An improved LC filter for reduction of WWAN noise

A common-mode (CM) filter is usually used to remove CM currents on differential-mode (DM) signal lines [1]. However, in this paper we propose the application of an improved LC filter to reduce EMI noise of DM signal lines. The most important points of applying the LC filter are the consideration of the timing skew and notch points. It has been difficult to find the proper LC filter for DM signal lines, so a new LC filter was developed only for the LCD panel. Three factors are studied for our new LC filter: (1) DC resistance, (2) shape of capacitor, and (3) dielectric constant. Because the LC filter is much cheaper than the CM filter and has advanced properties, the new LC filter is very useful and promising for LCD panels. The new LC filter can be used to reduce EMI of the LCD panel for wireless network systems.