Equivalent Parallel Capacitance Research Articles

Discrimination of Inner Injury of Korla Fragrant Pear Based on Multi-Electrical Parameters.

Inner-injury fragrant pears are easily prone to rot during storage. Discriminating inner injury in the Korla fragrant pear from the normal pear is difficult as the flesh may be injured while the peel of the fruit remains intact. This study demonstrated the recognition of inner-injury pears based on their electric characteristics to pick out the inner-injury pears before storage. The electrical parameters parallel equivalent capacitance, quality factor, parallel equivalent inductance, parallel equivalent resistance, complex impedance, and phase angle were measured using the fruit electrical characteristic detection instrument. Principal component analysis and correlation analysis were used to determine the characteristic parameters, connected with the qualitative value of the fragrant pear to establish three discrimination models. When the measurement frequency was 100 kHz, compared with the Naïve Bayes and K-nearest neighbor models, the Support Vector Machine model with the characteristic parameters of quality factor, parallel equivalent resistance, and phase angle performed best. The recognition accuracy of the test set was 92.00%, the precision was 92.41%, the recall was 97.33%, and the F1 score was 0.95. Therefore, the electrical characteristic technique effectively detected the inner injury of fragrant pears and provided a new way to distinguish the inner injury of fruits.

Non-destructive quality assessment method for Korla fragrant pears based on electrical properties and adaptive neural-fuzzy inference system

This study aimed to achieve the rapid and non-destructive quality assessment of Korla fragrant pears, thereby maximising the value of damaged pears and improving the market supply–demand balance. The electrical characteristics of damaged Korla fragrant pears were measured using a fruit electrical property detector and the trends in the quality of the fragrant pears within their shelf life were analysed. The quality of damaged Korla fragrant pears was predicted by using an adaptive neural-fuzzy inference system (ANFIS). Electrical properties were used as inputs to the system and quality was the output of the system. A total of eight functional models with different degrees of membership were constructed and the optimal one was selected. The results demonstrated that the equivalent parallel capacitance (Cp) of the damaged Korla fragrant pears increased gradually throughout their shelf life, while equivalent parallel resistance (Rp) and complex impedance (Z) decreased. Additionally, the green–red difference (a*) increased gradually, while hardness and soluble solid content (SSC) decreased continuously. Based on the combination of electrical properties and the ANFIS, gbellmf was the optimal model to determine the SSC of the damaged Korla fragrant pears (R2 = 0.9123) and gaussmf was the optimal model to determine the hardness and a* of the damaged Korla fragrant pears (R2 = 0.9112 and 0.8853, respectively). It was concluded that the combined use of electrical properties and the ANFIS method enabled the successful quality assessment of fragrant pears. This approach was conducive to facilitating the optimisation and updating of non-destructive quality assessment technologies for fragrant pears, promoting quality and efficiency improvement in the fragrant pear industry.

Frequency Characteristics of Power Transformer for Isolated DC-DC Converter

The operational frequency of a transformer is an important factor in the configuration of an isolated DC-DC converter. However, discussions of this frequency are inadequate. This study focuses on the frequency characteristics of the transformers. The frequency characteristics of the impedance and loss of the transformer were obtained to explain their fundamental attributes. When a transformer is employed in a power electronic transformer (PET), the waveform of the voltage is rectangular. The loss under this waveform was obtained in order to observe its characteristics. Furthermore, the problems with the isolated DC-DC converter are explained. The natural frequency, composed of leakage inductance and equivalent-parallel capacitance, determines the performance of the isolated DC-DC converter. When the operational frequency of the isolated DC-DC converter is below its natural frequency, the loss increases under the no-load or light-load conditions. This increase in the loss is caused by the current, which contains the natural frequency of the transformer owing to the ringing.

