The ideal capacitor has a fast charging and discharging speed (close to the speed of light), but in fact, there is so-called dielectric polarization in the capacitor, that is, the dielectric between the electrodes is polarized and leads to the accumulation of charges.
Because the polarization of the medium is slow, there will be a period of delay, so it is often used in high-speed integrating circuits that need to be charged and discharged correctly, which causes errors and leads to circuit action errors.
The tangent of dielectric polarization effect and loss caused by inductance (Ls) and resistance (Rs) of conductor is called dielectric loss tangent (tan δ). The smaller the tangent of dielectric loss angle, the closer to the ideal capacitance. In other words, the smaller the power (i.e. heating value) lost by the capacitor, the better, i.e. DF= energy lost/energy stored.
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Classification of capacitors
(1) There are fixed capacitors, variable capacitors and semi-variable capacitors according to the structure and whether the capacitors are adjustable.
(2) According to different dielectric materials: organic dielectric capacitors (including paint film capacitors, mixed dielectric capacitors, paper dielectric capacitors, organic film dielectric capacitors, paper film composite dielectric capacitors, etc. ) and inorganic dielectric capacitors (including ceramic capacitors, mica capacitors, glass film capacitors, glass glaze capacitors, etc. ).
Electrolytic capacitors (including aluminum electrolytic capacitors, tantalum electrolytic capacitors, niobium electrolytic capacitors, titanium electrolytic capacitors and alloy electrolytic capacitors, etc.). ) and gas dielectric capacitors (including air capacitors, vacuum capacitors and gas-filled capacitors, etc. ).
(3) According to different functions and uses, there are high-frequency capacitors, low-frequency capacitors, high-voltage capacitors, low-voltage capacitors, coupling capacitors, bypass capacitors, filter capacitors, neutralization capacitors and tuning capacitors.
(4) According to the different package shapes, there are cylindrical capacitors, circular capacitors, tubular capacitors, stacked capacitors, rectangular capacitors, bead capacitors, square block capacitors and irregular capacitors.
(5) According to different leads, there are axial lead capacitors, radial lead capacitors, common lead capacitors and leadless (patch) capacitors.
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