Mutual Capacitance Research Articles

Temporal Homogenization of Linear ODEs, with Applications to Parametric Super-Resonance and Energy Harvest

We consider the temporal homogenization of linear ODEs of the form $\dot{x}=Ax+\epsilon P(t)x+f(t)$, where $P(t)$ is periodic and $\epsilon$ is small. Using a 2-scale expansion approach, we obtain the long-time approximation $x(t)\approx \exp(At) \left( \Omega(t)+\int_0^t \exp(-A \tau) f(\tau) \, d\tau \right)$, where $\Omega$ solves the cell problem $\dot{\Omega}=\epsilon B \Omega + \epsilon F(t)$ with an effective matrix $B$ and an explicitly-known $F(t)$. We provide necessary and sufficient condition for the accuracy of the approximation (over a $\mathcal{O}(\epsilon^{-1})$ time-scale), and show how $B$ can be computed (at a cost independent of $\epsilon$). As a direct application, we investigate the possibility of using RLC circuits to harvest the energy contained in small scale oscillations of ambient electromagnetic fields (such as Schumann resonances). Although a RLC circuit parametrically coupled to the field may achieve such energy extraction via parametric resonance, its resistance $R$ needs to be smaller than a threshold $\kappa$ proportional to the fluctuations of the field, thereby limiting practical applications. We show that if $n$ RLC circuits are appropriately coupled via mutual capacitances or inductances, then energy extraction can be achieved when the resistance of each circuit is smaller than $n\kappa$. Hence, if the resistance of each circuit has a non-zero fixed value, energy extraction can be made possible through the coupling of a sufficiently large number $n$ of circuits ($n\approx 1000$ for the first mode of Schumann resonances and contemporary values of capacitances, inductances and resistances). The theory is also applied to the control of the oscillation amplitude of a (damped) oscillator.

A Wideband Common-Mode Suppression Filter With Compact-Defected Ground Structure Pattern

A complementary-defected ground structure (DGS) common stopband filter is proposed. The filter uses two kinds of DGS patterns: a $\Pi$ -shaped DGS pattern is used in both sides of the filter and a button-headed H-shaped DGS pattern is adopted at the middle of the filter. The filter utilizes the mutual inductance and mutual capacitance that exists among the DGS patterns to improve the in-band gain-flatness of the filter, which is useful to broaden the bandwidth and improve the rejection ratio in the low cutoff frequency. The simulated and measured results show that the differential signal under the DGS filter is nearly intact and the common-mode noise can be reduced by 15 dB from 3.2 to 12.4 GHz. The area of the filter is only 10 mm × 10 mm. The fractional bandwidth of the stopband can reach 118%.

Defining the mutual coupling of capacitive power transfer for wireless power transfer

Capacitive power transfer (CPT) based on electric field coupling has been proposed recently as an alternative technology for wireless power transfer, and a good understanding of the capacitive coupling is of great importance in the design and evaluation of CPT systems. A new term named capacitive coupling coefficient kE is introduced to provide a quantitative measure of the coupling condition between the coupling plates. The term is derived by modelling the capacitive coupling plates based on electric charge balance, and its physical meaning is explained clearly in relation to the equivalent primary/secondary and mutual capacitances, which is also experimentally demonstrated by comparing two CPT systems with different cross-coupling configurations.

A Broadband and Equivalent-Circuit Model for Millimeter-Wave On-Chip M:N Six-Port Transformers and Baluns

A new equivalent-circuit model and parameter-extraction method for six-port M:N on-chip transformers and baluns are presented in this paper. All of the elements in the proposed model are extracted directly by $S$ -parameters based on full-wave electromagnetic (EM) simulations. Series branches in the model are used to capture the characteristics of the primary and secondary windings. The shunt impedance networks on the terminals represent the substrate loss. The magnetic coupling effects of windings are denoted by six mutual inductances. The electrical coupling effects are represented by mutual capacitances. In this paper, we have developed a parameter-extraction methodology for mutual inductances of six-port transformers. The proposed model and parameters extraction methodology are verified with a number of six-port transformers with different turn ratio by measurements and full-wave EM simulations. The proposed model shows good agreement with measured data over a wide frequency band.

