain the oscillation of the sensor signal in a sensing frequency band associated with the sensor.

Description

Attorney Docket No. M0925.71083WO00DATA INTEGRATION CIRCUIT AND SYSTEM FOR LOW QUALITY FACTOR SENSORSRELATED APPLICATION

[0001] This application claims priority under 35 U.S.C. § 119 to U.S. Provisional Application No. 63 / 754,387, titled “DATA INTEGRATION CIRCUIT AND SYSTEM FOR LOW QUALITY FACTOR SENSORS,” filed on February 5, 2025, which is herein incorporated by reference in its entirety.FIELD

[0002] The techniques described herein relate generally to circuits and, more particularly, to data integration circuits and systems for low quality factor sensors.BACKGROUND

[0003] Low quality factor (Q) sensors are utilized in various applications such as those where a broader detection range or faster response time is needed. A sensor with a low Q factor indicates that the sensor has a wider bandwidth and less energy stored within the sensor, which allows the sensor to react more quickly to changes in the measured parameter. Some such low Q factor sensors are deployed in applications where rapid response time is prioritized over high sensitivity where quick detection of changes may be more important than precise measurement details.SUMMARY

[0004] In accordance with the disclosed subject matter, data integration circuits and systems for low quality factor sensors are provided.

[0005] Some embodiments relate to a circuit for interrogating a sensor to output a decaying signal, the circuit comprising a resonant circuit configured to receive a wirelessly transmitted sensor signal as feedback from the sensor, and oscillate the sensor signal at an oscillation frequency, and a phase shift circuit configured to provide a phase shift to the sensor signal to sustain the oscillation of the sensor signal in a sensing frequency band associated with the sensor.

[0006] Some embodiments relate to a system for interrogating a sensor, the system comprising a sensor configured to output a sensor signal in a sensing frequency band and in response to receiving an excitation signal, and an oscillator circuit. The oscillator circuit 1#14827600v2Attorney Docket No. M0925.71083WO00comprises a resonant circuit configured to receive and oscillate the sensor signal at an oscillation frequency, a feedback network coupled to the resonant circuit and configured to input a feedback signal to the resonant circuit, and a phase shift circuit coupled to the feedback network, the phase shift circuit configured to provide a phase shift to the sensor signal to generate the feedback signal, and provide the feedback signal to the resonant circuit through the feedback network to sustain the oscillation of the sensor signal in the sensing frequency band.

[0007] Some embodiments relate to a method for interrogating a wireless sensor associated with a low quality factor. The method comprising inductively providing an excitation signal to the wireless sensor, receiving, in response to the excitation signal, a sensor signal from the wireless sensor, and oscillating, using an oscillator circuit, the sensor signal at a sustained oscillation frequency. The oscillator circuit comprises a resonant circuit configured to receive and oscillate the sensor signal at the oscillation frequency, a feedback network coupled to the resonant circuit and configured to input a feedback signal to the resonant circuit, and a phase shift circuit coupled to the feedback network and configured to provide a phase shift to the sensor signal to output the feedback signal to sustain the oscillation of the sensor signal in a sensing frequency band of the wireless sensor.

[0008] The foregoing summary is not intended to be limiting. Moreover, various aspects of the present disclosure may be implemented alone or in combination with other aspects.BRIEF DESCRIPTION OF FIGURES

[0009] Various aspects and embodiments will be described with reference to the following figures. In the figures, each identical or nearly identical component that is illustrated in various figures is represented by a like reference character. For purposes of clarity, not every component may be labeled in every drawing. The drawings are not necessarily drawn to scale, with emphasis instead being placed on illustrating various aspects of the techniques and devices described herein.

[0010] FIG. 1 is an illustration of an example system including a sensing platform and a sensor configured for detecting a condition associated with a composite part in a vehicle, in accordance with some embodiments of the technology described herein.

[0011] FIG. 2 shows example measurement graphs associated with a first sensor having a high quality factor and a second sensor having a low quality factor, respectively, in accordance with some embodiments of the technology described herein.2#14827600v2Attorney Docket No. M0925.71083WO00

[0012] FIG. 3 is a block diagram of an example implementation of the sensing platform of FIG. 1 including an example wireless sensing circuit, in accordance with some embodiments of the technology described herein.

[0013] FIG. 4 is a block diagram of an example implementation of the wireless sensing circuit of FIG. 3, in accordance with some embodiments of the technology described herein.

[0014] FIG. 5 is a block diagram of an example implementation of a portion of the wireless sensing circuit of FIGS. 3 and / or 4, in accordance with some embodiments of the technology described herein.

[0015] FIG. 6 is a schematic illustration of an example implementation of the wireless sensing circuit of FIGS. 3, 4, and / or 5, in accordance with some embodiments of the technology described herein.

[0016] FIG. 7 is a block diagram of an example implementation of a data integration system that may correspond to a portion of the sensing platform of FIGS. 1 and / or 3, in accordance with some embodiments of the technology described herein.DETAILED DESCRIPTION

[0017] The present application generally provides techniques for interrogating sensors that output extremely low decaying signals, such as due to the sensors being low quality factor (Q) passive wireless resonant sensors. Some such resonant sensors may have a low Q factor of, for example, 1 or less, and generate output signals in a frequency range from 100 hertz (Hz) to 100 megahertz (MHz). The present application provides techniques for sustaining the oscillation of the output signals at a constant amplitude and for a time duration such that the output signal may be acquired and processed. The output signals may be processed to effectuate a data analysis operation, such as detecting a condition associated with a part of a vehicle, industrial equipment, or in another system (e.g., detecting a structural condition of a composite part of an aircraft, boat, or turbine).

[0018] The Q factor of a resonant system is a dimensionless parameter that typically represents the ratio of the energy stored in the resonant system to the energy lost per cycle of oscillation. A higher Q factor may indicate that a resonant system stores more energy relative to the energy lost per cycle, resulting in a sharper resonant peak in the system’s response and improved selectivity in a circuit. For example, a higher Q may imply lower damping and slower signal decay. Conversely, a lower Q factor may indicate that a resonant system stores less energy relative to the energy lost per cycle, resulting in a more rounded resonant peak in3#14827600v2Attorney Docket No. M0925.71083WO00the system’s response. For example, a lower Q may imply higher damping and quicker signal decay.

[0019] A sensor with a low Q factor indicates that the sensor has a wider bandwidth and less energy stored within the sensor (compared to a sensor with a high Q factor), which allows the sensor to react more quickly to changes in the measured parameter. Accordingly, low Q factor sensors may be utilized in applications such as those where a broader detection range or faster response time is needed.

