Laminated dielectric filter, and antenna duplexer and communication equipment using the same

• US 6,696,903 B1
• Filed: 08/04/2000
• Issued: 02/24/2004
• Est. Priority Date: 08/05/1999
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Yamada, Toru, Nakakubo, Hideaki, Kushitani, Hiroshi, Kawahara, Emiko
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): Jones, Stephen E.
• Application Number:
  US09/631,744
• Time in Patent Office: 1,299 Days
• Field of Search: 333/204, 333/134, 333/185, 333/219
• US Class Current: 333/134
• CPC Class Codes: H01P 1/20345 Multilayer filters
• CPC Class Codes: H01P 1/2135 using strip line filters H01P1/2131 takes precedence

Abstract

A laminated dielectric filter is formed by coupling a plurality of resonators to one another by electromagnetic-field coupling. In the laminated dielectric filter, a bypass circuit formed of a series circuit including bypass capacitors and transmission lines is provided in parallel to a magnetic-field bypass coupling between non-adjacent resonators. Thus, capacitance of the bypass capacitors can be regulated without being affected by the magnetic-field bypass coupling between the non-adjacent resonators. As a result, attenuation poles outside a passband can be controlled freely.

Claims

1. A filter, comprising a plurality of resonators, the resonators being coupled to one another by electromagnetic-field coupling,

wherein non-adjacent resonators of said plurality of resonators are electrically coupled to each other with a bypass circuit formed of a bypass capacitor and a non-grounded transmission line, the bypass circuit functioning as a capacitive coupling parallel to a magnetic-field bypass coupling between non-adjacent resonators;

wherein adjacent resonators of said plurality of resonators are electrically coupled to each other with a series circuit formed of an inter-stage capacitor and a transmission line, each series circuit functioning as a capacitive coupling parallel to a magnetic-field coupling between the adjacent resonators;

wherein the plurality of resonators and the transmission line are formed inside a dielectric body.

2. A dielectric filter, comprising:

a plurality of resonator electrodes formed of at least three front end short-circuit ¼

wavelength transmission lines;

a plurality of inter-stage coupling capacitor electrodes, each of which has portions opposing respective portions of two adjacent resonator electrodes included in the plurality of resonator electrodes, the plurality of inter-stage coupling capacitor electrodes each functioning as a capacitive coupling parallel to a magnetic-field coupling between the two adjacent resonator electrodes;

a plurality of loading capacitor electrodes having portions opposing portions of the plurality of inter-stage capacitor electrodes, respectively for regulating resonance frequencies of the resonator electrodes; and

a bypass electrode having portions opposing portions of the plurality of inter-stage capacitor electrodes, the bypass electrode functioning as a bypass circuit parallel to a magnetic-field bypass coupling between two non-adjacent resonator electrodes.

3. The dielectric filter according to claim 2, wherein the plurality of resonator electrodes, the plurality of inter-stage coupling capacitor electrodes, the bypass electrode, and the plurality of loading capacitor electrodes are formed between a plurality of shield electrodes, and the plurality of shield electrodes are connected to each other, and then are grounded.

4. The dielectric filter according to claim 2, wherein loading capacitor electrodes of the plurality of loading capacitor electrodes oppose open ends of the plurality of resonator electrodes and are grounded.

5. A dielectric filter, comprising:

a plurality of shield electrodes formed on outer faces of a dielectric body;

a plurality of resonator electrodes formed of at least three front end short-circuit ¼

wavelength transmission lines;

a plurality of first capacitor electrodes, each of which has portions opposing respective portions of two adjacent resonator electrodes included in the plurality of resonator electrodes;

a plurality of second capacitor electrodes having portions opposing portions of the plurality of first capacitor electrodes, respectively; and

a bypass electrode having portions opposing portions of the first capacitor electrodes, the bypass electrode functioning as a bypass circuit parallel to a magnetic-field bypass coupling between two non-adjacent resonator electrodes,

wherein the plurality of resonator electrodes, the plurality of first capacitor electrodes, the bypass electrode, and the plurality of second capacitor electrodes are formed between the plurality of shield electrodes;

wherein the dielectric filter includes a plurality of input/output coupling capacitor electrodes opposing resonator electrodes of the plurality of resonator electrodes on outermost sides, and the plurality of input/output coupling capacitor electrodes are connected to a plurality of side electrodes to form input/output terminals.

6. A laminated dielectric filter, comprising:

a first dielectric layer;

a second dielectric layer;

a third dielectric layer;

a fourth dielectric layer;

a first shield electrode;

a second shield electrode;

at least three resonator electrodes comprising front end short-circuit ¼

wavelength transmission lines;

a plurality of inter-stage coupling capacitor electrodes, each of which is formed of a transmission line having portions opposing respective portions of two adjacent resonator electrodes of said at least three resonator electrodes, the plurality of inter-stage coupling capacitor electrodes each functioning as a capacitive coupling parallel to a magnetic-field coupling between the two adjacent resonator electrodes; and

a non-grounded bypass electrode having portions opposing the plurality of inter-stage coupling capacitor electrode, the non-grounded bypass electrode functioning as a bypass circuit parallel to a magnetic-field bypass coupling between two non-adjacent resonator electrodes,

wherein the first dielectric layer is laminated above the first shield electrode, the resonator electrodes are formed on an upper surface of the first dielectric layer, the second dielectric layer is laminated above the resonator electrodes, the inter-stage coupling capacitor electrodes are formed on an upper surface of the second dielectric layer, the third dielectric layer is laminated above the inter-stage coupling capacitor electrodes, the non-grounded bypass electrode is formed on an upper surface of the third dielectric layer, the fourth dielectric layer is laminated above the non-grounded bypass electrode, and the second shield electrode is positioned on an upper surface of the fourth dielectric layer.

