Nonlinear properties of electrometric dynamic capacitors

IEEE Transactions on Instrumentation and Measurement, 2003

IEEE Transactions on Instrumentation and Measurement, 2010

1990

A technique for measuring low-frequency and low-level capacitance variations is proposed. It is based on a lock-in detection circuit with a feedback loop, containing an integrator and a modulator for zeroing the capacitance mean value. This approach provides a good signal-to-noise ratio and high sensitivity. Capacitance variations can be on the order of 100 p.p.m. of the mean value, and the frequency of the variations can be as low as 0.1 Hz. Stray capacitances and the drift due to the environmental conditions are automatically compensated. The measurement technique, experimental apparatus, and initial results are described. Small variations, about 10 fF, have been measured in the presence of 10-pF mean value.>

IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2010

The harmonic distortion in ferroelectric capacitors is measured using a parallel resonant circuit approach. The measured results have been compared with simulated results based on the nonlinearities in capacitance versus the voltage characteristics of ferroelectric capacitors.

In this work, the charge and discharge cycle of a supercapacitor was examined from which it was observed that the capacitance of the supercapacitor changes while charging and discharging. So also, the capacitance was observed to vary with frequency when frequency response analysis was performed on it.

Chaos Theory - Modeling, Simulation and Applications - Selected Papers from the 3rd Chaotic Modeling and Simulation International Conference (CHAOS2010), 2011

We briefly analyze and demonstrate several nonlinear signal generators, according to the principles proposed in . These systems apparently should not oscillate, because they include only capacitors in the positive feedback loops. However, the design attempted to make use of the well-known parasitic elements of the capacitors to create a selective feedback loop with physical capacitors only. The use of the resonant (piezoelectric) load adds a new potential mode of oscillation. The design aimed to make achievable as many as possible frequency points where oscillation modes ay exist, against the rather common belief that a single oscillation mode can be supported at one time in electronic oscillators. For this purpose, variable, independent gains have been provided to the positive feedback loops that correspond to the various modes in the circuit. We describe the schemes, briefly analyze their behavior, show simulation and experimental results, and discuss potential uses. The paper is largely based on [1].

IEEE Open Journal of Power Electronics

Multilayer Ceramic Capacitors (MLCCs) are of paramount importance in electronics and ferroelectric Class II dielectrics enable outstanding energy-density values. However, the non-linear dielectric constant and associated low-frequency large-signal excitation losses of Class II MLCCs may cause critical overheating. A peak-charge based Steinmetz loss model entitled iGSE-C Q is known in literature and allows to accurately calculate MLCC low-frequency large-signal excitation losses under various operating conditions including biased and non-sinusoidal excitation voltage waveforms. Such a macroscopic iGSE-C Q model, however, is inherently limited to a specific MLCC, and in contrast to Steinmetz loss modeling for ferromagnetic inductor cores, the losses of other devices employing the same dielectric material cannot be predicted. Recent literature therefore proposed a microscopic and/or material specific MLCC Steinmetz Model entitled iGSE-C D which allows to calculate the losses of any MLCC of the same dielectric material based upon just a single set of Steinmetz parameters. However, due to the lack of information on the internal device geometry, the iGSE-C D could be verified only indirectly so far by means of a loss normalization based on the device capacitance and rated voltage. In this paper, we demonstrate the feasibility of a microscopic iGSE-C D MLCC loss model enabled by manufacturer data on the internal capacitor structure. The iGSE-C D is verified for two different MLCC series employing a conventional X7R dielectric and a novel Hiteca (with reduced non-linearity) Class II dielectric material with loss estimation error below 22%. This error results due to component tolerances and is acceptable, especially when compared to the loss calculation based on the datasheet information which can be off by up to a factor of ten. The analysis of the Hiteca dielectric reveals a frequency behavior different to the X7R material, and is discussed in the Appendix of this paper.

Measurement Techniques, 1978

Of the high-resistance modulators used in instruments for measuring small currents with input-signal transformation, the dynamic capacitor [I] is closest in its characteristics to an ideal modulator. However, the serious drawbacks of the dynamic capacitor are the low modulation frequency (usually not greater than 500 Hz), due to the mechanical oscillatory system, and also the re]atively large dimensions and mass. Below we present the results of investigations of a semiconductor analog of the dynamic capacitor, in which the capacitance of a metal-oxide-semiconductor (MOS) surface varactor structure [2] is varied by the action of light. The possibility of developing an opoptoelectronic high-resistance modulator of this type is determined by at least two factors: first, by the availability of miniature semiconductor light radiators (light diodes) with fairly high output power [3], and second, by the possibility of constructing MOS photovaractors in which the resistance of the oxide layer is fairly high, while on .the plates of the surface capacitance, which varies under the action of light, one can induce a charge proportional to the modulated voltage. The specimens of an optoelectronir dynamic capacitor obtained combine a light diode and an MOS photovaractor in a single mounting of diameter 12 mm and height 17 mm.

IEEE/ACES International Conference on Wireless Communications and Applied Computational Electromagnetics, 2005., 2005

MEMS technology is growing rapidly in RF field, because of the advantage over p-i-n diode or FET switches. An accurate knowledge of the electromagnetic field evolution around a moving or rotating body is very important for the design, optimization and realization of new optical devices or microwave devices, such as the RF-MEMS structures. We propose the numerical technique based on the finite-difference time-domain method with an adaptive implementation of grid generation. This simulation method is applied to the analysis of a two-dimensional MEMS variable capacitor with accelerated motions. The acceleration of the MEMS capacitor is derived under the equilibrium between the spring force and electrical force. Using this acceleration, the numerical results that express the relationship between the acceleration of the plates and the spring constant and the mass of the plates are shown.