Parasitic capacitance

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

Methods and circuits for measuring the conductivity of solutions

Abstract: Improved circuits for measuring the conductivity of a solution confined between two electrodes in a cell compensate for series capacitance and parallel capacitance between the electrodes. A bipolar square-wave signal is applied to the cell. In one embodiment, the current through the cell is measured by an op-amp in current-to-voltage converter configuration. A feedback resistance employed with the op-amp in a feedback loop is controlled to a low value to ensure that the parallel capacitance is fully charged during an initial portion of each half-cycle of the drive signal. The feedback resistance is then selected so that the gain of the feedback loop is responsive to the range of the resistivity of the solution, and the measurement is made. In a further embodiment, charge proportional to the current through the cell is integrated across the op-amp, and the rate of charge is measured by measuring the time required to integrate the current to a predetermined level, and used to determine the resistivity of the solution. In this embodiment, the parallel capacitance is fully charged before each integration period begins. The voltage developed across the series capacitance is constant and can be compensated mathematically.

Inverter circuit for use with discharge tube

Abstract: An inverter circuit for use with a discharge tube or lamp such as a cold-cathode fluorescent lamp, a hot-cathode fluorescent lamp, a mercury arc lamp, a metal halide lamp, a neon lamp or the like is provided. The secondary side circuit of a step-up transformer used in the inverter circuit is constructed as a high frequency power supply circuit and a parasitic or stray capacitance produced in the secondary side circuit of the step-up transformer is utilized as a portion or component of a resonance circuit consisting of an inductive ballast or the inductive output of a leakage flux type step-up transformer and the parasitic capacitance.

Common-Mode Noise Reduction for Power Factor Correction Circuit With Parasitic Capacitance Cancellation

Abstract: In this paper, a method using negative capacitance to cancel the common-mode (CM) parasitic capacitance of boost power factor correction (PFC) converters is proposed. Both the theoretical analysis and experiments show that the proposed method is very easy to implement and very efficient to reduce CM noise.

Capacitive electrode system for detecting open solder joints in printed circuit assemblies

Abstract: Disclosed is a system that determines whether input and output leads of semiconductor components are present and properly soldered to a printed circuit board. The system includes a signal source which is connected to a wiring trace on the printed circuit board, which is soldered to the lead being tested. A capacitive test probe is placed on top of the component and connected to a capacitance measuring device. The signal source signal is capacitively coupled through the lead of the integrated circuit package being tested to the capacitive test probe, so if a predetermined capacitance is measured by the capacitance measuring device, the lead is connected to the circuit assembly. As the capacitances being measured are small, the capacitive test probe may include an amplifier, a shield or a buffer circuit to reduce stray capacitance.

Systems for an electrostatic stylus within a capacitive touch sensor

Abstract: Systems are described for transmitting and receiving signals in an active stylus for a capacitive touch sensor, for which the systems have at least one circuit for receiving a current from an electrode and for transmitting a voltage onto the electrode. The systems include components for receiving the current in a receiving mode, a switch, and a switchmode power supply circuit having at least a transformer and a diode, for which the diode is coupled to the transformer. In a transmission mode, there is means for electrically isolating at least some of the components configured for receiving the current in the receiving mode from the voltage formed across the stray capacitance. In the receiving mode, there is a means for electrically isolating at least some of the components configured for receiving the current in the receiving mode from an inductance of the transformer in the switchmode power supply circuit.