Radio-frequency filter comprising an even mode resonance of a same phase inside the bandwidth and an odd mode resonance of a reverse phase outside the bandwidth

A radio-frequency filter comprising:

• a first substrate;
• a second substrate;
• a first resonance element including a first circuit element formed on the first substrate, a second circuit element formed on the second substrate, and a transmission line connecting the first circuit element and the second circuit element, a peak of even mode resonance in which the first circuit element and the second circuit element resonate in a same phase being within a bandwidth of a filter circuit, a peak of odd mode resonance in which the first circuit element and the second circuit element resonate in a reverse phase being outside the bandwidth;
• a second resonance element formed on the first substrate and connected to the first resonance element;
• and
• a third resonance element formed on the second substrate and connected to the first resonance element,
• wherein when a central frequency of the filter circuit is represented as f0, and the bandwidth is represented as BW, an electrical length φ of the transmission line satisfies one of two limitations identified in the following formula 1,
• 0
• <
• ϕ
• <
• 90
• -
• BW
• f
• 0
• ·
• 180
• ,
• ⁢
• 90
• ·
• n
• +
• BW
• f
• 0
• ·
• 180
• <
• ϕ
• <
• 90
• ·
• (
• n
• +
• 1
• )
• -
• BW
• f
• 0
• ·
• 180
• formula
• ⁢
• ⁢
• 1
• (n is a positive integer).

A resonance element for transmitting a radio-frequency signal, comprising:

• a first circuit element group;
• a second circuit element group;
• a first circuit element belongs to the first circuit element group, the first circuit element having resonant property;
• a second circuit element belongs to the second circuit element group, the second circuit element having a first resonant property;
• and
• a transmission line connecting the first circuit element and the second circuit element,
• wherein a peak of even mode a second resonance in which the first circuit element and the second circuit element resonate in a same phase is within a bandwidth of a transmission signal, and a peak of odd mode resonance in which the first circuit element and the second circuit element resonate in a reverse phase is outside the bandwidth, and
• wherein when a central frequency of the transmission signal is represented as f0 and the bandwidth of the transmission signal is represented as BW, an electrical length φ of the transmission line satisfies one of two limitations identified in the following formula 1,
• 0
• <
• ϕ
• <
• 90
• -
• BW
• f
• 0
• ·
• 180
• ,
• ⁢
• 90
• ·
• n
• +
• BW
• f
• 0
• ·
• 180
• <
• ϕ
• <
• 90
• ·
• (
• n
• +
• 1
• )
• -
• BW
• f
• 0
• ·
• 180
• formula
• ⁢
• ⁢
• 1
• (n is a positive integer).