Measurement-Based Modeling and Worst-Case Estimation of Crosstalk Inside an Aircraft Cable Connector

Crosstalk within cable bundles can degrade system performance. In aircraft systems that use shielded twisted pairs, the crosstalk occurs primarily in the connector where individual signal wires are not shielded or twisted. In many cases, the parameters which determine crosstalk within the connector are unknown because the connector is closed and wires cannot be easily accessed. Expanding on prior research [14] , a methodology for measuring coupling parameters and modeling crosstalk within aircraft cable connectors at low frequencies (<400 MHz) was developed. The values of mutual inductance and capacitance were extracted from measurements made with a vector network analyzer (VNA). The characteristics of the individual wires were extracted from VNA-measured TDR response. The accuracy of the model was evaluated through comparison of simulated and measured results. Additionally, a closed-form solution was developed to estimate the worst-case envelope of the differential crosstalk. The calculated results match the measured peak values well. This worst-case crosstalk estimate allows effective evaluation of the impact of crosstalk within different connectors. The developed method can be effective for analyzing complex aircraft cable assemblies and connectors without requiring extensive knowledge of the assembly procedure.

60.1: Distinguished Paper: A Capacitive Touch Panel for Simultaneous Detection of Non‐Conductive and Conductive Objects

We present a mutual capacitance touch panel with a novel electrode pattern and recognition algorithms for the simultaneous detection of conductive and non‐conductive objects. A prototype of the novel touch panel was fabricated using standard techniques and integrated with a standard touch panel controller to demonstrate its improved usability.

Device/Circuit Mixed-Mode Simulations for Analysis and Design of Projected-Capacitive Touch Sensors

A device/circuit mixed-mode simulation method is proposed to effectively characterize the physical effects of the structure parameters and external noise signals on the sensing performance of projected-capacitive touch sensor devices for physical explanation and optimal design in touch screen applications. With this method, the electrostatic characteristics of the intrinsic capacitive sensor structure were obtained by numerical simulations, and then embedded into the circuit simulation environment to predict the resulted sensing performance. A single-layer mutual capacitance structure sensor device sample was fabricated to verify the simulation method. The related physical mechanisms during the touching procedure were analyzed with the simulation method, which was in agreement with the experimental measurement results.

A 143&lt;formula formulatype="inline"&gt;&lt;tex Notation="TeX"&gt;$\,\times\,$&lt;/tex&gt; &lt;/formula&gt;81 Mutual-Capacitance Touch-Sensing Analog Front-End With Parallel Drive and Differential Sensing Architecture

This paper presents an analog front-end (AFE) IC for mutual capacitance touch sensing with 224 sensor channels in 0.18 $~\mu\hbox{m}$ CMOS with 3.3 V drive voltage. A 32-in touch sensing system and a 70-in one having 37 dB SNR for 1 mm diameter stylus at 240 Hz reporting rate are realized with the AFE. The AFE adopts a parallel drive method to achieve the large format and the high SNR simultaneously. With the parallel drive method, the measured SNRs of the AFE stay almost constant at a higher level regardless of the number of sensor channels, which was impossible by conventional sequential drive methods. A novel differential sensing scheme which enhances the immunity against the noise from a display device is also realized in the AFE. While the coupled LCD is on and off, the differences between the measured SNRs are less than 2 dB.

Concurrent Driving Method with Fast Scan Rate for Large Mutual Capacitance Touch Screens

A novel touch screen control technique is introduced, which scans each frame in two steps of concurrent multichannel driving and differential sensing. The proposed technique substantially increases the scan rate and reduces the ambient noise effectively. It is also extended to a multichip architecture to support excessively large touch screens with great scan rate improvement. The proposed method has been implemented using 0.18 μm CMOS TowerJazz process and tested with FPGA and AFE board connecting a 23-inch touch screen. Experimental results show a scan rate improvement of up to 23.8 times and an SNR improvement of 24.6 dB over the conventional method.

Characterization and Modeling of Multiple Coupled Inductors Based on On-Chip Four-Port Measurement

Because of the compact layout of RFICs and mm-wave ICs, coupling effects among neighboring inductors may seriously degrade circuit performance. This paper analyzes the coupling effects among multiple on-chip spiral inductors and develops a fully scalable compact lumped element model for multiple coupled inductors by using four-port S-parameters. Each single inductor model is directly extracted from four-port S-parameters based on a one-port extraction algorithm. Mutual inductance and coupling capacitance among inductors is extracted and added to the single inductor models. Compared with the measurement, the proposed model can accurately predict the physical behavior of multiple coupled inductors from dc to self-resonant frequencies, as well as EM simulation results. The test structures were fabricated in a commercial 0.18 μm RFCMOS process.

