Dual-band multilayer bandpass filter

A dual-band multilayer bandpass filter having at least one of dual-band transmission frequencies and dual-band reception frequencies, the dual-band multilayer bandpass filter comprising:

• a first filter unit for filtering a first signal having a first frequency, and comprising a plurality of stacked ceramic layers having a strip line resonator and a coupling electrode, and forming a first capacitor at an input side of said first filter unit and a second capacitor at an output side of said first filter unit;
• a second filter unit for filtering a second signal having a second frequency greater than said first frequency, and comprising a plurality of stacked ceramic layers having a strip line resonator and a coupling electrode, and forming a third capacitor at an input side of said second filter unit and a fourth capacitor at an output side of said second filter unit;
• a shield electrode inserted between said first and second filter units;
• said second filter unit stacked under said first filter unit to define a stacked structure;
• a first blocking element coupled to at least one of said first and second capacitors of said first filter unit for blocking said second signal from being applied to said first filter unit;
• and
• a second blocking element that is independent of the first blocking element and is coupled to at least one of said third and fourth capacitors of said second filter unit for blocking said first signal from being applied to said second filter unit.

A dual-band multilayer bandpass filter comprising:

• a first filter unit that filters a first signal having a first frequency, and comprises a plurality of stacked ceramic layers having a strip line resonator and a coupling electrode;
• a second filter unit that filters a second signal having a second frequency that is higher than the first frequency, and that blocks the first frequency, the second filter unit comprising a stacked ceramic layer having open stubs electro-magnetically coupled;
• and
• said second filter unit stacked under said first filter unit to define a stacked structure.

A multilayer bandpass filter comprising:

• a first filter unit that filters a first signal having a first frequency, and comprises a plurality of stacked ceramic layers having a strip line resonator and a coupling electrode;
• a second filter unit that filters a second signal having a second frequency greater than said first frequency, the second filter unit comprising a plurality of stacked ceramic layers having a strip line resonator and a coupling electrode;
• a shield electrode inserted between said first and second filter units;
• said second filter unit stacked under said first filter unit to define a stacked structure;
• a first blocking element coupled to said first filter unit for blocking said second signal from being applied to said first filter unit;
• and
• a second blocking element coupled to said second filter unit for blocking said first signal from being applied to said second filter unit,
• wherein said first blocking element is connected to an input side and an output side of said first filter unit, and wherein said second blocking element is connected to an input side and an output side of said second filter unit, and said first and second blocking elements are connected to each other on the input side, and said first and second blocking elements are connected to each other on the output side to present a one-input one-output dual-band multilayer bandpass filter.

A dual-band multilayer bandpass filter comprising:

• a first filter unit that filters a first signal having a first frequency, and comprises a plurality of stacked ceramic layers having a strip line resonator and a coupling electrode;
• a second filter unit that filters a second signal having a second frequency that is lower than the first frequency and blocks a signal having a frequency larger than the second signal, the second filter comprising a plurality of stacked ceramic layers having open stubs and a strip line constituting a notch filter;
• and
• said first filter unit stacked under said second filter unit to define a stacked structure.