What is the parasitic effect of the capacitor What is the parasitic effect of the capacitor

A capacitor is an element that stores electric quantity and electric energy (electric potential energy). One conductor is surrounded by another conductor, or the electric field lines emitted by one conductor are all terminated in the conductor system of the other conductor, which is called a capacitor, including paper capacitors, mica capacitors, air capacitors, tantalum capacitors, thin film capacitors (polyethylene film, polystyrene film, polypropylene film, etc.), aluminum capacitors and ceramic capacitors.

Capacitors play an important role in tuning, bypass, coupling, filtering and other circuits. It is used in the tuning circuit of transistor radio and the coupling circuit and bypass circuit of color TV.

With the rapid development of electronic information technology, the updating speed of digital electronic products is getting faster and faster. The production and sales of consumer electronic products mainly including flat-panel TVs (LCD and PDP), notebook computers, digital cameras and other products continue to grow, driving the growth of the capacitor industry.

Parasitic means that the capacitance is not designed in that place, but there is always mutual capacitance between the wires, which is like parasitic capacitance between the wires, so it is called parasitic capacitance, also known as stray capacitance.

Parasitic capacitance generally refers to the capacitance characteristics of inductors, resistors, chip pins, etc. under high frequency conditions. In fact, a resistor is equivalent to a capacitor, an inductor, and a series connection of a resistor. It is not obvious at low frequency, but the equivalent value will increase at high frequency, which cannot be ignored. We should take it into account in the calculation. ESL is the equivalent inductance and ESR is the equivalent resistance. Whether it is resistance, capacitance, inductance, diode, triode, MOS transistor, or IC, we should consider their equivalent capacitance and inductance in the case of high frequency.

On the other hand, in addition to the capacitance between the plates, the sensor also has capacitive contact with the surrounding body (various elements and even the human body). This capacitance is called parasitic capacitance. It not only changes the capacitance of the capacitive sensor, but also the parasitic capacitance is extremely unstable due to the small capacitance of the sensor itself, which also leads to the unstable characteristics of the sensor and serious interference to the sensor.

Distributed capacitances distributed between wires, between coils and casings, and between some elements are called parasitic capacitances. Although their values are small, they are an important cause of interference.