Filters are mounted on Note

2012-04-02

On-board filters is not ideal for high frequency filtering effect, but if properly applied, to meet most of the products for civilian electromagnetic compatibility requirements. When used to pay attention to the following:

A "clean"

If you decide to use the on-board filters need to be aware when wiring the cable port, leaving a "clean", filters and connectors are installed in the "clean". By the preceding discussion, we can see the signal line is a very serious interference. Directly to the cable filter capacitor connected to the ground line, can cause serious problems of common-mode radiation. To obtain better filtering effect, you must prepare a clean. And signal ground only at one point to connect the distribution point is called the "bridge", all signal lines from the bridge through to reduce the signal loop area.

2, the filter should be side by side set

All the wires in the cable within the same group is not filtering part - from the filtering part together. Otherwise, the filtering part of another wire in a wire Lei filtering part will re-pollution cable overall filter failure.

3, the filter should be as close as possible to the cable port

Distance of wire between the filter panel should be as short as possible. When necessary, the use of metal plate blocking, isolation of near-field interference.

4, filter and chassis lap

Dry Zheng to install filters with metal chassis and reliable lap up, if the chassis is not metal, set in the bottom of the circuit board of a large metal plate as a filter to. Cleanly and the overlap between the metal chassis to ensure a low RF impedance. If necessary, can use the electromagnetic gasket lap, increasing the overlap area, reducing the RF impedance.

5, filter ground wire to the short

Taking into account the pin inductance effect, its importance has been discussion earlier occupied by the enemy, and pay special attention to the connection structure of the local wiring of the filter and design a circuit board and chassis (metal plate).

6, the filter line and did not filter line grouping

Cable of port filtering and filtering of cable should be kept away to prevent the occurrence of the above coupling problem.