Parasitic capacitance

About: Parasitic capacitance is a research topic. Over the lifetime, 10029 publications have been published within this topic receiving 110331 citations.

A sensitive differential capacitance to voltage converter for sensor applications

Abstract: There is a need for capacitance to voltage converters (CVC's) for differential capacitive sensors like pressure sensors and accelerometers which can measure both statically and dynamically. A suitable CVC is described in this paper. The CVC proposed is based on a symmetrical structure containing two half ac bridges, is intrinsically immune to parasitic capacitances and resistances, is capable of detecting capacitance changes from dc up to at least 10 kHz, is able to handle both single and differential capacitances, and can easily be realized with discrete components. Its sensitivity is very high: detectable capacitance changes of the order of 2 ppm of the nominal value (24 aF with respect to a nominal capacitance of 12 pF) result in a measured output voltage of 1.5 mV. However, due to drift the absolute accuracy and resolution of the CVC is limited to 3.5 ppm. A differential accelerometer for biomedical purposes was connected to the CVC and showed a sensitivity of 4 V/g. The measured rms output voltage noise in the frequency range of 2-50 Hz is 750 /spl mu/V, resulting in a signal to noise ratio of 75 dB at an acceleration of 1 g in the frequency range of 2-50 Hz.

Common mode voltage in case of transformerless PV inverters connected to the grid

Abstract: For safety reasons grid connected PV systems include galvanic isolation. In case of transformerless inverters, the leakage ground current through the parasitic capacitance of the PV panels, can reach very high values. A common-mode model based on analytical approach is introduced, used to predict the common-mode behavior, at frequencies lower than 50 kHz, of the selected topologies and to explain the influence of system imbalance on the leakage current. It will be demonstrated that the neutral inductance has a crucial influence on the leakage current. Finally experimental results will be shown for the NPC topology, emphasizing the low leakage current for the case of a grid connection without galvanic isolation.

Improving the Characteristics of integrated EMI filters by embedded conductive Layers

Abstract: Discrete electromagnetic interference (EMI) filters have been used for power electronics converters to attenuate switching noise and meet EMI standards for many years. Because of the unavoidable structural parasitic parameters of the discrete filter components, such as equivalent parallel capacitance (EPC) of inductors and equivalent series inductance (ESL) of capacitors, the effective frequency range of the discrete filter is normally limited. Aiming at improving high frequency performance and reducing size and profile, the integrated EMI filter structure has been proposed based on advanced integration and packaging technologies , . Some improvements have been made but further progress is limited by EPCs of the filter inductors, which is restricted by dimension, size and physical structure. In this paper, a new structural winding capacitance cancellation method for inductors is proposed. Other than trying to reduce EPCs, a conductive ground layer is embedded in the planar inductor windings and the structural capacitance between the inductor winding and this embedded layer is utilized to cancel the parasitic winding capacitance. In order to obtain the best cancellation effect, the structural winding capacitance model of the planar spiral winding structure is given and the equivalent circuit is derived. The design methodology of the layout and area of the embedded ground layer is presented. Applying this method, an improved integrated EMI filter is designed and constructed. The experimental results show that the embedded conductive layer can effectively cancel the parasitic winding capacitance, hence ideal inductor characteristics can be obtained. With the help of this embedded conductive layer, the improved EMI filter has much smaller volume and profile and much better characteristics over a wide frequency range, compared to the former integrated EMI filter and the discrete EMI filter.

Leakage current evaluation of a singlephase transformerless PV inverter connected to the grid

Abstract: For low-power grid connected applications a single phase converter can be used. In PV applications it is possible to remove the transformer in the inverter in order to reduce losses, costs and size. Galvanic connection of the grid and the DC sources in transformerless systems can introduce additional leakage currents due to the earth parasitic capacitance. This currents increase conducted and radiated electromagnetic emissions, harmonics injected in the utility grid and losses. Amplitude and spectrum of leakage current depends on the converter topology, on the switching strategy and on the resonant circuit formed by the ground capacitance, the converter, the AC filter and the grid. In this paper, the leakage current in a 1.5 kW PV installation is measured under different conditions and used to build simulation model. The installation includes a string of sixteen PV panel, a full bridge inverter and a LCL filter. This model allows studying the influence of the harmonics injected by the inverter on the leakage current.

Transient analysis of MOS transistors

Abstract: Two methods have been developed for analyzing MOS transients. One method is analytical and uses the quasi-static approximation. It is useful when the stray capacitance dominates MOS transient performance. The second method is numerical and uses a new boundary value method which can be applied over a wide range of operating speeds. This method includes secondary effects and nonuniform doping, The validity and limits for both methods are verified by comparison with measurements. Transit-time delay and charge-pumping effects are also analyzed using the numerical method. Examples of short-channel behavior of MOS devices are included.