Dual bandpass filter having serial configuration of coupled-line filters

Abstract

Two second-order bandpass filter are connected serially to obtain a dual bandpass filter. One is inductive and the other is capacitive. One has a low passband and the other has a high passband. Between them, a finite transmission zero is formed to suppress noise. The present invention achieves a passband as wide as 1 gigahertz so that it can be applied to a wireless local network, communication equipments and electronic devices.