Patent ID: 8299876

Claim:
A filter for filtering noise generated by a differential signal having a specific wavelength transmitted by a first transmission line and a second transmission line together, the filter comprising: a multi-layer substrate for carrying the first transmission line and the second transmission line; a first microstrip line disposed at the multi-layer substrate, one end of the first microstrip line is electrically connected to the first transmission line through a first via; and a second microstrip line disposed at the multi-layer substrate, one end of the second microstrip line is electrically connected to the second transmission line through a second via; wherein the impedances of the first microstrip line and the second microstrip line match the impedances of the first transmission line and the second transmission line, respectively, the maximum length of the first microstrip line is a quarter of the specific wavelength, and the maximum length of the second microstrip line is a quarter of the specific wavelength.