By-pass capacitor is an energy storage device that provides energy to a device. It makes use of the capacitance's frequency impedance characteristic (the ideal capacitance's frequency characteristic decreases with increasing frequency), like a pond, which can make the output voltage output uniform and reduce the load voltage fluctuation.The bypass capacitor should be as close as possible to the pin of the power supply and the pin of the load device, which is the impedance requirement.
Special attention should be paid when drawing A PCB. Only when it is close to a component can it suppress the ground potential elevation and noise caused by excessive voltage or other input signals.To put it bluntly, the AC component of the DC power supply is coupled to the power supply through capacitance, which plays a role in purifying the DC power supply.
The decoupling capacitor takes the interference of the output signal as the filter object. The decoupling capacitor ACTS as a battery, charging and discharging it so that the amplified signal will not be disturbed by the sudden change of current.Its capacity depends on the frequency of the signal and the degree of ripple suppression. The decoupling capacitor plays the role of a "battery" to meet the change of the current of the drive circuit and avoid the coupling interference between each other.
The by-pass capacitor is also decoupled, except that the by-pass capacitor generally refers to the high frequency by-pass, that is, to increase the low impedance leakage path for the high frequency switching noise.The high frequency bypass capacitance is generally small, and 0.1F and 0.01F are generally taken according to the resonant frequency. The capacity of the uncoupled capacitor is generally large, which may be 10F or larger, depending on the distribution parameters in the circuit and the variation of the drive current. The bypass takes the interference in the input signal as the filtering object, while the decoupling takes the interference in the output signal as the filtering object to prevent the interference signal from returning to the power supply.
Post time: Sep-24-2020