Rapid detection of catechins during black tea fermentation based on electrical properties and chemometrics

Catechins are important to evaluate the quality of black tea. In this study, a quantitative prediction model was established based on the measurement of electrical properties and a chemometrics method to detect the catechin content in fermented black tea. The effects of different preprocessing, variable screening methods, and nonlinear algorithms on the model were studied. Results show that the electrical parameters most sensitive to catechin content are equivalent parallel capacitance, loss factor, and reactance mainly at low frequencies (0.05–0.1 kHz). Normalization processing (Zscore), variable combinations' population analysis and the iterative retained information variable algorithm (VCPA-IRIV), and the nonlinear intelligent algorithm random forest (RF) can all effectively improve the performance of a catechin prediction model. In the VCPA-IRIV-RF model, the number of introduced variables was reduced from 162 to 9 with a compression ratio of 94.5%; the root mean square error of prediction and the root mean square error of validation of this model were only 0.269 and 0.214, respectively. The predictive correlation coefficient, correlation coefficient of calibration, and residual predictive deviation increased to 0.988, 0.994, and 5.47, respectively, indicating the good performance of the model. The rapid and nondestructive determination of catechin content in black tea fermentation using a method to detect the electrical properties seems to be practical.

Modeling and Increasing the High-Frequency Impedance of Single-Layer Mn-Zn Ferrite Toroidal Inductors With Electromagnetic Analysis

This article first investigates the equivalent parallel capacitance (EPC) and equivalent parallel resistance (EPR) due to the electromagnetic field inside the Mn-Zn ferrite toroidal cores of the inductors with a single-layer winding based on electromagnetic theory. From the investigation, the effects of core's cross-sectional shape and number of winding turns on the EPC and EPR are explored. A stacked core structure was studied to increase the inductor's high-frequency (HF) impedance for electromagnetic interference suppression. The article further investigated the EPC due to the electric field energy in the space between winding turns, and between the winding turns and the core. The effect of the number of winding turns on total EPC was also explored. The technique to achieve high HF impedance was proposed with an optimal number of winding turns. Both simulations and experiments were conducted to validate the developed theory and techniques.

A nondestructive testing method for soluble solid content in Korla fragrant pears based on electrical properties and artificial neural network.

The detection of soluble solid content in Korla fragrant pear is a destructive and time‐consuming endeavor. In effort to remedy this, a nondestructive testing method based on electrical properties and artificial neural network was established in this study. Specifically, variations of electrical properties (e.g., equivalent parallel capacitance, quality factor, loss factor, equivalent parallel resistance, complex impedance, and equivalent parallel inductance) of Korla fragrant pears with accumulated temperature were tested using a workbench developed by ourselves. After that the characteristic variables of electrical properties were constructed by principal component analysis (PCA). In addition, three models were constructed to predict SSC in Korla fragrant pears based on the characteristic variables: general regression neural network (GRNN), back‐propagation neural network (BPNN), and adaptive network fuzzy inference system (ANFIS). The results indicated that the GRNN model has the best prediction effects of SSC (R 2 = 0.9743, RMSE = 0.2584), superior to that of the BPNN and ANFIS models. Results facilitate a successful, alternative application for rapid assessment of SSC of the maturation stage Korla fragrant pear.

Structure, electric and dielectric properties of PbFe1/3Ti1/3W1/3O3 single perovskite compound

A conventional solid-state method was used to prepare Pb(Fe1/3Ti1/3W1/3)O3 single perovskite material. The sample sintered at 900?C was studied by XRD and after Rietveld refinement the orthorhombic structure with Pbam space group was confirmed. The FTIR frequency bands corresponding to Pb-O, Ti-O, O-lattice, W- O-W and Fe-O stretching vibrations together with the XRD data also confirmed that Fe2+ and W6+ ions are incorporated in the structure and most probably substituted Ti4+ ions at the B site of the perovskite ABO3 structure. The average grain size of the perovskite ceramics, estimated from SEM micrograph, was 1 to 2 ?m. Variation of dielectric properties and AC conductivity with frequency and temperature revealed that the material had semiconducting nature and negative temperature coefficient of resistance (NTCR). The Nyquist plots were modelled with an equivalent circuit consisted of parallel capacitance, resistance and constant phase element corresponding to the grains (bulk) and grain boundaries. It was observed that grain resistance (Rb) of the sample decreases with the rise of temperature, which supports the NTCR behaviour. The semi-circular arcs of the Nyquist and Cole-Cole plots confirm the semiconducting nature of the sample.

