Common Mode Filters
Common mode filter may occur to many people that your electronic equipment buzzes when running. In most cases, it does not seem to affect the device while the noise actually suggests that unwanted signals are interfering with the circuit. To scale down the high-frequency noise and maintain the stability of your electronics, a common mode filter is required. The common mode filter, also common mode choke or inductor, is essentially a toroidal core wrapped with two magnetic coils. In a complete circuit, there are two lines. The current and signal transmit from a source to a load on one line and travel from the load back to the source on the other. In a common model, the current goes in the same direction on both lines. The common-mode noise filter creates an opposing magnetic field to filter the noise.