ANALYSIS OF MUTUAL CAPACITANCE AND INDUCTANCE OF PRINTED CIRCUIT

The article analyzes the mutual capacitance and inductance of printed circuit and introduces an evaluation technique for conductor-to-conductor capacitance under electrical connections tracing, the technique based on a multi-layer channel model.

Influence of a Defect Between Closely-Spaced Disks on Their Mutual Capacitance

The influence of a hollow between closely-spaced disks on their mutual capacitance was investigated. It was established that the mutual capacitance of neighboring bodies of a heavily compounded composite material determines their heat-conduction and electrical-conduction properties. It is shown that a hollow between the indicated bodies can be used as a model of a defect of their matrix.

Efficient Multi-Touch Detection Algorithm for Large Touch Screen Panels

Large mutual capacitance touch screen panels (TSP) are susceptible to display and ambient noise. This paper presents a multi-touch detection algorithm using an efficient noise compensation technique for large mutual capacitance TSPs. The sources of noise are presented and analyzed. The algorithm includes the steps to overcome each source of noise. The algorithm begins with a calibration technique to overcome the TSP mutual capacitance variation. The algorithm also overcomes the shadow effect of a hand close to TSP and mutual capacitance variation by dynamic threshold calculations. Time and space filters are also used to filter out ambient noise. The experimental results were used to determine the system parameters to achieve the best performance.

Analysis of the electrical characteristics and structure of Cu-Filled TSV with thermal shock test

The electrical characteristics and failure of a Through-Silicon Via (TSV) were investigated using a thermal shock test. The electrical characteristics, such as resistance (R), self-inductance (Ls), self-capacitance (Cs), and mutual capacitance (Cm), were extracted using a T-equivalent circuit. A cross section of the Cu-filled via was observed by field emission-scanning electron microscopy and the electrical characteristics were measured using a commercial Agilent E4980A LCR Meter. The experimental results revealed R, Ls, Cs, and Cm values of 3.2 mΩ, 29.3 pH, 12 fF, and 0.42 pF, respectively. Cm occurred between the charge-holding TSVs, which changed from 0.42 pF to 0.26 pF due to a permittivity transition of the Cu ion drift. After 1,000 cycles of a thermal shock test, cracks were observed between the opening and around the side of the TSV and Si wafer due to mismatch of the coefficient of thermal expansion between the Cu-plug and Si substrate.

The Research of the Electric Vehicle Wiring Harness Dynamic Crosstalk Based on Statistical Simulation Method

In the actual situation, because of the shock of automobile in the movement process and the wire harness in undulating tube placement is random, leading to the relative position of the wire harness is not fixed, Thus lead to crosstalk value has certain dynamic range. In this paper, obtained the unit mutual inductance and mutual capacitance of wire with insulation layer using mirror image method, simulation and prediction of crosstalk dynamic interval by statistical simulation method, obtain harness near end crosstalk changes range within 3dB at a confidence level of 80%. This provides a reference for EMC design of automotive wiring harness.

Interplay of classical and quantum capacitance in a one-dimensional array of Josephson junctions

Even in the absence of Coulomb interactions phase fluctuations induced by quantum size effects become increasingly important in superconducting nano-structures as the mean level spacing becomes comparable with the bulk superconducting gap. Here we study the role of these fluctuations, termed "quantum capacitance", in the phase diagram of a one-dimensional (1D) ring of ultrasmall Josephson junctions (JJ) at zero temperature by using path integral techniques. Our analysis also includes dissipation due to quasiparticle tunneling and Coulomb interactions through a finite mutual and self capacitance. The resulting phase diagram has several interesting features: A finite quantum capacitance can stabilize superconductivity even in the limit of only a finite mutual-capacitance energy which classically leads to breaking of phase coherence. In the case of vanishing charging effects, relevant in cold atom settings where Coulomb interactions are absent, we show analytically that superfluidity is robust to small quantum finite-size fluctuations and identify the minimum grain size for phase coherence to exist in the array. We have also found that the renormalization group results are in some cases very sensitive to relatively small changes of the instanton fugacity. For instance, a certain combination of capacitances could lead to a non-monotonic dependence of the superconductor-insulator transition on the Josephson coupling.

