BAND PASS FILTER

• US 20100007438A1
• Filed: 02/06/2009
• Published: 01/14/2010
• Est. Priority Date: 07/09/2008
• Status: Active Grant

• Current Assignee: Advanced Semiconductor Engineering Inc (ASE Technology Holding Co., Ltd.)
• Original Assignee: Advanced Semiconductor Engineering Inc (ASE Technology Holding Co., Ltd.)
• Inventors: Chiu, Chi-Tsung, Lee, Pao-Nan
• Granted Patent: US 8,502,623 B2
• Time in Patent Office: Days
• US Class Current: 333/176
• CPC Class Codes: H03H 2001/0085 Multilayer, e.g. LTCC, HTCC, green sheets
• CPC Class Codes: H03H 7/0115 comprising only inductors and capacitors H03H7/075, H03H7/09, H03H7/12, H03H7/13 take precedence
• CPC Class Codes: H03H 7/075 Ladder networks, e.g. electric wave filters
• CPC Class Codes: H03H 7/09 Filters comprising mutual inductance
• CPC Class Codes: H03H 7/1708 Comprising bridging elements, i.e. elements in a series path without own reference to ground and spanning branching nodes of another series path H03H7/07 takes precedence
• CPC Class Codes: H03H 7/1766 Parallel LC in series path H03H7/1783 takes precedence
• CPC Class Codes: H03H 7/1775 Parallel LC in shunt or branch path H03H7/1791 takes precedence

Abstract

A band pass filter includes an original circuit. An interaction of at least two of components of the original circuit produces at least a mutual capacitor or at least a mutual inductor, which constitutes a resonance circuit with the original circuit to produce at least a transmission zero for increasing the attenuation rate of the stop band.

Claims

1. A band pass filter, comprising:

a first serial inductor;

a first serial capacitor, with one end electrically connected to one end of the first serial inductor;

a second serial capacitor, with one end electrically connected to the other end of the first serial capacitor;

a second serial inductor, with one end electrically connected to the other end of the second serial capacitor;

a first branch capacitor, with one end electrically connected to the other end of the first serial inductor, and the other end electrically connected to ground;

a second branch capacitor, with one end electrically connected to the other end of the second serial capacitor, and the other end electrically connected to ground;

a central capacitor, with one end electrically connected to the other end of the first serial capacitor, and the other end electrically connected to ground; and

a central inductor, with one end electrically connected to the other end of the first serial capacitor, and the other end electrically connected to ground,

wherein the above elements form an original circuit, and an interaction of at least two of the above elements produces at least a mutual capacitor or at least a mutual inductor, which constitutes a resonance circuit with the original circuit to produce at least a transmission zero.

2. The band pass filter according to claim 1, wherein the mutual capacitor is produced from an interaction between the first serial inductor and the first serial capacitor.

3. The band pass filter according to claim 2, wherein the first serial inductor is a planar coil, and a planar electrode of the first serial capacitor is adjacent to but not coplanar with the first serial inductor.

4. The band pass filter according to claim 3, wherein the planar electrode of the first serial capacitor and the first serial inductor are partially overlapped on a horizontal projection plane.

5. The band pass filter according to claim 2, wherein the first serial inductor is a planar coil, and a planar electrode of the first serial capacitor is adjacent to and substantially coplanar with the first serial inductor.

6. The band pass filter according to claim 1, wherein the mutual capacitor is produced from an interaction between the first serial inductor and the second serial capacitor.

7. The band pass filter according to claim 6, wherein the first serial inductor is a planar coil, and a planar electrode of the second serial capacitor is adjacent to the first serial inductor.

8. The band pass filter according to claim 1, wherein the mutual capacitor is produced from an interaction between the first serial capacitor and the second serial capacitor.

9. The band pass filter according to claim 8, wherein each of the first serial capacitor and the second serial capacitor comprises a multi-finger planar electrode, and the fingers of the multi-finger planar electrodes are staggered at an interval.

10. The band pass filter according to claim 1, wherein the mutual capacitor is produced from an interaction between the first serial inductor and the second serial inductor.

11. The band pass filter according to claim 10, wherein the first serial inductor and the second serial inductor are two planar coils, which are adjacent and substantially coplanar.

12. The band pass filter according to claim 1, wherein the mutual inductor is produced from an interaction between the first serial inductor and the second serial inductor.

13. The band pass filter according to claim 12, wherein the first serial inductor and the second serial inductor are two planar coils, which are adjacent and substantially coplanar.

14. The band pass filter according to claim 1, wherein the first serial inductor and the second serial inductor are two planar coils, and a part of a planar electrode of the first serial capacitor is located between the first serial inductor and the second serial inductor and adjacent to the first serial inductor and the second serial inductor.

15. The band pass filter according to claim 14, wherein the part of the planar electrode of the first serial capacitor is substantially coplanar with the first serial inductor and the second serial inductor.

16. The band pass filter according to claim 1, wherein the first serial inductor and the second serial inductor are two planar coils;

a part of a planar electrode of the first serial capacitor is located between the first serial inductor and the second serial inductor, adjacent to the first serial inductor and the second serial inductor, and substantially coplanar with the first serial inductor and the second serial inductor; and

a part of a planar electrode of the second serial capacitor and the part of the planar electrode of the first serial capacitor are partially overlapped on a horizontal projection plane.

17. The band pass filter according to claim 16, wherein the part of the planar electrode of the first serial capacitor and the part of the planar electrode of the second serial capacitor are totally overlapped on the horizontal projection plane.