Equivalent Parallel Capacitance Cancellation of Common Mode Chokes Using Negative Impedance Converter for Common Mode Noise Reduction

Equivalent Parallel Capacitance Cancellation of Common Mode Chokes Using Negative Impedance Converter for Common Mode Noise Reduction

Mathematical correlations between selected quality attributes and electrical parameters of apple juice

This study aimed at determining mathematical correlations between total soluble solids (TSS) content, content of organic acids (OA), pH value (pH), and density (D) of apple juice and their electrical conductance and capacitance using the RCC equivalent model of food products (resistance and capacitance). Linear correlations were determined between total soluble solids content, organic acids content, and density of aqueous solutions of the apple juice concentrate and values of their impedance (Z) and admittance (Y) in a frequency from 100 to 100,000 Hz; and their equivalent parallel capacitance (Cp) at frequencies of 100, 120, and 1,000 Hz; as well as their equivalent series capacitance (Cs) at frequency of 100,000 Hz. It was concluded that the correlations obtained from grounds for future studies on the development of a method for detecting adulterations (through watering) of apple juices based on measurements of electrical parameters, including the impedance or admittance. Practical applications Due to increasing requirements for the food quality and safety, as well as an increased demand for apple juice, many research works on the development of modern techniques for identification, detection of adulteration, and predicting its quality have been undertaken. Taking this into account, the research was undertaken to determine the mathematical relationships between selected quality attributes of apple juice (TSS, organic acids, pH, density) and their electrical parameters. The obtained significant mathematical correlations (r > 0.87 and p ≤ 0.01), indicate that the quality of apple juices can be predicted on the basis of simple impedance and admittance measurements at f = 100 Hz. These dependencies also justify the use of the RCC electric model for predicting the basic attributes of the apple juice quality, which in the future will make possible the development of a method for detecting its adulteration with water. On this basis, a relevant patent has been yet obtained.

Winding Scheme With Fractional Layer for Differential-Mode Toroidal Inductor

This paper studies how an outer fractional winding can impact the equivalent parallel capacitance (EPC) of a differential-mode inductor, which is a critical passive component in a power electronic converter to combat with electromagnetic noises, and proposes a winding scheme that can reduce EPC and increase inductance, achieving both high-frequency filtering performance and high density. To perform these studies, a comprehensive layer capacitance model based on energy equivalence principle is established, which decouples EPC contribution among three elements, i.e., outer fraction layer, layer-to-layer, and layer-to-core, thus enabling the impact evaluation of different winding elements and schemes. Experimental comparison results have validated the accuracy of this EPC model and excellent performance of the proposed winding scheme with EPC reduction by 4×. It reveals that contrary to previous understanding, the inverse winding, in fact, is more effective for EPC reduction than the direct winding in most of the partial layer scenarios, and that by using this scheme with the outer fraction layer, 45% higher inductance and slightly less EPC can be achieved, compared to the single-layer winding design.

Imbalance Current Analysis and Its Suppression Methodology for Parallel SiC MOSFETs with Aid of a Differential Mode Choke