Supercapacitors have an asymmetric electrode potential and charge due to nonelectrostatic electrolyte interactions

In recent years we have built up a theoretical framework which aims to explain ion specific effects observed in colloids at high salt concentrations. Our approach adds nonelectrostatic ion interactions (ion dispersion energies) alongside the usual electrostatic interactions of the ions.Using these techniques we have explored the impact that ion specificity may have on supercapacitors. Our model uses graphite electrodes at constant potential difference in 1.2M Li salt dissolved in propylene carbonate. For the counterion we used the common battery anions, PF6−, BF4− and ClO4− along with BrO4−, IO4− and Cl−.When nonelectrostatic ionic interactions are included, a potential difference V will not be split symmetrically between the two electrodes. We address two alternative mechanisms for partitioning the potential difference. If the circuit is isolated, then the charge at each electrode must be equal. This defines a potential ψeq≠V/2 at the positive electrode and therefore ψeq−V at the negative. Alternatively, if the circuit is connected to an external environment (ground, defining zero potential), then the state of the system is determined by minimisation of the total free energy, resulting in asymmetric electrode charges as well as potentials. The potentials determined by the two mechanisms are different, ψmin≠ψeq, with both the difference (averaging about 10%) and the direction of the difference between them depending on the ions. The free energy of the system with equalised charge exceeds the minimised free energy by less than 10%. Total free energies follow the Hofmeister series Cl−>PF6−>BF4−>ClO4−>BrO4−>IO4−.Despite the differences in electrode potential and charge under the two potential partitioning mechanisms, the capacitances under both mechanisms are similar. Local electrode capacitances C1=dσ/dψ relative to the positive electrode potential follow the same Hofmeister series as the energy. The energy–capacitance slope is nonlinear, becoming smaller as C1 increases. The Hofmeister series in the differential capacitance C2=dσ/dV relative to the potential difference V swaps BF4−>PF6−.The asymmetry in capacitance between positive and negative electrodes indicates that the capacitance of a two-electrode supercapacitor or battery ought be treated as a two-value quantity rather than as a single value, similar to the matrix of mutual capacitances used in multielectrode devices.

Predicting ion specific capacitances of supercapacitors due to quantum ionic interactions

A new theoretical framework is now available to help explain ion specific (Hofmeister) effects. All measurements in physical chemistry show ion specificity, inexplicable by classical electrostatic theories. These ignore ionic dispersion forces that change ionic adsorption.We explored ion specificity in supercapacitors using a modified Poisson–Boltzmann approach that includes ionic dispersion energies. We have applied ab initio quantum chemical methods to determine required ion sizes and ion polarisabilities. Our model represents graphite electrodes through their optical dielectric spectra. The electrolyte was 1.2M Li salt in propylene carbonate, using the common battery anions, PF6-,BF4- and ClO4- . We also investigated the perhalate series with BrO4- and IO4-.The capacitance C=dσ/dψ was calculated from the predicted electrode surface charge σ of each electrode with potential ψ between electrodes. Compared to the purely electrostatic calculation, the capacitance of a positively charged graphite electrode was enhanced by more than 15%, with PF6- showing >50% increase in capacitance. IO4- provided minimal enhancement. The enhancement is due to adsorption of both anions and cations, driven by ionic dispersion forces. The Hofmeister series in the single-electrode capacitance was PF6->BF4->ClO4->BrO4->IO4- . When the graphite electrode was negatively charged, the perhalates provided almost no enhancement of capacitance, while PF6- and BF4- decreased capacitance by about 15%.Due to the asymmetric impact of nonelectrostatic ion interactions, the capacitances of positive and negative electrodes are not equal. The capacitance of a supercapacitor should therefore be reported as two values rather than one, similar to the matrix of mutual capacitances used in multielectrode devices.

Investigations on the Leakage Effect in Capacitive Sensing

Abstract In the measurement of mutual capacitance between electrodes both the coupling and the leakage effect contribute to the measurement result whereas the leakage mode is dominant in the self capacitance mode. While the coupling effect is mainly defined by the geometry and material distribution close to the electrodes, the root cause or modulation of the leakage effect may be far away from the electrode. It is shown that utilizing both effects may lead to an improvement of an ECT-like scenario reconstruction performance in open environments (e.g. pretouch applications).

Simulation of the Leakage Effect In Capacitive Sensing

Abstract In the measurement of mutual capacitance between electrodes both the coupling and the leakage effect contribute to the measurement result whereas the leakage mode is dominant in the selfcapacitance mode. While the coupling effect is mainly defined by the geometry and material distribution close to the electrodes, the root cause or modulation of the leakage effect may be far away from the electrode. In this paper we demonstrate that the leakage mode concept allows for simulation of 3D problems in 2D. This is useful in applications such as Electrical Capacitance Tomography or object classification as it allows simplifying the computational complexity while providing additional information compared to the classical 2D approach.