Single-Layer Capacitor Development History
The most original capacitor was the lleyton bottle, invented by p. mossberg, of Leiden university in the Netherlands in 1745. It was the prototype of a glass capacitor.In 1874, M. ball invented the mica capacitor.In 1876, England d. Fitzgerald invented the paper capacitor.In 1900, Italian L. Lombardi invented the porcelain dielectric container. In the 1930s, it was found that the addition of titanate in ceramics could double the dielectric constant, thus making a cheaper porcelain capacitor.In 1921, a liquid aluminium electrolytic capacitor was developed, and a dry aluminum electrolytic capacitor with a porous paper impregnated by a porous paper was improved around 1938.Liquid sintered tantalum electrolytic capacitor appeared in 1949 and solid sintered tantalum electrolytic capacitor was made in 1956.After the invention of the transistor in the early 1950s, the components developed in a miniaturized direction.Along with the development of the hybrid integrated circuit, there are small chip capacitors with no leads and other external sticking capacitors.In the 1970s, with the invention of the laser, using capacitors to supply power to laser weapons became the assumption that supercapacitors were born.
In electronic circuits, capacitors are used to block direct current through communication, and are also used to store and release charges to act as filters to smooth out the ripple signals.In general, the capacitance of the above 1 mu F is the electrolytic capacitor, and the capacitance of the less than 1 mu F is mainly porcelain chip capacitance.Large capacitors are often used as filters and storage charges.Small capacitance, usually used in high-frequency circuits, such as radios, transmitters, and oscillators.
With the development of mobile Internet and Internet of things, the wireless data traffic exploding, this business needs vast amounts of data, not only depends on the evolution of the more advanced wireless transmission technology, also need the support of more spectrum.At present, the frequency band used by the mainstream mobile communication system is mainly the VHF/UHF band below 6G. However, these low-frequency bands are now difficult to find the continuously available broadband spectrum resources.Therefore, the spectrum is extended to the high frequency band, and the development of high frequency wireless communication has become an industry trend.
Resonant frequency of the capacitor in high frequency applications, not only with its own parasitic inductance, but also on the PCB via the parasitic inductor, capacitor and other components, such as chip connection wire (including printed wiring) parasitic inductance, etc.In low frequency, these parasitic parameters are small and negligible.The situation is very different when the working frequency is in the rf/microwave range.A metal wire not only has its own resistance and inductance or capacitance, but also a function of frequency.In high frequency circuit, the loss ratio of metal loss is very high, and low loss (ultra low ESR) capacitance is an important consideration in all rf/microwave circuit design.
Because current integrated component technology cannot make capacitors with large capacity, it is very difficult to obtain large capacitance through integrated circuit with existing technology. Used in microwave circuit chip capacitor adopts the temperature coefficient is close to zero and minimal loss of microwave microwave dielectric ceramic as a dielectric layer, this kind of capacitor residual small inductance, high Q value, since the resonant frequency.The capacitance combination with other components in a package, not only realize the multifunction, and saves the PCB area, easy to use, more important is to shorten the distance between the capacitor and the chip, thus parasitic inductance reduces the wiring.The miniaturized monolithic microwave single-layer ceramic dielectric vessel (SLC) shows a good development prospect.