Parallel connection of silicon carbide (SiC) MOSFETs is a cost-effective solution for high-capacity power converters. However, transient imbalance current, during turn- on and - off processes, challenges the safety and stability of parallel SiC MOSFETs. In this paper, considering the impact factors of device parameters, circuit parasitics, and junction temperatures, in-depth mathematical models are created to reveal the electrothermal mechanisms of the imbalance current. Moreover, with the incorporation of a differential mode choke (DMC), an effective approach is proposed to suppress the imbalance current among parallel SiC MOSFETs. Physics concepts, operation principles, and design guidelines of the DMC-based suppression method are fully presented. Besides, to reduce the equivalent leakage inductance and equivalent parallel capacitance of the DMC, winding patterns of the DMC are comparatively studied and optimized to suppress turn- off over-voltage and switching ringing. Concerning the influence of winding patterns, load currents, gate resistances, and junction temperatures, experimental results are comprehensively demonstrated to confirm the validity of theoretical models and the function of the proposed DMC-based suppression method. It is turned out the low-cost DMC is easy to design and utilize without complex feedback circuits or control schemes, which is a cost-effective component to guarantee consistent and synchronous on–off trajectories of parallel SiC MOSFETs.

Correlations between selected quality and electrical parameters of musts from stone and pome fruits

The aim of the research was to determine a correlation between the basic physicochemical quality parameters of musts from selected stone (plums, cherries) and pome (apples, pears) fruits and their electrical parameters—conductivity and capacitance ones. The results of the measurements and their statistical analysis showed strong correlations (p ≤ 0.01) between the Z (impedance) and Y (admittance) values measured at the frequency of 100 Hz and acidity values of pome and stone fruits as well as between their Z and pH values (p ≤ 0.05). High correlation coefficients (from − 0.765 to − 0.874) were also obtained between the Z and Y values and density and ash content as well as between Y and pH values (− 0.870) of the analyzed musts. They also showed strong correlations (p ≤ 0.01) between the Cs (series equivalent capacitance) and Cp (parallel equivalent capacitance) values measured at f = 100 Hz and pectin content and acidity as well as between Cp values measured at f = 100 kHz and f = 100 Hz (p ≤ 0.05) and contents of dry matter and ash, viscosity, and pH values of the studied musts. It was found that the results indicate the possibility of describing these correlations with mathematical equations, which in the future may form grounds for the development of a novel, rapid, and simple method for quality assessment of naturally cloudy juices, as an alternative to the standard methods.

Folded Feedthrough Multilayer Ceramic Capacitor EMI Filter

A chip three-terminal multilayer ceramic capacitor (MLCC) electromagnetic interference (EMI) filter with a good stopband characteristic was designed. Parasitic effects on the internal signal electrode, including equivalent parallel capacitance and series inductance, were utilized to form a tunable transmission zero in stopband by folding the traditional chip three-terminal feedthrough MLCC. Based on a network theory, an equivalent circuit was constructed in ADS to explain the operating mechanism of the proposed structure. The ADS and HFSS were utilized to simulate the proposed structure, and the measured results corresponded to the simulation results. The structure of the proposed EMI filter presents a new method to improve the stopband characteristic of capacitor EMI filters.

Calibrated complex impedance of CHO cells and E. coli bacteria at GHz frequencies using scanning microwave microscopy

The application of scanning microwave microscopy (SMM) to extract calibrated electrical properties of cells and bacteria in air is presented. From the S11 images, after calibration, complex impedance and admittance images of Chinese hamster ovary cells and E. coli bacteria deposited on a silicon substrate have been obtained. The broadband capabilities of SMM have been used to characterize the bio-samples between 2 GHz and 20 GHz. The resulting calibrated cell and bacteria admittance at 19 GHz were Ycell = 185 μS + j285 μS and Ybacteria = 3 μS + j20 μS, respectively. A combined circuitry-3D finite element method EMPro model has been developed and used to investigate the frequency response of the complex impedance and admittance of the SMM setup. Based on a proposed parallel resistance–capacitance model, the equivalent conductance and parallel capacitance of the cells and bacteria were obtained from the SMM images. The influence of humidity and frequency on the cell conductance was experimentally studied. To compare the cell conductance with bulk water properties, we measured the imaginary part of the bulk water loss with a dielectric probe kit in the same frequency range resulting in a high level of agreement.