7. The laminated dielectric filter according to claim 6, further comprising loading capacitor electrodes formed of transmission lines opposing open ends of the resonator electrodes, wherein said loading capacitor electrodes are grounded.

8. The laminated dielectric filter according to claim 6, further comprising a plurality of input/output coupling capacitor electrodes opposing the resonator electrodes on outermost sides, wherein the plurality of input/output coupling capacitor electrodes are connected to side electrodes to form input/output terminals.

9. The laminated dielectric filter according to claim 6, wherein the first shield electrode is provided on an upper surface of a fifth dielectric layer.

10. The laminated dielectric filter according to claim 6, further comprising a sixth dielectric layer laminated above the second shield electrode.

11. The laminated dielectric filter according to claim 6, wherein the first shield electrode and the second shield electrode are connected and then are grounded.

12. An antenna duplexer, comprising a dielectric filter including:

a plurality of resonator electrodes formed of at least three front end short-circuit ¼

wavelength transmission lines;

a plurality of inter-stage coupling capacitor electrodes, each of which has portions opposing respective portions of two adjacent resonator electrodes included in the plurality of resonator electrodes, the plurality of inter-stage coupling capacitor each electrodes functioning as a capacitive coupling parallel to a magnetic-field coupling between the two adjacent resonator electrodes;

a plurality of loading capacitor electrodes having portions opposing portions of the plurality of inter-stage coupling capacitor electrodes, respectively for regulating resonance frequencies of the resonator electrodes; and

a bypass electrode having portions opposing portions of the plurality of inter-stage coupling capacitor electrodes, the bypass electrode functioning as a bypass circuit parallel to a magnetic-field bypass coupling between two non-adjacent resonator electrodes,

wherein the dielectric filter is used as one of or both of filters on transmission and reception sides.

13. An antenna duplexer, comprising a laminated dielectric filter including:

a first dielectric layer;

a second dielectric layer;

a third dielectric layer;

a fourth dielectric layer;

a first shield electrode;

a second shield electrode;

at least three resonator electrodes comprising front end short-circuit ¼

wavelength transmission lines;

a plurality of inter-stage coupling capacitor electrodes, each of which is formed of a transmission line having portions opposing respective portions of two adjacent resonator electrodes of said at least three resonator electrodes, the plurality of inter-stage coupling capacitor electrodes each functioning as a capacitive coupling parallel to a magnetic-field coupling between the two adjacent resonator electrodes; and

a non-grounded bypass electrode having portions opposing the plurality of inter-stage coupling capacitor electrodes and not grounded, the non-grounded bypass electrode functioning as a bypass circuit parallel to a magnetic-field bypass coupling between two non-adjacent resonator electrodes,

wherein the first dielectric layer is laminated above the first shield electrode, the resonator electrodes are formed on an upper surface of the first dielectric layer, the second dielectric layer is laminated above the resonator electrodes, the inter-stage coupling capacitor electrodes are formed on an upper surface of the second dielectric layer, the third dielectric layer is laminated above the inter-stage coupling capacitor electrodes, the non-grounded bypass electrode is formed on an upper surface of the third dielectric layer, the fourth dielectric layer is laminated above the non-grounded bypass electrode, and the second shield electrode is positioned on an upper surface of the fourth dielectric layer; and

the laminated dielectric filter is used as one of or both of filters on transmission and reception sides.

14. Communication equipment, comprising a dielectric filter including:

a plurality of resonator electrodes formed of at least three front end short-circuit ¼

wavelength transmission lines;

a plurality of inter-stage coupling capacitor electrodes, each of which has portions opposing respective portions of two adjacent resonator electrodes included in the plurality of resonator electrodes, the plurality of inter-stage coupling capacitor each electrodes functioning as a capacitive coupling parallel to a magnetic-field coupling between the two adjacent resonator electrodes;

a plurality of loading capacitor electrodes having portions opposing portions of the plurality of inter-stage coupling capacitor electrodes, respectively for regulating resonance frequencies of the resonator electrodes; and

a bypass electrode having portions opposing portions of the plurality of inter-stage coupling capacitor electrodes, the bypass electrode functioning as a bypass circuit parallel to a magnetic-field bypass coupling between two non-adjacent resonator electrodes.

15. Communication equipment, comprising a laminated dielectric filter including:

a first dielectric layer;

a second dielectric layer;

a third dielectric layer;

a fourth dielectric layer;

a first shield electrode;

a second shield electrode;

at least three resonator electrodes comprising front end short-circuit ¼

wavelength transmission lines;

a plurality of inter-stage coupling capacitor electrodes, each of which is formed of a transmission line having portions opposing respective portions of two adjacent resonator electrodes of said at least three resonator electrodes, the plurality of inter-stage coupling capacitor electrodes each functioning as a capacitive coupling parallel to a magnetic-field coupling between the two adjacent resonator electrodes; and

a non-grounded bypass electrode having portions opposing the plurality of inter-stage coupling capacitor electrodes and not grounded, the non-grounded bypass electrode functioning as a bypass circuit parallel to a magnetic-field bypass coupling between two non-adjacent resonator electrodes,

wherein the first dielectric layer is laminated above the first shield electrode, the resonator electrodes are formed on an upper surface of the first dielectric layer, the second dielectric layer is laminated above the resonator electrodes, the inter-stage coupling capacitor electrodes are formed on an upper surface of the second dielectric layer, the third dielectric layer is laminated above the inter-stage coupling capacitor electrodes, the non-grounded bypass electrode is formed on an upper surface of the third dielectric layer, the fourth dielectric layer is laminated above the non-grounded bypass electrode, and the second shield electrode is positioned on an upper surface of the fourth dielectric layer.