A multiple-band matching network using bypass circuits concept applying on active filter

This paper presents a novel matching method by using bypass circuits in both input and output networks to design a tri-band active filter. Shunting proper bypass circuit can block each operation frequency. Both input and output matching networks are constructed with microstrip line in this tri-band design. The filter in this paper works at 900MHz, 1800MHz, and 2.4GHz. Experimental results show that the individual gain are 17.8dB, 13.6dB, and 10.6dB.