[0020] An example application that may involve low Q factor sensors is detecting changes in a condition of a composite part of a vehicle or industrial equipment (e.g., a turbine). For example, a sensing element may be embedded inside a composite material, such as being embedded in a wing of an aircraft or a blade of a turbine. The detected condition may be internal damage of the composite part such as a crack or delamination, which are the most typical failures in composite parts. For example, the detected condition may be a crack in a turbine blade or delamination in an aircraft wing (and / or portion thereof such as a flap).

[0021] In condition-based monitoring applications (and others), rapid response time is prioritized over high sensitivity where quick detection of changes (e.g., an initial detection of a delamination or crack) may be more important than precise measurement details (e.g., a size of the delamination or crack). Low Q factor sensors may be used to achieve the rapid response time. However, it has been recognized, within the context of the present disclosure, that there exist several technological challenges with deploying low Q factor sensors for data integration circuits and systems.

[0022] First, it has been recognized, within the context of the present disclosure, that if the Q factor of the sensor is low (e.g., a Q factor of 2 or less, 1.5 or less, 1 or less, etc.), the signal output from the sensor decays too rapidly, causing the signal duration, amplitude, and signal-to-noise ratio (SNR) to be smaller. Smaller signal duration, amplitude, and SNR increases the difficulty in acquiring the signal to estimate frequency with high accuracy. Thus, it has been recognized, within the context of the present disclosure, that a higher sampling rate needs to be employed to appropriately estimate the signal frequency. However, it has been recognized, within the context of the present disclosure, that damping in the medium (e.g., the composite material) during wireless acquisition contributes to the damping in addition to the low Q factor and requires the use of specialized circuitry to sense small signal amplitudes.

[0023] Second, it has been recognized, within the context of the present disclosure, that even if specialized circuitry were used, their power consumption is typically too much for power-constrained systems. For example, a data integration circuit and system may require use of a 4#14827600v2Attorney Docket No. M0925.71083WO00passive wireless resonant sensor intended to operate at a fundamental frequency fo = 1 MHz. In such an example, the selection of circuitry (e.g., analog-to-digital converters (ADCs)) capable of sampling at a maximum frequency of Fs = 1 MHz, while still ensuring sufficient quantization resolution, is limited. Further, complicated frequency estimation techniques may be needed to accurately determine the acquired sensor frequency, which requires additional computational ability and thereby additional power consumption.

[0024] One aspect of the disclosure relates to the development of example data integration circuits and systems for low Q factor sensors that, in accordance with certain embodiments, overcome the aforementioned technological challenges. An example data integration circuit and system disclosed herein includes an operational amplifier (op-amp) based oscillator for interrogating sensors that output extremely low decaying signals, such as due to having a low Q factor of, for example, 1 or less. The circuit and system can oscillate the signal output from the sensor for a desired time duration with the signal amplitude remaining constant to enable the acquisition and / or processing of the signal output with high certainty of frequency estimation.

[0025] In some embodiments, the circuit and system include an adjustable gain stage to sustain the oscillation. In some embodiments, the circuit and system include a phase compensation stage to a resonant circuit, and the phase compensation stage can be configured to shift the phase of the signal returned from the sensor by 90 degrees (90°) to bring the output signal in phase at the target sensing frequency band. In some such embodiments, the phase compensation stage includes and / or implements a phase shift circuit. In some such embodiments, the phase shift is a 90 degree phase shift and the phase shift circuit can be configured to provide the 90 degree phase shift to the sensor signal to bring the sensor signal in-phase with the resonant circuit to sustain the oscillation of the sensor signal at the oscillation frequency.

[0026] In some embodiments, the circuit and system include an automatic gain control circuit to generate an output voltage to maintain the output level constant. In some embodiments, the circuit and system include a mixer and antialiasing filter stage to down-convert the output signal to low frequency and enhance SNR enabling sampling at any low frequency starting from, for example, 50 kilohertz (kHz), for output frequency estimation using a short duration of the signal captured.

[0027] Beneficially, the circuit and system, in accordance with certain embodiments, overcome the technological challenge of acquiring and / or processing a signal output from a low Q factor sensor that decays too rapidly by oscillating the signal output for a desired time 5#14827600v2Attorney Docket No. M0925.71083WO00duration with the signal amplitude remaining constant. Beneficially, the circuit and system, in accordance with certain embodiments, overcome the technological challenge of circuitry selection being limited due to power constraints by configuring the circuit and system in an arrangement that utilizes low power consuming circuitry, such as op-amps.

[0028] The techniques described herein may be implemented in any of numerous ways, as the techniques are not limited to any particular manner of implementation. Examples of details of implementation are provided herein solely for illustrative purposes. Furthermore, the techniques disclosed herein may be used individually or in any suitable combination, as aspects of the technology described herein are not limited to the use of any particular technique or combination of techniques.

[0029] Turning to the figures, FIG. 1 is an illustration of an example system 100 that includes a sensing platform 102 and at least one sensor 104. The sensing platform 102 and the at least one sensor 104 can be configured for detecting a condition associated with a composite part 106 in a vehicle 108. The sensing platform 102 and the at least one sensor 104 can be a data integration system that integrates and / or incorporates data from the at least one sensor 104 into determination logic implemented by the sensing platform 102 for detecting the condition. For example, the sensor 104 may wirelessly output a sensor signal to the sensing platform 102, and the sensing platform 102 may determine that the sensor signal is indicative of a change in a condition of the composite part 106.

[0030] The sensors 104 of this example are wireless sensors. The wireless sensors may be passive wireless resonant sensors. The passive wireless resonant sensors may be frequency variation sensors. Alternatively, one or more of the sensors 104 may be active wireless resonant sensors and / or a different type of passive wireless resonant sensor.

[0031] The sensors 104 of this example respectively have a low Q factor of 1 or less.Alternatively, one or more of the sensors 104 may have a low Q factor of 2 or less, 1.5 or less, etc.

[0032] In some embodiments, the sensors 104 may comprise (or may be comprised solely of) structural materials. For example, all or a portion of the sensors 104 may be respectively constructed from a structural epoxy and carbon nanotubes (CNTs). In such an example, the sensors 104 may respectively be a CNT-polymer nanocomposite based parallel plate capacitor.