Modeling small-signal response of GaN-based metal-insulator-semiconductor high electron mobility transistor gate stack in spill-over regime: Effect of barrier resistance and interface states

We provide theoretical and simulation analysis of the small signal response of SiO2/AlGaN/GaN metal insulator semiconductor (MIS) capacitors from depletion to spill over region, where the AlGaN/SiO2 interface is accumulated with free electrons. A lumped element model of the gate stack, including the response of traps at the III-N/dielectric interface, is proposed and represented in terms of equivalent parallel capacitance, Cp, and conductance, Gp. Cp -voltage and Gp -voltage dependences are modelled taking into account bias dependent AlGaN barrier dynamic resistance Rbr and the effective channel resistance. In particular, in the spill-over region, the drop of Cp with the frequency increase can be explained even without taking into account the response of interface traps, solely by considering the intrinsic response of the gate stack (i.e., no trap effects) and the decrease of Rbr with the applied forward bias. Furthermore, we show the limitations of the conductance method for the evaluation of the density of interface traps, Dit, from the Gp/ω vs. angular frequency ω curves. A peak in Gp/ω vs. ω occurs even without traps, merely due to the intrinsic frequency response of gate stack. Moreover, the amplitude of the Gp/ω vs. ω peak saturates at high Dit, which can lead to underestimation of Dit. Understanding the complex interplay between the intrinsic gate stack response and the effect of interface traps is relevant for the development of normally on and normally off MIS high electron mobility transistors with stable threshold voltage.

Techniques for Improving the High-Frequency Performance of the Planar CM EMI Filter

This paper has developed two techniques to reduce the parasitic parameters and improve the high-frequency performance of the planar integrated electromagnetic interference (EMI) filter. First, each developed technique has been analyzed, respectively, then the performance of an EMI filter with both the developed techniques has been researched. The research contents are as follows. 1) Analyzing the improvement of the equivalent parallel capacitance (EPC) for a common mode (CM) EMI filter by two CM windings overlapped and interleaved layout. The EPC of the integrated EMI filter is about 14% of the reference EMI filter. 2) Analyzing the improvement of the equivalent series inductance (ESL) in the parallel branch for a CM EMI filter by each CM winding coupled with two ground winding layers. The resonance frequency brought by ESL is shifted to a higher frequency. At 30 MHz, the insertion loss is increased by 45 dB compared with the reference. In the mean time, the structure is equivalent to a two-stage L-type low-pass filter, which can largely increase the high-frequency attenuation compared with the one-stage L-type low-pass filter for the reference one. (3) Researching the performance of an EMI filter with both the proposed techniques. The developed EMI filter can not only decrease the EPC, but also reduce the negative effect of ESL. The developed EMI filter improves the high-frequency performance dramatically compared with the EMI filter with only one of the developed techniques. In the mean time, the differential mode (DM) capacitor is formed by the two overlapped and interleaved windings, and does not need an extra lumped DM capacitor. Therefore, CM inductors, CM capacitors, and DM capacitors can be integrated in the overlapped and interleaved L-C winding structure, so miniaturized EMI filter can be realized. The experiment results indicate effectiveness of the developed integrated EMI filters, and the cost and complexity is the same as the reference EMI filter.

Design and validation of low-pass filter using microstrip stub and defected ground structure

In this article, a compact microstrip low-pass filter using conventional elliptical headed dumbbell-shaped defected ground structure (DGS) is presented.The proposed structure with main dimension parameters has been analyzed as a design guide, which can be used to fabricate the filter in future. The H-shape open stub increases the equivalent parallel capacitance to improve the out-band suppression. The proposed LPF shows low cut-off frequency response, low insertion loss, sharp transition, and fairly good rejection in stop band. For the five-array DGS filter, including stubs provides the rejection in stop band from 2.8 GHz to higher frequencies. DGSs have shown increasing potential for implementation in different applications: microwave integrated circuit (MIC), monolithic microwave integrated circuit (MMIC), and radio frequency integrated circuit (RFIC). They provide sharp, distinct electromagnetic band-gap, and high slow wave factor, which lead to smaller size circuits and takes lots of engineering challenges. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:571–573, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27361

