Application of Offset Trimming Circuit for Reducing the Impact of Parasitics in Capacitive Sensor Readout Circuit

As a non-metallic composite material, widely applied in industry, rigid polyurethane (PUR) foams require knowledge of their dielectric properties. In experimental determination of PUR foams’ dielectric properties protection of one-side capacitive sensor’s active area from adverse effects caused by the PUR foams’ test objects has to be ensured. In the given study, the impact of polytetrafluoroethylene (PTFE) films, thickness 0.20 mm and 0.04 mm, in covering or simulated coating the active area of one-side access capacitive sensor’ electrodes on the experimentally determined true dielectric permittivity spectra of rigid PUR foams is estimated. Penetration depth of the low frequency excitation field into PTFE and PUR foams is determined experimentally. Experiments are made in order to evaluate the difference between measurements on single PUR foams’ samples and on complex samples “PUR foams + PTFE film” with two calibration modes. A modification factor and a small modification criterion are defined and values of modifications are estimated in numerical calculations. Conclusions about possible practical applications of PTFE films in dielectric permittivity measurements of rigid PUR foams with one-side access capacitive sensor are made.

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The SI and EMI Analysis of Sub-Femto-Farad readout circuit for capacitive sensor

2019 12th International Workshop on the Electromagnetic Compatibility of Integrated Circuits (EMC Compo) ◽

10.1109/emccompo.2019.8919907 ◽

2019 ◽

Author(s):

Xinquan Lai ◽

Yuheng Wang ◽

Mingming Liu ◽

Lingfei Zhang

Keyword(s):

Capacitive Sensor ◽

Readout Circuit

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A 5-V 290- $\mu\hbox{W}$ Low-Noise Chopper-Stabilized Capacitive-Sensor Readout Circuit in 0.8- $\mu\hbox{m}$ CMOS Using a Correlated-Level-Shifting Technique

IEEE Transactions on Circuits & Systems II Express Briefs ◽

10.1109/tcsii.2014.2304888 ◽

2014 ◽

Vol 61 (4) ◽

pp. 254-258 ◽

Cited By ~ 14

Author(s):

Jack Shiah ◽

Shahriar Mirabbasi

Keyword(s):

Capacitive Sensor ◽

Low Noise ◽

Readout Circuit ◽

Correlated Level Shifting

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Wide Input Range Supply Voltage Tolerant Capacitive Sensor Readout Using On-Chip Solar Cell

Journal of Circuits System and Computers ◽

10.1142/s0218126616400065 ◽

2015 ◽

Vol 25 (01) ◽

pp. 1640006

Author(s):

Suyan Fan ◽

Man-Kay Law ◽

Mingzhong Li ◽

Zhiyuan Chen ◽

Chio-In Ieong ◽

...

Keyword(s):

Solar Cell ◽

Power Consumption ◽

Supply Voltage ◽

Capacitive Sensor ◽

Cmos Process ◽

Readout Circuit ◽

Worst Case ◽

Average Power Consumption ◽

Input Range ◽

On Chip

In this paper, a wide input range supply voltage tolerant capacitive sensor readout circuit using on-chip solar cell is presented. Based on capacitance controlled oscillators (CCOs) for ultra-low voltage/power consumption, the sensor readout circuit is directly powered by the on-chip solar cell to improve the overall system energy efficiency. An extended sensing range with high sensing accuracy is achieved using a two-step successive approximation register (SAR) and delta-sigma ([Formula: see text]) analog-to-digital (A/D) conversion (ADC) scheme. Digital controls are generated on-chip using a customized sub-threshold digital standard cell library. Systematic error analysis and optimization including the finite switch on-resistance, buffer input-dependent delay, and SAR quantization nonlinearity are also outlined. High power supply rejection ratio (PSRR) is ensured by using a pseudo-differential topology with ratiometric readout. The complete sensing system is implemented using a standard 0.18[Formula: see text][Formula: see text]m complementary metal-oxide-semiconductor (CMOS) process. Simulation results show that the readout circuit achieves a wide input range from 1.5[Formula: see text]pF to 6.5[Formula: see text]pF with a worst case PSRR of 0.5% from 0.3[Formula: see text]V to 0.42[Formula: see text]V (0.67% from 0.3[Formula: see text]V to 0.6[Formula: see text]V). With a 3.5[Formula: see text]pF input capacitance and a 0.3[Formula: see text]V supply, the [Formula: see text] stage achieves a resolution of 7.1-bit (corresponding to a capacitance of 2.2[Formula: see text]fF/LSB) with a conversion frequency of 371[Formula: see text]Hz. With an average power consumption of 40[Formula: see text]nW and a sampling frequency of 47.5[Formula: see text]kHz, a figure-of-merit (FoM) of 0.78[Formula: see text]pJ/conv-step is achieved.

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CONTACTLESS CAPACITIVE SENSOR OF THE SYSTEM FOR MONITORING THE PARAMETERS OF THE BEATING OF THE POWERFUL ELECTRICAL MACHINES SHAFTS

Praci Institutu elektrodinamiki Nacionalanoi akademii nauk Ukraini ◽

10.15407/publishing2020.57.081 ◽

2020 ◽

Vol 2020 (57) ◽

pp. 81-88

Author(s):

V.O. Bereznychenko ◽

◽

I.O. Zaitsev ◽

Keyword(s):

Measuring Transducer ◽

Capacitive Sensor ◽

Response Characteristic ◽

Guard Ring ◽

Element Analysis ◽

Modeling Tools ◽

Potential Electrode ◽

General Plane ◽

Change Response ◽

The Impact

In this paper presents the results of the definition the need to use a Kelvin guard ring to reduce the impact of external fields and non-uniformity of equipotential lines to change response characteristic of the capacitive sensor with a central high-potential electrode and a Kelvin guard ring. Measuring transducer placing in the immediate vicinity of the electrodes of the sensor, which eliminates the need to use a triaxial cable, was proposed. The sensor is designed to measure powerful generators shafts cylindrical surfaces parameters run-out. Capacitive sensor response characteristic function which depending on distance between the general plane of electrodes of the sensor and the grounded surface of a shaft is determined analytically and by computer simulation methods. The expediency of using computer modeling tools by finite element analysis methods for studying the metrological characteristics of sensors was shown. References 21, figures 4, table 1.

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