[0033] In some embodiments, the sensors 104 comprise electrically conductive sensor elements (e.g., the electronic pathway of the inductor, the electrodes of the capacitor, etc.). The electrically conductive sensor elements comprise, in some embodiments,6#14827600v2Attorney Docket No. M0925.71083WO00nanocomposites (e.g., formed by arranging electronically conductive elongated nanostructures within a conductive or non-conductive matrix material). Examples of the use of electronically conductive nanostructures embedded in matrices (e.g., conductive or non-conductive matrices) to form circuit components are described, for example, in the following patent applications and publications, which are incorporated herein by reference in their entireties for all purposes: International Patent Application Publication No. WO 2019 / 118706, published on June 20, 2019, filed on December 13, 2018, as International Application No. PCT / US2018 / 065422, and entitled “Structural Electronics Wireless Sensor Nodes”; U.S. Patent Application No. 16 / 900,159, filed on June 12, 2020, published as U.S. Patent Publication No. 2020 / 0309674 on October 1, 2020, and entitled “Structural Electronics Wireless Sensor Nodes”; International Patent Application Publication No. WO 2023 / 114257, published on June 22, 2023, filed on December 14, 2022, as International Application No. PCT / US2022 / 052780, and entitled “Sensors and Related Systems and Methods”;International Patent Application Publication No. WO 2024 / 263902, published on December 26, 2024, filed on June 21, 2024, as International Application No. PCT / US2024 / 035000, and entitled “Crack Sensors and Related Systems and Methods”; and International Patent Application Publication No. WO 2024 / 263875, published on December 26, 2024, filed on June 21, 2024, as International Application No. PCT / US2024 / 034959, and entitled “Corrosion / Erosion Sensors and Related Systems and Methods”.

[0034] In example operation, the sensors 104 may operate such that a condition change (e.g., a delamination crack) in the composite part 106 can cause a change in capacitance of the sensors 104 leading to a change in its resonant frequency. The sensing platform 102 can interrogate the sensors 104 with an excitation signal and the sensors 104 can output a sensor signal in accordance with the change in its resonant frequency. The sensing platform 102 can wirelessly receive the sensor signal, detect the change in the resonant frequency, and determine that the detected change represents a change in the condition of the composite part 106.

[0035] As shown, the composite part 106 is a wing of an aircraft. The aircraft wing may be constructed from at least one composite material. Examples of composite materials include carbon fiber, fiberglass, and aramid fibers. For example, the composite part 106 can be constructed from fiberglass. Alternatively, the composite part 106 may be a different type of composite part, such as a vertical stabilizer, or a composite part of a different assembly, such as a blade of a turbine (e.g., a turbine generator).7#14827600v2Attorney Docket No. M0925.71083WO00

[0036] As shown, the vehicle 108 is an aerial vehicle. Examples of aerial vehicles include manned vehicles (e.g., a commercial airliner, a military jet) and unmanned aerial vehicles (e.g., drones). As shown, the vehicle 108 is a manned commercial airliner. Alternatively, the vehicle 108 may be a different type of aerial vehicle.

[0037] Alternatively, the vehicle 108 may be a different type of vehicle such as a land vehicle, a marine vehicle, or a space vehicle. Examples of land vehicles include automobiles, buses, trucks, and vans. Examples of marine vehicles include boats, ships, and vessels.Examples of space vehicles include satellites and space orbiters.

[0038] In the illustrated example, the system 100 is implemented at least in part using laminated composites 110. As shown, the sensing platform 102 is disposed on a surface (e.g., a top surface) of one of the laminated composites 110. As shown, the sensors 104 are installed, embedded, and / or disposed in the interlaminar region 114 of the laminated composites 110. In some embodiments, one(s) of the sensors 104 and the sensing platform may be separated by a distance of 0.25 to 0.50 inches.

[0039] Also shown in FIG. 1 is a computed tomography image 112 of the interlaminar region 114 of the laminated composites 110 and its expanded view. The image 112 depicts a condition of the composite part 106, which in this example is a delamination crack 116 in the laminated composites 110. Also shown in FIG. 1 is an arrangement of laminae 118 in laminated composites.

[0040] In example operation, the sensing platform 102 wirelessly interrogates the sensors 104 to cause the sensors 104 to output a sensor signal. The sensor signal can be representative of structural health information of the laminated composites 110 and / or, more generally, the composite part 106. The sensing platform 102 can wirelessly receive the sensor signal and determine, based on the sensor signal, that a condition of the composite part 106 has changed. For example, the sensing platform 102 can detect an initial presence of the delamination crack 116 based on a detected change in the sensor signal output from one(s) of the sensors 104. Beneficially, the sensing platform 102 can acquire and / or process the sensor signal, which is a rapidly decaying signal output from the sensor 104, by sustaining an oscillation of the signal output at a constant amplitude and for a sufficient time period to enable the acquisition and / or processing of the sensor signal.

[0041] FIG. 2 shows measurement graphs 202, 204 associated with a first sensor having a high quality factor and measurement graphs 206, 208 associated with a second sensor having a low quality factor. The measurement graphs 202, 204, 206, 208 are shown to convey the8#14827600v2Attorney Docket No. M0925.71083WO00technological challenges that have been recognized, in the context of the present disclosure, with acquiring data from low Q factor sensors.

[0042] As shown, the measurement graphs 202, 204 include a first measurement graph 202 and a second measurement graph 204 associated with a first sensor having a Q factor of 12.57. The measurement graphs 206, 208 include a third measurement graph 206 and a fourth measurement graph 208 associated with a second sensor having a low Q factor of 1.26. For example, the second sensor can be one of the sensors 104 of FIG. 1.

[0043] The first and third measurement graphs 202, 206 include waveforms representing the voltage (in volts (V)) of sensor signals that are output from the first and second sensors with respect to time of decay (in seconds (sec)). As shown in the first measurement graph 202, the sensor signal output from the high Q factor sensor oscillates with sufficient amplitude and for a sufficient time period that the sensor signal can be detected and processed. However, as shown in the third measurement graph 206 and as has been recognized in the context of the present disclosure, the sensor signal output from the low Q factor sensor does not oscillate with sufficient amplitude and for an insufficient time period such that the sensor signal is unable to be detected and processed without power hungry specialized circuitry.

[0044] The second and fourth measurement graphs 204, 208 include waveforms representing the amplitude (in decibels (dB)) of sensor signals that are output from the first and second sensors with respect to frequency (in megahertz (MHz)). The second and fourth measurement graphs 204, 208 represent the frequency response extracted from the voltage signal of the first and second sensors that is shown in the first and third measurement graphs 202, 206.

