Common mode filter

摘要

To pass an ultra high-speed differential signal and make it difficult to pass a common mode noise. Lamped-constant differential delay line DL is formed by arranging inductors Lo, being passive series elements, and capacitors Co, being passive parallel elements, in a differential four terminal network of a ladder shape composed of the passive series elements and the passive parallel elements arranged in differential lines 1 and 3. The lumped-constant differential delay line DL is composed of capacitors Co including two capacitors Co/2 and Co/2, or Co and Co equivalent to the aforementioned capacitors, having equal values, and connected in series. Inductors L1 to L4 for attenuating a common mode noise are connected between connection points of the capacitors Co/2 and Co/2 or Co and Co connected in series, and a ground potential, so that attenuation poles are formed for attenuating the common mode noise together with the capacitors Co/2 and Co.