Differential Capacitive Readout Circuit Using Oversampling Successive Approximation Technique

Zhong, Longjie; Lai, Xiaojun; Song, Hongjiang; Xu, Donglai

doi:10.1109/tcsi.2018.2849992

Cited by 13 publications

(7 citation statements)

References 23 publications

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“…SNR value is very important for accurate measurement of physical quantity, and to obtain a higher SNR we need to increase the signal power while reducing the noise power [41]. In addition, power consumption and low supply voltage is very important as capacitive accelerometers are widely used in small devices [42]. Since sensitivity is important when detecting, the values of the circuit elements should be chosen correctly for readout circuits.…”

Section: Cihat Ediz Akbaba Mahmud Yusuf Tanrıkulumentioning

confidence: 99%

MEMS capacitive accelerometer: A review

AKBABA,

TANRIKULU

2023

Artıbilim: Adana Alparslan Türkeş Bilim Ve Teknoloji Üniversitesi Fen Bilimleri Dergisi

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Micro-electro-mechanical systems sensors are integrated systems used in many fields such as consumer electronics, the automobile industry, and biomedical, and their dimensions change between micrometers and millimeters. MEMS capacitive accelerometers are the most widely used sensor type among MEMS accelerometer sensors. As a result of the external force applied to the capacitive accelerometer sensor, the proof mass inside the sensor moves, and the capacitive change is measured as an electrical signal using reading circuits. In this review paper, general information about MEMS sensors is given, and a comprehensive review is made of MEMS capacitive accelerometers. In the study, the dynamic circuit of the MEMS capacitive accelerometer is given, and the calculation of the important values for the mechanical and electronic structure during the design of the capacitive MEMS accelerometer is explained. In addition, information about the readout circuits used to convert the capacitive change to voltage is given. Finally, the fabrication processes used to produce the final product are explained, and the studies on sample fabrication processes found in the literature are mentioned.

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Section: Cihat Ediz Akbaba Mahmud Yusuf Tanrıkulumentioning

confidence: 99%

MEMS capacitive accelerometer: A review

AKBABA,

TANRIKULU

2023

Artıbilim: Adana Alparslan Türkeş Bilim Ve Teknoloji Üniversitesi Fen Bilimleri Dergisi

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“…However, this circuit design increases the power consumption and area, which should be considered together. Oversampling successive approximation circuit structures and methods have been proposed to remove gain error using methods besides the design of a high-performance Op Amp [ 19 , 20 ]. These methods reduce the gain error gradually by accumulating and repeating the phase for storing and compensating the gain error several times to obtain one output result.…”

Section: Technical Issues Of the Capacitive Sensor Readout Systemmentioning

confidence: 99%

Readout Circuits for Capacitive Sensors

Yoo

Choi

2021

Micromachines

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The development of microelectromechanical system (MEMS) processes enables the integration of capacitive sensors into silicon integrated circuits. These sensors have been gaining considerable attention as a solution for mobile and internet of things (IoT) devices because of their low power consumption. In this study, we introduce the operating principle of representative capacitive sensors and discuss the major technical challenges, solutions, and future tasks for a capacitive readout system. The signal-to-noise ratio (SNR) is the most important performance parameter for a sensor system that measures changes in physical quantities; in addition, power consumption is another important factor because of the characteristics of mobile and IoT devices. Signal power degradation and noise, which degrade the SNR in the sensor readout system, are analyzed; circuit design approaches for degradation prevention are discussed. Further, we discuss the previous efforts and existing studies that focus on low power consumption. We present detailed circuit techniques and illustrate their effectiveness in suppressing signal power degradation and achieving lower noise levels via application to a design example of an actual MEMS microphone readout system.

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“…As a result, the capacitance variation of the sensing element (femtofarad level) is much lower than the capacitance of the parasitic capacitance of the sensing element (pico-farad level), which results in a significant deterioration of gain error and thermal noise. The oversampling successive approximation (OSA) readout technique and the Nested-OSA technique were reported to deal with these deterioration problems [23,24]. However, a high sampling frequency of the capacitance-to-voltage converter (CVC) based on the OSA or Nested-OSA technique leads to high power consumption of the readout circuit [25,26].…”

Section: Introductionmentioning

confidence: 99%

High-Power-Efficiency Readout Circuit Employing Average Capacitance-to-Voltage Converter for Micro-Electro-Mechanical System Capacitive Accelerometers

Li,

Lai,

Wang

et al. 2023

Sensors

Self Cite

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A capacitance-to-voltage converter (CVC) is proposed in this paper and applied to a readout circuit for a micro-electro-mechanical system (MEMS) accelerometer to improve the power efficiency. In a traditional readout circuit, the front-end CVC has to operate at a high sampling frequency to resist thermal noise deterioration due to the large parasitic capacitance introduced by the mechanical sensing element. Thus, the back-end analog-to-digital converter (ADC) also has to operate at a high sampling frequency to avoid noise aliasing when sampling the output signal of the CVC, which leads to high power consumption. The average CVC technique is proposed in this paper to reduce the sampling frequency requirement of the back-end ADC and thus reduce the power consumption. Both the traditional readout circuit and the proposed readout circuit are simulated with a commercial 0.18 μm BCD process. The simulation results show that noise aliasing occurs, and the noise power spectral density (PSD) of the traditional readout circuit increases by 12 dB when the sampling frequency of back-end ADC is reduced by 24 dB. However, in the proposed readout circuit, a noise aliasing effect does not occur. Moreover, the proposed readout circuit reduces the power consumption by 53% without thermal noise deterioration. In addition, the proposed CVC circuits are fabricated in an 0.18 μm BCD process, and the test results show that the presented readout circuit based on the average CVC technique can obtain better performance than the traditional CVC-based readout circuit.

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Differential Capacitive Readout Circuit Using Oversampling Successive Approximation Technique

Cited by 13 publications

References 23 publications

MEMS capacitive accelerometer: A review

MEMS capacitive accelerometer: A review

Readout Circuits for Capacitive Sensors

High-Power-Efficiency Readout Circuit Employing Average Capacitance-to-Voltage Converter for Micro-Electro-Mechanical System Capacitive Accelerometers

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