[0045] As shown in the second measurement graph 204, the frequency response extracted from the first sensor signal (e.g., the high Q factor sensor signal) has a relatively large peak with low uncertainty at the fundamental frequency of 1 MHz and thus represents a high-quality response. As shown in the fourth measurement graph 208, the frequency response extracted from the second sensor signal (e.g., the low Q factor sensor signal) has a shallower peak than the second measurement graph 204 with high uncertainty at the fundamental frequency of 1 MHz and thus represents a low-quality response. Beneficially, as discussed further below, certain of the data integration circuits and systems described herein improve the frequency response of sensor signals that are output from low Q factor sensors by oscillating the sensor signals at a constant amplitude and for a sufficient time period such that the certainty of the detected signal is increased, which thereby achieve performance of low Q factor sensors to more closely align with the performance of high Q factor sensors.9#14827600v2Attorney Docket No. M0925.71083WO00

[0046] FIG. 3 is a block diagram of an example implementation of a sensing platform 300 configured to wirelessly interrogate a sensor 302 and receive a sensor signal from the sensor 302. In some embodiments, the sensing platform 300 implements and / or corresponds to the sensing platform 102 of FIG. 1. In some embodiments, the sensor 302 implements and / or corresponds to at least one of the sensors 104 of FIG. 1.

[0047] The sensing platform 300 of this example includes a wireless sensing circuit 304, a first controller 306, a second controller 308, a sensor interface 310, and storage 312. The wireless sensing circuit 304 can be a reader (e.g., a sensor reader) configured to receive and / or process a sensor signal that is output from a sensor, such as the sensor 302. Although only one sensor 302 is shown, the sensing platform 300 can be configured to interrogate multiple sensors 302 and receive data from the multiple sensors 302.

[0048] The sensor 302 of this example is a resonant sensor. The resonant sensor may be a passive wireless resonant sensor. The passive wireless resonant sensor may be an LC resonator. For example, the sensor 302 can be an LC resonator configured to operate at a fundamental frequency fo = 1 MHz. Alternatively, the sensor 302 can be configured to operate at a different fundamental frequency. The sensor 302 may be a low Q factor sensor. For example, the sensor 302 may have a Q factor of 2 or less, 1.5 or less, 1 or less, etc.Alternatively, the sensor may have a different Q factor.

[0049] As shown, the sensor 302 is inductively coupled (e.g., wirelessly) to the sensing platform 300 through the wireless sensing circuit 304. For example, the wireless sensing circuit 304 can interrogate the sensor 302 to cause the sensor 302 to output a sensor signal to the wireless sensing circuit 304. In such an example, the wireless sensing circuit 304 can interrogate the sensor 302 by emitting and / or outputting an excitation signal to the sensor 302.

[0050] In some embodiments, the wireless sensing circuit 304 includes and / or is implemented at least in part by a sampler and signal processing unit. For example, the wireless sensing circuit 304 can implement a data integration circuit, or portion thereof. In such an example, the sensing platform 300 can be a data integration system that includes the wireless sensing circuit 304 as a data integration circuit.

[0051] The sensing platform 300 includes the first controller 306 to control interrogation of the sensor 302. As shown, the first controller 306 is coupled to the wireless sensing circuit 304. For example, the wireless sensing circuit 304 may be coupled to the first controller 306 through any type of computing and / or electrical bus, such as an Inter- Integrated Circuit (I2C) bus or a Serial Peripheral Interface (SPI) bus.10#14827600v2Attorney Docket No. M0925.71083WO00

[0052] As shown, the first controller 306 is a microcontroller. Alternatively, the first controller 306 may be implemented by one or more analog circuits (e.g., capacitors, comparators, diodes, inductors, operational amplifiers, resistors, transistors, etc.), one or more digital circuits (e.g., logic gates, etc.), one or more hardware-implemented state machines, one or more application specific integrated circuits (ASICs), etc., and / or any combination(s) thereof.

[0053] The first controller 306 is coupled to a second controller 308. As shown, the second controller 308 is a handshake and communication protocol controller, which can be configured to receive data representing sensor signals from the first controller 306 and / or the sensor interface 310. Alternatively, the second controller 308 may be implemented by one or more analog circuits, one or more digital circuits, one or more hardware-implemented state machines, one or more ASICs, etc., and / or any combination(s) thereof.

[0054] The second controller 308 can be configured to receive data representing the sensor signal output from the sensor 302. The second controller 308 can be configured to receive data from other sensors via the sensor interface 310. For example, the sensor interface 310 can be configured to receive data from other sensors such as delamination sensors, corrosion sensors, erosion sensors, etc. The second controller 308 can be configured to provide the data from the other sensors (received via the sensor interface 310) to the first controller 306. For example, the first controller 306 and / or the second controller 308 can be configured to map the sensor signal from the sensor 302 and / or the other sensor(s) to a measured parameter including at least one of corrosion, erosion, or fatigue crack length in an object, such as the composite part 106 of FIG. 1.

[0055] The second controller 308 can be configured to store received data (e.g., sensor data) in the storage 312. In some embodiments, the storage 312 can be implemented by any technology for storing data. For example, the storage 312 can be implemented by a volatile memory (e.g., a Synchronous Dynamic Random Access Memory (SDRAM), a Dynamic Random Access Memory (DRAM), a RAMBUS Dynamic Random Access Memory (RDRAM), etc.) and / or a non-volatile memory (e.g., flash memory). The storage 312 may additionally or alternatively be implemented by one or more double data rate (DDR) memories, such as DDR, DDR2, DDR3, DDR4, DDR5, mobile DDR (mDDR), etc.

[0056] While an example implementation of the sensing platform 300 is depicted in FIG. 3, other implementations are contemplated. For example, one or more blocks, components, functions, etc., of the sensing platform 300 may be combined or divided in any other way. The sensing platform 300 of the illustrated example may be implemented by hardware alone,11#14827600v2Attorney Docket No. M0925.71083WO00or by a combination of hardware, software, and / or firmware. For example, the sensing platform 300 may be implemented by one or more analog circuits (e.g., capacitors, comparators, diodes, inductors, operational amplifiers, resistors, transistors, etc.), one or more digital circuits (e.g., logic gates, etc.), one or more hardware-implemented state machines, one or more programmable processors, one or more ASICs, etc., and / or any combination(s) thereof. The sensing platform 300 of the illustrated example can be implemented by one or more integrated circuits (ICs) on the same die or one or more ICs on two or more different dies, such as one or more ICs on a first die and one or more ICs on a second die.

