Multi-layer band-pass filter

A multi-layer band-pass filter comprising:

• an unbalanced input for receiving unbalanced signals;
• a first balanced output and a second balanced output for outputting balanced signals;
• a band-pass filter section provided between the unbalanced input and the first and second balanced outputs and incorporating a plurality of resonators each of which is made up of a TEM line;
• and
• a multi-layer substrate used for integrating the resonators, wherein:
• the band-pass filter section incorporates, as the resonators, a half-wave resonator for balanced output that is made up of a half-wave resonator having open-circuited ends, and quarter-wave resonators for balanced output each of which is made up of a quarter-wave resonator, the quarter-wave resonators for balanced output being provided to form one or more stages each of which consists of a pair of the quarter-wave resonators for balanced output, and being disposed between the half-wave resonator for balanced output and the first and second balanced outputs;
• and
• the first and second balanced outputs are connected to a pair of the quarter-wave resonators for balanced output of a final stage, respectively,
• the multi-layer band-pass filter further comprising a capacitor made up of part of the multi-layer substrate and provided in at least one of a location between the unbalanced input and the resonator connected thereto and a location between each of the first and second balanced outputs and the pair of the quarter-wave resonators of the final stage, wherein:
• the pair of the quarter-wave resonators of the final stage are only provided as the quarter-wave resonators for balanced output;
• one of the pair of the quarter-wave resonators of the final stage is coupled to one of half portions of the half-wave resonator for balanced output;
• and the other one of the pair of the quarter-wave resonators of the final stage is coupled to the other one of the half portions of the half-wave resonator for balanced output, the half portions of the half-wave resonator for balanced output being taken along a length thereof.

A multi-layer band-pass filter comprising:

• an unbalanced input for receiving unbalanced signals;
• a first balanced output and a second balanced output for outputting balanced signals;
• a band-pass filter section provided between the unbalanced input and the first and second balanced outputs and incorporating a plurality of resonators each of which is made up of a TEM line;
• and
• a multi-layer substrate used for integrating the resonators, wherein:
• the band-pass filter section incorporates, as the resonators, a half-wave resonator for balanced output that is made up of a half-wave resonator having open-circuited ends, and quarter-wave resonators for balanced output each of which is made up of a quarter-wave resonator, the quarter-wave resonators for balanced output being provided to form one or more stages each of which consists of a pair of the quarter-wave resonators for balanced output, and being disposed between the half-wave resonator for balanced output and the first and second balanced outputs;
• and
• the first and second balanced outputs are connected to a pair of the quarter-wave resonators for balanced output of a final stage, respectively,
• the multi-layer band-pass filter further comprising a capacitor made up of part of the multi-layer substrate and provided in at least one of a location between the unbalanced input and the resonator connected thereto and a location between each of the first and second balanced outputs and the pair of the quarter-wave resonators of the final stage, wherein:
• a plurality of stages of the quarter-wave resonators for balanced output are provided;
• one of a pair of the quarter-wave resonators of a first stage closest to the half-wave resonator for balanced output is coupled to one of half portions of the half-wave resonator for balanced output;
• and the other one of the pair of the quarter-wave resonators of the first stage is coupled to the other one of the half portions of the half-wave resonator for balanced output, the half portions of the half-wave resonator for balanced output being taken along a length thereof.

A multi-layer band-pass filter comprising:

• an unbalanced input for receiving unbalanced signals;
• a first balanced output and a second balanced output for outputting balanced signals;
• a band-pass filter section provided between the unbalanced input and the first and second balanced outputs and incorporating a plurality of resonators each of which is made up of a TEM line;
• and
• a multi-layer substrate used for integrating the resonators, wherein:
• the band-pass filter section incorporates, as the resonators, a half-wave resonator for balanced output that is made up of a half-wave resonator having open-circuited ends, and quarter-wave resonators for balanced output each of which is made up of a quarter-wave resonator, the quarter-wave resonators for balanced output being provided to form one or more stages each of which consists of a pair of the quarter-wave resonators for balanced output, and being disposed between the half-wave resonator for balanced output and the first and second balanced outputs;
• and
• the first and second balanced outputs are connected to a pair of the quarter-wave resonators for balanced output of a final stage, respectively,
• the multi-layer band-pass filter further comprising a capacitor made up of part of the multi-layer substrate and provided in at least one of a location between the unbalanced input and the resonator connected thereto and a location between each of the first and second balanced outputs and the pair of the quarter-wave resonators of the final stage, wherein the band-pass filter section incorporates at least one half-wave resonator having open-circuited ends, the open-circuited ends being connected to each other through a capacitor.

A multi-layer band-pass filter comprising:

• an unbalanced input for receiving unbalanced signals;
• a first balanced output and a second balanced output for outputting balanced signals;
• a band-pass filter section provided between the unbalanced input and the first and second balanced outputs and incorporating a plurality of resonators each of which is made up of a TEM line;
• and
• a multi-layer substrate used for integrating the resonators, wherein
• the band-pass filter section incorporates, as the resonators, an input resonator to which the unbalanced input is connected, and a half-wave resonator for balanced output to which the first and second balanced outputs are connected, the half-wave resonator for balanced output being made up of a half-wave resonator having open-circuited ends,
• the multi-layer band-pass filter further comprising first and second output capacitors made up of part of the multi-layer substrate and provided between the half-wave resonator for balanced output and the first and second balanced outputs, respectively, wherein:
• the first balanced output is connected through the first output capacitor to an end of a length of the half-wave resonator for balanced output, and the second balanced output is connected through the second output capacitor to the other end of the length of the half-wave resonator for balanced output;
• and
• the first output capacitor and the second output capacitor have different capacitances.

A multi-layer band-pass filter comprising:

• an unbalanced input for receiving unbalanced signals;
• a first balanced output and a second balanced output for outputting balanced signals;
• a band-pass filter section provided between the unbalanced input and the first and second balanced outputs and incorporating a plurality of resonators each of which is made up of a TEM line;
• and
• a multi-layer substrate used for integrating the resonators, wherein
• the band-pass filter section incorporates, as the resonators, an input resonator to which the unbalanced input is connected, and a half-wave resonator for balanced output to which the first and second balanced outputs are connected, the half-wave resonator for balanced output being made up of a half-wave resonator having open-circuited ends,
• the multi-layer band-pass filter further comprising a capacitor made up of part of the multi-layer substrate and provided in at least one of a location between the unbalanced input and the input resonator and a location between each of the first and second balanced outputs and the half-wave resonator for balanced output, wherein
• the band-pass filter section incorporates at least one half-wave resonator having open-circuited ends, the open-circuited ends being connected to each other through a capacitor.