# US 2010/0164652 A1 · Filter, communication module, and communication apparatus

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- Number: US 2010/0164652 A1
- Document ID: US20100164652A1
- Status: Published application
- Kind: A1
- Application number: 12/632,098
- Filed: 2009-12-07
- Published: 2010-07-01
- Earliest claimed: 2008-12-25
- Assignees: Fujitsu Limited
- Inventors: Xiaoyu Mi; Satoshi Ueda; Osamu Toyoda
- Web page: https://patentgrep.com/patent/US20100164652A1

## CPC

- H03H 7/0123: {comprising distributed impedance elements together with lumped impedance elements}
- H01P 1/203: Strip line filters
- H01P 1/2135: {using strip line filters (H01P1/2131 takes precedence)}
- H01P 1/2136: {using comb or interdigital filters; using cascaded coaxial cavities (H01P1/2131, H01P1/2135 take precedence)}
- H01P 3/082: {Multilayer dielectric}
- H03H 7/0153: {Electrical filters; Controlling thereof}
- H01P 1/20381: {Special shape resonators}
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)
- H01P: WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE (operating at optical frequencies G02B)

## Abstract

A filter includes a substrate; a signal line formed on the substrate and including an input terminal and an output terminal at either end of the signal line; and a first pair of resonant lines connected between the signal line and a ground portion, wherein the first pair of resonant lines are connected to the signal line at the same point.

## Claims

### Claim 1

A filter comprising:
a substrate;
a signal line formed on the substrate and including an input terminal and an output terminal at either end of the signal line; and
a first pair of resonant lines connected between the signal line and a ground portion, wherein
the first pair of resonant lines are connected to the signal line at a same point.

### Claim 2 (depends on 1)

The filter according to claim 1, further comprising:
a second pair of resonant lines connected between the signal line and the ground portion; and
a coupling section provided between the first pair of resonant lines and the second pair of resonant lines.

### Claim 3 (depends on 2)

The filter according to claim 2, wherein
the coupling section includes:
a first circuit block connected to the signal line and including a first terminal and a second terminal;
a second circuit block connected between the first terminal of the first circuit block and the ground portion; and
a third circuit block connected between the second terminal of the first circuit block and the ground portion.

### Claim 4 (depends on 2)

The filter according to claim 2, wherein
the coupling section includes:
a first circuit block and a second circuit block connected in series to the signal line; and
a third circuit block connected between a point between the first circuit block and the second circuit block, and the ground portion.

### Claim 5 (depends on 1)

The filter according to claim 1, wherein
the resonant lines are connected on opposite sides across the signal line.

### Claim 6 (depends on 1)

The filter according to claim 1, wherein
a length of the resonant line is (λ/8)×n (λ is a resonant wavelength, and n is a positive integer).

### Claim 7 (depends on 2)

The filter according to claim 2, wherein
a characteristic impedance of the resonant line is lower than a characteristic impedance of the signal line.

### Claim 8 (depends on 1)

The filter according to claim 1, wherein
the plurality of resonant lines are connected to the same ground portion.

### Claim 9 (depends on 7)

The filter according to claim 7, wherein
the resonant lines are formed into an arc shape.

### Claim 10 (depends on 1)

The filter according to claim 1, further comprising:
a variable capacitor including a variable capacitor electrode provided above the resonant line via an air gap and a drive electrode for changing distance between the variable capacitor electrode and the resonant line.

### Claim 11 (depends on 1)

The filter according to claim 1, wherein
the substrate is a ceramic substrate including a plurality of laminated internal wirings.

### Claim 12 (depends on 2)

The filter according to claim 2, wherein
the coupling section includes a variable capacitor or variable inductor.

### Claim 13 (depends on 2)

The filter according to claim 2, wherein
an impedance of the resonant line is lower than an impedance of the signal line.

### Claim 14 (depends on 1)

The filter according to claim 1, wherein
an input-output impedance of the filter is about 50Ω.

### Claim 15

A communication module including a filter, wherein
the filter includes:
a substrate;
a signal line formed on the substrate and including an input terminal and an output terminal at either end of the signal line; and
a pair of resonant lines connected between the signal line and a ground portion, wherein
the resonant lines are connected to the signal line at a same point.

### Claim 16

A communication apparatus including a filter, wherein
the filter includes:
a substrate;
a signal line formed on the substrate and including an input terminal and an output terminal at either end of the signal line; and
a pair of resonant lines connected between the signal line and a ground portion, wherein
the resonant lines are connected to the signal line at a same point.