[0057] In some embodiments, the sensing platform 300, or portion(s) thereof, may be implemented by a system on a chip or system-on-chip (SoC). An SoC is an integrated circuit design that combines elements of an electronic device onto a single chip instead of using separate components. For example, an SoC may include and / or incorporate within itself one or more programmable processors, input and output (VO) ports, memory, analog input blocks, analog output blocks, etc., and / or any combination(s) thereof. For example, the sensing platform 300 may be implemented by a single platform and integrates an entire electronic device (or portion(s) thereof), such as a receiver device, onto the platform.

[0058] FIG. 4 is a block diagram of an example implementation of the wireless sensing circuit 304 of FIG. 3. The wireless sensing circuit 304 of this example includes an inductor 402, a clock 404, a signal generator 406, a modulator 408, and a sampler 410. The sampler 410 of this example is coupled to and / or outputs signals to a signal processing unit 412.Alternatively, the wireless sensing circuit 304 may include the signal processing unit 412.

[0059] The modulator 408 can be configured to receive a clock signal from the clock 404. The clock 404 can be a circuit (e.g., a clock circuit) configured to generate and / or output the clock signal. The clock signal may be a square wave with a 50% duty cycle. The clock signal may have an amplitude selected from a voltage range of 4.5 to 5.5 V and a frequency selected from a range of 45 to 55 kilohertz (kHz). For example, the clock signal can be a 5 V amplitude, 50 kHz square wave at 50% duty cycle.

[0060] The modulator 408 can be configured to receive a drive signal from the signal generator 406. The signal generator 406 can be a sinusoidal drive signal generator configured to generate and / or output a sinusoidal signal. The signal generator 406 can be configured to generate and / or output the sinusoidal signal at a frequency of 1 MHz. Alternatively, the signal generator 406 may be configured to output a different type of signal and / or at a different frequency.12#14827600v2Attorney Docket No. M0925.71083WO00

[0061] In example operation, the wireless sensing circuit 304 wirelessly interrogates the sensor 302 via the inductor 402 using an excitation signal output from the modulator 408. For example, the modulator 408 can modulate the clock signal output from the clock 404 with the drive signal output from the signal generator 406 to generate and / or output an excitation signal. In such an example, the modulator 408 can output the excitation signal to the inductor 402, which inductively couples the excitation signal to the sensor 302.

[0062] In example operation, in response to the excitation signal, the sensor 302 outputs a sensor signal that is inductively coupled back to the wireless sensing circuit 304 via the inductor 402. The inductor 402 outputs the received sensor signal to the sampler 410. In some embodiments, the sampler 410 can be configured to perform and / or execute sampling and quantization through an ADC at a sampling rate. The ADC may be a 16-bit successive approximation ADC. The sampling rate may be 1 MHz. Alternatively, the ADC may be a different type of ADC and / or have a different bit resolution. Alternatively, the sampling rate may be different than 1 MHz.

[0063] In example operation, the sampler 410 outputs the sampled and quantized sensor signal to the signal processing unit 412. In some embodiments, the signal processing unit 412 can be implemented by and / or correspond to the first controller 306 of FIG. 3. In some such embodiments, the sampler 410 of FIG. 4 can output the sampled and quantized sensor signal to the first controller 306 of FIG. 3.

[0064] While an example implementation of the wireless sensing circuit 304 is depicted in FIG. 4, other implementations are contemplated. For example, one or more blocks, components, functions, etc., of the wireless sensing circuit 304 may be combined or divided in any other way. The wireless sensing circuit 304 of the illustrated example may be implemented by hardware alone, or by a combination of hardware, software, and / or firmware. For example, the wireless sensing circuit 304 may be implemented by one or more analog circuits (e.g., capacitors, comparators, diodes, inductors, operational amplifiers, resistors, transistors, etc.), one or more digital circuits (e.g., logic gates, etc.), one or more hardware-implemented state machines, one or more programmable processors, one or more ASICs, etc., and / or any combination(s) thereof. The wireless sensing circuit 304 of the illustrated example can be implemented by one or more ICs on the same die or one or more ICs on two or more different dies, such as one or more ICs on a first die and one or more ICs on a second die.

[0065] FIG. 5 is a block diagram of an example implementation of a portion of the wireless sensing circuit 304 of FIGS. 3 and / or 4. The portion includes a gain circuit 502, a phase shift 13#14827600v2Attorney Docket No. M0925.71083WO00circuit 504, and an automatic gain control (AGC) circuit 506. The gain circuit 502 and the AGC circuit 506 may form an oscillator circuit 508 configured to oscillate the sensor signal output from the sensor 302 at a constant amplitude. Alternatively, the oscillator circuit 508 may include the phase shift circuit 504. The oscillator circuit 508 can be configured to oscillate the sensor signal from the sensor 302 at a sustained oscillation frequency. The oscillator circuit 508 may generate an output 510, which may be provided to a controller, such as the first controller 306 of FIG. 3. The sensor 302 may constitute a part of the feedback network of the oscillator circuit 508.

[0066] The gain circuit 502 can receive the sensor signal output from the sensor 302. For example, the gain circuit 502 can receive the sensor signal from the sensor 302 via the inductor 402 of FIG. 4. The sensor signal can be a rapidly decaying signal from the sensor 302.

[0067] The gain circuit 502 can implement an adjustable gain stage configured to sustain the oscillation of the decaying signal. The phase shift circuit 504 can implement a phase shift stage (e.g., a phase adjust stage) configured to shift the phase of the signal returned from the sensor 302 by 90° to bring the output signal in phase at the target sensing frequency band. The AGC circuit 506 can be an output voltage controlled stage configured to maintain the output level constant.

[0068] Although not shown, the implementation of the portion of the wireless sensing circuit 304 shown in FIG. 5 may be further complemented by a mixer and antialiasing filter stage to down-convert the output signal to low frequency and enhance SNR. The down-conversion and enhanced SNR may enable sampling at any low frequency starting from, for example, 50 kHz, for output frequency estimation using a short duration of the signal captured.

[0069] FIG. 6 is a schematic illustration of an example implementation of the sensor 302 of FIGS. 3, 4, and / or 5 and the wireless sensing circuit 304 of FIGS. 3, 4, and / or 5. As shown, the sensor 302 is a passive wireless resonant sensor and is represented by a circuit model including an inductor (identified by Ls) in parallel with a capacitor (identified by Cs) and a resistor (identified by Rs). For example, the sensors 104 of FIG. 1 may be respectively represented by the circuit model shown in FIG. 6.