A miniature and low‐power 24 GHz CMOS VCO using tunable lc source‐degeneration and transformer feedback techniques for automotive radars

AbstractA 24 GHz voltage‐controlled oscillator (VCO) using tunable LC source‐degeneration and transformer‐feedback techniques for automotive radar systems is demonstrated in a standard 0.18 μm CMOS process. The tunable LC source‐degeneration is made by adding two tunable LC tanks, which use varactors as the needed capacitors, to the source terminals of the cross‐coupled transistor pair of the VCO. Compared with the traditional cross‐coupled transistor pair, the equivalent parallel capacitance (CEQ) can be significantly decreased. This in turn results in the increase of both the operation frequency and the tuning range of the VCO. In addition, a differential‐to‐differential spiral‐transformer‐shaped layout is adopted to realize the needed four inductors, that is, the two drain inductors and the two source inductors. This in turn results in the layout area and the power consumption of the VCO is minimized. The VCO core draws 7.2 mA current from a 0.85 V power supply, that is, it only consumes 6.12 mW. The VCO achieves a wide tuning range of 3.03 GHz, from 22.32 to 25.35 GHz. In addition, the VCO achieves a phase noise of −103 dBc/Hz at 1 MHz offset from 24 GHz. The corresponding figure‐of‐merit is −182.7 dBc/Hz, one of the best results ever reported for a K‐band CMOS VCO. The core circuit occupies a chip area of only 0.36 × 0.56 mm2, that is, 0.202 mm2. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2553–2558, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27143

A 28/56 GHz dual-band CMOS VCO using reversely tunable LC source degeneration and the push-push technique

A 28/56 GHz dual-band voltage-controlled oscillator (VCO) using reversely tunable LC source-degeneration and the push–push technique is demonstrated in a standard 0.13 μm CMOS process. The reversely tunable LC source degeneration is made by adding two reversely tunable LC tanks, which use varactors as the needed capacitors, to the source terminals of the cross-coupled transistor pair of the VCO. Compared with the traditional cross-coupled transistor pair, the proposed one significantly decreases the equivalent parallel capacitance (CEQ). This in turn results in the increase of both the operation frequency and the tuning range of the VCO. The VCO core draws 10.48 mA current from a 0.9 V power supply, that is, it only consumes 9.43 mW. The VCO achieves a tuning range of 27.7–28.7 GHz at the fundamental port and a tuning range of 55.176–58.124 GHz at the push–push port. In addition, at the fundamental port, the VCO achieves a low phase noise of −120.46 dBc/Hz at 1-MHz offset from 28.19 GHz. The corresponding figure-of-merit is −199.7 dBc/Hz, one of the best results ever reported for a K-band or Ka-band CMOS VCO. The circuit occupies a chip area of 0.724 × 0.681 mm2, that is, 0.493 mm2, including the test pads. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2272–2278, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27046

Possibilities of Using Electrical Parameters of Milk for Assessing its Adulteration with Water

This manuscript presents results of a research aimed at conducting a statistical analysis of correlation between the percentage addition of water to milk and its electrical parameters, which are used to determine the degree of milk dilution and the level of milk adulteration with water. The results of milk conductivity parameters analysed in the study showed admittance and conductance to decrease systematically with water addition from ca. 10.8 to 7.8 mS. In contrast, impedance and resistance values were observed to increase from ca. 91 to 128 Ω. Results of the measurements of capacitance parameters showed that with an increasing content of distilled water in milk the value of equivalent parallel capacitance was decreasing from 1.4 to 0.65 μF. In turn, along with water content increasing to 15%, the value of equivalent series capacitance was increased from 212 to 237 μF. Still, at water content of milk exceeding 15%, the value of that parameter remained unchanged. The statistical analysis demonstrated a close linear correlation (0.989 ≤ r ≤ 0.998) between the percentage of water added to the milk and electrical parameters of impedance, resistance, admittance, conductance, as well as equivalent parallel capacitance of milk.