The Function of Capacitor(I)

1) Bypass.

By-pass capacitance is a kind of energy storage device which can provide energy for local devices. It can make the output of voltage stabilizer uniform and reduce the load requirement. Like small rechargeable batteries, bypass capacitors can be charged and discharge into the device. To minimize impedance, bypass capacitors should be as close as possible to the power supply pin and the ground pin of the load device. This can prevent the ground potential and noise caused by the input value being too large. The earth bomb is the voltage drop at the ground connection as it passes through a large current burr.

2) removing lotus root.

Go to lotus root, also called lotus root. From the circuit point of view, it is always possible to distinguish between the source of the drive and the load being driven. If the load capacitance is larger, the drive circuit has to charge and discharge the capacitance to complete the jump of the signal. When the rising edge is steep, the current ratio is larger, so the driving current will absorb a very large power supply current. Because the inductance in the circuit, resistor (especially on the chip pin inductance, can produce bounce back, this kind of current is actually a kind of noise relative to the normal condition, can affect the normal operation of the front stage, this is called "coupling".

Decoupling capacitance is to play a "battery" role, to meet the current changes in the drive circuit, to avoid mutual coupling interference. Combining bypass capacitors with decoupling capacitors will make it easier to understand. The bypass capacitance is actually de-coupled, but the bypass capacitance is generally referred to the high-frequency bypass, that is, to improve the high-frequency switching noise a low-impedance leakage way. The high frequency bypass capacitance is generally smaller, generally taking 0.1F, 0.01F and so on according to the resonant frequency, while the capacity of decoupling capacitor is generally larger, which may be 10F or larger, which is determined by the distribution parameters in the circuit and the change of driving current. The bypass takes the interference in the input signal as the filter object, while the decoupling takes the interference of the output signal as the filter object to prevent the interference signal from returning to the power supply. It's supposed to be their essential difference.