[0070] The sensor 302 is inductively coupled to a resonant circuit 602 through an inductor 604 (identified by Lr) and mutual inductance M. The resonant circuit 602 can be configured to receive a wirelessly transmitted sensor signal as feedback from the sensor 302. As shown, the wireless sensing circuit 304 includes and / or implements the resonant circuit 602. The resonant circuit 602 includes the inductor 604 coupled in parallel to a capacitor 60614#14827600v2Attorney Docket No. M0925.71083WO00(identified by Cr). The resonant circuit 602 can be tuned (e.g., pre-tuned) to resonate at a specific desired frequency. For example, the resonant circuit 602 can be tuned by selecting the inductor 604 and / or the capacitor 606 to have specific values (e.g., a specific inductance, a specific capacitance) such that the resonant circuit 602 can resonate at the specific desired frequency. In such an example, the resonant circuit 602 can be tuned to oscillate at an oscillation frequency corresponding to the inductance of the inductor 604 and / or the capacitance of the capacitor 606.

[0071] The wireless sensing circuit 304 includes an excitation signal generator 608 to effectuate interrogation of the sensor 302. In some embodiments, the excitation signal generator 608 can implement and / or correspond to the clock 404 of FIG. 4.

[0072] The excitation signal generator 608 can be configured to periodically excite the sensor 302, which allows the sensor signal that is output from the sensor 302 to oscillate for some finite time. As shown, the excitation signal generator 608 is implemented by a relaxation oscillator that uses an operational amplifier (op-amp) (identified by U3) as a comparator. The circuit contains a voltage divider in the form of the R1-R2 resistor network from the output to the noninverting input of the op-amp and sets the threshold voltage for switching the output level between positive saturation voltage (+Vsat) and negative saturation voltage (-Vsat) of the op-amp. The inverting input has an RC network. The voltage divider provides a feedback to the op-amp.

[0073] Iteratively charging and discharging the capacitor Cfb results in a square wave with duty cycle 50% at the output of the excitation signal generator 608 whose frequency is controlled by the charging and discharging of the capacitor Cfb. For example, the excitation signal generator 608 can generate a periodic excitation signal using a square wave with duty cycle 50% and couple the excitation signal to Lr 604 via capacitor Cc. The capacitor Cc may have a relatively small capacitance and can differentiate the square wave and couple it to Lr 604 such that no direct current (DC) level is coupled to Lr 604. The excitation signal passes from Lr 604 to Ls through the mutual inductance M.

[0074] In example operation, the sensor 302 can generate a sensor signal in response to the excitation signal. The signal of interest is the signal coupled back to the primary inductor Lr 604 by the sensor 302. The signal of interest is output from the wireless sensing circuit 304 as output 605. The output 605 can be provided as input to the first controller 306 of FIG. 3 and / or as input to the sampler 410 of FIG. 4.

[0075] In the illustrated example, the sensor signal passes through Ls and couples to Lr 604 through the mutual inductance M. This amounts to a 180° phase shift between the dotted 15#14827600v2Attorney Docket No. M0925.71083WO00terminals (e.g., a 90° lag each time while passing through Lr 604 and coupling via mutual inductance M). When the sensor signal couples back to the primary inductor Lr 604, it has to do so via M, the mutual inductance between the two inductors. As a net result, the signal from the sensor 302 coupled back to Lr 604 has a phase lag of 90° and appears at the dotted terminal of Lr 604. This phase lag needs to be compensated so that oscillation conditions are satisfied.

[0076] In some embodiments, the wireless sensing circuit 304 includes a phase compensation stage configured to compensate the phase lag so that oscillation conditions are satisfied. As shown, the phase compensation stage is implemented by a phase shift circuit 610. In some embodiments, the phase shift circuit 610 implements and / or corresponds to the phase shift circuit 504 of FIG. 5.

[0077] The phase shift circuit 610 can be configured to provide the 90° phase shift to the sensor signal to bring the sensor signal in-phase with the resonant circuit 602 to sustain the oscillation of the sensor signal at the oscillation frequency. For example, the oscillation frequency can be a frequency in a sensing frequency band associated with the sensor 302. The sensing frequency band can be a range of 100 Hz to 100 MHz. For example, a sensing range of the sensor 302 can be 100 hertz to 100 megahertz. Other sensing frequency bands are contemplated, such as a range of 50 Hz to 200 MHz. The phase shift circuit 610 can be phase shift adjustable such that it can provide a phase shift anywhere between 0° and 180°.

[0078] In some embodiments, the phase shift circuit 610 implements an all-pass filter. For example, the phase shift circuit 610 can be configured to change the phase of the input signal without altering its magnitude. The all-pass filter may be a first order all-pass lag filter or a first order all-pass lead filter.

[0079] In the illustrated example, the feedback signal from the sensor 302, which is coupled to the input filter (voltage at the dotted terminal of Lr 604) is lagging by 90°. Thus, as shown, the phase shift circuit 610 is a first order all-pass lag filter implemented as an op-amp based low-pass filter with a cutoff frequency fc= l / 2nRC to cause a phase compensation of 90° lag to generate a 180 degree phase shift for sustained oscillation.

[0080] In some embodiments, the wireless sensing circuit 304 includes a gain stage (e.g., a gain adjust stage), which can be adjustable, for the proper operation of the oscillator circuit. As shown, the gain stage is implemented by a gain adjust circuit 612. In some embodiments, the gain adjust circuit 612 implements and / or corresponds to the gain circuit 502 of FIG. 5.16#14827600v2Attorney Docket No. M0925.71083WO00

[0081] The gain adjust circuit 612 includes an op-amp with sufficiently high gain-bandwidth product (GBW) at the oscillation frequency. The op-amp may be an inverting gain op-amp such that the gain adjust circuit 612 is configured in an arrangement to implement an inverting gain op-amp circuit. The gain of the circuit is Avand is adjustable by varying Rf.

[0082] In some embodiments, the wireless sensing circuit 304 includes an AGC stage to ensure that the oscillation conditions are met so that the output level does not keep on increasing without bound. As shown, the AGC stage is implemented by an AGC circuit 614. In some embodiments, the AGC circuit 614 implements and / or corresponds to the AGC circuit 506 of FIG. 5.

