PCB News - Circuit board proofing manufacturer's decoupling filter circuit

In order to reduce the noise coupled through the power system, it is usually necessary to provide decoupling for each circuit or each group of circuits. The use of resistors, capacitors (RC) decoupling filters or inductors, capacitors (LC) decoupling filters can effectively Isolate the circuit from the power supply, eliminate the coupling between the circuits and prevent the noise of the power supply system from entering the circuit. The circuit using RC decoupling filter and LC decoupling filter is shown in Figure 6-1.

For RC filters, because the voltage drop on the resistor will cause the power supply voltage to the circuit to drop, it is usually necessary to consider the effect of the voltage drop on the resistor.

The LC filter can reduce the drop in the power supply voltage caused by the resistance, and in particular can provide better filtering of high-frequency noise. However, it should be noted that for an LC filter, there is a resonant frequency. At this resonant frequency, the high-frequency noise signal transmitted through the filter may be greater than the high-frequency noise signal when the filter is not used. . When designing, it is necessary to ensure that the resonance frequency of the LC filter is outside the passband of the connected circuit. If necessary, add a resistor in series with the inductor to improve damping. The inductor used must always be able to pass the DC current required by the circuit without saturation.

Circuit board proofing manufacturer's decoupling filter circuit

The dotted line capacitance can be added to every part of the circuit, so that the decoupling filter circuit becomes a 71-type filter circuit, which can enhance the filtering of the noise fed back from the circuit to the power supply.

When considering noise reduction, the RC decoupling filter is more effective than the LC decoupling filter. The RC decoupling filter is in the form of an absorption filter, and the noise voltage is converted into heat and dissipated. The LC decoupling filter is a reflective filter. At this time, the noise voltage does not appear on the load, but on the inductance, so that it may be radiated and cause interference to other parts of the circuit, so it may be necessary Use shielding measures to eliminate its radiation.

The above is the circuit introduction of the decoupling filter of the circuit board proofing manufacturer. Ipcb is also provided to the PCB manufacturer and PCB manufacturing technology