An Interface for Eddy-Current Displacement Sensors With 15-bit Resolution and 20 MHz Excitation

Nabavi, M.R.; Pertijs, Michiel A. P.; Nihtianov, Stoyan

doi:10.1109/jssc.2013.2281692

Cited by 35 publications

(19 citation statements)

References 17 publications

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“…The tail current source is cascoded to prevent modulation due to oscillator output swing. One important point to note is that the effective oscillator amplitudenoise also flows through both ECS coils (like I LC ) and is suppressed with ratiometric measurement [4].…”

Section: A Front-end Excitation Oscillatormentioning

confidence: 99%

“…They are also sensitive to environmental conditions such as humidity, dirt etc. Eddy-current sensors (ECSs), on the other hand, are immune to these disadvantages, but their stability is limited by the skin-effect [4], [5]. Since eddycurrent is induced deep with in the target, the effective displacement sensed by an ECS is dependent on the skin-depth δ (= 1/ √ πµσf exc ), where µ is the magnetic permeability, σ is the electrical conductivity and f exc is the excitation frequency of the ECS.…”

Section: Introductionmentioning

confidence: 99%

“…However, the efficacy of this suppression is limited by the presence of any non-linearity, e.g. due to g m stages, in the demodulator [4], [17]. It is also more difficult to attain high linearity (> 70 dB THD) at a high f exc .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A 19.8-mW Eddy-Current Displacement Sensor Interface With Sub-Nanometer Resolution

Chaturvedi¹,

Vogel

Makinwa

et al. 2018

IEEE J. Solid-State Circuits

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This paper presents an eddy-current sensor (ECS) interface intended for sub-nanometer displacement sensing in hitech applications. The interface employs a 126 MHz excitation frequency to mitigate the skin-effect, and achieve high resolution and stability. An efficient on-chip sensor-offset compensation scheme is introduced which removes sensor-offset proportional to the standoff distance. To assist in the ratiometric suppression of noise and drift of the excitation-oscillator, the ECS interface consists of a highly linear amplitude-demodulation scheme that employs passive capacitors for voltage-to-current conversion. Using a PCB-based pseudo-differential ECS, stability tests were performed which demonstrated a thermal drift of < 7.3 nm/ • C and long-term drift of only 29.5 nm over a period of 60 hours. The interface achieves an effective noise floor of 13.4 pm/ √ Hz which corresponds to a displacement resolution of 0.6 nm in a 2 kHz noise-bandwidth. The ECS interface is fabricated in TSMC 0.18 µm CMOS technology and dissipates only 19.8 mW from a 1.8 V supply.

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Section: A Front-end Excitation Oscillatormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A 19.8-mW Eddy-Current Displacement Sensor Interface With Sub-Nanometer Resolution

Chaturvedi¹,

Vogel

Makinwa

et al. 2018

IEEE J. Solid-State Circuits

Self Cite

View full text Add to dashboard Cite

show abstract

“…14, the simplified architecture of the proposed demodulator (including two channels) is depicted in Fig. 16 [28]. Performing the mixing operation in the current domain provides more linearity (than in the voltage domain) since the series on-resistance of the switches cannot introduce distortion to a current signal.…”

Section: Synchronous Detection-based Ecs Interfacementioning

confidence: 99%

“…Furthermore, BJTs offer a considerably lower 1/ f noise than their MOS counterparts (about two orders of magnitude in the technology employed, with a similar biasing current and die area). The combination of a [13] Relaxation oscillator [18] LC oscillator [14] LC oscillator with ratiometric and precision peak detection [22] LC oscillator with ratiometric and synchronous detection [28] Excitation lower 1/ f noise and a larger transconductance (under similar conditions) makes the BiCMOS process a proper choice for ECS interfacing, which requires a high excitation frequency, high measurement stability, and low-power functionality.…”

Section: Synchronous Detection-based Ecs Interfacementioning

confidence: 99%

Design Strategies for Eddy-Current Displacement Sensor Systems: Review and Recommendations

Nabavi¹,

Nihtianov

2012

IEEE Sensors J.

134

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This paper presents a comprehensive study of the design aspects of eddy-current displacement sensor (ECS) systems. In accordance with the sensor analysis presented in this paper, design strategies to compensate for important sensor imperfections are recommended. To this end, the challenges that are associated with ECS interfaces are identified, with focus on advanced industrial applications. This paper also provides a technical overview of the design advances of ECS interfaces proposed in the last decade and evaluates their pros and cons. Recently reported interface solutions for demanding industrial applications with respect to high resolution, stability, bandwidth, and low power consumption, at a sufficiently high excitation frequency, are addressed in more detail.

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Ultra-Low Power Displacement Sensor

Bertacchini

Lasagni

Sereni

2020

Lecture Notes in Electrical Engineering

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An Interface for Eddy-Current Displacement Sensors With 15-bit Resolution and 20 MHz Excitation

Cited by 35 publications

References 17 publications

A 19.8-mW Eddy-Current Displacement Sensor Interface With Sub-Nanometer Resolution

A 19.8-mW Eddy-Current Displacement Sensor Interface With Sub-Nanometer Resolution

Design Strategies for Eddy-Current Displacement Sensor Systems: Review and Recommendations

Ultra-Low Power Displacement Sensor

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