[0083] In some embodiments, the AGC circuit 614 reduces the gain after a certain output voltage level has been reached. For example, the AGC circuit 614 can be configured to clip the signal as the signal crosses (e.g., exceeds) this threshold voltage using diodes as shown. The diodes may be silicon diodes. In the illustrated example, two sets of three diodes (in series) are connected in parallel so that conduction for both the positive and negative cycles of the signal is maintained. As shown, three diodes can clip the signal at a threshold voltage (e.g., a threshold voltage of 2.1 V) in the positive half cycle and three diodes can clip the signal at the threshold voltage in the negative half cycle. Any threshold voltage may be used, such as 1.5 V, 2 V, 2.1 V, 2.5 V, etc. Such clipping reduces the gain of the circuit and maintains a constant output voltage from the oscillator. In example operation, the diodes of the AGC circuit 614 conduct when the output signal is greater than the threshold voltage (e.g., the threshold voltage of 2.1 V) and serve to bypass the feedback resistor Rf of the gain circuit 612 thereby reducing gain and acting as AGC.

[0084] In some embodiments, the wireless sensing circuit 304 includes a feedback network to provide a feedback signal to the resonant circuit 602. The feedback network may be implemented by a series impedance network. As shown, the series impedance network is implemented by at least one resistor 616 (identified by R). By adding the resistor 616 in series to the input LrCr filter, the feedback signal can be coupled with the primary inductor Lr 604. For example, the series impedance network is a load between the sensor feedback and the op-amp output of the excitation signal generator 608 to achieve maximum energy transfer of the excitation signal. In some embodiments, the impedance load can be configured to match the impedance of Lr 604 at the system working and / or sensing frequency.

[0085] In some embodiments, one or more portions of the wireless sensing circuit 304 can implement an oscillator circuit. For example, an oscillator circuit can include at least one of17#14827600v2Attorney Docket No. M0925.71083WO00the resonant circuit 602, the excitation signal generator 608, the phase shift circuit 610, the gain adjust circuit 612, or the AGC circuit 614.

[0086] In some embodiments, one or more portions of the wireless sensing circuit 304 can implement a reader (e.g., a sensor reader, a reader circuit). For example, a reader can include at least one of the resonant circuit 602, the excitation signal generator 608, the phase shift circuit 610, the gain adjust circuit 612, or the AGC circuit 614.

[0087] FIG. 7 is a block diagram of an example implementation of a data integration system 700. In some embodiments, the data integration system 700 implements and / or corresponds to the sensing platform 102 of FIG. 1 and / or the sensing platform 300 of FIG. 3. The data integration system 700 can be configured to acquire and process a rapidly decaying signal output from a low Q factor sensor, such as the sensor 302 of FIGS 3, 4, 5, and / or 6.

[0088] The data integration system 700 includes a wireless sensing circuit 702 to receive a rapidly decaying signal output from a low Q factor sensor, and oscillate the signal output at a constant amplitude and for a sufficient time period. In some embodiments, the wireless sensing circuit 702 can be the wireless sensing circuit 304 of FIGS. 3, 4, 5, and / or 6.

[0089] The wireless sensing circuit 702 can output the signal output (e.g., the output 605 of FIG. 6) to a buffer 704. The buffer 704 can be configured to prevent loading on the input voltage source and ensure that its operation is not affected by the subsequent load. The buffer 704 can be implemented by a unity gain buffer (e.g., a voltage follower). For example, the buffer 704 can be implemented by a unity gain noninverting op-amp circuit.

[0090] The buffer 704 can provide the output signal to a first mixer 706 (identified by Mixer 1). The first mixer 706 can be configured to bring the frequency of the output signal from a first frequency to a second frequency. The first frequency can be approximately 2 MHz (e.g., 1.93 MHz) and the second frequency, as shown, can be approximately 185 kHz.

[0091] The output of the first mixer 706 can be a sum of sinusoidal frequency components. This output can be passed through a first filter 708 (identified by Filter 1) to eliminate all the high frequency components as the signal of interest is a low frequency signal. For example, the first filter 708 can be a low-pass filter configured with a cutoff frequency of approximately 200 kHz.

[0092] The output from the first filter 708 is input to a first gain circuit 710 (identified by Gain 1) to change the gain of the output from the first filter 708 for ease of processing it in the subsequent blocks. Output from the first gain circuit 710 is output to a second mixer 712. The second mixer 712 can be configured to modulate the output from the first gain circuit 710 from the second frequency to a third frequency. As shown, the third frequency is18#14827600v2Attorney Docket No. M0925.71083WO00approximately 25 kHz. Like the first mixer 706, the output of the second mixer 712 can be a sum of sinusoidal frequency components.

[0093] Although not shown, the output of the second mixer 712 can be passed through a low-pass filter to eliminate all the high frequency components as the signal of interest is a low frequency signal. Output from the low-pass filter can be passed through a gain stage to change the gain for ease of processing in subsequent blocks. Output from the gain stage can be used to detect a condition (e.g., a change in a condition) of a composite part, such as the composite part 106 of FIG. 1. For example, the frequency of the gain stage output can be sampled and processes to estimate the frequency.

[0094] High frequency output 713 from the wireless sensing circuit 702 can be provided to a third mixer 714 (identified by Quadrature Mixer). The third mixer 714 is shown as a quadrature mixer configured to modulate the signal output from the wireless sensing circuit 702 from the first frequency to the second frequency (e.g., approximately 185 kHz). The third mixer 714 can be configured to use a reference signal that is quadrature shifted with respect to the reference signal of the first mixer 706 for proper operation of the sensor detect logic 720.

[0095] The output from the third mixer 714 is passed through a second filter 716 (identified by Quadrature Filter) to eliminate all the high frequency components as the signal of interest is a low frequency signal. For example, the second filter 716 can be a low-pass filter configured with a cutoff frequency of approximately 200 kHz. The signal is input to another gain circuit 718 (identified by Gain 3) to change the gain of the output from the second filter 716 for ease of processing it in the subsequent blocks.

[0096] The data integration system 700 includes the sensor detect logic 720 to detect the presence of a sensor, such as the sensor 302 of FIGS. 3, 4, 5, and / or 6. The sensor detect logic 720 can use the outputs from the first gain circuit 710 and the second gain circuit 718 to make the determination. For example, the sensor detect logic 720 can determine whether the frequency of the output signal from the wireless sensing circuit 702 is greater than a threshold frequency. Beneficially, in some embodiments, the data integration system 700 can determine at least one of (i) a detection of a presence of a low Q factor sensor, such as the sensor 302, based on the output of the sensor detect logic 720 or (ii) a detection of a condition (e.g., a change in a condition) of a composite part, such as the composite part 106, based on an estimation of the frequency of the output of the wireless sensing circuit 702.

