The meaning of large capacitors and small capacitors-magnetic levitation products, because large capacitors are generally large due to their large capacity, and are usually made using multi-layer winding(it should be very experienced to remove aluminum electrolytic capacitors. Untorn can also be taken to see several different capacitors), which leads to a relatively large distributed inductance of large capacitors(also called equivalent series inductors, English abbreviated as ESL). It is known that the impedance of the inductor to the high-frequency signal is very large, so the high-frequency performance of the large capacitor is not good. Some small-capacity capacitors, on the other hand, are just the opposite. Due to the small capacity, the volume can be made very small(shortening the lead, reducing the ESL because a wire can also be seen as an inductor), and often use a flat plate capacitor structure., This small capacity capacitor has a small ESL, so it has a good high-frequency performance, but due to the small capacity, the impedance to the low-frequency signal is large. Therefore, if we want to allow low frequency and high frequency signals to pass well, we use a large capacitor and a small capacitor. The commonly used small capacitor is a 0.1 uF porcelain capacitor. When the frequency is higher, smaller capacitors can also be connected in parallel, such as a few pFs and several hundred pFs. In digital circuits, a 0.1 uF capacitor is generally connected to the power supply of each chip(this capacitor is called a decoupling capacitor, which can also be understood as a power filter capacitor. The closer it is to the chip, the better), because the signals in these places are mainly high-frequency signals, and smaller capacitance filters can be used.
Serial parallel capacity formula for capacitors-parallel partial voltage formula for capacitors
1. Series formula: C = C1 * C2 /(C1 C2)
2. Parallel formula C = C1 C2 C3
Supplementary:
Series partial pressure ratio-V1 = C2 /(C1 C2) * V. .. .. .. .. .. .. .. The larger the capacitance, the smaller the voltage, and the same under AC DC conditions.
Parallel shunt ratio-I1 = C1 /(C1 C2) * I. .. .. .. .. .. .. .. The greater the capacitance, the greater the current, of course, under the condition of AC.
A large capacitor in parallel, a small capacitor.
Due to its large capacity, large capacitors are generally larger in size and are usually made using multi-layer winding. This leads to a relatively large distributed inductance of large capacitors(also called equivalent series inductance, English abbreviated as ESL).
The impedance of the inductor to the high-frequency signal is very large, so the high-frequency performance of the large capacitor is not good. Some small-capacity capacitors, on the other hand, are just the opposite. Due to the small capacity, the volume can be made very small(shortening the lead, reducing the ESL because a wire can also be seen as an inductor), and often use a flat plate capacitor structure., This small capacity capacitor has a small ESL so that it has a good high-frequency performance, but due to the small capacity, the impedance to the low frequency signal is large.
Therefore, if we want to allow low frequency and high frequency signals to pass well, we use a large capacitor and a small capacitor.
The commonly used CBB capacitor with a small capacitance of 0.1 uF is better(porcelain capacitance is also good), and when the frequency is higher, smaller capacitors can also be connected in parallel, such as a few pFs and a few hundred pFs. In digital circuits, a 0.1 uF capacitor is generally connected to the power supply of each chip(this capacitor is called a decoupling capacitor, which can also be understood as a power filter capacitor, the closer the chip is, the better). Because the signals in these places are mainly high-frequency signals, smaller capacitance filters can be used.
The ideal capacitor, whose impedance decreases with frequency(R = 1/jwc), but the ideal capacitor does not exist. Due to the distributed inductance effect of the capacitor pin, the capacitor in the high-frequency segment is no longer a simple capacitor. It should be regarded as a series of high-frequency equivalent circuits of capacitors and inductors. When the frequency is higher than its resonant frequency, the impedance exhibits the characteristics of increasing with the frequency, that is, the inductive characteristic. In this case, the capacitor is like an inductor. Now. In contrast, inductors also have the same characteristics.
Large capacitors are widely used in power source filtering. The fundamental reason lies in the self-resonant characteristics of capacitors. The size capacitance combination can well suppress low-frequency to high-frequency power interference signals, small capacitance filter high frequency(high self-resonant frequency), large capacitance filter low frequency(low self-resonant frequency), the two complement each other.