[0097] While an example implementation of the data integration system 700 is depicted in FIG. 7, other implementations are contemplated. For example, one or more blocks,19#14827600v2Attorney Docket No. M0925.71083WO00components, functions, etc., of the data integration system 700 may be combined or divided in any other way. The data integration system 700 of the illustrated example may be implemented by hardware alone, or by a combination of hardware, software, and / or firmware. For example, the data integration system 700 may be implemented by one or more analog circuits (e.g., capacitors, comparators, diodes, inductors, operational amplifiers, resistors, transistors, etc.), one or more digital circuits (e.g., logic gates), one or more hardware-implemented state machines, one or more programmable processors (e.g., CPUs, DSPs, FPGAs, GPUs, etc.), one or more ASICs, one or more memories (e.g., non-volatile memory, volatile memory, etc.), etc., and / or any combination(s) thereof. The data integration system 700 of the illustrated example can be implemented by one or more ICs on the same die or one or more ICs on two or more different dies, such as one or more ICs on a first die and one or more ICs on a second die. In some embodiments, the data integration system 700, or portion(s) thereof, may be implemented by an SoC.

[0098] Various aspects of the embodiments described above may be used alone, in combination, or in a variety of arrangements not specifically discussed in the embodiments described in the foregoing and is therefore not limited in its application to the details and arrangement of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments.

[0099] The phrase “and / or,” as used herein in the specification and in the claims, should be understood to mean “either or both,” of the elements so conjoined, e.g., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and / or” should be construed in the same fashion, e.g., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and / or B,” when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[0100] The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”

[0101] As used herein in the specification and in the claims, the phrase, “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element 20#14827600v2Attorney Docket No. M0925.71083WO00selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently, “at least one of A and / or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0102] Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

[0103] Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

[0104] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0105] Having thus described several aspects of at least one embodiment, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the spirit and scope of the principles described herein. Accordingly, the foregoing description and drawings are by way of example only.21#14827600v2

Claims

Attorney Docket No. M0925.71083WO00CLAIMS1. A circuit for interrogating a sensor to output a decaying signal, the circuit comprising:a resonant circuit configured to:receive a wirelessly transmitted sensor signal as feedback from the sensor; andoscillate the sensor signal at an oscillation frequency; anda phase shift circuit configured to provide a phase shift to the sensor signal to sustain the oscillation of the sensor signal in a sensing frequency band associated with the sensor.

2. The circuit of claim 1, wherein the phase shift is a 90 degree phase shift, and the phase shift circuit is configured to provide the 90 degree phase shift to the sensor signal to bring the sensor signal in-phase with the resonant circuit to sustain the oscillation of the sensor signal at the oscillation frequency.

3. The circuit of claim 1, further comprising a feedback network comprising a series impedance network coupled to the resonant circuit.

4. The circuit of claim 3, wherein the series impedance network comprises at least one resistor, the at least one resistor provides a feedback signal, based on the sensor signal, to the resonant circuit.

5. The circuit of any one of claims 1-4, further comprising an excitation signal generator to generate an excitation signal to interrogate the sensor.

6. The circuit of any one of claims 1-5, further comprising an automatic gain control circuit coupled to the phase shift circuit in a configuration to adjust a gain to maintain a constant amplitude of the sensor signal.

7. The circuit of claim 6, wherein the automatic gain control circuit comprises:at least one diode configured to clip the sensor signal when the sensor signal exceeds a threshold voltage; anda gain adjust circuit configured to adjust the gain when the sensor signal exceeds the threshold.22#14827600v2Attorney Docket No. M0925.71083WO008. The circuit of any one of claims 1-7, wherein the circuit is configured to oscillate the sensor signal having a quality factor of 1 or less.

9. The circuit of any one of claims 1-8, further comprising a controller configured to map the sensor signal to a measured parameter comprising at least one of corrosion, erosion, or fatigue crack length in an object.

10. A system for interrogating a sensor, comprising:a sensor configured to output a sensor signal in a sensing frequency band and in response to receiving an excitation signal; andan oscillator circuit comprising:a resonant circuit configured to receive and oscillate the sensor signal at an oscillation frequency;a feedback network coupled to the resonant circuit and configured to input a feedback signal to the resonant circuit; anda phase shift circuit coupled to the feedback network, the phase shift circuit configured to:provide a phase shift to the sensor signal to generate the feedback signal; andprovide the feedback signal to the resonant circuit through the feedback network to sustain the oscillation of the sensor signal in the sensing frequency band.

11. The system of claim 10, wherein the sensor is a passive wireless resonant sensor inductively coupled to the resonant circuit.

12. The system of any one of claims 10-11, wherein a sensing range of the sensor is 100 hertz to 100 megahertz.

13. The system of any one of claims 10-12, further comprising a controller configured to map the sensor signal to a measured parameter comprising at least one of corrosion, erosion, or fatigue crack length in an object.23#14827600v2Attorney Docket No. M0925.71083WO0014. The system of claim 13, wherein the sensor is embedded in the object.

15. The system of any one of claims 10-14, wherein a quality factor associated with the sensor is 1 or less.

16. A method for interrogating a wireless sensor associated with a low quality factor, comprising:inductively providing an excitation signal to the wireless sensor;receiving, in response to the excitation signal, a sensor signal from the wireless sensor; andoscillating, using an oscillator circuit, the sensor signal at a sustained oscillation frequency, the oscillator circuit comprising:a resonant circuit configured to receive and oscillate the sensor signal at the oscillation frequency;a feedback network coupled to the resonant circuit and configured to input a feedback signal to the resonant circuit; anda phase shift circuit coupled to the feedback network and configured to provide a phase shift to the sensor signal to output the feedback signal to sustain the oscillation of the sensor signal in a sensing frequency band of the wireless sensor.

17. The method of claim 16, wherein:receiving the sensor signal comprises causing a first phase shift of the sensor signal by 90 degrees, andthe phase shift circuit providing the phase shift to the sensor signal comprises providing a second phase shift of 90 degrees to the sensor signal to generate a 180 degree phase shift for sustained oscillation.

18. The method of any one of claims 16-17, further comprising clipping the sensor signal when the sensor signal exceeds a threshold voltage.

19. The method of claim 18, further comprising adjusting a gain when the sensor signal exceeds the threshold voltage.24#14827600v2Attorney Docket No. M0925.71083WO0020. The method of any one of claims 16-19, further comprising mapping the sensor signal to a measured parameter comprising at least one of corrosion, erosion, or fatigue crack length in an object.#14827600v2

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